Genome-wide identification, characterization, and expression analysis of the monovalent cation-proton antiporter superfamily in maize, and functional analysis of its role in salt tolerance

Abstract

BackgroundSodium toxicity and potassium insufficient are important factors affecting the growth and development of maize in saline soil. The monovalent cation proton antiporter (CPA) superfamily comprises Na+/H+ exchanger (NHX), K+ efflux antiporter (KEA), and cation/H+ exchanger (CHX) subfamily proteins, which play vital functions in maize salt tolerance.ResultsA total of 35 ZmCPA genes were identified in maize, and they were phylogenetically classified into 13 ZmNHXs, 16 ZmCHXs and 6 ZmKEAs. ZmCPA genes have a conserved gene structure, with the determined introns range from 11 to 25, 0 to 5 and 16 to 19 in ZmNHXs, ZmCHXs, ZmKEAs, respectively. All proteins have transmembrane domains, with an average transmembrane number of 8, 10, and 10 in ZmNHX, ZmCHX and ZmKEA proteins, respectively. Transient expression in maize protoplasts showed that ZmCHX16 and ZmNHX8 are located in the cell membrane. All ZmCHX subfamily genes showed lower expression compared to ZmNHX and ZmKEA subfamilies. Diverse expression in the 60 tissues and modulated expression in response to salt stress suggested ZmCPAs’ role in maize development and salt stress. Yeast complementary experiment revealed the function of ZmNHX8, ZmCHX8, -12, -14, -16 and ZmKEA6 in salt tolerance. Maize mutants zmnhx8 and zmkea6 further validated the important function of ZmNHX8 and ZmKEA6 in salt tolerance. Phosphorylation sites and cis-acting regulation elements analyses indicated that phosphorylation and transcriptional regulation may be involved in salt tolerance of ZmCPA genes.ConclusionsOur study provides comprehensive information about ZmCPA gene superfamily, which would be useful in their future functional characterization.

The classical SOS pathway confers natural variation of salt tolerance in maize

“…2c), among which, Zm00001d031232 encodes a NHX family Na + /H + antipoter. There were 13 NHX family genes in maize ( ZmNHX1 – ZmNHX13 ) (Kong et al ., 2021). The phylogenetic analysis indicated that Zm00001d031232/ZmNHX7 and the Arabidopsis SOS1 (AtSOS1) fell into the same clade (Fig.…”

Joint GWAS and WGCNA uncover the genetic control of calcium accumulation under salt treatment in maize seedlings

“…Previous studies revealed that the salt tolerance was significantly enhanced by overexpressing a sodium/proton antiporter in Arabidopsis thaliana and tobacco (Pehlivan et al, 2016;Wang et al, 2018;Zhang et al, 2012). Moreover, GRMZM2G051032 was also identified by a genome-wide identification in a previous study (Kong et al, 2021). The SCaS-correlated hub gene GRMZM2G004314 encodes a V-type proton ATPase (also known as vacuolar-type H + -ATPase, VHA) subunit, which is an extremely conserved multi-subunit endomembrane proton pump involved in ion homeostasis and environmental stresses (Kluge et al, 2003;Ratajczak, 2000).…”

“…Ma et al (2018) identified a total of 40 candidate genes by GWAS, which were associated with the embryogenic callus regeneration ability of maize, including the previously reported gene WOX2 . Moreover, 35 ZmCPA genes were identified in the recent genome‐wide identification of maize cation‐proton antiporter under salt stress (Kong et al, 2021). Similarly, several genes associated with salt tolerance were also detected by GWAS in maize, including ZmHKT1 , ZmCLCg , and ZmPMP3 (Luo et al, 2021; Zhang et al, 2018).…”

“…Moreover, 35 ZmCPA genes were identified in the recent genomewide identification of maize cation-proton antiporter under salt stress (Kong et al, 2021). Similarly, several genes associated with salt tolerance were also detected by GWAS in maize, including ZmHKT1, ZmCLCg, and ZmPMP3 (Luo et al, 2021;Zhang et al, 2018).…”