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玉米开花期土壤干旱可使叶细胞中的超氧物歧化酶(SOD)活性降低,丙二醛(MDA)含量增加;酸性磷酸酯酶活性增强,可溶性磷含量增加.随干旱加强,MDA含量增加与亚麻酸含量降低呈极显著负相关,亚油酸含量增加与亚麻酸含量降低呈极显著负相关,酸性磷酸酯酶活性与膜脂脂肪酸不饱和度的变化呈相反的趋势.电镜观察发现,干旱加强,质膜、叶绿体膜系统受损加重,起初(ψ_L=-0.41MPa)质膜,叶绿体被膜膨散,尔后断裂,重度干旱(ψ_L=-1.83MPa)几乎解体.叶绿体片层结构随干旱加强,排列混乱,且间质片层对干旱较敏感.同时,细胞内脂类小滴增多增大.表明干旱下增加的活性氧启动了膜脂过氧化和膜磷脂的脱酯化反应.推测活性氧伤害膜的“原初机制”可能是干旱下活性氧含量增加首先启动了膜脂过氧化,导致膜脂脂肪酸不饱和度降低,对为膜束缚的酸性磷酸酯酶起明显的增溶溶解,进而促进膜磷脂脱酯化反应,加速了膜结构与功能的破坏.
Soil drought at the flowering stage of maize reduced the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in the leaf cells, the activity of acid phosphatase increased and the content of soluble phosphorus increased.With the increase of drought, the MDA content increased There was a significantly negative correlation between the content of linoleic acid and the content of linolenic acid. The change of acid phosphatase activity and the fatty acid unsaturation of membrane lipid showed the opposite trend.Electron microscope observation showed that, In the early stage (ψ_L = -0.41MPa), the membrane of plasma membrane and chloroplast expanded and then ruptured, the severe drought (ψ_L = -1.83MPa) almost disintegrated. The chloroplast lamella structure changed with the drought Strengthen and disarranged, and the interstitial sheet is more sensitive to drought.At the same time, the increase of intracellular lipid droplets increases.It is suggested that the increase of reactive oxygen species under drought initiates the de-esterification of membrane lipid peroxidation and membrane phospholipids. The “primary mechanism” of reactive oxygen species damage may be due to the increase of reactive oxygen species (ROS) content under drought. Membrane lipid peroxidation is initiated first, leading to a decrease in fatty acid unsaturation of membrane lipids, significant solubilization and dissolution of membrane-bound acidic phosphatase, Enter And to promote the membrane phospholipid deesterification, accelerated the destruction of membrane structure and function.