玉米持绿与早衰品种叶片衰老过程中光化学活性的变化

Changes of Photochemistry Activity during Senescence of Leaves in Stay Green and Quick-Leaf-Senescence Inbred Lines of Maize

为了探讨不同衰老型玉米叶片在衰老过程中光化学反应及其对光合能力维持的贡献,本研究使用持绿玉米品种"齐319"和早衰玉米品种"黄早四",在控制的条件下,用乙烯利诱导离体叶片衰老,通过快速叶绿素荧光诱导动力学曲线(OJIP曲线)和820nm光吸收等技术,研究了衰老过程中叶片叶绿素含量、光合速率、光系统I(PSI)、光系统II(PSII)以及光合电子传递体活性的变化。结果表明,在衰老过程中,齐319叶片叶绿素含量和光合速率的下降速度明显慢于黄早四,是功能型持绿品种。玉米叶片的衰老伴随着OJIP曲线的J、I、K、L点荧光的增加,以及远红光诱导820nm光信号落差的下降。与齐319相比,黄早四叶片的OJIP曲线和820nm光吸收曲线的变化更剧烈。我们认为,在衰老过程中PSI和PSII光化学活性的快速下降和光合电子传递功能的衰退是玉米叶片光合能力迅速下降的重要原因之一。在此基础上,讨论了衰老过程中玉米叶片中与光合作用有关蛋白与光合能力下降的可能关系。

In order to explore the changes of photochemistry activity and the contribution of photochemistry activity to the main- tenance of photosynthetic capacity in maize leaves during senescence, the chlorophyll content, photosynthetic rate, PSI and PSII activities during senescence of leaves in the stay green maize （Zea mays L.） inbred line Qi 319 and the quick-leaf-senescence maize inbred line Huangzaosi were investigated by analyzing chlorophyll a fluorescence transient and 820 nm transmission. This study showed that both the chlorophyll content and the photosynthetic capacity in leaves decreased later and slower in Qi 319 than in Huangzaosi, indicating that Qi 319 is a functional stay-green inbred line. The L, K, J, and I steps of chlorophyll a fluorescence transient （OJIP transient） increased during senescence, which accompanied by a decrease in the amplitude of 820 nm transmission. Compared with Qi 319, the changes of OJIP transient and 820 nm transmission were more prominent in Huangzaosi. The results indicated that the quicker decrease in PSI and PSII photochemistry activities and severer deterioration of electron transfer activity are two of the most important reasons to cause earlier senescence in quick-leaf-senescence maize inbred line Huangzaosi; and the synthetic capacity of photosynthesis related protein, especially the fast turn-over protein in leaves may be one of the factors in maintenance of the photosynthetic capacity.