Genome-Wide Characterization and Function Analysis of ZmERD15 Genes' Response to Saline Stress in Zea mays L.

Early responsive dehydration (ERD) genes can be rapidly induced by dehydration. ERD15 genes have been confirmed to regulate various stress responses in plants. However, the maize ERD15 members have not been characterized. In the present study, a total of five ZmERD15 genes were identified from the maize genome and named ZmERD15a, ZmERD15b, ZmERD15c, ZmERD15d, and ZmERD15e. Subsequently, their protein properties, gene structure and duplication, chromosomal location, cis-acting elements, subcellular localization, expression pattern, and over-expression in yeast were analyzed. The results showed that the ZmERD15 proteins were characterized by a similar size (113-159 aa) and contained a common domain structure, with PAM2 and adjacent PAE1 motifs followed by an acidic region. The ZmERD15 proteins exhibited a close phylogenetic relationship with OsERD15s from rice. Five ZmERD15 genes were distributed on maize chromosomes 2, 6, 7, and 9 and showed a different exon-intron organization and were expanded by duplication. Besides, the promoter region of the ZmERD15s contained abundant cis-acting elements that are known to be responsive to stress and hormones. Subcellular localization showed that ZmERD15b and ZmERD15c were localized in the nucleus. ZmERD15a and ZmERD15e were localized in the nucleus and cytoplasm. ZmERD15d was localized in the nucleus and cell membrane. The results of the quantitative real-time PCR (qRT-PCR) showed that the expression of the ZmERD15 genes was regulated by PEG, salinity, and ABA. The heterologous expression of ZmERD15a, ZmERD15b, ZmERD15c, and ZmERD15d significantly enhanced salt tolerance in yeast. In summary, a comprehensive analysis of ZmERD15s was conducted in the study. The results will provide insights into further dissecting the biological function and molecular mechanism of ZmERD15s regulating of the stress response in maize.

Comprehensive Identification and Functional Analysis of Stress-Associated Protein (SAP) Genes in Osmotic Stress in Maize.

Stress-associated proteins (SAPs) are a kind of zinc finger protein with an A20/AN1 domain and contribute to plants' adaption to various abiotic and biological stimuli. However, little is known about the SAP genes in maize (Zea mays L.). In the present study, the SAP genes were identified from the maize genome. Subsequently, the protein properties, gene structure and duplication, chromosomal location, and cis-acting elements were analyzed by bioinformatic methods. Finally, their expression profiles under osmotic stresses, including drought and salinity, as well as ABA, and overexpression in Saccharomyces cerevisiae W303a cells, were performed to uncover the potential function. The results showed that a total of 10 SAP genes were identified and named ZmSAP1 to ZmSAP10 in maize, which was unevenly distributed on six of the ten maize chromosomes. The ZmSAP1, ZmSAP4, ZmSAP5, ZmSAP6, ZmSAP7, ZmSAP8 and ZmSAP10 had an A20 domain at N terminus and AN1 domain at C terminus, respectively. Only ZmSAP2 possessed a single AN1 domain at the N terminus. ZmSAP3 and ZmSAP9 both contained two AN1 domains without an A20 domain. Most ZmSAP genes lost introns and had abundant stress- and hormone-responsive cis-elements in their promoter region. The results of quantitative real-time PCR showed that all ZmSAP genes were regulated by drought and saline stresses, as well as ABA induction. Moreover, heterologous expression of ZmSAP2 and ZmSAP7 significantly improved the saline tolerance of yeast cells. The study provides insights into further underlying the function of ZmSAPs in regulating stress response in maize.