Genomic Analysis of Stress Associated Proteins in Soybean and the Role of GmSAP16 in Abiotic Stress Responses in Arabidopsis and Soybean

Abstract

Stress associated proteins (SAPs) containing A20/AN1 zinc finger domains have emerged as novel regulators of stress responses. In this study, 27 SAP genes were identified in soybean. The phylogenetic relationships, exon-intron structure, domain structure, chromosomal localization, putative <i>cis</i>-acting elements, and expression patterns of SAPs in various tissues under abiotic stresses were analyzed. Among the soybean SAP genes, <i>GmSAP1</i>6 was significantly induced by water deficit stress, salt, and abscisic acid (ABA) and selected for further analysis. GmSAP16 was located in the nucleus and cytoplasm. The overexpression of <i>GmSAP16</i> in <i>Arabidopsis</i> improved drought and salt tolerance at different developmental stages and increased ABA sensitivity, as indicated by delayed seed germination and stomatal closure. The <i>GmSAP16</i> transgenic <i>Arabidopsis</i> plants had a higher proline content and a lower water loss rate and malondialdehyde (MDA) content than wild type (WT) plants in response to stresses. The overexpression of <i>GmSAP16</i> in soybean hairy roots enhanced drought and salt tolerance of soybean seedlings, with higher proline and chlorophyll contents and a lower MDA content than WT. RNA inference (RNAi) of <i>GmSAP16</i> increased stress sensitivity. Stress-related genes, including <i>GmDREB1B;1</i>, <i>GmNCED3</i>, <i>GmRD22</i>, <i>GmDREB2</i>, <i>GmNHX1</i>, and <i>GmSOS1</i>, showed significant expression alterations in <i>GmSAP16</i>-overexpressing and RNAi plants under stress treatments. These results indicate that soybean SAP genes play important roles in abiotic stress responses.