NaCl胁迫加重强光胁迫下超大甜椒叶片的光系统II和光系统I的光抑制

快速叶绿素荧光动力学可以在无损情况下探知叶片光合机构的损伤程度, 快速叶绿素荧光测定和分析技术(JIP-test)将测量值转化为多种具有生物学意义的参数, 因而被广泛应用于植物光合机构对环境的响应机制研究。该文研究了超大甜椒(Capsicum annuum)幼苗在强光及不同NaCl浓度胁迫下的荧光响应情况。与单纯强光胁迫相比, NaCl胁迫引起了叶绿素荧光诱导曲线的明显改变, 光系统II (PSII)光抑制加重, 同时PSII反应中心和受体侧受到明显影响, 而且高NaCl浓度胁迫下PSII供体侧受伤害明显, 同时PSI反应中心活性(P700⁺)在盐胁迫下明显降低。这些结果表明, NaCl胁迫会增强强光对超大甜椒光系统的光抑制, 并且浓度越高抑制越明显, 但对PSI的抑制作用低于PSII。高NaCl浓度胁迫易对PSII供体侧造成破坏, 且PSI光抑制严重。

NaCl stress aggravates photoinhibition of photosystem II and photosystem I in Capsicum annuum leaves under high irradiance stress

Aims Our aim was to study effects of salt stress and high irradiance on photoinhibition of photosystem II (PSII) and I (PSI) in leaves of sweet pepper (Capsicum annuum).
Methods We used the chlorophyll a fluorescence technique and the JIP-test to study the responses of sweet pepper leaves to salt stress with different NaCl concentrations and under high irradiance (1 000 μmol·m^–2·s^–1).
Important findings The chlorophyll a fluorescence induction curves changed greatly as induced by NaCl stress under high irradiance, and photoinhibition of PSII was aggravated with apparent effects on PSII reaction centers and the acceptor side. Also, the donor side of PSII was damaged by high NaCl concentration under high irradiance. Additionally, the activity of PSI reaction centers (P700⁺) was inhibited by NaCl stress under high irradiance. Therefore, NaCl stress could aggravate photoinhibition of sweet pepper photosystem under high irradiance, and photoinhibition was greater with higher NaCl concentration. However, PSI photoinhibition was less than PSII photoinhibition. Additionally, high NaCl concentration could induce both damage to PSII donor sides and PSI.