Heterologous expression of soybean E3 ubiquitin ligase Glycine max Ring Zinc Finger 1-Like 1 (GmRZFL1) negatively responds to osmotic stress by participating in the abscisic acid signaling pathway in Arabidopsis

Protein ubiquitination is an important post-translational modification process that is involved in abiotic and biotic stress responses, hormone responses, cell cycle progression, and cell differentiation. Previous studies have demonstrated that the Arabidopsis thaliana Ring Zinc Finger 1 (AtRZF1) exhibits E3 ubiquitin (Ub) ligase activity and negatively mediates the water-deficit stress response by regulating proline metabolism. However, the role of soybean AtRZF1 orthologs in the dehydration response is unknown. In the present study, Glycine max Ring Zinc Finger 1-Like 1 (GmRZFL1), a soybean ortholog of AtRZF1, was isolated and functionally characterized. In immunoblot assays, GmRZFL1 exhibited E3 Ub ligase activity similar to AtRZF1. Abscisic acid (ABA) treatment, osmotic stress, and drought all reduced the expression of GmRZFL1 in soybean seedlings. GmRZFL1-expressing transgenic Arabidopsis lines exhibited reduced cotyledon greening and shorter roots under osmotic stress and ABA treatment compared to wild-type (Col-0). Furthermore, expression analysis of ABA signaling-related genes revealed altered transcription of ABA-insensitive 5 (ABI5), ABA-responsive elements (ABRE)-binding factor 3 (ABF3), and ABA-Responsive Element-Binding Protein 2 (AREB2) in transgenic lines under osmotic stress. The E3 Ub ligase GmRZFL1 negatively participates in osmotic stress response via the ABA signaling pathway.