Exploring OsHAK transporters for the salt responsiveness in rice

Environmental stresses are the major constraint in crop growth and productivity, particularly in rice. Improving rice against major abiotic stressors such as salinity is one of the major thrust areas. In this direction, the trait of sodium exclusion was the primary focus among the rice breeders to enhance salt tolerance. Along similar lines, increased uptake of potassium, the counter ion of Na⁺, through high-affinity potassium transporters (HAK) assumes significance in the context of maintaining a favorable Na/K ratio, a low Na/K is an indicator of salt tolerance. The OsHAK family in rice includes 27 members and an insight into the evolution, structure, and expression through in silico approaches was attempted. Phylogenetic analysis exhibited four distinct groupings of the OsHAK family, and functional motif analysis revealed a characteristic consensus sequence among the OsHAK transporters. Relative gene expression analysis based on published microarray data put forth the differential regulation of OsHAK3 X2, OsHAK8, OsHAK14(X2), OsHAK15 and OsHAK26 between salt-tolerant landrace Pokkali and susceptible cultivar IR29 and their tissue-specific expression profiles predicted. This study narrowed down a set of putative OsHAKs from the larger family for their role in enhancing cellular potassium under salt stress thus paving the way for crop improvement.