Investigation of the Role of Epicuticular Wax On Heat and Drought Tolerance in Wheat (Triticum aestivum).

Plant epicuticular wax has been shown to have an effect on the ability of plants to withstand heat and drought. In this project, the role of epicuticular wax in maintaining grain yield and quality after a heat shock or drought effect will be analyzed. Both genotypic (SSR) and phenotypic data will be collected in a population of recombinant inbred lines (RILs). Phenotypic data will include yield, grain quality, canopy temperature depression, and leaf wax content. Data analysis will be complimented by Transmission Electron Microscopy (TEM) analysis of leaf tissue from selected lines. Quantitative Trait Loci (QTLs) will be identified based upon a map of 300 SSR markers. The RILs are derived from a cross between heat tolerant line ‘Halberd’ and ‘Len,’ a line with good agronomic characters. The population will be grown under both field and greenhouse conditions. Replicated field trials will be grown at two Texas sites: College Station and Uvalde. Growth conditions at Uvalde are expected to include heat stress. Three replicated greenhouse populations will be grown, each set of replications being treated to either heat, drought, and control conditions. Heat conditions will be simulated by the application of 37?C day 24?C night. The control and drought stress populations will be maintained at 20?C day and 18?C night. The drought stressed population will be maintained at a moisture level of 30% of field capacity. The heat and control populations will be maintained at 80% of field capacity. This project will assist in the development of heat and drought tolerant lines, through the identification of QTLs which may be used in Marker Assisted Selection (MAS). Additionally, a better understanding of the role of epicuticular wax in abiotic stress tolerance may allow the development of new selection criteria for more environmentally stable wheat varieties.