GENOMIC APPROACHES FOR IMPROVEMENT OF DROUGHT ADAPTATION IN WHEAT

Abstract

Breeding for yield stability under water limited conditions plays an essential role in the reduction of economic and social consequences of global climate changes. We show that two exotic drought resistant genotypes (Kobomughi and Plainsmann) differ in root growth rate, root/shoot ratio, and adaptation to low soil water content. These genotypes exhibit characteristic transcript profiles as shown by barley macroarray studies using 10500 unigenes. Reprogramming of gene expression primarily occurred during the 1-2 weeks of water stress, and 6,1% of tested genes were up-regulated in roots of the more adaptive Plainsmann plants. The time course for expression of gene clusters from Kobomughi genotype revealed a prompt and transient gene activation that can help the survival of plants through function of various defense mechanisms. The aldo-keto reductases (AKRs) can detoxify lipid peroxidation products (4-hydroxynon-2-enal) and glycolysis-derived reactive aldehydes (metylglyoxal) that contribute significantly to cellular damages caused by variety of environmental stresses such as drought, high light intensity, UV-B irradiation, cold). Overproduction of AKRs in transgenic tobacco or wheat plants provides considerable stress tolerance and resistance to methylglyoxal. Several transgenic wheat genotypes have been produced with production of elevated level of AKR enzyme. The drought tolerance of these materials was tested by a complex stress diagnostic system, that integrates imaging of plants and monitoring the leaf temperature and fluorescence induction. Based on these parameters, we can conclude that this transgenic strategy that is based on detoxification of lipid aldehyde can result in improved stress adaptation and reduced yield loss.