Can Genotypic Variability in Membrane Thermo-Stability and Chlorophyll Fluorescence Be Used to Improve Heat Tolerance in Wheat?.

Improving wheat’s adaptation to higher temperatures would underpin its resilience to climate change in the coming decades, especially at low latitudes where 280 million tons of wheat are produced on over 100 million ha. While genetic gains of wheat yield in hot environments have been achieved, the crop still shows significant productivity losses in warmer than average years. Membranes are known to be disrupted by high temperature impeding many physiological processes including photosynthesis and transport. Both electrolyte leakage (EL) and chlorophyll fluorescence (CF) measure different, though probably overlapping, aspects of membrane thermo-stability, and neither have been systematically deployed in genetic resource screening or breeding. Before that can happen, screening methodologies need to be developed that maximize the resolution for their genetic expression. This study compares expression of EL and CF at different growth stages and in contrasting thermal regimes in order to establish such protocols Both EL and CF were measured on flag leaves at different reproductive stages of wheat Genotypic variability for membrane thermo-stability was estimated in elite sets of Mexican and Iranian  landraces, as well in lines derived from re-synthesized hexaploid wheat and elite lines. Lines encompassing complementary physiological characteristics -including favorable expression of EL and CF- are used as parents for designing strategic crosses to accumulate heat adaptive alleles.