Comparative analysis of drought‐responsive transcriptome in Indica rice genotypes with contrasting drought tolerance

摘要

Summary Genetic improvement in drought tolerance in rice is the key to save water for sustainable agriculture. Drought tolerance is a complex trait and involves interplay of a vast array of genes. Several genotypes of rice have evolved features that impart tolerance to drought and other abiotic stresses. Comparative analysis of drought stress-responsive transcriptome between drought-tolerant (DT) landraces/genotypes and drought-sensitive modern rice cultivars will unravel novel genetic regulatory mechanisms involved in stress tolerance. Here, we report transcriptome analysis in a highly DT rice landrace, Nagina 22 (N22), versus a high-yielding but drought-susceptible rice variety IR64. Both genotypes exhibited a diverse global transcriptional response under normal and drought conditions. Gene ontology (GO) analysis suggested that drought tolerance of N22 was attributable to the enhanced expression of several enzyme-encoding genes. Drought susceptibility of IR64 was attributable to significant down-regulation of regulatory components that confer drought tolerance. Pathway analysis unravelled significant up-regulation of several components of carbon fixation, glycolysis/gluconeogenesis and flavonoid biosynthesis and down-regulation of starch and sucrose metabolism in both the cultivars under drought. However, significant up-regulation of α - linolenic acid metabolic pathway observed in N22 under drought appears to be in good agreement with high drought tolerance of this genotype. Consensus cis -motif profiling of drought-induced co-expressed genes led to the identification of novel cis -motifs. Taken together, the results of the comparative transcriptome analysis led to the identification of specific genotype-dependent genes responsible for drought tolerance in the rice landrace N22.