Genome-Wide Identification and Characterization of the Shaker-Type K(+) Channel Genes in Prunus persica (L.) Batsch

Shaker-type K(+) channels are critical for plant K(+) acquisition and translocation that play key roles during plant growth and development. However, molecular mechanisms towards K(+) channels are extremely rare in fruit trees, especially in peach. In this study, we identified 7 putative shaker-type K(+) channel genes from peach, which were unevenly distributed on 5 chromosomes. The peach shaker K(+) channel proteins were classified into 5 subfamilies, I-V, and were tightly clustered with pear homologs in the phylogenetic tree. Various cis-acting regulatory elements were detected in the promoter region of the shaker-type K(+) channel genes, including phytohormone-responsive, abiotic stress-responsive, and development regulatory elements. The peach shaker K(+) channel genes were expressed differentially in distinct tissues, and PpSPIK was specifically expressed in the full-bloom flowers; PpKAT1 and PpGORK were predominantly expressed in the leaves, while PpAKT1, PpKC1, and PpSKOR were majorly expressed in the roots. The peach shaker K(+) channel genes were differentially regulated by abiotic stresses in that K(+) deficiency, and ABA treatment mainly increased the shaker K(+) channel gene expression throughout the whole seedling, whereas NaCl and PEG treatment reduced the shaker K(+) channel gene expression, especially in the roots. Moreover, electrophysiological analysis demonstrated that PpSKOR is a typical voltage-dependent outwardly rectifying K(+) channel in peach. This study lays a molecular basis for further functional studies of the shaker-type K(+) channel genes in peach and provides a theoretical foundation for K(+) nutrition and balance research in fruit trees.