强光胁迫下外源NO对霍山石斛叶绿素荧光的影响

以兼性景天酸代谢CAM植物霍山石斛为材料,研究了强光胁迫条件下,外源一氧化氮(NO)对霍山石斛叶绿素荧光参数的影响。结果表明:在强光胁迫下,0.1mmol/L硝普钠(SNP,NO供体)处理显著缓解强光对霍山石斛光合系统Ⅱ(PSⅡ)的抑制,霍山石斛PSⅡ荧光参数潜在光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)、光化学猝灭系数qL、非光化学猝灭系数NPQ和ΦNPQ下降缓慢,且非光化学猝灭系数ΦNO值较低,PSⅡ反应中心恢复较快,说明该处理缓解了光抑制的发生,保护了光合机构免受强光胁迫的伤害,而经0.5mmol/L SNP处理后,霍山石斛的Fv/Fm、ΦpsⅡ、qL、NPQ和ΦNPQ下降程度增加,ΦNO也较高,恢复较慢,表明该处理加剧了PSⅡ反应中心光抑制的发生。可见,高浓度(0.5mmol/L)SNP处理可加剧光抑制的发生,而低浓度(0.1mmol/L)SNP处理可缓解强光对石斛的胁迫作用。

EFFECTS OF EXOGENOUS NITRIC OXIDE ON THE CHLOROPHYLL FLUORESCENCE PARAMETERS OF D. HUOSHANENSE UNDER INTENSIVE LIGHT STRESS

The effects of NO donor sodium nitroprusside(SNP) on the chlorophyll fluorescence parameters of Dendrobium huoshanense under intensive light stress were studied.The result showed that the photo inhibition on leaves of Dendrobium huoshanense were significantly alleviated by presoaking with 0.1mmol/L SNP,which caused less decrease of the chlorophyll parameters Fv/Fm、Φ_(psⅡ)、qL、NPQ and Φ_(NPQ).And the parameter Φ_(NO) was also relatively low,which indicated that the inhibition and damage to PSⅡ reaction center under intensive light was alleviated.The recovery of PSⅡ reaction center was fast.On contrary,the leaves presoaked in 0.5mmol/L SNP were severely inhibited by the intensive light,of which the parameters Fv/Fm、Φ_(psⅡ)、qL、NPQ and Φ_(NPQ) decreased significantly, and the Φ_(NO) was rather high,the recovery was slow,all of these showed the severe inhibition and damage to PSⅡ reaction center.In a word,the leaves presoaked in 0.5mmol/L SNP were severely inhibited photo inhibition under an intensive light,while presoaked in 0.1mmol/L SNP could alleviate the photo inhibition on the leaves of Dendrobium huoshanense significantly.