The SAP Gene Family in Oat (Avena sativa L.): Genome-Wide Identification, Gene Expression Analysis, and Functional Characterization of AvSAP1 in Response to Stress Conditions

The stress-associated proteins (SAPs) correspond to zinc-finger proteins containing A20/AN1 domains that are involved in plant responses to a wide range of biotic and abiotic stresses. However, in oat, no information has been available so far regarding the characteristics and regulation of these genes. In the current research work, eleven <i>AvSAP</i> genes were identified in oats genome (OT3098 variety) named <i>AvSAP1</i> to <i>AvSAP11</i>. Eight proteins contained both A20 and AN1 domains located at the N- and C-terminal portions of the proteins, respectively. Subsequently, the gene structure and duplication, chromosomal location, cis-acting elements, and protein properties were analyzed using bioinformatic tools. Moreover, genes expression profiles revealed that <i>AvSAP</i> genes present hormones and stress-responsive cis-elements in their promoters. These observations were confirmed using QRT-PCR analysis. Indeed, the majority of identified <i>AvSAP</i> genes were responsive to NaCl, PEG, heat, ethylene, and metallic (Mn, Cu, and Cd) stresses. Moreover, ABA phytohormone induced a significant upregulation of nine <i>AvSAP</i> genes in leaves (5.8-6.5-fold induction) and roots (1.9-4.2-fold induction), corroborating their crucial role of those genes in plants' response to a wide range of abiotic stresses. In contrast, GA and IAA exert a slight effect on those genes. Finally, <i>AvSAP1</i> protein expression in bacterial cells conferred tolerance to ionic and osmotic stress. Our results provide deeper insight into <i>AvSAP</i> genes in plants and support advanced functional analyses of this gene family in oats.