Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
Photosynth Res. 2013 Sep;116(1):93-105. doi: 10.1007/s11120-013-9908-0. Epub 2013 Aug 14.
To gain a better understanding of how photosynthesis is adapted under altered gravity forces, photosynthetic apparatus and its functioning were investigated in rice (Oryza sativa L.) seedlings grown in a random positioning machine (RPM). A decrease in fresh weight and dry weight was observed in rice seedlings grown under RPM condition. No significant changes were found in the chloroplast ultrastructure and total chlorophyll content between the RPM and control samples. Analyses of chlorophyll fluorescence and thermoluminescence demonstrate that PSII activity was unchanged under RPM condition. However, PSI activity decreased significantly under RPM condition. 77 K fluorescence emission spectra show a blue-shift and reduction of PSI fluorescence emission peak in the RPM seedlings. In addition, RPM caused a significant decrease in the amplitude of absorbance changes of P700 at 820 nm (A 820) induced by saturated far-red light. Moreover, the PSI efficiency (Φ I) decreased significantly under RPM condition. Immunoblot and blue native gel analyses further illustrate that accumulation of PSI proteins was greatly decreased in the RPM seedlings. Our results suggest that PSI, but not PSII, is down-regulated under RPM condition.
为了更好地了解光合作用在改变的重力环境下是如何适应的，我们研究了在随机定位机（RPM）中生长的水稻（Oryza sativa L.）幼苗中的光合作用装置及其功能。在 RPM 条件下生长的水稻幼苗的鲜重和干重均下降。RPM 和对照样品之间的叶绿体超微结构和总叶绿素含量没有明显变化。叶绿素荧光和热致发光分析表明，PSI 活性在 RPM 条件下保持不变。然而，PSI 活性在 RPM 条件下显著下降。77K 荧光发射光谱显示 RPM 幼苗中 PSI 荧光发射峰发生蓝移和减少。此外，RPM 导致由饱和远红光诱导的 P700 在 820nm 处的吸收变化幅度（A820）显著降低。此外，PSI 效率（ΦI）在 RPM 条件下显著下降。免疫印迹和蓝色 native 凝胶分析进一步表明，PSI 蛋白在 RPM 幼苗中的积累大大减少。我们的结果表明，PSI 而不是 PSII 在 RPM 条件下被下调。
