Overexpression of GmSUMO2 gene confers increased abscisic acid sensitivity in transgenic soybean hairy roots

Small ubiquitin-like modifier (SUMO) participates in post-translational modification of various target proteins. SUMOylation is an important molecular regulatory mechanism for plants to respond to abiotic stress. In the present study, GmSUMO2 gene was isolated from soybean seedlings for further study because of the highest expression level among these six SUMO genes in soybean. qRT-PCR results showed that GmSUMO2 gene were detected in root, leaf, cotyledon, seed root, flower, pod and seed, with the highest transcription level in cotyledon. Moreover, GmSUMO2 gene was transcriptionally regulated by 200 mM NaCl, 42 °C, 25 μM abscisic acid (ABA) and 20% PEG6000 during the 24 h period of treatment. Besides, western blot analysis using AtSUMO1 antibody indicated that the free SUMO levels and SUMOylation dynamics were regulated by ABA stimulus. Functional analysis indicated that overexpression of GmSUMO2 gene in soybean hairy roots accentuated the sensitivity to exogenous ABA. Furthermore, the expression levels of ABI3, ABI5, SnRK1.1 and SnRK1.2 were differentially regulated by GmSUMO2 in transgenic soybean hairy roots. Overall, these results provided a preliminary understanding of molecular characterization, expression and function of GmSUMO2 in soybean.