信号分子水杨酸减缓干旱胁迫对紫御谷光合和膜脂过氧化的副效应

Signal chemical salicylic acid mitigates the negative effects of drought on photosynthesis and membrance lipid peroxidation of purple majesty

为研究信号分子水杨酸(SA)对干旱胁迫下紫御谷光合和膜脂过氧化的影响,为SA应用于紫御谷抗旱育苗提供理论依据,测定分析了SA处理对干旱胁迫下紫御谷幼苗叶片光合和膜脂过氧化相关指标的变化。结果表明:(1)干旱胁迫破坏了紫御谷叶绿体的膜结构,使基粒数量明显减少,垛叠不明显,排列比较松散,而SA处理能在一定程度上保护叶绿体的膜结构。(2)干旱胁迫降低了紫御谷幼苗叶片的叶绿素b和总叶绿素含量,而SA处理能提高干旱胁迫下紫御谷幼苗叶片的叶绿素a、叶绿素b、总叶绿素和胡萝卜素含量。(3)干旱胁迫降低了叶片的净光合速率、气孔导度、蒸腾速率、光饱和点和暗呼吸速率,增加了叶片的光补偿点、CO2饱和点、CO2补偿点和光呼吸速率,而SA处理则增加了紫御谷幼苗叶片的净光合速率、气孔导度、光饱和点和暗呼吸速率,降低了紫御谷幼苗叶片的光补偿点、CO2饱和点、CO2补偿点和光呼吸速率。(4)干旱胁迫降低了紫御谷幼苗叶片的Fv/Fm和ΦPSⅡ,显著增加了叶片的相对电导率和丙二醛含量,而SA处理则增加了幼苗叶片的Fv/Fm和ΦPSⅡ,降低了叶片的相对电导率和丙二醛含量。表明:信号分子水杨酸能够有效减缓干旱胁迫对紫御谷光合和膜脂过氧化的影响。

Purple majesty（Pennisetum glaucum） named as pearl millet belongs to Poaceae,Pennisetum.Purple majesty as an important cereal crops was once grown as livestock feed in the world,but now is widely been grown as ornamental plant.Up to day,most studies are concentrated in evaluating and screening cultivars,but the research related biological characteristics is less.In the present study,purple majesty was used to study the effect of signal chemical salicylic acid on photosynthetic characteristics,chlorophyll fluorescence parameters and membrance lipid peroxidation under drought stress.Purple majesty seedlings with four to five leaves were treated with signal chemical salicylic acid and drought stress.Photosynthetic and chlorophyll fluorescence parameters were determined by LI-6400,membrance lipid peroxidation parameters were determined by chemical method and chloroplast membrane structure were observed by electron microscope.The results showed that：（1） Drought stress could destroy the chloroplast membrane structure,decrease the number of chloroplast grana,obscure the grana stacking and loose the array of grana lamella,while salicylic acid could protect chloroplast membrane structure;（2） Drought stress reduced the contents of chlorophyll b and total chlorophyll while salicylic acid increased the contents of chlorophyll a,chlorophyll b,total chlorophyll and carotene under drought stress;（3） Drought stress reduced the net photosynthesis rate（Pn）,transpiration rate（Tr） and stomatal conductance（Gs）,the light saturation point（LSP） and dark respiration rate,and increased the light compensation point（LCP）,the CO2 saturation point（CSP）,the CO2 compensation point（CCP） and light respiration rate significantly,while salicylic acid increased the net photosynthesis rate（Pn）,transpiration rate（Tr）,the light saturation point（LSP） and dark respiration rate,and reduced the light compensation point（LCP）,the CO2 saturation point（CSP）,the CO2 compensation point（CCP） and light respiration rate significantly;（4） Drought stress reduced the photochemical efficiency of PSⅡ（Fv/Fm） and actual photochemical efficiency of PSⅡ（ΦPSⅡ）,and increased the relative conductivity of leaves and the content of malondialdehyde（MDA）,while salicylic acid increased the photochemical efficiency of PSⅡ（Fv/Fm） and actual photochemical efficiency of PSⅡ（ΦPSⅡ）,and reduced the relative conductivity of leaves and the content of malondialdehyde（MDA）.All the results showed that Signal chemical salicylic acid mitigates the negative effects of drought on photosynthesis and membrance lipid peroxidation of purple.The present study provides a reference for seedling preparation and field plantation of pearl millet under drought condition and for the screening of drought-tolerant and water-saving cultivars.