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 genes in maize ( L.). In the present study, the genes were identified from the maize genome. Subsequently, the protein properties, gene structure and duplication, chromosomal location, and -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 W303a cells, were performed to uncover the potential function. The results showed that a total of 10 genes were identified and named to 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 genes lost introns and had abundant stress- and hormone-responsive -elements in their promoter region. The results of quantitative real-time PCR showed that all genes were regulated by drought and saline stresses, as well as ABA induction. Moreover, heterologous expression of and 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.