Pretreatment with Danshensu Promotes Germination of Cucumber (Cucumis sativus L.) Seeds by Regulating Reactive-Oxygen Species and Endogenous Phytohormones

Danshensu (DSS), the aqueous extracts of Salvia miltiorrhiza has been widely used in biomedical science due to its outstanding capacity in ROS scavenger. However, studies regarding its effects on plant physiology are still scare. In the present study, cucumber seeds were soaked in different concentrations of DSS solution for 24 h before subjected to germination to test its effects on seed germination, and further to explore the metabolic and molecular mechanisms. The results shown that 0.1% DSS had significantly promoted the germination rate, radical length, as well as soluble sugar and H2O2 contents. DSS pretreatment upregulated transcript levels of genes involved in SOD, POD, and CAT biosynthesis, concurrent with promoted enzyme activities. In accordance with lower ABA, but higher GA contents, transcript levels of genes involved in ABA and GA biosynthesis were down and upregulated, respectively, in DSS pretreated seeds. DSS pretreatment also stimulated ethylene production and related genes expression levels. These positive effects of DSS on seed germination were confirmed by addition of inhibitors of GA, ABA, NADPH oxidase, and H2O2 scavenger. In conclusion, DSS stimulated cucumber seed germination by mediating the regulation of endogenous hormones with promoted ROS levels. Our results highlight the potentiality of DSS in plant science.