High temperature stress during reproductive development is a major problem to wheat production and end-use quality in the Southern Great Plains and to wheat production in many environments worldwide.  We have initiated a project to integrate genotypic (QTL), phenotypic, and transcript level data to identify genes controlling reproductive stage heat tolerance in heat tolerant genotypes of wheat as it relates to yield and end-use quality maintenance.  Efforts have initially focused on building recombinant inbred lines (RILs), mapping of QTL linked to reproductive stage heat tolerance, and development of cDNA libraries enriched, through suppressive subtractive hybridization, for genes induced by the heat stress.  RILs were derived from a cross between heat tolerant spring wheat cv Halberd, and a susceptible winter wheat cv Cutter or cv Karl92. These parents were used as models to define the two adaptive responses to heat stress (heat avoidance (susceptible) and heat tolerance).  Major QTL controlling the maintenance of kernel weight, kernel number, grain filling duration, and seed abortion following a three-day heat treatment have been mapped, with some QTL being present in both susceptible backgrounds. The selected tissues for library construction included wheat heads and flag leaves isolated from plants subjected to heat stress at 10 days after pollination.  Over 1920 unique ESTs have been sequenced.  These genes include some potential regulatory proteins, heat shock proteins, lipid-transfer proteins as well as many novel genes that may belong to uncharacterized pathways involved in response to heat stress.