Physiological Characterization and Differential Gene Expression Analysis in Contrasting Wheat Genotypes under Water Deficit Stress
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Date
2020
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Abstract
The investigation was conducted to carry out morpho-physiological, biochemical and molecular evaluation of two contrasting bread wheat genotypes namely WH 1025 (drought tolerant) and WH 1105 (drought susceptible). Twenty days seedlings were subjected to stress using 15% PEG- 6000. Tolerant WH 1025 and susceptible WH 1105 genotype in non-stressed conditions performed almost in similar way morphologically, physiologically and biochemically but on stress imposition, WH 1025 showed higher activity of antioxidants, showed higher chlorophyll stability index and lower Plasma membrane damage, less impact on shoot & root length and biomass, better seedling vigor, more relative water content and relatively lesser water loss rate and accumulate more osmoprotectants such as proline. Transcriptome analysis of the two contrasting genotypes revealed significant differences in terms of adaptive responses as evident from the gene expression pattern during water deficit condition in early growth period of wheat seedling. At 72 hours of stress a considerably higher number of genes (65,698 out of the total 1,36,770 genes) were expressed in WH 1025 as compared to WH 1105 where the number of gene expressed were less ( 54,195 out of 1,3 6,770 total genes). It also supported the results obtained in morpho-physiological and biochemical investigations. More DEGs were upregulated (204) & less downregulated (10) in WH 1025 whereas less DEG were upregulated (114) & more downregulated (12) in WH 1105. Moreover, Pathway analysis unveiled that out of six major categories mentioned in KEGG pathway Database, DEGs that is found to enrich one was, “Metabolism” pathway. Also, it revealed that the genes and the pathways involved in WH 1025 were the most important factor to make a difference between the genotypes for drought tolerance. In the present study, more up-regulated genes are enriching transcription factors like Trihelix, bHLH, ERF, C2H2, MYB families. C2H2 and MYB were found to be uniquely upregulated in WH 1025 thus, resulted in better drought tolerance and showed adaptability for tolerance. The identified TFs/Genes in the experiment, particularly those which were up-regulated in roots of WH 1025 during drought stress, were potential candidates for enhancing tolerance to drought. This information can be used to improve drought tolerance in elite wheat cultivars and to develop tolerant germplasm for other cereal crops.