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 <i>R5421</i>, <i>Arabidopsis akt1</i> mutant, and <i>Xenopus</i> oocytes. The results showed that <i>PbrAKT1</i> 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 <i>Xenopus</i> 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 <i>R5421</i> and <i>Arabidopsis akt1</i> 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.