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Photosynthetic heat tolerance in wheat: Evidence for genotype-by-environment interactions
  • +9
  • Onoriode Coast,
  • Bradley Posch,
  • Bethany Rognoni,
  • Helen Bramley,
  • Oorbessy Gaju,
  • John MacKenzie,
  • Claire Pickles,
  • Alison Kelly,
  • Meiqin Lu,
  • Yong-Ling Ruan,
  • Richard Trethowan,
  • Owen Atkin
Onoriode Coast
Australian National University

Corresponding Author:[email protected]

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Bradley Posch
Australian National University
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Bethany Rognoni
Queensland Department of Agriculture and Fisheries
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Helen Bramley
The University of Sydney
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Oorbessy Gaju
Australian National University
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John MacKenzie
Australian National University
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Claire Pickles
Birchip Cropping Group
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Alison Kelly
Queensland Department of Agriculture and Fisheries
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Meiqin Lu
Australian Grain Technologies, 12656 Newell Highway Locked Bag 1100 Narrabri NSW 2390
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Yong-Ling Ruan
The University of Newcastle
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Richard Trethowan
The University of Sydney
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Owen Atkin
Australian National University
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Abstract

High temperature stress inhibits wheat photosynthetic processes and threatens wheat production. Photosynthetic heat tolerance (commonly measured as Tcrit – the critical temperature at which incipient damage to photosystem II occurs) in wheat genotypes could be improved by exploiting genetic variation and genotype-by-environment interaction (GEI) for this trait. Flag leaf Tcrit of a total of 54 wheat genotypes were evaluated in 12 thermal environments over three years in Australia using linear mixed models for assessing GEI effects. Nine of the 12 environments had significant genotypic effect and highly variable broad-sense heritability (H2 ranged from 0.15 to 0.75). Tcrit GEI was variable, with 55.6% of the genetic variance across environments accounted for by the factor analytic model. Mean daily growth temperature preceding anthesis was the most influential environmental driver of Tcrit GEI, suggesting varied scales of biochemical, physiological, and structural adaptations to temperature requiring different durations to manifest at the thylakoid membrane and leaf levels. These changes help protect or repair photosystem II upon exposure to heat stress. To support current wheat breeding, we identified genotypes superior to commercial cultivars commonly grown by farmers, and showed that there is potential for developing genotypes with greater photosynthetic heat tolerance.