Transcriptomic analysis of Glycine soja and G. max seedlings and functional characterization of GsGSTU24 and GsGSTU42 genes under submergence stress

Abstract The plant-specific tau-class of glutathione S-transferase (GSTU) has high stress-inducing expression characteristics that can play an important protective role in plant tolerance to different environmental stresses. To explore the mechanisms underlying submergence and reoxygenation tolerance in soybean plants, the transcriptomic analysis of leaves under submergence was firstly performed using the highly submergence-tolerant G. soja accession (P18B) and the submergence-sensitive G. max cultivar (KF1), and two potential submergence-responsive GSTU genes, GsGSTU24 and GsGSTU42, were identified. Their physiological functions in tolerance to submergence and subsequent desubmergence were compared in GsGSTU24- and GsGSTU42-overexpressing hairy root composite soybean plants or transgenic Arabidopsis plants. The results showed that, overexpression of GsGSTU24 or GsGSTU42 could alleviate submergence and subsequent desubmergence stress on soybean hairy root composite plants or transgenic A. thaliana seedlings by enhancing antioxidant ability for leaf ROS detoxification or homeostasis reestablishment, and by improving the chlorophyll content and quantum efficiency of chlorophyll fluorescence (Fv/Fm) for maintenance of leaf photosynthetic capacity. Our results further indicate that, the genes GsGSTU42 or GsGSTU24 from high submergence-tolerant G. soja P18B could be considered as the vital submergence tolerance determinants for utilization in molecular breeding designs for flooding-tolerant crop improvement in the future.