强光及外源活性氧对莴苣叶绿素荧光的影响

Effects of Strong Light and Exogenous Active Oxygen Species on Chlorophyll Fluorescence in Lettuce

莴苣叶绿体在强光处理下发生先抑制，主要表现为叶绿素荧光参数Fv／Fm和ΦPSⅡ降低；外源活性氧H2O2、O2·OH和1O2均能引起叶绿体PSⅡ光化学效率Fv／Fm不同程度的下降，其中以1O2影响最明显；H2O2在诱导叶绿体荧光猝灭过程中，引起荧光产量降低，而使qp、qN、ΦPSⅡ、KD上升；在H2O2诱导的叶绿体荧光猝灭过程中，Fe2+能使qN和KD低于对照；由于1O2的产生对PSⅡ反应中心造成了损伤，引起qp和ΦPSⅡ下降。

The relationship between active oxygen species and photoinhibitionin chloropasts by using chlorophyll fluorescence technique has been studied.The results indicated that PS Ⅱ photochemistry efficiency(Fv/Fm) and PS Ⅱelecbo transport quantum efficiency (PSⅡ ) decreased in lettuce (Lactucasativa L. ) chloroplasts along with an increase in strong ligh treatment time (Fig. 1). Compared to the results of low ligh treatment, strong light lowered significantly Fv/fm and ere (Fig. 2), which showed tha photinhibition took place. Exogenous active oxygen species decreased Fv/Fm to different degrees, 1 O2 decreased significantly Fv/Fm and PSⅡ (Fig. 3) During the induction of chlorophyll fluorescence quenching by exogenous active oxygen species, H2O2 lowed the chlorophyⅡ fluorescence yield, and increased qP PS Ⅱ qN andKD(Fig- 4). Fe2+ nated with H2O2 to form. oH which damagd the photosynthehc apparatus to a certain extent, and decreased qN and KD (Fig 5 ) - As 1 O2was highly destructive it decreased qpand PS Ⅱ during the indution of chlorophyll fluorescence quenching (Fig. 6). Based on the results it is deduced that the occurrence of photinhibihon in chloroplasts is related to the production of active oxygnn peies in strong light.