Genome-Wide Analysis of Potassium Transport-Related Genes in Chickpea (Cicer arietinum L.) and Their Role in Abiotic Stress Responses

Potassium is the most abundant inorganic cation that constitutes up to 10% of the total plant dry weight and plays a prominent role in plant growth and development. Plants exhibit a complex but highly organized system of channels and transporters, which are involved in absorption and distribution of K+ from soil to different parts of plants. In this study, we explored the K+ transport system in chickpea genome and identified 36 genes encoding potassium channels and transporters. The identified genes were further classified on the basis of their domain structure and conserved motifs. It includes K+ transporters (23 genes: 2 HKTs, 6 KEAs, and 15 KUP/HAK/KTs) and K+ channels (13 genes: 8 Shakers and 5 TPKs). Chromosomal localization of these genes demonstrated that various K+ transporters and channels are randomly distributed across all the eight chromosomes. Comparative phylogenetic analysis of K+ transport system genes from Arabidopsis thaliana, Glycine max, Medicago truncatula, and Oryza sativa revealed their strong conservation in different plant species. Similarly, gene structure analysis displayed conservation of family-specific intron/exon organization in the K+ transport system genes. Evolutionary analysis of these genes suggested the segmental duplication as principal route of expansion for this family in chickpea. Several abiotic stress-related cis-regulatory elements were also identified in promoter regions suggesting their role in abiotic stress tolerance. Expression analysis of selected genes under drought, heat, osmotic, and salt stress demonstrated their differential expression in response to these stresses. This signifies the importance of these genes in the modulation of stress response in chickpea. Present study provides the first insight into K+ transport system in chickpea and can serve as a basis for their functional analysis.