午间强光胁迫下叶黄素循环对小麦叶片光合机构的保护作用

通过测定田间小麦叶片叶黄素循环组分，光合速率和叶绿素ａ荧光，探讨了叶黄素循环对小麦光合机构的保护作用，晴天中午强光下叶黄素库（Ｖ＋Ａ＋Ｚ）增大，叶黄素循环三组分转化百分率（Ａ＋Ｂ）／（Ｖ＋Ａ＋Ｚ）明显增加。弱光下无过剩光能，（Ａ＋Ｚ）／（Ｖ＋Ａ＋Ｚ）中午不增加。用二硫苏糖醇抑制叶黄素循环，中午强光照射２小时后光抑制加重。

The Role of Xanthophyll Cycle in Protecting the Photosyn-thetic Apparatus of Wheat Leaves against Midday High Light Stress

To investigate the role of the xanthophyll cycle in protecting the photosynthet-ic apparatus of wheat leaves from light stress, the carotenoid composition, photosynthetic rate andchlorophyll a fluorescence prarameter were measured. Under strong sunlight, the xanthophyllpool, namely violaxanthin antheraxanthin zeaxanthin (V A Z) and (A Z)/(V A Z)increased around noon. Under weak light without excess sunlight energy, (A Z)/(V A Z)did not increase during midday. Dithiothreitol (DTT) treatment reduced the (A Z) contentand exacerbated photoinhibition of photosynthesis under strong sunlight for 2 h. These resultsindicated that under field conditions with strong sunlight, the xanthophyll cycle can protect thephotosynthetic apparatus of wheat leaves from photodamage by the increased radiationless energydissipation.