In-Depth Genomic and Transcriptomic Analysis of Five K+ Transporter Gene Families in Soybean Confirm Their Differential Expression for Nodulation

Hafiz M. Rehman, Muhammad A. Nawaz, Zahid Hussain Shah, Ihsanullah Daur, Sadia Khatoon, Seung Hwan Yang, Gyuhwa Chung

Plants have evolved a sophisticated network of K(+) transport systems to regulate growth and development. Limited K(+) resources are now forcing us to investigate how plant demand can be satisfied. To answer this complex question, we must understand the genomic and transcriptomic portfolio of K(+) transporters in plants. Here, we have identified 70 putative K(+) transporter genes from soybean, including 29 HAK/KT/KUP genes, 16 genes encoding voltage-gated K(+) channels, 9 TPK/KCO genes, 4 HKT genes, and 12 KEA genes. To clarify the molecular evolution of each family in soybean, we analyzed their phylogeny, mode of duplication, exon structures and splice sites, and paralogs. Additionally, ortholog clustering and syntenic analysis across five other dicots further explored the evolution of these gene families and indicated that the soybean data is suitable as a model for all other legumes. Available microarray data sets from Genevestigator about nodulation was evaluated and further confirmed with the RNA sequencing data available by a web server. For each family, expression models were designed based on Transcripts Per Kilobase Million (TPM) values; the outcomes indicated differential expression linked to nodulation and confirmed the genes' putative roles. In-depth studies such as ours provides the basis for understanding K(+) inventories in all other plants.