光抑制条件下水稻籼粳亚种及其正反交F_1杂种的PSⅡ光化学效率和CO_2交换特点

Photochemical Efficiency of PSⅡ and Characteristics of Photosynthetic CO 2 Exchange in Indica and Japonica Subspecies of Rice and Their Reciprocal Cross F 1 Hybrids Under Photoinhibitory Conditions

测定了水稻（ＯｒｙｚａｓａｔｉｖａＬ．）不同正反交组合的ＰＳⅡ电子传递活性、Ｄ１蛋白量、叶绿素ａ荧光、净光合速率（ＰＮ）、光呼吸速率（ＰＲ）、ＲｕＢＰＣａｓｅ／Ｏａｓｅ活性，并对ＲｕＢＰＣａｓｅ进行了动力学分析。结果表明：光抑制条件下粳（ｊａｐｏｎｉｃａ）亚种中Ｄ１蛋白净降解少，ＰＳⅡ电子传递活性和光化学效率高，表现耐光抑制，而籼（ｉｎｄｉｃａ）亚种则相反，籼、粳正反交Ｆ１的上述指标介于双亲值之间且偏向其母本。进一步观察它们的ＣＯ２交换特点，所有基因型水稻ＰＲ保持稳定、ＰＮ降低，因而ＰＲ／ＰＮ增加。与耐光抑制的粳亚种相比，对光抑制敏感的籼亚种中ＰＮ降低较多、ＰＲ／ＰＮ增加较多。正反交Ｆ１杂种的ＰＲ／ＰＮ介于双亲值之间且偏向其母本。ＣＯ２交换的关键酶ＲｕＢＰＣａｓｅ／Ｏａｓｅ活性和ＲｕＢＰＣａｓｅ动力学参数没有变化且在基因型间无差异。相关分析表明，Ｄ１蛋白量与Ｆｖ／Ｆｍ、ＰＲ／ＰＮ的相关系数分别为０．９５０１和－０．９７６８。看来，质基因编码的Ｄ１蛋白是籼粳杂种稻光抑制特性及其生理遗传的分子基础。

To elucidate photoinhibitory characteristics and their genetic background in rice (Oryza sativa L.), PSⅡ electron transport activities, D1 protein contents, chlorophyll a fluorecence parameters, net photosynthetic rates ( P N ), photorespiratory rates ( P R ) and RuBPCase/Oase activities were measured, and kinetic analysis of RuBPCase was carried out in indica and japonica subspecies of rice and their reciprocal cross F 1 hybrids after photoinhibitory treatment in 21% O 2 and CO 2 free gases under a PFD of 1000 μmol photons·m -2 ·s -1 for 3 h. The results are as follows: Japonica rice, keeping less net degradation of D1 protein and maintaining higher PSⅡ electron transport activities and photo chemical efficiency of PSⅡ ( F v/F m ), was more tolerant to photo inhibition as compared with indica rice. However, the D1 protein contents, PSⅡ electron transport activities and F v/F m in their reciprocal cross F 1 hybrids, though lying between the values of their parents, were closer to those in their maternal lines rather to their paternal lines. Characteristics of photosynthetic CO 2 exchange were further observed. The P R was relatively stable, yet the P N decreased obviously and, as a results, the P R/P N increased in all genotypes. There were more decrease in P N and more increase in P R/P N in photoinhibition sensitive indica than in the photoinhibition tolerant japonica. However, the P R/P N in the reciprocal cross F 1 hybrids, though lying between the values of their parents, was closer to that in their maternal lines than to paternal lines. No obvious changes were observed in the activities of RuBPCase/Oase, K m (CO 2) and V max (CO 2) of RuBPCase in indica and japonica rice and their reciprocal cross F 1 hybrids before and after photoinhibitory treatment. Furthermore, markedly positive correlation between D1 protein contents and F v/F m ( r =-0.9501), and negative correlation between D1 protein contents and P R/P N (r = 0.9768 ) were demons trated. These results infer that the D1 protein encoded by the plastid gene from maternal line was the molecular basis of photoinhibitory characteristics and their physiological inheritance.