午间强光下籼粳杂种稻的叶黄素循环和CO_2交换特性

Traits Related to Xanthophyll Cycle and Photosynthetic CO 2 Exchange in Indica Japonica Hybrid Rice under Midday Strong Light

以籼亚种 30 37、Palghar (对光抑制敏感 )和粳亚种 0 2 42 8、0 2 9(耐光抑制 )及其籼粳亚种间杂种 F1 为材料进行试验。水稻叶片中叶黄素循环 (叶黄素组分紫黄质、环氧玉米黄质、玉米黄质的含量 V、A、Z )、Pr/Pn、非光化学猝灭 (q N)、表观光合量子效率 (AQY)、PS 光化学效率 (Fv/Fm)和 D1蛋白量有明显的日变化 ,且在不同基因型水稻间有显著差异。在午间强光下 ,与籼亚种相比 ,粳亚种有较高的 AQY、Fv/Fm 和 D1蛋白量 ,较低的 (A+Z) /(A+Z+V)、Pr/Pn 和 q N 值 ,籼粳正反交 F1 杂种的上述生理指标介于双亲值之间 ,且偏向其母本。相关分析表明 ,D1蛋白量与 Fv/Fm 或 AQY之间有极显著的正相关关系 ,与 (A+Z) /(A+Z+V)或 Pr/Pn 或 q N 之间有显著的负相关关系 ,(A+Z) /(A+Z+V)与 q N 之间有极显著的正相关关系。叶黄素循环抑制剂 DTT使午间强光下玉米黄质的含量明显降低 ,结果导致 D1蛋白更多地降解。上述证据证明 ,质基因编码的 D1蛋白水平、稳定性是水稻不同基因型间叶黄素循环和 CO2 交换特性差异的生理基础 。

To elucidate the protective mechanisms against photodamage in photosynthetic apparatus of rice, the difference in traits related to xanthophyll cycle, chlorophyll fluorescence and photosynthetic CO 2 exchange among indica japonica hybrids and their parents under midday strong light were studied. Obviously diurnal variation of apparent quantum yield (AQY), D1 protein content, ratio of photorespiration/photosynthesis (P r/P n), PS Ⅱ photochemical efficiency (F v/F m),non photochemical quenching (q N) and xanthophyll cycle[content of violaxanthin(V), antheraxanthin(A), and zeaxanthin(Z)] in leaves of different genotype rice were observed. Japonica rice kept higher D1 protein content, F v/F m and AQY, but lower level of (A+Z)/(A+Z+V), P r/P n and q N, as compared with indica rice. However, the physiological parameters mentioned above in reciprocal cross F 1 hybrids were between those of their parents, but closed to their maternal lines. The lower AQY and F v/F m and higher (A+Z)/(A+Z+V) and P r/P n in indica/japonica F 1 hybrids than in japonica/indica F 1 hybrids were depended on different source of their plastid genes. Data processing showed that markedly positive correlation between D1 protein content and F v/F m or AQY and negative correlation between D1 protein content and (A+Z)/(A+Z+V), P r/P n or q N were presented. Besides, a positive correlation between (A+Z)/(A+Z+V) and q N was also observed. Furthermore, there was less zeaxanthin content and , as a result, more net loss of D1 protein in the leaves treated with dithiothretol (DTT) than those in control leaves under midday strong light. According to these results, the levels and stabilities of D1 protein encoded by plastid gene from maternal line were proposed as the main physiological basis of the difference in characteristics related to xanthophyll cycle, chlorophyll fluorescence and photosynthetic CO 2 exchange among different genotypes of rice, and the xanthophyll cycle in leaves played an important role in protecting photosynthetic apparatus against photodamage.