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Fig2.Rela%veabundanceofdifferentfungalclasses(A)andgenera(B)iden%fiedfromdifferentfarms.

Background:SorghumisanimportantcropinSouthAfrica,butitisexposedtoavarietyofpathogenicfungithatcausemanydiseasesleadingtosignificantlossesinyieldsandreduc%oninqualityoftheproduct,therebythreateningfoodsecurity.Althoughseveralcontrolmethodsthathavebeenappliedhavebeensuccessful,pathogensadaptandevolvequickly.Preciseknowledgeofthediseasecausalagentsisessen%alforthedevelopmentofeffec%vecountermeasurestofungalinfec%ons.Theaimofthestudywastosurveylocalsorghumfungalpathogensandusemorphologicalandmolecularapproachesforiden%fica%on.Results:Sorghumfungalpathogendiversitywasinves%gatedinelevenproducingregionsinSouthAfricausingaculture-dependenttechnique.Morphologicalcharacteris%csandITS2 sequence data generated from IlluminaMiSeq was used to iden%fy the fungal isolates. A total of 253 fungal isolates were obtained from leaf samples, fromwhichopera%onaltaxonomicunitsbelongingto36generawereiden%fiedasbelongingtoAscomycota(98%)andBasidiomycota(2%)phyla.Fusariumwasthedominantgenera(38.9%rela%veabundanceofthedetectedsequences)followedbyCurvalaria(14.7%)andSarocladium(8.7%).Thediversityandabundanceofdifferenttaxonomicgroupsdifferedwithsamplingloca%ons.

Significance: Studying the fungal pathogens, which cause diseases threatening the produc%on of one of the important crops, sorghum has a significant impact in cropproduc%on.AbeTerunderstandingofthesepathogenswill leadtoeffec%vemanagementandthereforefoodsecurityformanyleavinginpovertyinSouthAfrica.Pathogenscause diseases by producing enzymes that deconstruct the plant cell walls. Their ability to produce hydroly%c enzymes can be exploited for industrial bioconversion. Thediversityofthefungiobtainedinthisstudysuggeststhattheenzymesproducedarecapableofprovidingthediversityandstrengthofac%vityrequiredforbioconversion.Thisstudywillhaveasignificantcontribu%oninfoodsecurityandinenergyproduc%on.

Abstract

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ITS2sequencesclusteredinto220OTUsand95%belongedtoFungi,while the other 5% were either plant or bacterial sequences.Membersof thephylumAscomycotaweredominant inall samples,collec%vely accoun%ng for 98% of the total number of detectedfungalsequences,andBasidiomycotaaccountedfor2%.Ascomycotasequences were largely iden%fied as members of the classesSordariomycetes and Dothideomycetes (57.9% and 34%respec%vely), followed by Euro%omycetes (4.4%), Saccharomyctes(2.2%) and Leo%omycetes (0.4%). Within Basidiomycota phylaAgaricomyceteswasthemostabundantclasswith0.6%,Therela%veabundance of other classes Tremellomycetes, CystobasiomycetesandExobasidiomyceteswas0.2%(Fig.2A).

Furtheranalysisoftheiden%fiedOTUsclassifiedtheminto36generawhich were characterized by the prevalence of Fusarium (38.9%),Curvularia(14.7%)Sarocladium(8.7%),Alternaria(6.9%),Nigrospora(5.4%), Bipolaris (5.3%) and Phoma (4.7%). The representa%on ofotherdetectedgenerawas limitedwith rela%veabundance rangingfrom0.1%-2.4(Fig.2B).

Results

DiscussionResults indicate that a wide variety of fungal taxa inhabit sorghum plants. The high diversity of fungi iden%fied is comparable to themetagenomicstudiesdonepreviouslyandthisresultwasnotexpectedconsideringthelowdiversityofisolatedfungireportedinotherstudies.The abundanceofFusariumwas expected as it has been reported as a natural contaminant in cereals, specificallymaize and sorghum. Thecomposi%on and diversity of fungi varied significantly in the sampling regions and this may be due to the differences in applied farmmanagementmethods.Thediseaseseverityandincidencelevelscorrespondedwiththediversitylevelsanalyzedusingmorphologicalmolecularmethods.

Leafsamplesshowingvaryingdiseasesymptomswereselected(≈14)and isolated from each collec%on site. The disease symptomsincluded circular or elongated lesions, streaks, and veinal/midribbrowning. Leaf lesions were the most observed disease symptomacross all sampling loca%ons while leaf streaks were the leastobserved (Fig. 1). The incidence and prevalence of the diseasesymptomsshowedcorrela%on.

Fungalstrainswereisolatedfromtheleavesandmaintainedonmaltextractagar (MEA)andatotalof853 isolateswererecoveredfromall collec%on sites. They were were grouped according to theirmorphological traits and 318 morphotypes were selected for DNAextrac%on.TheuniversalprimersITS3-ITS4targe%ngtheITS2regionoftheribosomalDNAwereusedand253amplifiedsuccessfullyandweresequencedusingIlluminaMiSeq.

Results

*ZaneleNoqobo1&2,IdanChiyanzu1,JasperRees1andSaneLeMarx21AgriculturalResearchCouncil,BiotechnologyPlaDorm,Onderstepoort,0110,SouthAfrica

2North-WestUniversity,SchoolofChemicalandMineralsEngineering,Potchefstroom,2520,SouthAfrica*Correspondence: noqoboz@arc.agric.za, +27 781613694

Illumina-basedanalysisofsorghumfungalpathogensculRvatedinvitro

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Fig1.Meandiseaseincidence%andseverity%ofobserveddiseasesymptomsonSorghumleaves.TheleafsampleswerecollectedfromfarmsindifferentprovincesofSouthAfrica.

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Acknowledgments:Dr.K.O.Bezuidtforassis%ngwithbioinforma%canalysis,BTP-coreforsequencingandthefarmersforsamples.References: (1) Anjum, et al., (2013) An insight into the basis of resistance in Sorghum bicolor against Colletotrichum sublineolum. African journal of microbiology research,1397-1408. (2)AbdelfaTah,etal.(2016)MetagenomicanalysisoffungalonStrawberryplantsandtheeffectofofmanagementprac%cesonthefungalcommunitystructureofaerialorgans.PlosOne,1-17.