National Seminar“Checkmating evolution of race group 77 of wheat

leaf rust pathogen”

on 14th March, 2010 (Sunday)

Abstracts

Compilation and processing:

J. KumarM.Sivasamy

P.JayaprakashV.K. Vikas

Indian Agricultural Research InstituteRegional Station, Wellington

Distt. Nilgiris, Tamil Nadu643231

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INDEXSESSION 1

S.No. TITLE AND AUTHORS PAGENo.

S1.i Upsurgence of race group 77 of wheat brown rust pathogen inIndia

J.Kumar, M. Sivasamy, P. Jayaprakash, V.K. Vikas and R. Nisha

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S1.ii Leaf rust race 77-complex in India : Evolution and ManagementA.N. Mishra

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S1.iii Leaf rust races in India – an overall account including yield lossesS.C. Bhardwaj, M. Prashar and Y.P. Sharma

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S1.iv Evolutionary Sequence of races in 77 group of leaf rust pathogen— spatial and temporal account

M. Prashar, S.C. Bhardwaj and Y.P. Sharma

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S1.v Impact of brown rust epiphytotics on wheat yield losses in north-west India in the last decade - emphasis on race group 77

Sanjay Kumar & Dharam Pal

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S1.vi Variability mechanisms in wheat rust pathogens – emphasis onrace 77 group of wheat leaf rust pathogen

U. D. Singh,

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S1.viiDominance of 77 group of wheat leaf rust pathotype over the

years:AICW&BIP survey report

I.K. Kalappanavar

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S1.viii Virulence Variation in Race 77 of Puccinia triticina in IndiaR.G.Saini

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S1.ix Influence of resistance genes on evolution of leaf rust races– the Australian experience

J.B.Sharma and Vinod

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SESSION 2S.No. TITLE AND AUTHORS

PAGENo

S2.i Trends of resistance gene deployment for containing leaf rust in IndiaK V Prabhu, J. B. Sharma and Vinod 18

S2.iiIncorporation of known rust resistance genes in Indian wheat cultivars andstocks raised at IARI Wellington and the possible impact on evolution of Leaf

rust pathogenSivasamy.M, Vinod, S.M.S.Tomar Menon.M.K , Jagdish Kumar,Jayaparkash.P and V.K.Vikas

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S2.iiiMolecular marker assisted pyramiding of rust resistance genes to counter

the threat posed by evolution of new virulences in common wheatVinod, M. Sivasamy, J.B. Sharma, Kailash B. Bhawar, Pallavi Sinha, Sushma Tiwari,

B.Singh and S.M.S.Tomar

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S2.iv HS 424: A potential checkmate against biotypes of race 77 of wheat leafrust pathogen in India

Dharam Pal, JK Pallavi, SC Bhardwaj, M Prashar and Sanjay Kumar20

S2.v Dicoccum in ‘Puccinia path’ as genetic barrier against the spread ofPuccinia triticina

Gyanendra Pratap Singh, Sivasamy.M, Jagdish Kumar, Bhakyalakshmi, K and John Peter21

S2.viIntrogression of Agropyron elongatum derived linked gene Lr19 + Sr25 into

some popular Indian bread wheat (Triticum aestivum L.) cultivars andconfirmation through markers

Divya G.G. Sivasamy M., Shailaja D, Senthil N., Raveendran M.22

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SESSION 3

S.No. TITLE AND AUTHORSPAGE

No

S3.i Application of Genome Sequence Information in UnderstandingMolecular Basis of Host –Pathogen Interaction

T.R. Sharma

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S3.iiBio-informatics tools for analysis of pathogenic evolution in plant

pathogens with emphasis on wheat rust pathogensRajender Singh and Ravish Chatrath

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S3.iii Fungal genomics in relation to variability for virulenceN.Senthil, M.Raveendran, M.R Sivasamy and Jagdish Kumar 26

RECOMMENDATIONS29-30

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SESSION 1Race group 77- History, epidemiology, prevalencepatterns, lossess inflicted, virulence/avirulence patterns

(Abstracts S1.i – S1.ix)

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S1.iUpsurgence of race group 77 of wheat brown rust pathogen in India

J.Kumar, M. Sivasamy, P. Jayaprakash, V.K. Vikas and R. NishaIARI, Regional Station, Wellington, the Nilgiris, T.N. - 643231

Brown rust caused by Puccinia triticina is one of the major diseases of wheat in India inflicting a wide range ofyield losses. The pathogen consists approximately 50 known races (pathotypes) prevailing in different agro –ecological wheat growing parts of the country. A special mention is made here on the distribution and theprevalence of race group 77 currently comprising more than a dozen biotypes. Pathotype 77 was originallyidentified in 1954 from Pusa (Bihar) at the time when NP 700 series of wheat cultivars were in the peak cultivationin North West and East Indian states alongwith Northern hills. At that time, races like 10(13R19),20(5R27) and63(0R8-1) used to dominate the Indian wheat fields. The 77 group pathotypes were confined to Nilgiris hills inSouth and Peninsular India till 1980. But afterwards this complex is quite prevalent throughout the country whereit used to be absent or else occurred in minor frequencies. Historical surveys reveal that 77 biotypes aggravatedthe leaf rust problem on widely grown wheat variety Sonalika in late seventies besides others which otherwise,were having field resistance. It is believed that widespread cultivation of Mexican semi-dwarf wheats Kalyansona,Chhotilerma, PV-18 and Sharbati Sonora favoured selection of 77 biotypes as a result biotypes 77A and 77A-1dominated the Indian wheat fields infecting the popular varieties like HD 2329, WL 711, HD 2009 and HD 2009 in thewheat bowl of North West plain zone during eighties. After decline of ruling cultivar HD 2329, a continuous searchwent on for suitable alternative which emerged in the form of Veery cultivars in India. IARI, regional station,Wellington, in addition to extending farm facilities to Indian wheat breeders during normal wheat season in winteralso facilitated growing breeding populations at its farm as off season summer crop. Weather at Wellingtonsituated in Nilgiri hills of Tamil Nadu permits all three rust pathogens of wheat survive throughout the year. At thissite the wheat crop remains in the field throughout the year and rust resistant germplasm including genes not yetused in breeding programs are exposed to the new mutational events. Consequently, the mutational events areselected for virulence on the new genes. A continued host –pathogen contact thus gets established resulting indirectional selection on several major resistance genes particularly available in the breeding progenies of Indianwheat breeders being raised for the purpose of generation advance at Wellington. Such indiscriminate shuttlebreeding at Wellington probably laid foundation for build up of various 77 biotypes which were essentially virulenton gene Lr 26. Mid eighties onwards, the cultivars with Lr26 just took over Indian wheat fields and the glaringexample is PBW 343 which is now ruling not only main wheat bowl of North West plain zone but is equallyspreading in other important zones of North East plain zone, Central zone and Peninsular zone. All these so calledVeery genotypes carrying Lr 26 are now susceptible to either one or combination of 77 pathotypes. Most of the 77variants have been picked up in South hills and national survey reports reveal that the veery cultivars beinggrown in central and Peninsular zones are the worst hit by 77 biotypes. Intriguingly, all the new 77 variants withpathogenicity on Lr26 have also gained additional virulence on other important genes like Lr9, Lr19, and Lr28. Allthese new variants were also initially identified from I.A.R.I. Regional Station, Wellington, Nilgiris, Tamil Nadu.Though the most virulent pathotypes 121R127 (77-7, which is virulent on Lr9) and 377R60 (77-10 that has virulencefor Lr28) are known, however, pathotype 121R63-1(77-5) predominate the Indian wheat brown rust flora atpresent.

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S1.iiLeaf rust race 77-complex in India : Evolution and Management

A.N. MishraIndian Agricultural Research Institute

Regional Station, Indore 452001

Additional variability was observed among 11 Indian pathotypes of leaf rust race 77, namely, 77 (45R31), 77-1(109R63), 77-2 (109R31-1), 77-3 (125R55), 77-4 (125R23-1), 77-5 (121R63-1), 77-6 (121R55-1), 77-7 (121R127), 77-8(253R31), 77A (109R31), and 77A-1 (109R23), when seedling tested with a large number of bread wheat stockscarrying known as well as unidentified genes for leaf rust resistance. Hence, evolution of leaf rust race 77 inIndia appears to be more divergent than that indicated by the currently used leaf rust differentials. Broadeningand diversifying the host resistance base is the need of the hour for checkmating the rapidly changing pathogen.Utilizing unexploited sources of resistance, judicious gene pyramiding and promoting durum wheat cultivation canbe some of the strategies for effective management of leaf rust, particularly race 77-complex. Relativelyunutilized, but highly effective genes like Lr29, Lr32, Lr36, Lr39, Lr40, Lr41, Lr42, Lr43 and Lr45 hold promise forfuture crop improvement. Pyramiding two or more of the genes with “overall resistance” (functional throughoutthe plant life) from among the still largely effective ones like Lr9, Lr19, Lr24, and Lr28, along with the `APR’ (genesexpressed in adult-plant stages) ones such as Lr34, Lr46, Lr48, Lr49 and `LrCPAN 1842’ can contribute to thedurability of resistance. The above mentioned 11 pathotypes of race 77 showed average virulence frequency ofaround 6% (range 2-12%) on durum wheat, compared to around 47% (range 19-92%) on bread wheat, based onseedling tests involving 120 genotypes each of durum and bread wheats. Hence, recently released resistantdurum wheat varieties can serve as “barriers” to the evolution of race 77 by reducing the pathogen populations.Effective resistance sources including the `APR’ ones may be included in differential sets for virulence-monitoring to facilitate pre-emptive breeding for leaf rust resistance.

S1.iiiLeaf rust races in India – an overall account including yield losses

S.C. Bhardwaj, M. Prashar and Y.P. SharmaRegional Station, D.W.R., Flowerdale,

Shimla 171002, H.P.

Leaf rust (Puccinia triticina) is a most widespread disease of wheat in India. Owing to its wider adaptability thepathogen has a potential to always cause some yield loss. Though the disease appears generally in lowproportions, however, loss up to 5% can commonly occur. During the leaf rust epidemic of 1971-72 and 1972-73, itcaused considerable loss of one million ton of wheat in 2.5 million hectares of Punjab, Haryana and Western UttarPradesh. Likewise in 1993, leaf rust of high intensity on HD2285 and HD2329 occurred in 4 million hectares ofNorth Western India which resulted in replacing these varieties with PBW343,WH542 and UP2338.Our estimatesreveal that in favourable years 3-4 million ton can be lost due to leaf rust.Dr. K.C. Mehta pioneered the raceidentification in India during late 1920’s.The first batch of races (11 and 63) is being maintained since 1931.Sincethen more than 50 races/ pathotypes have been reported from India and some of these have completed morethan 1200 generations in the national repository of pathotypes being maintained at our station. At present there

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are 48 races/pathotypes being maintained at the station. It includes 3 pathotypes which are in the process ofdocumentation. During the last 20 years 24 new pathotypes have been reported in P. triticina from India. Duringthese years new system of identification based on 3 sets of differentials including near isogenic lines , was putinto practice by Dr. Nagarajan and colleagues. Many useful resistance genes namely Lr1, Lr 3, Lr 9, Lr 10, Lr 19, Lr23, Lr 26 and Lr 28 have been rendered ineffective. Pathogen has also moved from virulence to few resistancegenes to many genes. Though the most virulent pathotypes 121R127 (77-7, which is virulent on Lr9) and 377R60(77-10 that has virulence for Lr28) are known, however, pathotypes 121R63-1(77-5) and 21R55(104-2) predominate theflora at present. Under the auspices of All India Coordinated Wheat and Barley Improvement Programme, aneffective programme to monitor the incidence of pathogen, pathogenic variability, testing of material forresistance, creation of artificial epiphytotics, characterization of resistance genes in elite wheat material andstrategy for rust management are in place. The success of the programme can be seen from the fact that therewas no major epidemic of wheat rusts during the past 38 years.

S1.ivEvolutionary Sequence of races in 77 group of leaf rust pathogen

— spatial and temporal accountM. Prashar, S.C. Bhardwaj and Y.P. Sharma

DWR, Regional Station, Flowerdale

Of the three wheat rusts, leaf rust continues to be important regularly occurring in most parts of the world. In India, itoccurs every year in all agro-climatic zones. Despite fluctuations in the climate that affect other two rusts, leaf rustcontinues to occur almost unaffected at many places every year. Continuous efforts aimed at introgression ofresistance against this rust have also not really thwarted this pathogen from infecting wheat crop. Remarkably, it hasalways adapted to new resistance in quick time and this feature has been both worrisome and elusive for wheatscientists. Leaf rust in India has evolved along this pathway hence posing a very serious challenge to wheat workers.The 77 group of races have produced more than 10 variants since 1950. Though most of the variants have been pickedup in South hills but few have also been picked up in North hills as well. Aided by wind dispersal these variants arose atone site but became very prevalent over a wide area in a short time. Thus spatial and temporal dynamics of this groupof rust variants has always been very challenging. The first adaptation for Lr10 was followed by Lr13, Lr23, Lr26 andrecent changes were observed on more important resistance genes like Lr9 and Lr28. Though some of these changeslike Lr10, Lr13, Lr26 could be related to the introgressed resistance in the host but others like Lr20, Lr9 and Lr28 weredifficult to relate to host resistance. Most of these pathogenic changes for different genes were observed to beadditive in nature thereby combining large and diverse resistance genes. Though challenge posed by different variantswas addressed in time nonetheless the danger posed by them cannot be undermined as these variants have thepotential to damage wheat yields if not checked from spreading. This challenge was met through picking up thevariants well before their build up through extensive survey and surveillance programme being conducted atFlowerdale, Shimla since 1930. However, unique attributes of this group of races like quick adaptation and occurrenceover a long range of temperature continues to remain an enigma for wheat rust scientists. It is suggested that futureefforts should be targeted to explore the contribution of pathogen genome to these characteristics. Some efforts,though still not conclusive, have been done in few laboratories at the genome level. Such studies would be very usefulnot only for control of leaf rust but may also suggest new frontiers for other rusts and plant diseases.

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S1.vImpact of brown rust epiphytotics on wheat yield losses in North- West India in the last

decade - emphasis on race group 77Sanjay Kumar & Dharam Pal

Indian agricultural Research Institute, Regional StationTutikandi Centre, Shimla 171004

[Email: sanjay_iari@rediffmail.com]India has achieved record wheat production of 80.58 million tonnes during 2008-09 and targeting to achievemore than 79.0 m. tonnes during current season of 2009-10. Though these production figures look quiteimpressive but if we compare last ten years data, productions are quite fluctuating on year to year basis. North-west India which account 40% area and produce around 60% of total wheat, also has same fluctuating trend inproduction. Out of several factors affecting the yield, rusts diseases are of major concern. Brown rust which haslarger potential threat due to more conducive environments throughout the country for its spread and also hasmajor threat in North-west India. Though most of the new genotype carries resistant genes against predominantpathotypes, they succumbed to new evolving pathotypes. All the major genotypes of NWPZ and NHZ (PBW343,PBW373, HD2687, WH542, Raj3765, UP2425, PBW502, HS240, HS295, VL616, VL738 ) which were showing 10-20Sagainst brown rust during 1998-2000 have sccumbed to brown rust with more than 60S score. Pathotypeanalysis showed that almost all the genotypes are susceptible to one or more pathotype of race group 77. Initially77-1 (109R63) and 77-5 (121R63-1) were real culprit to break resistance in most of the genotypes and affectingyield losses. With changing epiphytotic pattern, 77-7(121R127), 77-9(121R60-1) and 77-10(377R60-1) are becomingmore threat to new genotypes and presently we seldom have genotypes having resistance to all these newpathotypes. Even the field samples analyzed during last ten years also reported preponderance of 77 group with36 to 70% occurrence and a single pathotype 77-5 has occurred almost 25 to 65 % in North west India. HS431[INGR08807], a resistant source, showed monogenic recessive control against pathotype 77-5 and this type ofinheritance pattern of resistance is real barrier to develop more and more resistant sources. These reportshave clear indication of sensitivity of 77 group of brown rust pathotypes and more genetic studies are requiredfor newly evolved 77 group pathotypes to check their vulnerability and ultimately loss of wheat yield.

S1.viVariability mechanisms in wheat rust pathogens – emphasis on race 77 group of wheat

leaf rust pathogenU. D. Singh,

Division of Plant Pathology, IARI, New Delhi 110 012

Changes in the pathogen population are due to selection pressure in the host population and potentially virulentpathotypes are maintained in the large asexually reproducing population of the pathogen. In the absence of role ofalternate hosts in India, variation in the rust pathogen may arise by mutation, parasexualism or somaticrecombination. The condition in India is comparable with those of Australia, Kenya and South Africa, wherealternate host is unimportant and a few standard races occur. Pathogenic strains present before the cultivation

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of resistant wheat were wild or primitive. In the last 60 years, pathogen acquired additional virulence genes andevolved strains like 77, 77A, 77A-1 of leaf rust which were most virulent. During 1956-60, P. triticina races 10, 20,77 and 162 predominated and during 1961-65 races 20, 77 and 162 were prevalent. Race 77 produced virulence forgenes Lr3 and Lr20. Cultivars like NP710 and NP809 became susceptible to 77 and 162. During 1966-1980 leaf rustraces 12 and 77 remained prevalent. Cultivation of Sharbati Sonora favoured the selection of races 12, 77 and 104and further Chhotilerma exerted a strong selection pressure on the pathogen and resulted in the dominance ofrace 77 and 77A. Excessive dependence on major genes and release of varieties with vertical resistance indifferent parts of the country enabled the gradual build-up of virulence of predominant leaf rust pathotypes andnow at least 9 pathotypes in race77 have been detected

S1.viiDominance of 77 group of wheat leaf rust pathotype over the years:

AICW&BIP survey reportI.K. Kalappanavar

AICRP on Wheat, MARS, UAS, Dharwad

Wheat is the world’s most important food crop; serve as the prime item in the diet of millions of people. Amongthe major constraints of limiting the wheat production is leaf rust disease, which ranged a vast population ofplants in the past and continued to be important disease till date. Fast evolving Puccinia spp. are always aproblem. Hence, in all the years, rowing survey was taken up by wheat scientists in the wheat growing areas ofdifferent states. Rust affected samples were collected and brought to laboratory. These samples were cut intosmall (3-4”) pieces and pressed overnight in the newspaper. Next day individual samples were taken in smallpaper bags with proper labelling. These samples were sent to Flowerdale, Shimla for rust race identification.During the year 1955 to 1984, virulence of 77, 77A remained prevalent in Northern India (HP, Haryana, Punjab, NewDelhi and UP) whereas 77 group in Tamil Nadu. From 1985 to 1989 pathotypes 77, 77A, 77A-1, 77-1, 77-2 and 77-3were picked up from majority of the samples. During 1990-91, pathotype 77A-1 was most prevalent followed by 77-4, 77-2, 77-4 and 77-1. Pathotype 77A-1 and 77A were most widely distributed. Frequency of pathotype havingmatching virulence for Lr 23 has increased considerately in Nilgiri Hills. In 1991-92 over all pathotype 77-2(109R31-1) was most predominant followed by 77A-1 (109R23) in the country. It was interesting to note that 77-3(125R55) has been isolated from many states after its detection from Tamil Nadu in 1989. During 1992-93 over allpathotype 77-2 (109R31-1) was most predominant and was found in more than 51% samples followed by 77-4(125R23-1), 77A-1 (109R23) and 77A (109R31). Prevalence of pathotype with matching virulence for Lr 23 hasincreased considerately and was found in more than 83% compared to 53% last year. Over all in the countryduring 1993-94 pathotype 77-2 (109R31-1) was most predominant followed by 77-4 (125R23-1) which wereidentified in 29 % and 15% samples respectively. Both these pathotypes are virulent on Lr 23. In Nilgiri Hillspathotype 77-5 (121R63-1) was most predominant and was identified in 80% isolates. This pathotype withcombined virulence for both Lr 23 and Lr 26 , the most frequent resistant genes in Indian Wheats. During 1994-95and 1995-96 pathotype 77-5 (121R63-1) was the most predominant in Nilgiri Hills. In other states namelyMaharashtra, Gujarat, Karnataka, Rajasthan, Bihar, Punjab, Haryana, UP, HP and J.&K., pathotypes 77-2 (109R31-1)and 77-4 (125R23-1) constituted the major proportion of samples. During 1998-99 and 1999-00 brown rustresistant gene Lr 9 became susceptible in India with the detection of new pathotype 77-7 from Nilgiri Hills. Thispathotype was picked from HUW-234, HD-2285 and Sonalika with Lr 9 from IARI, Regional Station, Wellington.Overall in India, pathotype 77-5 (121R63-1) was most predominant in Nilgiri Hills whereas in other statespathotypes 77-2 (109R31-1) along with 77-5 (121R63-1) were the most predominant. In 1999, pathotype 77-5

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(121R63-1) was most frequent and predominant in Tamil Nadu and New Delhi whereas pathotype 77-2 (109R31-1) inBihar and UP. During 2000-01 to 2003-04, pathotypes 77-5 (121R63-1) was more widely distributed in differentstates followed by 77-2 (109R31-1) and 77-4 (125R23-1). Pathotype 77-5 (121R63-1) virulent on both Lr23 and Lr 26,the common resistant genes of Indian wheat material was most frequent in Nilgiri Hills and Maharashtra andKarnataka. In 9 samples from Karnataka and 4 samples from Gujarat the pathotype virulent on Lr 19 wasidentified in 2002-03 as 77-8 (253R31). Lr 19 was so for effective against brown rust in India. Frequency ofpathotype 77-8 (253R31) identified in 2004 having virulence for Lr 19 has increased in Karnataka and wasdetected in 29 samples. This pathotype since then have spread and it was found first time from Maharashtra in 18and Madhya Pradesh in 3 samples. Pathotype 77-5 (121R63-1) was the most wide spread and frequent inChatisgarh, Gujarat, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan and Tamil Nadu accounting for 41.5 % ofthe samples. From 2005-06 to 2008-09 proportion of pathotype 77-8 (253R31) virulent on Lr 19 has increased inKarnataka and Maharashtra. However, 77-5 (121R63-1) was most frequent in most of the states. Pathotype 77-5(121R63-1) was found wide spread in Wellington followed by 77-6 (121R55-1), 77A (109R23), 77-1 (109R63).Pathotype 77-8 (253R31) virulent on Lr 19 was traced in samples from Karnataka, Maharashtra and MadhyaPradesh during 2006-07 also. Two new pathotypes 77-9 and 77-10 (virulent on Lr 28) were identified during theyear (2007-08) from Wellington, Karnataka and Maharashtra.

S1.viiiVirulence Variation in Race 77 of Puccinia triticina in India

R.G.SainiSchool of Agricultural Biotechnology

Punjab Agricultural University,Ludhiana

Race 77 of Puccinia triticina having virulence to Lr genes in all the standard leaf rust differentials and otherknown genes owing their origin to bread wheat was reported from India in 1958. Wheat cultivars being grownduring this period did not have much resistance against most of the prevalent races including the race 77. Overthe years, frequency of race 77 increased in India making it the most frequently identified and virulent race inrace surveys carried out after 2000. Virulence variation within race 77 has been evolving since early sixtiesbecause of brisk breeding effort that increased diversity for Lr genes in cultivars being grown all over thecountry. This variation is detected using supplementary differentials NI5439 (Lr10?), IWP94 (Lr23) and Thew(Lr20). Eleven variants of race 77 have so far been reported with many of them having virulence even on aliengenes Lr9, Lr19, Lr26 and Lr28. Intriguingly, all the new variants having virulence on alien genes Lr9, Lr19, Lr26and Lr28 were initially identified from I.A.R.I. Regional Station, Wellington, Nilgiris, Tamil Nadu. At this site thewheat crop remains in the field throughout the year and rust resistant germplasm including genes not yet used inbreeding programs are exposed to the new mutational events. Consequently, the mutational events are selectedfor virulence on the new genes. In the absence of sexual cycle of reproduction due to non availability of alternatehost Thalictrum speciocissimum in India, all the virulence variation in Puccinia triticina races can only be ascribedto somatic hybridization and spontaneous mutation. Because somatic hybridization will lead to gross changes invirulence spectrum of new variants, new virulence variation in race 77 can not be ascribed to this phenomenon.Also, the acquisition of virulence to new genes in race 77 is often associated with simultaneous loss of virulenceon one or more of the gene (s) carried by supplementary differentials suggesting the role of spontaneousmutations in evolution of virulence in race 77. Recent studies suggest that Puccinia triticina genome is highlyheterozygous, that facilitate fast stepwise mutations from avirulence (Vv) to virulence (vv) and vice-versa ascompared to organisms having homozygous genomes. Therefore, it seems logical to conclude that the clonally

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reproducing race 77 appears to be rapidly evolving through stepwise mutations at virulence loci.Certainly,mutations from avirulence to virulence operating in isolation can not cause immediate breakdown of resistance.However, when mutation is coupled with its directional selection on a resistance gene, virulent mutants increasein frequency rapidly and cause a resistance gene to lose its effectiveness.

S1.ixInfluence of resistance genes on evolution of leaf rust races

– the Australian experienceJ.B.Sharma and Vinod

Division of Genetics, Indian Agricultural Research Institute, New Delhi-110012

Leaf rust occurs in all wheat growing regions of Australia. The wheat growing areas of Australia were divided into fourregions on the basis of differences in climate and wheat cultivars grown viz. Region1: Northern New South Wales andQueensland; Region 2: Southern New South Wales, Victoria and Tasmania; Region3: South Australia and Region4:Western Australia. Historically, leaf rust has been most commonly prevalent in Northern New SouthWales and Queensland where a predominantly summer rainfall provides greater opportunity for the over summering ofinoculum. In Region 2, cool temperatures during the late winter and early spring normally retard disease development.In most years, prevailing dry conditions in central wheat cultivation areas of Region 3 prevented serious out break ofleaf rust. Eastern edge of Region 4 is separated by approximately 1300 km of desert from Region 3 and inoculum isoccasionally exchanged between the two regions.Wheat cultivation in Australia is traced back to 1788 with Europeancolonization where the settlers attempted to grow European cultivars of wheat brought with them. The most convincinghypothesis of origin of wheat rust in Australia is that the rust urediospores got transported along with cereal haybrought with animals to feed them on ships. The first record of wheat rust in Australia is from or near to present dayUniversity of Sydney campus. As the area under wheat cultivars expanded in New South Wales and Victoria after 1850s,the wheat rust became a major problem for wheat cultivation. W.J. Farrer a government surveyor initiated a privatebreeding programme in 1886. The wheat varieties grown till 1860 were probably all of English origin. Farrer introducedwheat from South Africa and India for adaptation and crossed Canadian Fife wheats with early maturing Indian wheatsand Purple Straw and produced more adaptive types including the widely grown Federation (Purple Straw//Improvedfife/Etawah) in 1903.Pathotype analysis did not occur until 1920s, although at that time Lr10 was completely ineffectivebut Lr20 and Lr16 were effective. A large number of early Australian varieties including Federation carried leaf rustresistance gene Lr10. It is possible that Lr10 was effective at the time of Farrer and that might be a reason that thisgene got deployed in large number of varieties and led to the emergence and complete fixation of virulence for Lr10within Puccinia triticina population. Lr20 is present in Thew, another Farrer variety and Lr16 is present in Warden, bredin Victoria in 1900. Until 1946 only two virulent pathotypes were isolated on Thew (Lr20). The utilization of wheatcultivars with genetic resistance to leaf rust began with release of Gabo(Lr23) in 1945, When Gabo increased in areain NSW and Queensland, a new virulent strain on Gabo was detected that spread rapidly. During 1950s Hope (Lr14a)resistance varieties namely Glenwari, Spica, Galand and Lawrence were in cultivation and soon biotype virulent onLr14a was detected. In 1960 Gemenya and Mengavi with resistance gene Lr3 were released and there was a shift inrust flora virulent for Lr3. In 1963, Festiguay (Lr2a) was released and the variation in Gabo virulent pathotype wasobserved on Webster (Lr2a). Further pathogenic variability resulted from cultivation of wheat cultivars like Timgalen(Lr27+Lr31)-1967, Gatcher (Lr27+Lr31) -1968, Songlen and Timson (Lr17)-1975, Warimba (Lr3)-1976, Shortim(Lr1,Lr27+Lr31), Cook (Lr3)-1977, Lance (Lr20)-1978 etc. By contrast, widely grown cultivars Egret and Banks with Lr13remained resistant to all Australian isolates for a longer period and resulted in the evolution of pt. 53-1,(6),(7),10,11 andan avirulent mutant 53-(6),(7),10,11 on Lr20. Cultivars (Dollarbird, Hartog, Lowan, Suneca and Sunfield) with genecombination Lr1+ Lr13 and cultivar Miskle (Lr 2a+ Lr13) were resistant to isolated pathotypes while wheats (Comet,Corella, Lark, Sunstar, Banks, Flinders,Meteor and Vulcan) with only Lr13 were susceptible to both the pathotypes.

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Pt.104-2,3,(6),(7),11 of exotic origin was first detected in Victoria in 1984 and increased in frequency during 1988 to1991 and become the most frequent pathotype in Regions 1,2 and 3. The frequency of its derivative pathotype 104-1,2,3,(6),(7),11 having additional virulence for Lr20 increased more in Region 3 probably because of cultivation ofwheats carrying this gene e.g. Aroona, Lance, Schomburgk and Tatiara. Cultivars Cunningham, Janz, Perouse, Skua,Sunbird, Sunco, Sundor, Sunleg, Torres and Vasco carrying Lr24 were resistant to the pathotypes isolated during theseyears. The first wheat cultivar Torres with leaf rust resistance gene Lr24 was released in Queensland in 1983, sincethen another 27 cultivars with Lr24 were released until 2000, when a virulent isolate of Puccinia triticina(104-1,2,3,(6),(7),11,13) developed from pathotype 104-1,2,3,(6),(7),11 by mutation to virulence for Lr24 . The new pathotypewas first detected in South Australia (October 2000), and then in southern New South Wales (November 2000),Victoria (March 2001), and Queensland (March 2001), suggesting its origin in South Australia and then spreading toeastern parts. Another variant 104-1,2,3,(6),(7),9,11 of Pt. 104-1,2,3,(6),(7),11 having additional virulence for Lr26 wasdetected in 1998 from southern NSW on severe leaf rust infected crop of cv. Tiller(Lr26) in Murrumbidgee IrrigationArea.Comparison of pathotypes of Australia and India revealed that the leaf rust resistance genesLr1,Lr2a,Lr3,Lr10,Lr13,Lr14a,Lr17,Lr20 and Lr27+Lr31 are ineffective in both the countries. Where Lr24 is susceptible inAustralia but it is highly effective in India. In contrast virulence for Lr26 is in high frequency in India but in lowfrequency in Australia. Alien genes Lr9 and Lr19 are resistant in Australia but virulence for them are present in India inlow frequency. Virulence for Lr28 is detected in low frequency in both the countries.

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SESSION 2Race 77 group – Indian efforts on Breeding for host resistance (Genetics of Host/Pathogen interactions,

Victim Lr genes/cultivars, gene deployment

(Abstracts S2.i – S2.vi)

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S2.iTrends of resistance gene deployment for containing leaf rust in India

K V Prabhu, J. B. Sharma and VinodDivision of Genetics

IARI, New Delhi 110012kvinodprabhu@rediffmail.com

Defined as the use of different combination(s) of resistance genes corresponding to the virulence pattern indifferent regions of an epidemiological zone in the pathway of pathogen dispersal and spread aimed to containthe disease spread and minimize the loss in yield, gene deployment has paid rich dividends to wheat rust diseasemanagement strategy in India. Evidence for the success of the programme is the successful prevention ofepidemics of the three rusts in India even though virulenlce have been thrown up by the mutating pathogen everynow and then causing disease infection on the hitherto known resistance sources over the past two decades.With greater insights into the disease resistance genetics enabled through biotech tools and with molecularmarkers, the process of gene pyramiding in already deployed varieties is a distinct possibility keeping rest of thegenetic constitution same. Further, the option available for fast-tracking release and notification of the molecularmarker assisted selection based introgression lines enabled under the Seed Act is a boon to commercialize thetargeted varieties in the targeted zones with two years of testing of the isogenic lines or essentially derived genepyramided lines to endure resistance in the zone where the original variety was already established and adoptedby farmers. The latter has provided a strengthening tool to take full advantage of the gene deployment strategyfor rust management of wheat in India in a collaborative approach among breeders, biotechnologists andpathologists.

S2.iiIncorporation of known rust resistance genes in Indian wheat cultivars and stocks raised

at IARI Wellington and the possible impact on evolution of Leaf rust pathogenSivasamy.M1, Vinod2, S.M.S.Tomar2, Menon.M.K1 , Jagdish Kumar1,Jayaparkash.P1 and V.K.Vikas1

1- Indian Agricultural research Institute, Regional Sation, Wellington- 643 231

2- Division of Genetics, Indian Agricultural research Institute, New Delhi-12

Corresponding Authour email: iariwheatsiva@rediffmail.com

An assessment and exploitation of genetic variation for resistance to Puccinia recondita for stabilizing wheatproduction in India resulted in meticulously planned wheat improvement programme for incorporation ofeffective rust resistance genes, particularly leaf rust resistance genes at IARI, RS, Wellington, during mid-eighties. A strategy for gene deployment along the “Puccinia Path” for managing stem and leaf rusts of wheathas been proposed particularly for exploitation of Lr9, Lr19, Lr24, and Lr34. The diverse oligo-genic alien racespecific rust resistance genes Lr9, Lr19, Lr24, Lr26, Lr28, Lr32, Lr37 which were effective against theoccurring leaf rust pathotypes were deployed in the back-ground of number of popular Indian bread wheat

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cultivars employing conventional back-cross method. The near isogenic lines of Kalyansona, Sonalika, UP232,PBW 226, HD 2329, HD 2285, WH 147, Lok-1, C 306, HD 2402, HD 2009, HI 1077, HS 240, J24, NI 5439, WL 711etc., carrying these genes were constituted with number of BC varying from 6-9. Out of these some of theback-crossed lines were released as commercial cultivars in the country which include Sonak(Sonalika withLr24, Sr24), Amar(C 306 with Lr24+Sr24), WH 711(HD 2329 with Lr24+Sr24), Kurinji(PBW 226 withLr19+Sr25), Kausambi(HD 2402 with Lr19+Sr25), MACS 6145(C 306 with Lr28). Over exploitation and widespread deployment of cultivars carrying Lr26 lead to evolution of new virulent pathotype (77-5) in early 90’s.The cultivation of resistant varieties in a given geographical area is followed by changes in the pathogenpopulation enabling the pathogen to overcome the resistance gene(s) is likely reason for mergence of newvirulent forms. But even before large scale deployment of cultivars in a commercial scale the Aegilopsumbellulata-derived resistance gene Lr9 was knocked out by new pathotype 77-7. The virulent pathotypes forLr19(77-8) and Lr28 (77-9) have already been reported from India. The vertical resistance conferred bythese race specific genes although non-durable in combination with other desirable genes but it is likely togive effective protection against leaf rust. In India the most expoited gene for leaf rust resistance is Lr24 andmost of present day cultivars carry this gene in combinations. The rust resistance gene Lr24 has givenremarkable protection against leaf rust disease in India for the past three decades(no pathotype virulent onLr24 reported from India) could be well attributed to the fact that in combination with Lr34, Lr13, Lr23 andLr14a (which are commonly present in Indian cultivars) the rust resistance gene Lr24 conferred effectivedurable rust resistance. This necessitates a continuous search for effective genes and their efficientdeployment in a geographic area. Hence new diverse rust resistance gene sources like Lr35 (Ae.speltoides),Lr39, Lr42 (Ae.tauschii), Lr44 (Triticum spelta), Lr45 (Secale cereale) and Lr47 (Ae.speltoides), Lr53 andLr57 and its combinations are incorporated in at least 20 varietal back-grounds. The number of back-crosses were limited to only three so as to get advantage of the certain heterosis it received. Employingconventional and MAS approach the genes Lr19, Lr24, Lr28, Lr32 and Lr 37 were already pyramided innumber of popular Indian bread wheat cultivars which are expected to give the durable resistance.Pyramiding of Lr34 and Lr46 with minor, race non-specific APR genes in number of Indian bread wheatcultivars back-ground is now carried out employing MAS which confers horizontal resistance and it isexpected to be durable. With the pathogens displaying a high degree of pathogenic variability, until weunderstand the possible genetic mechanisms associated with frequent arisal of races in not only 77 group ofleaf rust pathogen but also likely emergence of other variants and mechanism of check-matting these it isimportant to evaluate the breeding materials against these potential pathotypes regularly for developing andreleasing of new wheat varieties

S2.iii

Molecular marker assisted pyramiding of rust resistance genes to counter the threat posedby evolution of new virulences in common wheat

Vinod, M. Sivasamy,1 J.B. Sharma, Kailash B. Bhawar, Pallavi Sinha, Sushma Tiwari, B.Singh and S.M.S.TomarDivision of Genetics, Indian Agricultural Research Institute, New Delhi-110012

1IARI Regional Station, Wellington, The Nilgiris, Tamil Nadu

Rust diseases in wheat inflict heavy losses to wheat production. Breeding for rust resistance has been one of themajor aims of wheat breeders worldover. Several methods have been developed and employed to protect the

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damage caused by the rust pathogens. By and large, wheat breeders have been successful in avoiding major rustepidemics in past few decades. Alien genes have played a major role in breeding rust resistant varieties. Howeversome of the alien genes have been knocked down by evolution of new virulent races, necessitating deployment ofnewer effective genes. For some of the major alien leaf rust resistance genes such as Lr9, Lr19 and Lr28 virulentraces 77-7, 77-8 and 77-10 respectively have been reported even before commercial deployment of these genes.Popular commercial cultivars such as PBW 343 and HD2687 which carried Secale linked genes Lr26/Sr31/Yr9became susceptible due to evolution of virulences against both leaf rust resistance gene Lr26 and stripe rustresistance geneYr9. Though stem rust resistance gene Sr31 is still effective in India but virulent races(Ug99 andits variants) may reach India sooner than later. Gene pyramiding is one way of achieving durable resistance andto overcome the threat posed by evolution of new races. The principle of gene pyramiding is based on combiningtwo or more genes conferring resistance to a particular disease in a single plant genotype. Conventionally, genepyramiding can be done if discriminating virulence of pathogens for each gene is available to be pyramided. A fewlinked genes can be pyramided if morphological or cytological markers are available for gene identification butthe method is difficult and laborious. Alternatively use of molecular markers allows plant breeders to keep a trackof resistance gene(s) in segregating populations as well as selection of resistant genotypes even in disease freecondition.In order to mitigate the threat posed by evolution of new races, two popular wheat cultivars, namely,HD2687 and WH147, were selected for marker assisted introgression of rust resistance genes such as Lr19, Lr24,Lr28 and Yr15 in HD2687 and Lr24, Lr28 and Lr37 in WH147 in various combinations. Near isogenic lines carryingYr15(HD2687*5/Yr15 ) were developed by backcross breeding using the molecular marker Xgwm273 for selectionof gene positive plants. Backcross lines of HD2687 carrying Lr28 and Lr24 developed earlier were crossed tocombine the two leaf rust resistance genes. Plants were selected using molecular markers SCS1302 for Lr24 andSCS421 for Lr28 and two gene combination plants were identified which were subsequently crossed with HD2687line carrying stripe rust resistance gene Yr15. In subsequent generations plants carrying various combinations ofgenes such as Lr24+Lr28+Yr15, Lr24+Yr15, Lr28+Yr15, were selected and selfed to identify homozygous lines. Leafrust resistance genes Lr19 and Lr28 were pyramided using backcross lines of HD2687 carrying these genes. In F2

generation from the cross HD2687(Lr19) X HD2687(Lr28), plants were identified carrying Lr19 and Lr28. For thegene Lr19 SSR marker Wmc221 was used for selecting gene positive plants. Background selection was alsopracticed in this case to identify plants closer to HD2687 in genomic constitution. Since virulence is reported forboth Lr19 (77-8) and Lr28 (77-10), the pyramided lines will provide effective resistance against both the races. Forpyramiding of leaf rust resistance genes in variety WH147, near isogenic lines of WH147 carrying leaf rustresistance genes Lr24, Lr28 and Lr37 developed earlier were utilized. Threeway cross was made involving thethree isogenic lines and in F2 generation plants were identified carrying different combinations of genes usingmolecular markers. Plants were selected carrying Lr24+Lr28, Lr24+Lr37, Lr28+Lr37 and Lr24+Lr28+Lr37. Adominant marker VENTRIUP-LN2 linked to gene Lr37 was used to select the plants carrying Lr37. Since markersused for these genes are dominant markers, F3 families were raised to identify homozygous lines. Sincepyramided lines of HD2687 additionally carry stripe rust resistance gene Yr15, it will also provide protectionagainst stripe rust. It is expected that the pyramided lines in the background of HD2687 and HW147 will provideprotection against virulent races which has emerged against some of these genes.

S2.ivHS 424: A potential checkmate against biotypes of race 77 of wheat leaf rust pathogen in

IndiaDharam Pal*, JK Pallavi, SC Bhardwaj, M Prashar and Sanjay Kumar

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* Corresponding author:IARI Regional Station, Cereal Breeding Centre, Tutikandi, Shimla –004

Plant genetic resources are most vital for developing high yielding rust resistant cultivars and orienting breedingstrategies to cope with the threat posed by leaf rust pathogens in wheat improvement. Evolution of new variantsof race 77 of leaf rust has forced breeders and pathologists to identify resistance sources which could be usefulto develop rust resistant wheat varieties. HS 424, developed from a cross CPAN 3004// HPW (DL)30 / HS 286,following pedigree method of breeding was reported to possess gene combination ofLr24+Lr26+Sr2+Sr24+Sr31+Yr9 for rust resistance. It has been phenotyped to carry resistance against differentbiotypes of leaf rust viz., 77, 77-1, 77-2, 77-3, 77-4, 77-5 (most virulent), 77-6, 77-7 at Rust Laboratory, DWR,Flowerdale. The presence of Lr24 in HS 424, imparting leaf rust resistance against 77 group was validated usingSCAR molecular marker SCS1302 607. The 607 bp marker was specifically amplified in the genetic stock known tocarry Lr24. The molecular marker SCS1302 607, showing 607bp band was polymorphic among the carrier and non-carrier genetic stocks, indicating its potential role in marker assisted breeding programmes (Fig.below). HS 424possess light green foliage at boot stage, 105 cm average plant height, parallel ear shape, brown ear colour andmatures in 165 days under northern hills condition. The grains of this stock are amber, soft, ovate shaped and 41gthousand grain weight. Diversification of germplasm involving HS 424 in hybridization would prove useful in wheatimprovement programme of India.

S2.vDicoccum in ‘Puccinia path’ as genetic barrier against the spread of Puccinia triticina

Gyanendra Pratap Singh1, Sivasamy.M2, Jagdish Kumar2, Bhakyalakshmi2, K and John Peter2

1-Division of genetics, Indian Agricultural Research Institute, New Delhi-122-Indian Agricultural Research Institute, Regional Station, Wellington

Triticum turgidum var. dicoccum popularly known as Khapli wheat or Samba wheat is widely and traditionallygrown tetra-ploid wheat in South India. It is much preferred because of its nutritional quality and therapeuticalvalue. The cultivars viz. NP 200, NP 201and NP 202 (tall ones) were released as New Pusa(NP) series from IARI,Regional station, Wellington, in nineteen sixties, which were the selections from Rishi Valley of Andhra Pradesh inIndia. NP 200 still considered as the best national check because of its dicoccum quality. In the recent pastseveral new high yielding semi-dwarf dicoccum wheat varieties were released for cultivation in Peninsular India.Most dicoccum varieties including the varieties released for cultivation in the recent times were all susceptible toyellow rust incidence particularly in Southern hills but, yellow rust is not a problem in Peninsular India. However

SCS1302607

Lr24Fig.1. M- Marker Lane,

1: HS420; 2: FLW13;

3: HS424; 4: FLW20;

5: HS240; 6: HS295

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dicoccum’s are considered to confer high degree of resistance to all the occurring races of Black and Brownrusts. Since sizeable area is under dicoccum cultivation in South Indian States like Tamil Nadu, Karnataka,Maharastra and Andhra Pradesh, diversifying the genetic base and popularizing them will act as genetic barrier ineffectively curtailing the spread of leaf rust from rust focus to Central India and further to Gangetic plains.Efforts were made at IARI and it’s Regional station Wellington to develop semi-dwarf dicoccum by adopting twoapproaches and one by deriving dwarfing gene from the dicoccum wheat stock namely “ Mexican Dwarf “ (MD )-carrying recessive gene for yellow rust resistance and the other by irradiation technique. The MD was crossed tothe tall, yellow rust susceptible cultivars of NP series NP 200, NP 201 and NP 202. Number of elite rust resistantlines were picked at F2 and the stable line were constituted at F8 stage and named as HW 5011, HW 5013, HW 5301,HW 5304, HW 2308 etc. The constituted lines were assessed for its quality and all of them possessed high proteincontent (>12%), sedimentation value(28ml) and Beta carotene(>3.5ppm) which were more than the recurrentparents and produced significantly high yield over the NP series. Secondly for developing high yielding diseaseresistant semi-dwarf dicoccum an attempt was made to use the irradiation technique The gamma irradiation of10(100 Gy), 20(200Gy), 30 (300Gy), 40 (400Gy) Kr γ-rays were given to NP200 and NP 201 tall dicoccum’sat optimal seed moisture level Gray. The Gray (Gy) is the unit of absorbed dose and is 1Joul per kg. The irradiatedseeds were sown as M1 and desirable plants were picked at M2 in 200Gy dose. The stable populations wereconstituted at M4 and named as HW 1095, HW 1096, HW 1097 and HW 1098. Out of these HW 1095 has beenreleased as CoW(SW2) in collaboration with TNAU, Coimbatore as state release and other lines are in differentstages of evaluation in AICW&BIP. The culture HW 1095 recorded a mean grain yield of 4040 kg/ha, which is anincrease of 26 % grain yield over the NP 200 with high protein 13.2%), high sedimentation value (25). Release ofthis Samba/Khapli wheat is likely to give boost to re-introduction of dicoccum wheat in a big way in thetraditional dicoccum belt and cultivation of dicoccum is more remunerative inturn will help resource poorfarmers to earn more, in addition effectively contain the spread of Leaf rust in Peninsular and Central India.

S2.vi

Introgression of Agropyron elongatum derived linked gene Lr19 + Sr25 into some popularIndian bread wheat (Triticum aestivum L.) cultivars and confirmation through markers

Divya G.G.¹, Sivasamy M.², Shailaja D.¹, Senthil N.³, Raveendran M.³¹Kongunadu Arts and Science College, Coimbatore

²Indian Agricultural Research Institute, Regional Station, Wellington, The Nilgiris³Centre for Plant and Molecular Biology, Tamil Nadu Agricultural University, Coimbatore

Leaf rust caused by Puccinia recondita causes about 40% loss in many bread wheat (Triticum aestivum L.)cultivars. Hence development of resistant wheat against this fungus is attempted using Marker Assisted breeding.The crosses were made between resistant donor parent (Wheat ear) and two popular bread wheat varieties whichshowed susceptible symptoms to leaf rust. Crosses were made during the breeding season in the year 2009. TheF1 were back crossed with the popular varieties HD2285 and HD2402, in order to bring the background genome ofpopular varieties along with the resistant gene. From the BC1-F1 plants, DNA was extracted during the seedlingstage and analyzed for Lr19 linked marker. The STS marker shows the presence of resistance allele of 130bp in thecultivar wheat ear and absence of the same in the susceptible parent. The segregation progeny were analyzedusing STS primer and the PCR products were resolved on 2% agarose gel. The marker showed highly repetitivePCR pattern in the repeated experiments, while working with parent and back cross progenies. Hence a total of 30BC1-F1 plants of the cross HD2285 X Wheat ear and 30 BC1-F1 plants of the cross HD2402 X Wheat ear was analyzedby DNA extraction and PCR using the primers GbF and GbR. The results showed that the BC1-F1 plants viz., BC1-F1-

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1,3,4,8,10,17,19 showed the presence of resistant alleles while in plants viz., BC1-F1- 2,5,25 the same was absent,which helps to identify the resistant progeny before the on-start of the infection. The back cross populations wereobserved and the scores recorded during the vegetative stage. Of the total 10 progeny studied, 7 plants showedresistance, while the rest 3 showed susceptible reactions. Susceptible plants showed 10MS-S and the resistantones showed R of leaf rust and stem rust in the cross HD2285 x Wheat ear. Hence the marker is highly useful forscreening the leaf rust resistance at an early stage of a crop and there occurs no need to wait until the infectionstage to identify the resistant plants. This shows that this marker is useful for the large scale screening of leafrust resistance and Lr19 molecular markers are thus validated.

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SESSION 3Race group 77 - Molecular aspects of pathogenicity/ host resistance, bio-informatics of fungalgenomics and host resistance genes

(Abstracts S3.i – S3.iii)

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S3.i

Application of Genome Sequence Information in Understanding Molecular Basis of Host –Pathogen Interaction

T.R. SharmaNational Research Centre on Plant Biotechnology

IARI, Pusa Campus, New Delhi 110012, India

The use of resistance cultivars is very important in any plant disease management programmes. In specializedpathogens a typical gene-for-gene system exists during host-pathogen interactions. This type of interactioninvolves recognition of host resistance (R) gene protein by a pathogen Avirulence (Avr) gene protein whichresults in resistance phenotype. In some host-pathogen systems it has been experimentally proved and validated.Since it is a typical protein-protein interaction, one can use bioinformatics approach to understand the basicmechanism of such interactions. For use of bioinformatics tools in such experiments, both R- and Avr- genesequences should be known. Though it is relatively easy to clone and characterize plant disease resistance genesusing map based cloning approach, the cloning and characterization of pathogen Avr genes is very difficult. Now– a- days many plant and plant pathogen genomes have been fully sequenced and the genome sequence data areavailable in public domain. Therefore, if we know the sequence of a specific R-gene, its counterpart Avr gene canbe identified by in silico protein modelling and protein interactions. Alternatively, if we know the nucleotidesequence of pathogen Avr gene its complementary R-gene can be identified in the plant genome sequence insilico. The protein-protein interaction studies will be presented in the conference by taking a specific example ofa cloned R- gene and complete sequence of the plant pathogen genome. The implication of study in understandinginteraction between rice- Magnaporthe oryzae system will be discussed during presentation.

S3.iiBio-informatics tools for analysis of pathogenic evolution in plant pathogens with

emphasis on wheat rust pathogensRajender Singh and Ravish Chatrath

Directorate of Wheat Research, Karnal 132001

Rusts are a group of obligate biotrotrophic basidiomycete fungi causing severe diseases on many important cropplants. Wheat is host to three different rust fungi, black or stem, brown or leaf, and yellow or stripe rust causingserious losses in wheat harvests. In order to understand plant diseases at molecular level, it will be necessary todefine accurately the pattern of gene expression that is deployed by pathogenic micro-organisms during plantinfection. Studying virulence-associated gene expression can be expected to lead to deeper insights into thedevelopment and physiological programmes that pathogenic microbe use to invade and overcome their hosts, andwill be important for development of effective control strategies. In case of fungal pathogens, draft genomesequences are being generated from several pathogenic species including wheat rust Puccinia graminis f. sp.

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tritici. Recently, expressed sequence tag (EST) database has been developed representing each of several lifecycle stages of P. triticina, and P. graminis. In planta expressed ESTs of P. graminis f. sp. tritici have also beengenerated and available in public domain. Several DNA sequence database resources of plant pathogens areavailable such as Broad Institute (http://www.broadinstitute.org) and National Centre of BiotechnologyInformation (http://www.ncbi.nlm.nih.gov). This vast amount of DNA sequence database can be used to study theevolution of plant pathogens. The EST database has been used to develop microsatellite or simple sequence repeat(SSR) markers using various bioinformatics tools which can be helpful in taxonomic and population geneticstudies. ESTs with similarity to virulence and pathogenicity genes (MAP kinase, serine/threonine-specific proteinphosphatase), detoxification of reactive oxygen species (superoxide dismutase), cell wall synthesis (chitinsynthase) and several other genes involved in host-pathogen interaction have been identified. Sequence variationin these genes can provide insight in pathogen evolution. Different sequence databases and bioinformatics toolsfor sequence analysis will be discussed.

S3.iiiFungal genomics in relation to variability for virulence

N.Senthil, M.Raveendran, M.R Sivsamay and Jagdish KumarCentre for Plant Molecular Biology, Tamil Nadu Agricultual University, Coimbtore-3

IARI Regional Station, Wellington

The genus Puccinia is the largest in the Pucciniales and is considered the most economically destructive generaof biotrophic fungi. Puccinia graminis f. sp. tritici, is the causal agent of wheat and barley stem rust (black rust);P. striiformis f. sp. tritici, wheat stripe rust (yellow rust); P. triticina, wheat leaf rust (brown rust). Cereal rustfungi are well suited to incite serious epidemics because they can produce large numbers of infectious spores(urediniospores) that are adapted for aerial transport and the crops they infect are often grown contiguouslyover large acreages. In 1999, a new highly virulent race TTKSK (Ug99) of P. graminis was identified in Uganda, andsince then has spread, causing a widening epidemic in Kenya and Ethiopia. The genetics, histology and pathology ofhost-rust pathogen interactions have been intensively explored over the last few decades. The molecularmechanisms of compatible and incompatible interactions between the host and pathogen, especially for thewheat- Puccinia triticina system, however, are poorly understood. Successful infection of a host plant by apathogen requires the induction of a subset of pathogen genes that are essential for pathogenicity. Less clear isthe role and expression of specific host genes that may be required for successful pathogen infection of the plant.Identification of both host and pathogen genes induced during a pathogen infection may provide insight into thecompatible host-pathogen interaction at the molecular level. Hence the BROAD institute started the pucciniagenome initiative and has sequenced the genomes of P. graminis f. sp. tritici and P. triticina, and will generatesequence for P. striiformis f. sp. tritici .The complete sequence information of major Puccinia races will givebetter insight into the fungal pathogen variability. The evolution of new races of pathogen will be identified if thegenome sequence of major reference pathogen available and further it will help for the monitoring of pathogenicrace evolution. Screening for differentially expressed genes is one of the most straightforward approaches toreveal the virulence of pathogen against the susceptible host in host-pathogen interaction environment. As adifferential screening method, cDNA-amplified fragment length polymorphism (cDNA-AFLP) is more stringent andreproducible than many other methods because it can amplify low-abundance transcripts. The cDNA-AFLPtechnique is a robust, high-throughput, genome-wide expression tool for gene discovery, where prior knowledgeof sequences is not required. The technique should be especially useful for studying genes of the leaf rustpathogen because the fungus does not have known sexual reproduction and is difficult to culture on an artificialmedium, which have limited the use of the traditional genetic and molecular techniques

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INDIAN AGRICULTURAL RESEARCH INSTITUTE, REGIONAL STATION, WELLINGTON – 634 231 (THENILGIRIS) – T.N.

Seminar on “Checkmating evolution of race group 77 of wheat leaf rust pathogens” on14th March, 2010

(Organising Committees)

Technical Committee:

Chairman : Dr. Jagdish Kumar, Pr. Scientist &HeadCo-chairman : Dr. M. Sivasamy, Sr. ScientistMembers : 1. Dr. P.Jayaprakash, Sr. Scientist

2. Dr. V.K. Vikas, Scientist3. Dr, R. Asir, Technical Officer T7/8

4. Mrs. K. Baghyalakshmi5. Miss. Rebekah Nisha

Accommodation and Transport

Chairman : Dr. M. Sivasamy, Sr. ScientistCo-Chairman : Dr. P.Jayaprakash, Sr. ScientistMembers : 1. Sh.C. Raju, Asst. Admn. Officer

2. Sh. Satya Prakash, T-33. Sh. K. Sivan, T-24. Sh. R. Suresh, T-1

Food committee

Chairman : Dr. M. Sivasamy, Sr. ScientistCo-chairman : Dr. V.K. Vikas, ScientistMembers : 1. Sh. Satya Prakash, T-3

2. K. Sivan, T-23. Sh. K. Paramasivan, SSS4. Miss. O. Gomathi5. Sh. John Peter

Budget Committee

Chairman : Dr. Jagdish Kumar Pr. Scientist &HeadCo- Chairman : Dr. M. Sivasamy, Sr. ScientistMembers : Dr. P.Jayaprakash, Sr. Scientist

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: Dr. R. Asir, Technical Officer T7/8: Sh. C. Raju, Asst. Admn. Officer: Sh. Satya Prakash, T-3 (cashier)

Hall Arrangement :

Chairman : Dr.P. Jayaprakash, Sr. ScientistCo-Chairman : Dr. V.K. Vikas, ScientistMembers : 1. Sh. C. Raju, Asst. Admn. Officer

: 2. Sh. K. Sivan, T-2: 3. Sh. Satya Prakash, T-3: 4. Sh. R. Suresh, T-1: 5. K. Paramasivan, SSS: 6. Mrs. K. Baghyalakshmi: 7. Miss. Shajitha

8. Sh. Arun Kumar

Registration and Reception (Welcome, Bags, Stationery, Kit Mementos, Cultural Programme)

Chairman : Dr. Asir, Technical Officer T7/8Members : 1. Mrs. K. Baghyalakshmi

: 2. Miss. Rebekah Nisha: 3. Sh. John Peter: 4. Miss. O. Gomathi: 5. Miss. Shajitha

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RECOMMENDATIONS

SESSION – I

RACE GROUP 77 – HISTORY, EPIDEMIOLOGY, PREVALENCE PATRTERNS, LOSSES INFLICTED, VIRULENCE /AVIRULENCE PATTERNS.Chairman – Dr.S.Nagarajan, Chairman , PPV&FRA, NAAS Complex, New Delhi

Rapporteur – Dr.I.K.Kalappanavar, Head, Crop Protection,UAS, Dharwad

1. Data resourced from various published reports of ICAR/SAU’s/miscellaneous literature (.books,journals, periodicals etc.) revealed dominance of race 77 group of pathotypes in India 77 races are alsodemonstrated to have evolved the fastest of all brown rust races particularly in post green revolutionera. Group felt that evolution of 77 races must be understood using molecular tools in addition to thatbased upon phenotypes resulting from host-pathogen interactions for elucidating the root causes offrequent variations happening in parental/wild populations.

2. Work on molecular pathotyping of 77 races must be facilitated at identified centres of excellence onwheat rust works such as, DWR Regional Station, Flowerdale, IARI, Regional Station, Wellington, NRCPB,IARI, New Delhi and deptt. of plant molecular biology, TNAU, Coimbatore through external/additionalfunding by ICAR, DBT, other research funding agencies etc.

3. Sample analysis for race identification must be simultaneously undertaken for hilly areas (inoculumsource) and plain areas (rust target areas) and data must be thoroughly examined for devising suitablestrategies of breeding resistant varieties and adequate deployment of rust resistance genes along the“Puccinia path” in the country.

4. Judicious pyramiding of APR genes along with promoting durum wheat cultivation in “Puccinia path”must be given due consideratation for curtailing inoculum transmission to the sensitive and vulnerableareas. Some of the durum varieties like DWR1006, GW1139, MACS2846 and NIDW295 which showresistance to race 77 group must be promoted in central India so that Nilgiri inoculum of 77 races is cutdown from entering northern western parts (wheat bowl) of the country.

5. Steps must be taken to understand inoculum sources existing across the border especially beyondAfghanistan so that appropriate strategies are devised for an effective gene deployment in Indiansubcontinent.

6. Some of 77 races are reported first time from Karnataka could not be correlated with existing Nilgiriflora. Studies must be intensified to understand the spatial origin of such races. The unknown sourcewhere emergence and evolution of brown rust races is expected to take place in south India exceptNilgiri and Palni hills must be investigated at war footing.

7. Studies must be initiated to understand mechanism of race variability such as somaticrecombinations/hybridization and reverse mutations.

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8. Mechanism of fitness for survival adopted by new variants most also be explicitely investigated in theIndian context for the purpose of devising suitable gene deployment strategies.

9. For understanding molecular basis of virulence diversity in races of race group 77, literature support ofdiversity aspects in mushroom fungi which are very close relatives of wheat rust fungi inbasidiomycetes must be brought into use.

SESSION-II

RACE 77 GROUP – INDIAN EFFORTS ON BREEDING FOR HOST RESISTANCE (GENETICS OF HOST/PATHOGENINTERACTIONS, VICTIM LR GENES/CULTIVARS, GENE DEPLOYMENT

Chairman - Dr.K.V. Prabhu, Divn. Of Genetics, IARI, New DelhiRapporteur - Dr.Sanjay Kumar, Head, IARI Wheat Breeding Station, TutiKandi, Shimla

1. Backcross programme and MAS should be immediately started for new varieties just after release.2. A marker bank for wheat should be created.3. For lines with partial resistance, 40MS-S should be acceptable to promote genotypes under co-

ordinated system.4. Effective gene should be used in combination with partial effective gene.5. Targetted and focused pre-breeding programme should be started.6. As per CIMMYT experience slow rusting lines should be given importance in crossing programme for

durable resistance followed by single backcross selective bulk method.

SESSION-III

RACE GROUP 77 - MOLECULAR ASPECTS OF PATHOGENICITY/ HOST RESISTANCE, BIOINFORMATICS OFFUNGAL GENOMICS AND HOST RESISTANCE GENES

Chairman- Dr. T.R. Sharma, Principal Scientist, NRCPB, New DelhiRapporteur- Dr. R.S. Khokhar, Sr. Scientist (Biotechnology), DWR, Karnal

1. Bioinformatic facilities should be created/enhanced in the laboratories of excellence in rust work suchas DWR Regional Station, Flowerdale, IARI, Regional Station, Wellington, NRCPB, IARI, New Delhi and deptt.of plant molecular biology, TNAU, Coimbatore through external/additional funding by ICAR, DBT, otherresearch funding agencies etc.

2. The genomic database of Puccinia should be used for diversity analysis.3. Host- pathogen interactions should be studied at molecular level in the line of gene for gene and protein

for protein hypotheses employing the concepts of pathogen virulence/avirulence as elicitors and hostresistance genes as receptors.

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Registration counter of the seminar

Delegates participated in the seminar