Genome-Wide Identification and Analysis of Arabidopsis Sodium Proton Antiporter (NHX) and Human Sodium Proton Exchanger (NHE) Homologs in Sorghum bicolor

Abstract

Na+ transporters play an important role during salt stress and development. The present study is aimed at genome-wide identification, in silico analysis of sodium-proton antiporter (NHX) and sodium-proton exchanger (NHE)-type transporters in Sorghum bicolor and their expression patterns under varied abiotic stress conditions. In Sorghum, seven NHX and nine NHE homologs were identified. Amiloride (a known inhibitor of Na+/H+ exchanger activity) binding motif was noticed in both types of the transporters. Chromosome 2 was found to be a hotspot region with five sodium transporters. Phylogenetic analysis inferred six ortholog and three paralog groups. To gain an insight into functional divergence of SbNHX/NHE transporters, real-time gene expression was performed under salt, drought, heat, and cold stresses in embryo, root, stem, and leaf tissues. Expression patterns revealed that both SbNHXs and SbNHEs are responsive either to single or multiple abiotic stresses. The predicted protein–protein interaction networks revealed that only SbNHX7 is involved in the calcineurin B-like proteins (CBL)- CBL interacting protein kinases (CIPK) pathway. The study provides insights into the functional divergence of SbNHX/NHE transporter genes with tissue specific expressions in Sorghum under different abiotic stress conditions.

Identification of NHXs in Gossypium species and the positive role of GhNHX1 in salt tolerance

“…To investigate the evolutionary relationships between NHXs of G. arboreum, G. raimondii, G. hirsutum and other plant species such as rice, mulberry, and Arabidopsis (Table S2), we built an unrooted phylogenetic tree using ClustalW and MEGA 6.0 with neighbor-joining (N-J) method. Similar to the previous studies in other plant species [30][31][32][33][34], the 47 NHX candidates of Gossypium were divided into three distinct classes based on the sequence conservation ( Table 1, Fig. 2).…”

“…NHXs are evolutionarily and functionally conserved proteins. To identify and compare the NHX members of cotton, the NHX protein sequences of Arabidopsis, rice, tomato, soybean, and mulberry [30][31][32][33][34][35] were downloaded from NCBI and used to build HMM to search against cotton genome database [23,36,37]. All putative NHXs were further analyzed by InterPro and SMART to reconfirm their signature sequences and conserved domains.…”

Identification of NHXs in Gossypium species and the positive role of GhNHX1 in salt tolerance

“…To investigate the evolutionary relationships between NHXs of G. arboreum, G. raimondii, G. hirsutum and other plant species such as rice, mulberry, and Arabidopsis (Table S2), we built an unrooted phylogenetic tree using ClustalW and MEGA 6.0 with neighbor-joining (N-J) method. Similar to the previous studies in other plant species [30,31,32,33,34], the 47 NHX candidates of Gossypium were divided into three distinct classes based on the sequence conservation ( Table 1, Figure S1) and had similar predicted pI and Mw values (Table S1). The phylogenetic tree and sequence alignment showed common gene duplication events associated with chromosome doubling in G. hirsutum compared to G. arboreum and G. raimondii, which were also found in the previous reports of gene family studies in G. hirsutum [38].…”

Identification of NHXs in Gossypium species and the positive role of GhNHX1 in salt tolerance

“…To investigate the evolutionary relationships between NHXs of G. arboreum, G. raimondii, G. hirsutum 6 and other plant species such as rice, mulberry, and Arabidopsis (Table S2), we built an unrooted phylogenetic tree using ClustalW and MEGA 6.0 with neighbor-joining (N-J) method. Similar to the previous studies in other plant species [30,31,32,33,34], the 47 NHX candidates of Gossypium were divided into three distinct classes based on the sequence conservation ( Table 1, Fig. 2).…”