NaCl胁迫下交替呼吸途径对叶绿素含量及其荧光特性的影响

摘要

以菜豆幼苗作为试验材料,分析了NaCl胁迫下交替呼吸对叶绿素含量以及叶绿素荧光特性变化特征的影响,以探讨交替呼吸途径在逆境下的生理学作用以及植物在盐胁迫下光系统Ⅱ(PSⅡ)的调节作用机制.结果表明:(1)随着NaCl胁迫浓度(0、100、200、300 mmol/L)的增高,菜豆幼苗叶片叶绿素含量显著下降,叶片光系统Ⅱ(PSⅡ)潜在最大光化学量子效率(Fv/Fm)、光适应下最大光化学效率(Fv′/Fm′)、PSⅡ光适应下实际光化学效率[Y(Ⅱ)]和光化学荧光猝灭(qP)与对照相比均显著性下降,而非光化学猝灭(NPQ)较对照组显著增加,同时交替呼吸容量在NaCl胁迫下也显著上升.(2)与单独NaCl胁迫相比,在NaCl胁迫下施加交替呼吸的抑制剂水杨基氧肟酸(SHAM)会导致菜豆幼苗叶片叶绿素含量、Fv/Fm、Fv′/Fm′、Y(Ⅱ) 和qP进一步显著下降、NPQ进一步显著增加.研究认为, NaCl胁迫导致菜豆叶片光系统Ⅱ光化学效率下降和光能耗散增加,交替呼吸途径可有效缓解NaCl胁迫下菜豆叶绿素含量的减少以及光系统Ⅱ光化学反应效率的下降.%By using the leaves of bean seedling, we studied the effects of alternative respiratory pathway on the chlorophyll content and the chlorophyll fluorescence characteristics under NaCl stress, to investigate the physiological effects of altemative respiratory pathways under stress and the regulation of photosystem Ⅱ(PSⅡ) in plants under salt stress.The results showed that: (1) the treatment of NaCl with increased concentration (0、100、200、300 mmol/L) caused significant decrease of the chlorophyll content in bean seedling leaves.The ratio of Fv/Fm (the potential maximal photochemical efficiency of PSⅡ), Fv′/Fm′ (the maximum quantum efficiency of PSⅡ photochemistry at illumination), Y(Ⅱ) (effective photochemical quantum yield of PSⅡ photosynthetic), and qP (photochemical quenching coefficient).However, the levels of NPQ (non-photochemical quenching) were significantly decreased.Meanwhile, the capacity of the alternative respiratory pathway was increased significantly.(2) The NaCl-stressed leaves, which were pretreated with salicylhydroxamic acid (the specific inhibitor of the alternative respiratory pathway, SHAM), exhibited lower levels of chlorophyll content, Fv/Fm, Fv′/Fm′, Y(Ⅱ) and qP, but higher levels of NPQ than the leaves subjected to NaCl stress alone.These results suggested that NaCl stress can cause a decrease of the photochemical efficiency of photosystem Ⅱ and an increase in dissipation of light energy in the bean leaves, and the alternate respiration pathway could play a role in alleviating the decreas of chlorophyll content and photochemical efficiency of photosystem Ⅱ (PSⅡ) under NaCl stress.