Transcript profiling of stress‐responsive genes and metabolic changes during salinity in indica and japonica rice exhibit distinct varietal difference

Abstract

In the present study, we carried out comprehensive transcriptional profiling of diverse genes under salinity (200 mM NaCl) at different time points, accompanied by certain biochemical alterations of the indica (IR-64 and Pokkali) and japonica (Nipponbare and M-202) rice. The higher susceptibility of Nipponbare and IR-64 was reflected by lower relative water content, chlorophyll loss, higher malondialdehyde content and accumulation of H2 O2 , and reduced nitrate reductase activity, compared to M-202 and Pokkali, where such changes were less pronounced. Enhanced levels of anthocyanins and reduced glutathione, together with elevated phenylalanine ammonia lyase activity, mainly conferred protection to Nipponbare and IR-64, while metabolites like phenolics, flavonoids, proline and polyamines were more induced in M-202 and Pokkali. Varietal differences in the expression pattern of diverse groups of genes to different durations (6, 24 and 48 h) of stress were striking. A gene showing early induction for a particular variety exhibited a delayed induction in another variety or a gradually decreased expression with treatment time. Pokkali was clearly identified as the salt-tolerant genotype among the test varieties based on increased antioxidant potential and enhanced expression of genes encoding for PAL, CHS and membrane transporters like SOS3, NHX-1 and HKT-1. The results presented in this work provide insight into the complex varying regulation patterns for different genes across the investigated rice varieties in providing salt tolerance and highlights distinct differences in expression patterns between susceptible and tolerant indica and japonica rice. This article is protected by copyright. All rights reserved.