Three-dimensional analysis of chloroplast protrusion formed under osmotic stress by polyethylene glycol in rice leaves.
Three-dimensional analysis of chloroplast protrusion formed under osmotic stress by polyethylene glycol in rice leaves.
复制标题
聚乙二醇渗透胁迫下水稻叶片叶绿体突起的三维分析
DOI：
10.1080/1343943x.2019.1709513
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发表时间：
2020
影响因子：
2.5
通讯作者：
Taniguchi M.
中科院分区：
文献类型：
--
作者：
Yamane K;Oi T;Taniguchi M.
叶绿体突起(CPS)是缺乏类囊体膜的大片基质区域，在含有Rubisco的小体(RCB)形成之前就存在。RCBs是发现于细胞质中的圆形小体，通过自噬途径运输到液泡中。在本研究中，我们观察了聚乙二醇诱导的渗透胁迫下水稻叶肉细胞中的CPS和RCBs，并对连续切片的透射电子显微镜图像进行了三维重建。渗透胁迫诱导了CPS和RCBs的形成，其特征与盐胁迫下观察到的相似，表明渗透效应有助于CPS和RCBs的形成。CPS的3D图像显示，一些CP远离主叶绿体形成，其中一个CP与远离主叶绿体的线粒体和过氧化物体发生物理接触。因此，CPS可能有助于远离主要叶绿体的线粒体和过氧化物体的结合。此外，在三维结构上观察到与主要叶绿体通过狭窄结构相连的CP。由于CPS的体积与RCB的体积相似，因此具有窄结构的CP可能是RCB释放到细胞质之前的前体结构。在本研究中，24个CP中有两个CP的体积明显大于其他CP和RCB的体积。因此，CP的庞大主体可能是一个无法释放RCB的可行结构。
Chloroplast protrusions (CPs), large stromal areas lacking thylakoid membranes, are present before the formation of Rubisco-containing bodies (RCBs). RCBs are round bodies found within the cytoplasm and transported to the vacuole via the autophagy pathway. In the present study, we observed CPs and RCBs in rice mesophyll cells under polyethylene glycol-induced osmotic stress following 3D reconstruction of transmission electron microscopy images of serial sections. Osmotic stress induced the formation of CPs and RCBs whose features were similar to those observed under salt stress, suggesting that osmotic effect contributes to the formation of CPs and RCBs. The 3D image of CPs revealed that some CPs were formed far from the main chloroplast body, and one of the CP was in physical contact with a mitochondrion and a peroxisome, which were located far from the main chloroplast body. Thus, the CPs may aid the association with mitochondria and peroxisomes far from the main chloroplast body. Additionally, a CP with a connection to the main chloroplast body by a narrow structure was observed three-dimensionally. Since the volume of CPs was similar to that of RCBs, the CP with the narrow structure may be a precursor structure just before the release of an RCB into the cytoplasm. In the present study, the volumes of two CPs among 24 CPs were markedly larger than the volumes of other CPs and RCBs. Thus, the large body of the CP could be an unviable structure that fails to release RCBs.