小麦旗叶光合功能衰退过程中PSII特性的研究

Study on Characteristics of PS II of Flag Leaves During Photosynthetic Functional Decline Process of Yangmai5 (Triticum aestivum L.)

小麦旗叶光合功能自然衰退过程中光合膜特性变化的观察结果表明 ,在光合功能可逆衰退阶段中 ,类囊体及PSII颗粒电子传递活性维持在较高水平 ,多肽组分也维持相对稳定。进入光合功能不可逆衰退阶段后 ,PSII活性呈快速下降趋势 ,PSII的OEC33kD、OEC17kD、CP4 3等组分均出现不同程度降解 ;在接近自然强光 (10 0 0、180 0μmolE·m-2 ·s-1)的光照处理下 ,不可逆阶段PSII活性下降的速度明显比可逆阶段快 ,人工极强光 (2 5 0 0、30 0 0μmolE·m-2 ·s-1)处理下 2个阶段PSII活性均显著下降 ;在光合功能衰退可逆阶段 ,与单纯光逆境胁迫相比较 ,高温强光逆境下PSII颗粒活性下降更加显著 ,OEC33kD、CP4 3也出现不同程度降解 ,在光合功能衰退不可逆阶段 ,由于PSII颗粒对光温敏感组分已基本降解 。

After flag leaf full expansion of wheat, the photosynthetic functional decline process was divided into reversible decline phase and irreversible decline phase. During the reversible decline phase, the photosynthetic membranes and PS II particles maintained higher electron transport activities. The polypeptide components of PS II particles remained relative steady. During the irreversible decline phase, there was a rapid decrease in electron transport activities. Small molecular polypeptides and OEC33kD, OEC17kD, CP43 of PS II particles were degraded. The decreases of thylakoid membrane and PS II particles electron transport activities in irreversible decline phase were significantly higher than that of reversible decline phase under strong illumination which was similar to natural climate. During the irreversible decline phase, the resistant capacity of thylakoid membranes to strong light stress was declined remarkably. The high temperature and strong light stress induced striking inactivation of PS II particles electron transport, and resulted in degradation of OEC33kD polypeptide and CP43 in reversible decline phase. During the irreversible decline phase, the PS II particles polypeptide components which were sensitive to light-temperature stress were degraded. The resistant capacity of PS II particles to light-temperature stress was obviously declined.