Unraveling the molecular basis of oxidative stress management in a drought tolerant rice genotype Nagina 22

Abstract

BackgroundDrought stress tolerance for crop improvement is an important goal worldwide. Drought is a complex trait, and it is vital to understand the complex physiological, biochemical, and molecular mechanisms of drought tolerance to tackle it effectively. Osmotic adjustment, oxidative stress management (OSM), and cell membrane stability (CMS) are major components of cellular tolerance under drought stress. In the current study, we explored the molecular basis of OSM in the drought tolerant rice variety, Nagina 22 and compared it with the popular drought sensitive rice variety, IR 64, under drought imposed at the reproductive stage, to understand how the parental polymorphisms correlate with the superiority of Nagina 22 and tolerant bulk populations under drought.ResultsWe generated recombinant inbred lines (RIL) from contrasting parents Nagina 22 and IR 64 and focussed on spikelet fertility (SF), in terms of its correlation with OSM, which is an important component of drought tolerance in Nagina 22. Based on SF under drought stress and its correlations with other yield related traits, we used superoxide dismutase (SOD), glutathione reductase (GR), and ascorbate peroxidase (APX) activity assays to establish the relationship between SF and OSM genes in the tolerant and sensitive lines. Among the OSM enzymes studied, GR had a significant and positive correlation with single plant yield (SPY) under drought stress. GR was also positively correlated with APX but negatively so with SOD. Interestingly, none of the enzyme-morphology correlations were significant under irrigated control (IC). Through genome-wide SNP analysis of the 21 genes encoding for OSM enzymes, we identified the functional polymorphisms between the parents and identified superior alleles. By using network analysis of OSM genes in rice, we identified the genes that are central to the OSM network.ConclusionsFrom the biochemical and morphological data and the SNP analysis, the superiority of Nagina 22 in spikelet fertility under drought stress is because of its superior alleles for SOD (SOD2, SODCC1, SODA) and GR (GRCP2) rather than for APX, for which IR 64 had the superior allele (APX8). Nagina 22 can bypass APX8 by directly interacting with SODA. For nine of the 11 genes present in the central network, Nagina 22 had the superior alleles. We propose that Nagina 22 tolerance could mainly be because of SODA which is a reactive oxygen scavenger in mitochondria which is directly associated with spikelet fertility.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3131-2) contains supplementary material, which is available to authorized users.

Morpho-Physiological and Genetic Responses of Bali Local Rice Cultivars to Drought Stress at Seedling Stage

“…'IR64' has the lowest root to shoot ratio, almost 1/3 of that in 'Putih Cempaka'. 'IR64' has been known as drought sensitive rice cultivar (Prakash et al, 2016). The high root to shoot ratio is to increase water uptake (Xu et al, 2015).…”

Biotechnological Perspective of Reactive Oxygen Species (ROS)-Mediated Stress Tolerance in Plants

“…Genome-wide analysis of genes of GR in rice has shed light on evolutionary conserved domains, which helps in better understanding of its role under normal and stressed conditions (Trivedi et al 2013). Genome-wide SNP analysis of antioxidative genes in rice has revealed functional polymorphism between resistant and susceptible genotypes that can be used to identify superior alleles in rice population studies (Prakash et al 2016). Integration of conventional plant breeding methods, together with advanced genomic tools and phenotyping methods, will rapidly deliver superior breeding material with improved genetic gains.…”

The effects of drought on rice cultivation in sub-Saharan Africa and its mitigation: A review

“…Although, complex traits such as yield are routinely dissected into their component traits namely grain size, test weight and number of productive tillers per plant in rice, sometimes resulting in the development of functional markers, the same is not true in drought stress research (Prakash et al, 2016). Earlier molecular genetic analyses identified several QTLs of secondary traits important to drought tolerance such as root architecture, leaf water status, panicle water potential, osmotic adjustment and relative water content.…”

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