Rice high affinity potassium transporters oshak1 and oshak5 are critical for salt tolerance in potassium deficient soils

M Al Nayef1, J Bose2, L Wh3, G Xu3 and S Shabala1

  1. School of Land and Food University of Tasmania, Hobart
  2. ARC Centre of Excellence in Plant Energy Biology, University of Adelaide
  3. Nanjing Agricultural University, Nanjing 210095, China

Plants evolved a complex network of potassium (K+) transporters and regulatory mechanisms to maintain optimal K+ concentration inside the cytosol, which is a pivotal requirement for survival during salt stress. Some members of the high affinity K+ transporter (HAK) family are characterized to be involved in K+ homeostasis under low K+ condition, and salt stress also altered their transcript levels. However, the exact role of HAK transporters and in planta functional characterisation of these transporters during salt stress remains elusive. The missing critical knowledge addressed in this work by studying the responses of rice (Oryza sativa) oshak1 and oshak5 mutants to salt and oxidative stress. The K+ ion flux and the gene expression analysis revealed that the loss of function of oshak1 and oshak5 mutants (1) loose more K+ from roots under low K (200 µM) and salt (40 mM) condition, and (2) decrease the expression level of respiratory burst oxidase homolog OsRboH protein under low K+ thereby lower K+ loss as compared to wild type during oxidative stress. In conclusion, the loss of function of oshak1 and oshak5 increases the sensitivity of mutant lines to salt stress, revealing the crucial role of OsHAK1 and OsHAK5 in K acquisition in response to hostile environmental conditions such as low potassium and high soil salinity.