干旱胁迫对3种不同光合类型荒漠植物叶绿体和线粒体超微结构的影响

摘要

以荒漠木本C3植物天山猪毛菜、C3-C4中间型植物松叶猪毛菜、C4植物木本猪毛菜为研究对象,采用盆栽控水试验,设置正常供水和轻度、中度和重度干旱处理(土壤含水量分别为田间持水量的80%、60%、45%和35%),研究不同程度干旱胁迫对3种不同光合类型荒漠植物叶片超微结构的影响。结果表明：(1)正常水分条件下,叶肉细胞中各细胞器结构完整。(2)轻度干旱胁迫下,3种植物叶片超微结构未受损伤,无明显变化。(3)中度干旱胁迫下,天山猪毛菜和松叶猪毛菜叶肉细胞壁界限不清晰,类囊体片层扩张且排列不紧密,不同之处在于,天山猪毛菜线粒体最先出现降解,内含物流失,而松叶猪毛菜线粒体外膜轮廓变形,嵴减少；木本猪毛菜线粒体无明显变化,叶绿体轻微扩张。(4)重度干旱胁迫下,天山猪毛菜和松叶猪毛菜叶绿体受损且结构混乱,线粒体出现降解；木本猪毛菜叶绿体出现膨胀,线粒体外膜轮廓模糊,嵴减少且结构模糊不清楚。研究认为,不同程度干旱胁迫下木本猪毛菜叶绿体和线粒体的受损程度都最低；干旱胁迫下天山猪毛菜和松叶猪毛菜叶绿体的受损程度大致相似；松叶猪毛菜和木本猪毛菜线粒体对干旱胁迫的耐受力要比叶绿体强。%Three desert plants with different photosynthetic types,including C3 plant Salsolajunatovii,C3-C4 plant S.laricifolia and C4 plant S.arbuscula,were used to investigate the effect of soil drought stress on the ultramicrostructure of mesophyll cells under pot culture condition using transmission electron mi-croscope.The results showed that:(1 )Under the normal water state,the organelles of mesophyll cells kept integrity.(2)Under the slight drought stress,the ultramicrostructure of three plants were not dam-aged.(3 )Under the condition of moderate drought stress,for S.junatovii and S.laricifolia,wall boundary of mesophyll cells were not clear and the thylakoids expanded,but the differences between these two plants were that mitochondria of S.junatovii firstly appeared degradation,and its inclusions were partly lost.For S.laricifolia,the outer membrane of mitochondria was deformed and the ridges were re-duced.The mitochondria of S.arbuscula remained normal,but the chloroplasts slightly expanded.(4 ) Under the severe drought stress,the chloroplasts of S.junatovii and S.laricifolia were damaged and mi-tochondria were degraded.For S.arbuscula,the chloroplasts expanded,the outer membrane of mitochon-dria was deformed and the ridges were reduced.These results have showed that the damage degree of S. arbuscula in chloroplasts and mitochondria under different degree of drought stress was the lowest;For S. junatovii and S.laricifolia,the damage degree of chloroplasts under drought stress was similar;the mi-tochondria had better tolerance to drought stress than chloroplasts in S.laricifolia and S.arbuscula.