硅对镉胁迫下烟草叶片PSⅡ叶绿素荧光特性的影响

Effects of silicon on chlorophyll fluorescence characteristics of PSⅡ in tobacco leaves under cadmium stress

为明确硅对镉胁迫下烟草叶片光系统Ⅱ(PSⅡ)叶绿素荧光特性的影响,以云烟87为材料,通过室内水培试验分析烟草PSⅡ快速叶绿素荧光诱导动力学特性。结果表明,镉胁迫可导致快速叶绿素荧光诱导动力学曲线(OJIP)发生变化,最小荧光值(Fo)和最大荧光值(Fm)显著降低。镉胁迫下最大光化学效率(Fv/Fm)、放氧复合体(OEC)、受体库容量(Sm)、电子传递量子产额(φEo)、单位面积反应中心数量(RC/CSo)和性能指数(PIabs)降低,K相相对可变荧光(Vk)、J相相对可变荧光(VJ)和QA还原速率(Mo)显著增加,说明镉胁迫导致烟草叶片光合机构完整性被破坏,单位PSⅡ反应中心数量发生变化,PSⅡ供、受体侧受到毒害,抑制光合电子传递。加硅处理的荧光动力学曲线基本与对照重合,OEC、Sm、φEo、RC/CSo、PIabs显著增加,Vk、VJ、Mo显著降低。因此,加硅处理能够稳定PSⅡ的结构和功能,缓解镉胁迫对烟草叶片光合机构的伤害,有利于光合电子的传递。

To study the effects of silicon on the chlorophyll fluorescence characteristics of photosystem Ⅱ(PSⅡ)in tobacco leaves under cadmium stress, an indoor hydroponic experiment was conducted to analyze the characteristics of fast chlorophyll fluorescence induction dynamics of PSⅡ in cv. Yunyan87. The results showed that the fast chlorophyll fluorescence induction dynamics curve(OJIP)changed under cadmium stress, and both the minimum fluorescence value(Fo)and maximum fluorescence value(F+m)significantly decreased. Under cadmium stress, the maximum photochemical efficiency(Fv/Fm), oxygen evolution complex(OEC), receptor library capacity(Sm),quantum yield for electron transport(φEo), density of reaction centers(RC/CSo)and performance index(PIabs)decreased. While the relative variable fluorescence at K-step(Vk), the relative variable fluorescence at J-step(V+J)and approximated initial slope of the fluorescence transient(Mo)significantly increased. These data indicated that cadmium stress damaged tobacco leaf’s photosynthetic integrity, altered the quantity of per PSⅡ reaction centers and the harmfulness to donor-and acceptor-side of PSⅡ and inhibited photosynthetic electron transmission. The fluorescence kinetic curves of Cd0.05+Si and Cd0.10+Si treatments coincided with that of the control. OEC, Sm,φEo, RC/CS+o and PIabs were significantly increased, while Vk, VJ and Mo significantly decreased. Therefore, Cd0.05+Si and Cd0.10+Si treatments stabilized the structure and function of PSⅡ, alleviated cadmium damage to photosynthesis of tobacco leaves and was beneficial to photosynthetic electron transport.