Isolation and functional determination of inward-rectifier K+ channel PbrAKT1 in pear

Potassium (K+) is essential to plant growth and development. The absorption and transport of K+ by plant roots occurs mainly through K+ channels or transporters. In this study, an AKT1-type channel named PbrAKT1 was successfully cloned and characterised by a series of detailed procedures, including protein sequence alignment, expression and subcellular localisation analysis, as well as functional verification by heterologous expression function validation in yeast mutant R5421, Arabidopsis akt1 mutant, and Xenopus oocytes. The results showed that PbrAKT1 is preferentially expressed in pear roots and exhibits plasma membrane localisation, but its expression is unaffected by low K+ treatment. PbrAKT1 exhibits the function of an inwardly-rectifying K+ channel, and its activity is autonomously regulated when expressed in Xenopus oocytes. In addition, a series of heterologous expression experiments confirmed that PbrAKT1 plays an indispensable role in the processes of K+ transport, as well as alleviating the low-K+ -sensitive phenotype of yeast mutant R5421 and Arabidopsis akt1 mutant. In summary, PbrAKT1 plays an indispensable role in the processes of K+ transport and provide new information on the molecular mechanism of K+ absorption in pear roots.