Genome-wide identification, characterization and evolutionary analysis of betaine aldehyde dehydrogenase (BADH), mitogen-activated protein kinase (MAPK) and sodium/hydrogen exchanger (NHX) genes in maize (Zea mays) under salt stress

Betaine aldehyde dehydrogenase ( BADH ), mitogen-activated protein kinase ( MAPK ) and sodium/hydrogen exchanger ( NHX ) play important roles in the response to salt stress. This is the first study to identify the BADH and NHX genes in maize ( Zea mays ) via genome-wide analysis. The qRT‒PCR results indicated that ZmNHX was upregulated by 4.38-fold, while a significant difference was not observed in ZmBADH or ZmMAPK, with fold changes of 0.96 and 1.06, respectively, under salinity stress. Genome-wide analysis revealed 8 ZmBADH, 19 ZmMAPK and 11 ZmNHX proteins in Z. mays . Domain analysis confirmed the presence of the aldehyde dehydrogenase superfamily (ALDH-SF), protein kinase and Na_H_Exchanger domains in the ZmBADH, ZmMAPK and ZmNHX proteins, respectively. Motif analysis indicated that the phylogenetic relationships were similar to the conserved motif distributions within the clade. The Ka / Ks ratio indicated that the ZmBADH, ZmMAPK and ZmNHX genes were influenced primarily by purifying selection. This study provides comprehensive identification, characterization, and evolutionary analysis for a better understanding of the ZmBADH, ZmMAPK and ZmNHX genes in maize.