eQTL regulates OsHAK5 in enhancing potassium content under salt stress in rice

To alleviate salt stress in rice, the role of potassium in countering the ill effects of sodium is gaining importance. Towards this, OsHAK5 a member of the high-affinity potassium transporter family was known for enhancing the intracellular potassium under reduced/low K⁺ availability during salt stress. The full-length cDNA of OsHAK5 was cloned and sequenced from the roots of Pokkali and cv. IR64 however, no nucleotide polymorphism detected. Interestingly, the expression of OsHAK5 in roots of salt-tolerant landrace Pokkali and salt susceptible cv. IR64 revealed a significant upregulation in the former under low K⁺ (1/4^th) condition. Subsequent analysis of the amino acid sequence of CBL-interacting protein kinase (OsCIPK23), the upstream regulator of OsHAK5 revealed two INDELs and one of them turned out to be functionally relevant. The OsCIPK23 variant from salt-tolerant Pokkali should be favorably regulating the expression of the downstream OsHAK5 leading to an increased K⁺ uptake under salt stress.