脓青素对光抑制条件下菠菜叶绿体的保护作用

The Protective Effects of Pyocyanine Against Photoinhibition in Spinach Chloroplasts

在有氧条件下，脓青素可以缓解强光对菠菜叶绿体电子传递的抑制作用。加入解联剂尼日利亚菌素消除跨膜质子梯度会加剧叶绿体的光抑制，但脓青素的保护作用并不消失。脓青素对光系统Ⅰ与光系统Ⅱ均表现出保护作用，但对ＰＳⅡ的保护在光抑制初期较明显；在厌氧条件下，脓青素加剧叶绿体的光抑制，引起ＤＣＩＰ光还原与水到ｐ－ＢＱ电子传递活力的降低。推测脓青素可能通过促进细胞色素ｂ５５９介导的ＰＳⅡ循环电子传递，减轻了叶绿体的光抑制。

Under aerobic conditions, pyocyanine alleviated strong-light-inducedinhibition of electron transport inspinach chloroplasts (Fig. 1 ). Althoughnigericin, an uncoupler eliminatingtransmembrane proton gradient, aggravated photoinhibition, it did not abolishthe protective effect of pyocyanine(Fig. 3 ). Pyocyanine could protectboth photosystem Ⅰ and photosystemⅡ, but the protection of photosystemⅡ was observbed only at the earlystage of photoinhibition (Fig. 6 ). Under anaerobic conditions, pyocyanineaggravated photoinhibition in chloroplasts and lowered the activity of DCIPphotoreduction (Fig. 7) and the rate ofelectron transport from water to P-BQ(Fig. 8). We assume that pyocyaninealleviates photoinhibition in chloroplastsby promoting cyclic electron transportaround photosystem Ⅱ mediated by cytochrome b559.