The application of exogenous gibberellic acid enhances wheat seedlings UV-B tolerance by ameliorating DNA damage and manipulating UV-absorbing compound biosynthesis in wheat seedling leaves

摘要

DNA damage is one of the key parameters to detect UV-B tolerance because DNA is one of the primary targets for UV-B light. Here, we evaluated UV-B stress-induced genomic DNA damages and its self-repair ability in wheat seedlings with or without gibberellic acid (GA 3 ) treatment. The application of exogenous GA 3 exhibited the better phenotypic development, less inhibition effects in biomass production and a lower accumulation level of cyclobutane pyrimidine dimer (CPD) and (6-4) photoproducts (6-4PPs) in leaves of wheat seedlings under supplementary UV-B stress than those without GA 3 treatment, indicating that GA 3 ameliorated the detrimental effects and DNA damages induced by the enhanced UV-B stress, in which the 150mg L -1 of GA 3 is the most effective treatment. After exogenous GA 3 treatment, the UV-absorbing compounds (UACs) contents and DNA photolyase activity also significantly increased, whereas reactive oxygen species (ROS) production were similar between two groups with or without GA 3 application under UV-B stress. These results have demonstrated that GA 3 enhanced wheat seedlings UV-B tolerance by initiating DNA damage repair pathway in leaves of wheat seedlings exposed to supplementary UV-B stress, which were mainly implemented through activating DNA photorepair capability and elevating UV-B absorbance amounts in vivo in plants.