叶黄素循环和D1蛋白周转在毛竹叶片光保护中的作用

利用叶绿素荧光技术,对强光胁迫下以及叶黄素循环抑制剂-二硫苏糖醇(DTT)和D1蛋白合成抑制剂-硫酸链霉素(SM)处理后毛竹(Phyllostachys edulis (Carr.) Lehaie)的光抑制特征进行研究。结果显示:在夏季中午强光或人为强光胁迫下,毛竹叶片最大光化学效率Fv/Fm均显著降低;在下午光强减弱或黑暗、弱光条件下,Fv/Fm可有效恢复。DTT和SM均可抑制毛竹叶片非光化学淬灭(NPQ),且DTT效果明显优于SM。另外,在强光下,DTT和SM处理均能使毛竹叶片Fv/Fm、实际光化学效率Y(Ⅱ)和光化学淬灭qP等荧光参数下降幅度增大。研究结果表明毛竹叶片具有完善的光破坏防御机制,NPQ与叶黄素循环和D1蛋白周转紧密关联,在叶片光保护机制中具有重要作用。

Role of xanthophyll cycle and D1 protein turnover in photoprotection of Phyllostachys edulis (Carr.) Lehaie leaves

To investigate the roles of the xanthophyll cycle and D1 protein turnover in photoprotection of bamboo, we applied chlorophyll fluorescence techniques to measure the characteristics of photoinhibition in moso bamboo (Phyllostachys edulis (Carr.) Lehaie) leaves under strong light and xanthophyll cycle inhibitor-dithiothreitol (DTT) and D1 protein synthesis inhibitor-streptomycin sulfate (SM) treatment, respectively. Results showed that the maximum photochemical efficiency (F_v/F_m) decreased significantly in leaves of Ph. edulis exposed to strong artificial light or strong natural noon light in summer. However, the F_v/F_m value could be restored under darkness or in the afternoon under decreased intensity of sunlight. Non-photochemical quenching (NPQ) in Ph. edulis leaves was inhibited by the DTT and SM treatments, with the inhibition effect of DTT significantly better than that of SM. In addition, the DTT and SM treatments increased the declining degree of chlorophyll fluorescence parameters in Ph. edulis leaves under strong light, including F_v/F_m, actual photochemical efficiency Y(Ⅱ), and photochemical quenching q_P. These results suggest that Ph. edulis leaves possess a complete photoprotection defense mechanism. NPQ is closely associated with the xanthophyll cycle and D1 protein turnover, which plays an important role in Ph. edulis photoprotection.