Genome-Wide Identification and Expression Profiling of the Shaker K⁺ Channel and HAK/KUP/KT Transporter Gene Families in Grape (<i>Vitis vinifera</i> L.)

Potassium (K⁺) is an essential macronutrient for plants to maintain normal growth and development. Shaker-like K⁺ channels and HAK/KUP/KT transporters are critical components in the K⁺ acquisition and translocation. In this study, we identified 9 Shaker-like K⁺ channel (VvK) and 18 HAK/KUP/KT transporter (VvKUP) genes in grape, which were renamed according to their distributions in the genome and relative linear orders among the distinct chromosomes. Similar structure organizations were found within each group according to the exon/intron structure and protein motif analysis. Chromosomal distribution analysis showed that 9 VvK genes and 18 VvKUP genes were unevenly distributed on 7 or 10 putative grape chromosomes. Three pairs of tandem duplicated genes and one pair of segmental duplicated genes were observed in the expansion of the grape VvKUP genes. Gene expression omnibus (GEO) data analysis showed that VvK and VvKUP genes were expressed differentially in distinct tissues. Various cis-acting regulatory elements pertinent to phytohormone responses and abiotic stresses, including K⁺ deficiency response and drought stress, were detected in the promoter region of VvK and VvKUP genes. This study provides valuable information for further functional studies of VvK and VvKUP genes, and lays a foundation to explore K⁺ uptake and utilization in fruit trees.