Genome-wide identification and expression analysis of WNK kinase gene family in soybean

Abstract WNK kinases are a unique class of serine/threonine protein kinases that lack a conserved catalytic lysine residue in the kinase domain. They are involved in various physiological processes in plants, such as circadian rhythm, flowering time, and stress response. In this study, we identified 26 WNK genes in soybean, a globally important crop, and analyzed their phylogenetic relationships, gene structures, conserved motifs, chromosomal distribution, cis-regulatory elements, and expression patterns. We found that soybean WNK genes were unevenly distributed on 15 chromosomes and underwent 21 segmental duplication events during evolution. We also detected 14 types of cis-regulatory elements in the promoters of WNK genes, indicating their potential involvement in different signaling pathways. Moreover, we observed tissue-specific and salt stress-responsive expression of WNK genes in soybean by using FPKM data and qRT-PCR analysis. We found that most WNK genes were significantly up-regulated by salt stress within 3 hours in both roots and leaves, except for WNK5, which showed a distinct expression pattern. Our findings provide valuable insights into the molecular characteristics and evolutionary history of the soybean WNK gene family and lay a foundation for further functional analysis of WNK genes in soybean.