Genome-Wide Identification, Genomic Organization, and Characterization of Potassium Transport-Related Genes in Cajanus cajan and Their Role in Abiotic Stress

Abstract

Potassium is the most important and abundant inorganic cation in plants and it can comprise up to 10% of a plant’s dry weight. Plants possess complex systems of transporters and channels for the transport of K+ from soil to numerous parts of plants. Cajanus cajan is cultivated in different regions of the world as an economical source of carbohydrates, fiber, proteins, and fodder for animals. In the current study, 39 K+ transport genes were identified in C. cajan, including 25 K+ transporters (17 carrier-like K+ transporters (KUP/HAK/KTs), 2 high-affinity potassium transporters (HKTs), and 6 K+ efflux transporters (KEAs) and 14 K+ channels (9 shakers and 5 tandem-pore K+ channels (TPKs). Chromosomal mapping indicated that these genes were randomly distributed among 10 chromosomes. A comparative phylogenetic analysis including protein sequences from Glycine max, Arabidopsis thaliana, Oryza sativa, Medicago truncatula Cicer arietinum, and C. cajan suggested vital conservation of K+ transport genes. Gene structure analysis showed that the intron/exon organization of K+ transporter and channel genes is highly conserved in a family-specific manner. In the promoter region, many cis-regulatory elements were identified related to abiotic stress, suggesting their role in abiotic stress response. Abiotic stresses (salt, heat, and drought) adversely affect chlorophyll, carotenoids contents, and total soluble proteins. Furthermore, the activities of catalase, superoxide, and peroxidase were altered in C. cajan leaves under applied stresses. Expression analysis (RNA-seq data and quantitative real-time PCR) revealed that several K+ transport genes were expressed in abiotic stress-responsive manners. The present study provides an in-depth understanding of K+ transport system genes in C. cajan and serves as a basis for further characterization of these genes.

Characterization of the Gene Expression Profile Response to Drought Stress in Populus ussuriensis Using PacBio SMRT and Illumina Sequencing

“…Some transporters, namely HvHAK1 , HvAKT2 , OsHAK1 , and OsHAK5 , have been shown to be involved in the uptake of K + in the roots [ 53 , 54 ]. Expression analysis in Cajanus cajan revealed that several K + transport genes, that is, CcHAK6 , CcHAK15 , CcAKT2 , and CcHKT1 , were up-regulated in response to drought stress [ 55 ]. Notably, the K content in the roots of P. ussuriensis was significantly higher than that of Na and Ca under PEG-induced drought stress ( Figure 9 A–C).…”

Genome-wide characterization and expression analysis of the HAK gene family in response to abiotic stresses in Medicago

“…The conserved amino acid sequences of six KUP/HAK/KT domains are GDLGTSPLY, ANDDNGEGG, GDGVLTPAIS, GSEAMFADLGHF, AYGIAVV, and FRCIVIYGYKD, respectively. All HAK members contain at least two KUP/HAK/KT domains, which were similar to those HAKs members from Gossypium raimondii [ 28 ] and Cajanus cajan [ 29 ].…”

Computational analysis and expression profiling of potassium transport-related gene families in mango (Mangifera indica) indicate their role in stress response and fruit development

“…Among K + channels, the presence of ANK, Ion_trans_2, and KHA domains in the Shaker proteins, similar to Arabidopsis K + channels, suggests their functional similarities ( Keisham et al., 2018 ). Likewise, the occurrence of the significantly conserved residues, i.e., GYGD and RSXpS/pTXP, in MiTPKs indicates potential functional similarities in M. indica and other plants ( Ge et al., 2020 ; Siddique et al., 2021 ).…”

“…The current study identified 37 potential genes of the K + transport system in M. indica genome. The number of PTGs is more or less similar in major plant groups represented by V. vinifera , Glycine max , Triticum aestivum , Vigna radiata , C. cajan , and A. thaliana ( Cuéllar et al., 2010 ; Isayenkov et al., 2011 ; Chen et al., 2017 ; Azeem et al., 2018 ; Azeem et al., 2021a ; Azeem et al., 2021b ; Ge et al., 2020 ; Siddique et al., 2021 ; Cai et al., 2021 ). It not only indicates the evolutionary conservation of PTGs in these plants but also predicts the existence of similar genetic mechanisms for K + in other fruit trees.…”