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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