Correlations Between Some Selected Genes Expressed Under High Temperature Stress and Phenotypic Traits Associated with Heat Stress Tolerance in Wheat.

Correlation between some selected genes expressed under high temperature stress and phenotypic traits associated with heat stress tolerance in wheat

 M.A. Babar, J.P. Fellers, A.K. Fritz,

 

Heat tolerance is a multiple gene controlling trait and genetic control could be attributed to different sets of good alleles in different individuals. Real-time PCR can compare mRNA levels of a gene of interest between different experimental conditions, and thus can confirm expression level of that gene. Association between expressed genes at the mRNA level and phenotypic characters can farther help to indentify genes to be associated with heat tolerance and could be used in the breeding programs for genetic gain. The objectives of the present research were to study the correlation between the expression of selected genes potentially related to heat tolerance and cell membrane damage, thylakoid membrane damage and chlorophyll content under long-tern high temperature stress. A subset of 14 ESTs were selected from microarray experiments to confirm their expression by using real-time PCR after 4, 7  and 10 days of post anthesis heat stress and correlate the expression of those genes with three phenotypic traits. The correlation analysis revealed a very strong and significant correlation between all three traits related to heat tolerance and the expression level of rubisco activase, inisitol-triphosphate 3-kinase, and RNA binding protein. Three genes expressed higher in the tolerant lines were not significantly correlated with those three traits, but leucine rich repeat family protein and zinc finger protein showed a positive trend of association with thylakoid membrane damage and chlorophyll content, and a negative trend of association with plasmamembrane damage. In general, all three traits showed significant but negative correlations with pheophorbide a oxygenase, cynteine-type endopeptidase, cysteine protease, and 4-aminobutyrate aminotransferase. There were negative but non-significant correlation between those three traits and taumatin-like protein and selenium-binding protein. Abscisic acid inducible protein kinase showed significant association with chlorophyll content , but not with other traits. The data indicated that the expression of some of these genes could be due to genetic variation created by heat stress and are candidate for further study to identify expression quantitative trait loci (eQTLs) for heat tolerance.