ABA Alleviated Soybean Seedling Stress Exposed to UV-C Radiation

In order to understand the roles of abscisis acid in soybean exposed to UV-C radiation, soybean seedlings were exposed to UV-C radiation and ABA was applied. The chlorophyll content, active oxygen metabolism and flavonoids content of soybean seedlings were investigated. The present study revealed that UV-C radiation significantly attenuated the chlorophyll content and suppressed PSII activity. It was observed that the contents of H2O2, malondialdehyde and O-2(-) were markedly increased, and the activities of antioxidant enzymes such as superoxide dismutase, peroxidase and catalase were enhanced, so were the flavonoids content, whereas the seedling height and biomass were significantly reduced. ABA application improved the activities of superoxide dismutase, peroxidase, catalase and the contents of flavonoids, decreased the contents of H2O2, MDA and O-2(-), and also increased the chlorophyll content and enhanced PSII performance, thus enhancing biomass accumulation. The results suggested that ABA alleviated UV-C damage to soybean seedlings by reducing ROS generation and enhancing antioxidase activity. The isoflavones daidzin and genistein were significantly responsive to UV-C.