Transcriptomic, physio-morphological and biochemical analyses of drought stress response in bread wheat Triticum aestivum L

Abstract

Drought is one of the greatest hazards to the sustainable production of wheat (Triticum aestivum L.), one of the world’s most vital staple foods. Screening of drought-tolerant wheat cultivars is a major priority for breeding programmes. Ten wheat varieties were subjected, at the maturity and seedling stages, to drought conditions of 50% and 25% water field capacity (WFC), respectively. Selection for drought tolerant cultivars was based on a comparative study of the physio-morphological and biochemical traits of the aerial tissues of the samples under drought and optimal conditions (100-85 WFC%). The results showed that the Atlas and ICARDA32331 cultivars were the most sensitive and tolerant genotypes, respectively. These cultivars were subjected to transcriptomic analysis which revealed that they shared 5068 differentially expressed genes (DEGs) and distinguish ICARDA32331 from Atlas cultivars by 8676 and 10284 DEGs, respectively. Gene ontology terms for ICARDA32331 were mainly related to lipid and cell wall metabolism, results coherent with the significant enrichment of fatty acid elongation, cutin, suberine and wax biosynthesis pathway, unlike the Atlas. The latter cultivar showed an enrichment in down-regulated DEGs, mainly associated with photosynthesis and chloroplast organisation. The cultivars ICARDA32331 and Atlas had an over expression of DEGs associated with dehydrin and proline biosynthesis, indicating that they had undergone osmotic adjustment to adapt to drought. A high number of SNPs and InDels were found in this transcriptomic study, which is a consequence of the genetic diversity of the chosen wheat cultivars. This study highlights the role of lipid metabolism and nitric oxide gene in drought tolerance and provides new molecular factors that can be targeted for the drought tolerance breeding programme.