草莓叶片光合作用对强光的响应及其机理研究

Response of strawberry leaves photosynthesis to strong light and its mechanism.

用便携式调制叶绿素荧光仪和光合仪研究了强光下草莓叶片荧光参数及表观量子效率的变化.结果表明,Fm、Fv/Fm、PSⅡ无活性反应中心数量和QA的还原速率在强光下降低,在暗恢复时升高;而PSⅡ反应中心非还原性QB的比例在强光下增加,在暗恢复时降低.上述荧光参数的变化幅度均以强光胁迫或暗恢复的前10min最大.强光下ΦPSII、ETR和qP先升高后降低,但qN先大幅度降低,然后小幅回升.强光处理4h后,丰香和宝交早生的表观量子效率(AQY)分别降低了209%和375%;qE(能量依赖的非光化学猝灭)为NPQ(非光化学猝灭)的最主要成分.强光胁迫下丰香的Fo、Fm、Fv/Fm、ΦPSII、ETR和AQY的变化幅度均明显比宝交早生小.DTT处理后,草莓叶片的Fm和Fv/Fm明显降低,Fo显著升高.可以认为,依赖叶黄素循环和类囊体膜质子梯度两种非辐射能量耗散在草莓叶片防御光损伤方面起着重要作用,丰香的光合机构比宝交早生更耐强光.

In this paper,PAM-2000 portable chlorophyll fluorometer and HCM-1000 photosynthesis measurement system were applied to measure the apparent quantum efficiency(AQY),initial fluorescence (Fo),maximal photochemical efficiency of PSII (Fv/Fm),maximal fluorescence(Fm),photochemical quenching(qP),non-photochemical quenching(qN),actual quantum yield of PSⅡ electron transport (Φ_~PSII ),electron transport rate (ETR),amount of inactive PSⅡ reaction centers (Fi-Fo),Q_A reduction rate,proportion of Q_B-non-reducing PSⅡ reaction centers[(Fi-Fo)/(Fp-Fo)],and energy-dependent quenching (qE),photoinhibitory quenching (qI) and state-transition quenching (qT) of non-photochemical quenching of strawberry leaves.The results showed that the Fv/Fm,Fm,Fi-Fo and Q_A reduction rate decreased in strong light and increased during subsequent dark recovery,but (Fi-Fo)/(Fp-Fo) was in reverse.They changed drastically within the first 10 minutes in strong light or in subsequent darkness.In strong light,Φ_~PSII ,ETR and qP increased firstly and then decreased,while qN decreased drastically firstly and then increased slightly.After exposure to strong light for 4 hours,the AQY of two varieties “Toyonoka' and “Houkouwase' decreased by 20.9% and 37.5%,respectively,and qE was 89.1% and 87.1%,respectively in NPQ (qE+qI+qT).In strong light,“Toyonoka' showed less changes than “Houkouwase' in Fo,Fv/Fm,Fm,ETR,Φ_~PSII and AQY.After treated with DTT,the Fv/Fm and Fm were lower,but Fo was much higher than control.It is deduced that in strong light,xanthophyll cycle-dependent non-radiative energy dissipation and pH-dependent heat dissipation could play an important protective role against photo-damage to the photosynthetic apparatus in strawberry leaves.