不同品种小麦PSⅠ颗粒光抑制过程的光谱学比较研究

Comparative Spectroscopic Studies on the Photoinhibition Process in Photosystem Ⅰ Complex from Two Wheat Cultivars

用不同品种小麦 (TriticumaestivumL .)“京 411”和“小偃 5 4”中分离纯化的PSⅠ颗粒为材料 ,研究了小麦PSⅠ光破坏过程的光谱特性 ,并比较了两者的异同。结果表明 ,强光导致PSⅠ中色素的破坏 ,特别是 6 83nm状态的Chla分子对强光敏感。光照过程中 ,荧光光谱的变化表明 ,光破坏还导致了PSⅠ中能量传递过程的破坏。“小偃 5 4”PSⅠ颗粒在光照初期 ,长波长状态的Chla分子的吸收度值略有下降后 ,可保持较长时间的稳定水平 ,在 40min后才开始明显下降 ,同时 ,在强光照射的初期荧光发射增强 ;而“京 411”PSⅠ颗粒在光抑制过程中没有这些变化。推测“小偃 5 4”PSⅠ可能通过将能量较多地分配给长波长状态的叶绿素分子和保持相对较少的天线色素分子 ,以避免过多的能量向P70 0反应中心传递 ,而起到保护作用。

The photodamage processes of PSⅠ particles isolated from two wheat cultivars 'Jing 411' and 'Xiaoyan 54' were studied by comparing the difference in spectroscopic properties. It was found that high light intensity caused the damage of pigments in PSⅡ, especially Chl a molecules with maximum absorption at 683 nm is very sensitive to high light. The change in fluorescence spectra revealed that photodamage also led to the damage of the process of energy transfer in PSⅠ. In the PSⅠ particles 'Xiaoyan 54', the absorption of Chl a molecules at 683 nm slightly decreased at the beginning of illumination and meanwhile the fluorescence become stronger, but the absorption become stable rather long, and declining after 40 min. On the other hand, PSⅠ particles of 'Jing 411' showed no such changes during the process of photodamage. Presumably in PSⅠ of 'Xiaoyan 54', excessive energy was distributed to long wave chlorophyll molecules and the number of antenna pigment molecules was less, so that less energy was transferred to the reaction center P700 and thus it was protected. This is the possible reason why 'Xiaoyan 54' was more resistant to photooxidation.