番茄叶衰老诱导质体小球降解的亚细胞途径分析

Subcellular Pathways for Plastoglobule Degradation in Tomato Leaves Caused by Senescence

叶衰老引起大分子和细胞器组分降解,质体小球是源于类囊体、由膜脂单分子层包围中性脂所组成的细胞器,然而目前对衰老叶中质体小球降解的亚细胞途径还了解甚少,因此采用超微技术对番茄叶衰老诱导的质体小球降解亚细胞途径进行了研究。结果发现,番茄叶衰老诱导质体小球体积增大之后以两种方式降解:一是质体小球离开叶绿体并向液泡内转移,在液泡中发生降解;二是质体小球不离开叶绿体,在叶绿体内发生降解,降解始于小球表面某一点,伴随小泡发生。因此,番茄叶衰老诱导质体小球通过两种亚细胞途径降解。

Leaf senescence causes degradation and recycling of cellular components.Plastoglobules are thylakoid memebrane-originated organelles consisting of a core of neutral lipids surrounded by a membrane lipid monolayer coated with proteins.However,little is known about the subcellular pathways for the degradation of plastoglobules during leaf senescence.Therefore,subcellular pathways of plastoglobules in senescent tomato leaves were examined by means of ultramicroscopy.During leaf senescence,following increase in size,plastoglobules underwent degradation in two different subcellular compartments.First,they were secreted out of chloroplasts and moved into vacuoles for degradation.Second,plastoglobules were degraded inside chloroplasts.The degradation was accompanied by the occurrence of a small vesicle.Obviously,there were two subcellular pathways for plastoglobule degradation:vacuole-associated pathway and chloroplast-associated pathway.