Salinity Stress in Rice : an Overview

Molecular and physiological traits imparting resistance/tolerance and susceptibility to a particular biotic and abiotic stress are important from crop production point of view. There are a number of biotic (viz., insect-pests and diseases) and abiotic stresses (viz., drought, water logging, salinity/alkalinity, low temperatures etc.), which affect crop, among abiotic stresses, high salinity stress is the most severe environmental stress, which impairs crop production on at least 20% of irrigated land worldwide. In response to high salinity stress, various genes get upregulated, the products of which are involved either directly or indirectly in plant protection. Some of the genes encoding osmolytes, ion channels, receptors, components of calcium signaling and some other regulatory signaling factors or enzymes are able to confer salinity-tolerant phenotypes, when transferred to sensitive plants. Overall, the susceptibility or tolerance to high salinity stress in plants is a coordinated action of multiple stress responsive genes. Molecular markers would provide reliable information about genetic diversity of crops. Since these molecular markers are numerous in number and thus, will have better coverage of whole genome especially for the traits associated with salinity tolerance. Salt stress effectively decreases the availability of water in the soil to plants not only this but, it also poses other effects such as salt ions impair enzyme function, inhibit protein synthesis, affect the structure and permeability of cell membranes, inhibit photosynthesis and lead to the production of toxic reactive oxygen species. By doing functional genomics analysis, we would be able to have better understanding of salinity tolerance mechanism i.e., transcription factors involved in regulation pathway of different mechanisms of the plants under saline conditions detailed understanding of genome structure and functioning will lead to great developments. For instance, combining techniques permitting modifications at the nucleotide level with the outcome of genomics will probably have a tremendous impact on breeders’ activities in a medium-term perspective. The objective of this review is to analyze the available literature and estimate yield losses for rice crop grown in salt-affected soils around the world. In particular, rice (Oryza sativa) studied as examples of staple food crops. Today, rice stands as a forerunner amongst the cereals in terms of details known on its genetics.