Raising salinity tolerant rice: recent progress and future perspectives

Abstract

With the rapid growth in population consuming rice as staple food and the deteriorating soil and water quality around the globe, there is an urgent need to understand the response of this important crop towards these environmental abuses. With the ultimate goal to raise rice plant with better suitability towards rapidly changing environmental inputs, intensive efforts are on worldwide employing physiological, biochemical and molecular tools to perform this task. In this regard, efforts of plant breeders need to be duly acknowledged as several salinity tolerant varieties have reached the farmers field. Parallel efforts from molecular biologists have yielded relevant knowledge related to perturbations in gene expression and proteins during stress. Employing transgenic technology, functional validation of various target genes involved in diverse processes such as signaling, transcription, ion homeostasis, antioxidant defense etc for enhanced salinity stress tolerance has been attempted in various model systems and some of them have been extended to crop plant rice too. However, the fact remains that these transgenic plants showing improved performance towards salinity stress are yet to move from 'lab to the land'. Pondering this, we propose that future efforts should be channelized more towards multigene engineering that may enable the taming of this multigene controlled trait. Recent technological achievements such as the whole genome sequencing of rice is leading to a shift from single gene based studies to genome wide analysis that may prove to be a boon in re-defining salt stress responsive targets.

Leaf expansion in grasses under salt stress

“…Genomic and proteomic analyses of salt stress responses in rice have been the subject of multiple research efforts, which have been reviewed by Grennan (2006), Parker et al (2006), Sahi et al (2006), and Singh et al (2008), among others. Singh et al (2008) have summarized transgenic attempts to increase salt tolerance in this species.…”

“…Genomic and proteomic analyses of salt stress responses in rice have been the subject of multiple research efforts, which have been reviewed by Grennan (2006), Parker et al (2006), Sahi et al (2006), and Singh et al (2008), among others. Singh et al (2008) have summarized transgenic attempts to increase salt tolerance in this species. Rice serves as a model crop for cereal genomics (Xu et al, 2005), and sequence comparisons among the grasses indicate that the information derived from the rice genome is a potentially powerful tool to understand the physiology of other plant species.…”

Participation of Phytohormones in Adaptation to Salt Stress

“…For example, one of the main food crops is rice, which is thought to be highly sensitive to salinity. In fact, its seedlings are highly salt sensitive, which greatly affects crops, whereas at the germination stage, rice is relatively resistant (Singh et al 2008 ).…”

Plant Hormones under Challenging Environmental Factors

“…They develop some adaptation mechanisms to monitor salt stress and regulate plant physiology and metabolism in order to cope with this stress (Sairam and Tyagi 2004 ). In fact, its seedlings are highly salt sensitive, which greatly affects crops, whereas at the germination stage, rice is relatively resistant (Singh et al 2008 ). Salinity tolerance depends on the stage of development.…”