Post on 24-Aug-2020
transcript
Heat tolerance QTL in wheat
Nick Collins, University of AdelaideInternational Wheat Genetics Symposium, Tulln, April 2017
Impact of heat waves on wheat yield in southern Australia
Data used from 600 southern-Australian NVTs, 2005-2010
Paul Telfer et al. 2015; AGT
Greenhouse/chamber assays
Our two greenhouse/chamber assays
Waagan x Drysdale heat tolerance QTL
Grain filling tolerance and stay green
Floret fertility tolerance
2B 3B 6B
Ppd-B1
1B 7A
Floret sterility is associated with an absence of starch in mature pollen grains
Drysdale(intolerant)
Waagan(tolerant)
Control Heat
Iodine staining
Dominance of the 2B-QTL (grain set)
a a a a a a
b b
c
b b
c
Family 1 Family 2
2B-QTL genotype:
DW DDWW
Score grain set
DW (heterozygous RIL plant)
Dominance of the 2B-QTL (pollen)
a a a aa
b
Score % starchy pollen
Intolerance may result from a loss of gene function
DW DDWW
Does the 2B-QTL tolerance affect female reproduction?
n=41
n=51
n=64n=61
n=61n=50 n=63
n=24
n=40
Family 1 Family 2 Family 3
2B-QTL genotype:
Emasculate
Apply pollen fromnon-heated plant
Score grain set
DW DDWW
No indication that it does (or at least to the same extent as it does the pollen)
Is the 2B-QTL tolerance the result of gene expression in haploid cells?
Family 1 Family 2
Heterozygote:
Progeny:
heat
DW
DW DD DW DD WW
Determine overall marker allele frequencies
No.Heat-stressing F1 hybrids will not work as a
selection tool for heat tolerance breeding
Mitotic divisions in (haploid) microspores
Image: Borg and Twell, 2011
Meiosis
Mitotic divisions were not affected...
‘Normal’ tri-nucleate pollen (DAPI staining):
Susceptible stage in cv. Drysdale
Early meiosis
Pre meiosis Meiosis Tetrad Early uninucleate
Late uninucleate
Binucleate Trinucleate
(80-90% of final spike length)
Starch accumulation normally begins
Tapetum degradation normally begins
Tolerance is suspected as being the result of gene action in the tapetal cells
Linkage to rust resistance genes (Drysdale x Waagan population)
D W
Yr27Lr23? Heat tolerance
2BSD W
• Rust resistance • Pseudo black chaff• Heat induced seedling chlorosis
Heat tolerance, staygreen
3BS
Sr2
D W
Heat tolerance, staygreen
6BS
No rust resistance?
Fertility toleranceGrain filling tolerance
ARC Industrial Transformation Research Hub forWheat in a Hot and Dry Climate
2016-2020• Univ. Adelaide (ACPFG), Univ. SA, Univ. Sydney• GRDC• AGT, Longreach, InterGrain NILs for heat tolerance QTLs will be field-
trialled under regular rain fed conditions.
Response to heat shock – senescence in the grain
heat
Dry weight per grain (mg)
Senescence gene A
Senescence gene A
Shirdelmoghanloo et al. 2016. Functional Plant Biology 43:919-930Shirdelmoghanloo et al. 2016. Acta Physiol Plant 38:208
Acknowledgements
Nick CollinsHamid ShirdelmoghanlooMillion ErenaMizanur RahmanIman LohrasebSigrid HeuerDiane MatherJulian TaylorSabela Munoz-Santa
Livinus EmebiriPeter Martin