臭氧胁迫下不同光强与温度处理对‘赤霞珠’葡萄叶片PSⅡ光化学活性的影响

Effects of Different Light Intensity and Temperature on PSⅡ Photochemical Activity in ‘Cabernet Sauvignon' Grape Leaves Under Ozone Stress

【目的】自然界中臭氧与强光和高温逆境因素往往同时存在,探讨光强和温度及臭氧的交叉胁迫对葡萄叶片光系统功能的伤害机制,为生产上通过调控光照、温度缓解臭氧对葡萄的危害提供理论依据。【方法】以盆栽‘赤霞珠’葡萄为试验材料,利用叶绿素荧光动力学技术,研究(120±20)nL·L^(-1)的臭氧浓度下,不同光强(800、1 600μmol·m^(-2)·s^(-1))与温度(26℃、40℃)处理对光系统Ⅱ光化学活性的影响。【结果】臭氧胁迫下40℃的高温和1 600μmol·m^(-2)·s^(-1)的强光均可以显著降低叶片最大光化学效率(F_v/F_m)、线性电子传递速率(ETR)、单位面积有活性反应中心的数量(RC/CS_m)以及光化学淬灭系数(q_P),同时降低了光系统I激发能分配系数(α),增大了光系统Ⅱ激发能分配系数(β),导致两个光系统之间的激发能分配严重偏离平衡,造成了光系统Ⅱ的伤害,1 600μmol·m^(-2)·s^(-1)的强光影响大于40℃的高温影响,强光、高温与臭氧复合胁迫对葡萄叶片影响最为严重。其中臭氧、适光、高温(T2)和臭氧、强光、适温(T3)处理后的叶片PSⅡ最大光化学量子产量F_v/F_m值分别比臭氧、适光、适温处理(T1)降低了10.3%和38.8%,臭氧、强光、高温(T4)处理后F_v/F_m降幅最大,达到54.8%。T2、T3和T4处理后叶片PSⅡ的潜在活性F_v/Fo分别比T1降低了30.4%、69.6%和80.3%。与T1相比,T2、T3和T4处理后的叶片单位面积内有活性反应中心的数量RC/CS_m值分别降低了26.8%、68.4%和70.2%,T2、T3和T4处理后的叶片Ψo值分别比T1降低了11.2%、21.6%、40.8%。T2、T3及T4处理葡萄叶片实际光化学效率F_v'/F_m'值分别比T1降低了7.9%、22.1%和42.3%;同时,各处理显著降低了植物叶片线性电子传递速率ETR,T4处理降幅最大,比T1降低了62.5%,T2和T3处理分别降低了17.6%和37.5%。T2、T3和T4的叶片光化学淬灭q_P值分别比T1降低了10.7%和19.8%和39.5%。T2、T3和T4处理后葡萄叶片吸收的光能用于光化学反应的比例均有所下降,分别比T1处理降低18.8%和38.8%和62.0%。与T1相比,T2、T3和T4处理吸收的光能用于热耗散的比例均增加,增幅分别为15.9%、36.2%和60.5%,同时,过剩光能分别增加12.5%、19.1%和25.2%。不同处理显著降低了叶片PSI激发能分配系数(α),与T1相比,T2、T3和T4分别下降了6.6%和12.8%和25.1%;同时,不同处理后叶片PSⅡ激发能分配系数(β)均显著上升,T2、T3、T4分别比T1升高了4.5%、8.7%、17.1%。光系统间激发能分配不平衡偏离系数(β/α–1)变化趋势与PSⅡ激发能分配系数一致,T2、T3处理的β/α–1分别比T1升高37.7%和78.3%,T4升高幅度最大,达到187.8%。【结论】温度、光照逆境增加了PSⅡ活性对臭氧胁迫的敏感性,以强光胁迫的作用效果更显著,而高温、强光胁迫下臭氧对PSⅡ活性抑制程度最大。

【Objective】Ozone stress,high light and high temperature usually exist simultaneously in nature,but little is known about the effect of the combination of three stress factors on plants.So the combined effects of different temperature(26,40℃),light(800,1 600μmol·m-2·s-1)and ozone treatments on the operation of photosynthetic apparatus were investigated to reveal the mechanism of inhibition of photosynthesis,which provided a theoretical basis for reducing ozone injury by regulating the light and temperature.【Method】Potted Cabernet Sauvignon grapes were used as materials to be treated with different temperatures(26,40℃),two kinds of light intensities(800,1 600μmol·m-2·s-1)combined with(120±20)nL·L-1 ozone.Chlorophyll a fluorescence parameters were analyzed to investigate the effects of different treatments on the PSⅡfunction.【Result】40℃and 1 600μmol·m-2·s-1 both significantly decreased the maximal photochemical efficiency(Fv/Fm),linear electron transport rate(ETR),the unit area number of reactive centers(RC/CSm)and photochemical quenching coefficient(qP)of leaf under ozone stress.At the same time,the decreased excitation energy partition coefficient(α)of PSI and increased excitation energy partition coefficient(β)of PSⅡinduced a serious imbalance of excitation energy distribution between the two photosystems and caused the damage of photosystemⅡ,and the influence of strong light intensity(1 600μmol·m-2·s-1)was more significant.The maximal photochemical efficiency(Fv/Fm)under T2 and T3 treatment decreased 10.3%and 38.8%than that under T1 treatment,Fv/Fm under T4 treatment decreased most for54.8%.PSⅡquantum efficiency Fv/Fo under T2,T3 and T4 treatment decreased 30.4%,69.6%and 80.3%than that of T1 treatment,respectively.The number of reaction centers per unit area(RC/CSm)under T2,T3 and T4 treatment decreased 30.4%,69.6%and80.3%than that of T1 treatment,respectively,and the probability of that a trapped exciton the moves an electron further than QA by trapped exciton(Ψo)under T2,T3 and T4 treatment decreased 11.2%,21.6%and 40.8%than that of T1 treatment,respectively.The effective photochemical efficiency Fv’/Fm’under T2,T3 and T4 treatment decreased 7.9%,22.1%and 42.3%than that under T1 treatment,respectively.Linear electron transport rate(ETR)of T4 decreased most(decreased 62.5%than that under T1 treatment),and ETR under T2 and T3 treatment decreased 17.6%and 37.5%than that of T1 treatment,respectively.The photochemical quenching coefficient(qP)under T2,T3 and T4 treatment decreased 10.7%,19.8%and 39.5%than that of T1 treatment,respectively.The photochemical reactions share under T2,T3 and T4 treatment decreased 18.8%,38.8%and 62.0%than that of T1 treatment,respectively.While the antennal heat dissipation share under T2,T3 and T4 treatment increased 15.9%,36.2%and 60.5%than that of T1 treatment,respectively,and the excess light energy share of T2,T3 and T4 treatment increased 12.5%,19.1%and 25.2%than that of T1 treatment,respectively,the excitation energy partition coefficient(α)of PSI under T2,T3 and T4 treatment decreased 6.6%,12.8%and 25.1%than that under T1 treatment,respectively,and the excitation energy partition coefficient(β)of PSⅡunder T2,T3 and T4 treatment increased 4.5%,8.7%and 17.1%than that under T1 treatment,respectively,and the change trend of imbalance of partitioning of excitation energy between PSⅠand PSⅡ(β/α-1)was consistent with the change of the excitation energy partition coefficient,β/α-1 under T2,T3 and T4 increased 37.7%,78.3%and 187.8%than that under T1 treatment.【Conclusion】Temperature and light stress increased the sensitivity of PSⅡactivity to ozone stress,and the influence of light stress was more significant,while high temperature and high light stress caused serious damage to photosystemⅡ.