Plants, as sessile organisms experience various abiotic stresses, which pose serious threat to crop production. Plants adapt to environmental stress by modulating their growth and development along with the various physiological and biochemical changes. This phenotypic plasticity is driven by the activation of specific genes encoding signal transduction, transcriptional regulation, ion transporters and metabolic pathways. Rice is an important staple food crop of nearly half of the world population and is well known to be a salt sensitive crop. The completion and enhanced annotations of rice genome sequence has provided the opportunity to study functional genomics of rice. Functional genomics aids in understanding the molecular and physiological basis to improve the salinity tolerance for sustainable rice production. Salt tolerant transgenic rice plants have been produced by incorporating various genes into rice. In this review we present the findings and investigations in the field of rice functional genomics that includes supporting genes and networks (ABA dependent and independent), osmoprotectants (proline, glycine betaine, trehalose, myo-inositol, and fructans), signaling molecules (Ca2+, abscisic acid, jasmonic acid, brassinosteroids) and transporters, regulating salt stress response in rice.

Salinity is one of the most common abiotic stresses encountered by plants in the environment and transgenic approaches offer new opportunities to improve tolerance. The mitogen activated protein kinase (MAPK) kinase (MKK) is a key component of MAPK cascade that plays important roles in intra and extra cellular signaling in plants. In the present study, a MKK from rice (Oryza sativa), OsMKK6 was functionally characterized in salt stress by transforming its constitutively active form. OsMKK6 was made constitutively active by mutating serine and threonine to glutamic acid by site directed mutagenesis, and transformed in indica cultivar rice var. Pusa Basmati-1. The transgenic seedlings growing in 200 mM NaCl solution showed increased root/shoot length and weight, less chlorophyll beaching and higher MAPK activity compared to the wild types. Present work suggest role of OsMKK6 gene in salt stress signaling in rice.