Enhancing soybean tolerance to drought by homologous expression of cytokinin synthase gene GmIPT10

Climatic change-induced osmotic stresses, especially drought and salinity, have arisen as major environmental constraints to crop productivity and sustainable agriculture. Previously, soybean GmIPT10, which encodes an adenine isopentenyl transferase enzyme working in the biosynthesis of cytokinin phytohormone, has been identified as a drought-responsive gene. In this study, the aim is to explore the drought-associated attributes of GmIPT10 in planta, by using homologous expression system. Our findings demonstrated that the transgenic plants might acquire better drought tolerance potential. Following the drought application at vegetative stage, they not only had higher drought-tolerance index by 3–4-fold but also displayed certain advantages in maintaining agronomic traits such as better plant growth, dry biomass accumulation and cellular water contents under adverse conditions than the wild-type plants. Importantly, the greater enhancement in antioxidant enzymatic activities in the transgenic plants (i.e. 2.4–3.8-fold increase) compared with the WT counterparts (1.2–2.3-fold increase) indicated the better defense ability towards drought-induced oxidative stress of the former group. Additional investigation on the drought effects at the reproductive stage further highlighted a less inhibition status of the photosynthetic activities in the transgenic lines, whereby they displayed more active gaseous exchange, higher chlorophyll contents and photochemical efficiency. Although there was no difference in average seed weights, the drought-treated transgenic plants could maintain higher average pod numbers by 10 %, which contributed to higher productivity. Taking these data altogether, our results demonstrated the beneficial role of soybean IPT10 and its mediating actions in alleviating the adverse drought effects on plants.