EXPRESSION QUANTITATIVE TRAIT LOCI MAPPING HEAT TOLERANCE DURING REPRODUCTIVE DEVELOPMENT IN WHEAT (TRITICUM AESTIVUM)

摘要

High temperature during reproductive development is a major limitation to wheatproduction and end-use quality in the Southern Great Plains (USA) and to wheatproduction in many environments worldwide. We have initiated a project to integrategenotypic (QTL), phenotypic and transcript level data to identify genes controllingreproductive stage heat tolerance in heat tolerant genotypes of wheat as it relatesto yield and end-use quality maintenance. Efforts have initially focused on buildingrecombinant inbred lines (RILs) and cDNA libraries enriched, through suppressivesubtractive hybridization, for genes induced by heat stress. The selected tissues forlibrary construction included wheat heads and flag leaves isolated from plants subjectedto heat stress 10 days after pollination. A heat tolerant spring wheat cultivar 'Halberd',and a susceptible winter wheat cultivar Cutter were used as models to define the twoadaptive responses to heat stress (heat avoidance (susceptible) and heat tolerance). Over1,920 unique ESTs have been sequenced. These genes include some potential regulatoryproteins, heat shock proteins and lipid-transfer proteins, as well as many novel genesthat may belong to uncharacterized pathways involved in response to heat stress. Forexample, a lipid transfer protein and an alpha amylase inhibitor remained stable duringheat shock in the heat-tolerant cultivar Halberd. These genes were also highly expressedin the most heat tolerant RILs but not in the most susceptible RILs. Expression-QTLmapping results will be presented which link QTLs controlling heat tolerance to theirregulation of discrete sets of the plant transcriptome.