Wang Yuwen, Zhang Jingjing, Yu Jing, Jiang Xiaohan, Sun Lingang, Wu Min, Chen Guoxiang, Lv Chuangen
Jiangsu Key Laboratory of Biodiversity and Biotechnology, Life Sciences College, Nanjing Normal University, Nanjing 210023, China.
Jiangsu Key Laboratory of Biodiversity and Biotechnology, Life Sciences College, Nanjing Normal University, Nanjing 210023, China; Zijin College, Nanjing University of Science and Technology, Nanjing 210023, China.
Plant Physiol Biochem. 2014 Sep;82:194-201. doi: 10.1016/j.plaphy.2014.06.005. Epub 2014 Jun 18.
Photosynthetic activities and thylakoid membrane protein patterns as well as the ultrastructure of chloroplasts in flag leaves were investigated during the senescence processes in high-yield hybrid rice LYPJ under field condition. The earlier decrease of PS I activity than PS II in LYPJ was primarily due to the significant degradation of PS I chlorophyll-protein complex. The degradation rate for each chlorophyll-protein complex was different and the order for the stability of thylakoid membrane complexes during flag leaf senescence in rice LYPJ was: LHCII > OEC > PSII core antenna > PSII core > PSI core > LHCI, which was partly supported by the BN-PAGE gel combined with immunoblot analysis. A decrease in the chlorophyll a/b ratio at the senescence stage was observed to coincide with stability of the LHCII subunits. Ultrastructural investigations revealed that the chloroplasts have large loosen stacking grana without interconnecting stroma thylakoids during the senescence processes. It was hypothesized that the stability of grana thylakoids harboring the major LHCII under high radiation condition in summer might played a key role in the dissipation of excess light energy. This alternative strategy would protect photosynthetic apparatus from photodamage and might be causally related to the high yield of this rice cultivar.
在田间条件下，对高产杂交水稻LYPJ衰老过程中剑叶的光合活性、类囊体膜蛋白模式以及叶绿体超微结构进行了研究。LYPJ中PS I活性比PS II更早下降，主要是由于PS I叶绿素 - 蛋白复合体的显著降解。各叶绿素 - 蛋白复合体的降解速率不同，水稻LYPJ剑叶衰老过程中类囊体膜复合体稳定性顺序为：LHCII > OEC > PSII核心天线 > PSII核心 > PSI核心 > LHCI，这在一定程度上得到了BN - PAGE凝胶结合免疫印迹分析的支持。观察到衰老阶段叶绿素a/b比值的下降与LHCII亚基的稳定性一致。超微结构研究表明，在衰老过程中叶绿体有大的松散堆积的基粒，没有连接的基质类囊体。据推测，在夏季高辐射条件下，含有主要LHCII的基粒类囊体的稳定性可能在过量光能的耗散中起关键作用。这种替代策略将保护光合机构免受光损伤，可能与该水稻品种的高产有因果关系。
