Changes in photosynthetic characteristics and photosystem stoichiometries in the lower leaves in rice seedlings
Changes in photosynthetic characteristics and photosystem stoichiometries in the lower leaves in rice seedlings
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水稻幼苗下部叶片光合特性和光系统化学计量的变化
DOI：
10.1016/s0168-9452(99)00132-6
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Y. Sugimura
中科院分区：
文献类型：
--
作者：
J. Yamazaki;Y. Kamimura;M. Okada;Y. Sugimura
本文研究了水稻叶片叶绿素a/B比值、电子传递、电子载体和光系统化学计量的变化。叶绿素a/B的比例是已知的，从顶部到底部的叶子逐渐减少，这表明相对于两个光系统的反应中心复合物的LHC II的丰度增加。结果表明：（1）从上到下，水稻冠层的光合活性和叶绿素含量逐渐降低，叶绿素a/B比值也从3.7下降到3.0;（2）以Chl含量为指标，C-550和Cyt f含量下降，而P-700含量无明显变化。结果表明，随着叶绿素含量的增加，PS Ⅱ/PS Ⅰ比值显著降低，Cyt f水平显著降低，而Cyt f的全链电子传递无损失，PS Ⅱ α丰度增加，而QA光还原和P-700光氧化速率常数逐渐降低。根据这些结果，我们推测水稻幼苗下部叶片Chla/B比值的下降与PS II/PS I比值的下降之间存在补偿关系。
Changes in the Chl a/b ratio, electron transport, electron carriers, and photosystem stoichiometries were examined in rice leaves in the present study. The Chl a/b ratio is known to decrease gradually from the top to the bottom leaves, indicating a increase in the abundance of LHC II relative to the reaction center complexes of the two photosystems. We used juvenile rice canopy and obtained the following results: (1) the photosynthetic activity and Chl content per leaf area decreased from the top to the bottom leaves, the Chl a/b ratio also declined from 3.7 to 3.0; (2) when determined on the basis of Chl content, C-550 and Cyt f content decreased, but there was no loss of P-700, Consequently, the PS II/PS I ratio significantly decreased; (3) on the basis of mmol Chl, the levels of Cyt f dramatically decreased and, therefore, no loss was observed for whole chain electron transport per Cyt f; and (4) the percentage abundance of PS IIα increased, but the rate constants of QAphotoreduction and P-700 photooxidation gradually decreased. From these results, we hypothesize that there is a compensatory relationship between the decline in the Chl a/b ratio and that in the PS II/PS I ratio in the lower leaves in rice seedlings.