Perrine-Walker F M, Kouchi H, Ridge R W
Department of Life Science, Division of Natural Sciences, International Christian University, Mitaka, 181-8585, Tokyo, Japan,
Protoplasma. 2014 Jul;251(4):817-26. doi: 10.1007/s00709-013-0584-x. Epub 2013 Dec 15.
The endoplasmic reticulum (ER) of the model legume Lotus japonicus was visualized using green fluorescent protein (GFP) fused with the KDEL sequence to investigate the changes in the root hair cortical ER in the presence or absence of Mesorhizobium loti using live fluorescence imaging. Uninoculated root hairs displayed dynamic forms of ER, ranging from a highly condensed form to an open reticulum. In the presence of M. loti, a highly dynamic condensed form of the ER linked with the nucleus was found in deformed, curled, and infected root hairs, similar to that in uninoculated and inoculated growing zone I and II root hairs. An open reticulum was primarily found in mature inoculated zone III root hairs, similar to that found in inactive deformed/curled root hairs and infected root hairs with aborted infection threads. Co-imaging of GFP-labeled ER with light transmission demonstrated a correlation between the mobility of the ER and other organelles and the directionality of the cytoplasmic streaming in root hairs in the early stages of infection thread formation and growth. ER remodeling in root hair cells is discussed in terms of possible biological significance during root hair growth, deformation/curling, and infection in the Mesorhizobium-L. japonicus symbiosis.
利用与KDEL序列融合的绿色荧光蛋白（GFP）对模式豆科植物百脉根的内质网（ER）进行可视化，通过实时荧光成像研究在有无百脉根根瘤菌的情况下根毛皮层内质网的变化。未接种的根毛呈现出内质网的动态形态，从高度浓缩的形态到开放的网状结构。在百脉根根瘤菌存在的情况下，在变形、卷曲和受感染的根毛中发现了与细胞核相连的高度动态的浓缩内质网形态，这与未接种和接种的生长区I和II根毛中的情况相似。开放的网状结构主要出现在成熟的接种区III根毛中，类似于在无活性的变形/卷曲根毛和感染丝发育异常的受感染根毛中发现的情况。GFP标记的内质网与透光成像的共成像显示，在感染丝形成和生长的早期阶段，内质网和其他细胞器的移动性与根毛中细胞质流动的方向性之间存在相关性。本文从根毛生长、变形/卷曲以及在百脉根根瘤菌共生体系中感染过程中内质网重塑可能具有的生物学意义方面进行了讨论。
