The Pleiomorphic Plant MTOC:An Evolutionary Perspective
The Pleiomorphic Plant MTOC:An Evolutionary Perspective作者机构:Department of BiologyUniversity of Louisiana-LafayetteLafayetteLA 70504USA
出 版 物:《Journal of Integrative Plant Biology》 (植物学报(英文版))
年 卷 期:2007年第49卷第8期
页 面:1142-1153页
核心收录:
学科分类:0710[理学-生物学] 071001[理学-植物学] 07[理学]
主 题:angiosperms bryophytes cell cycle life cycle microtubule mitosis γ-tubulin.
摘 要:γ-Tubulin is an essential component of the microtubule organizing center (MTOC) responsible for nucleating microtubules in both plants and animals. Whereas γ-tubulin is tightly associated with centrosomes that are inheritable organelles in cells of animals and most algae, it appears at different times and places to organize the myriad specialized microtubule systems that characterize plant cells. We have traced the distribution of γ-tubulin through the cell cycle in representative land plants (embryophytes) and herein present data that have led to a concept of the pleiomorphic and migratory MTOC. The many forms of the plant MTOC at spindle organization constitute pleiomorphism, and stage-specific “migration is suggested by the consistent pattern of redistribution of γ-tubulin during mitosis. Mitotic spindles may be organized at centriolar centrosomes (only in final divisions of spermatogenesis), polar organizers (POs), plastid MTOCs, or nuclear envelope MTOCs (NE-MTOCs). In all cases, with the possible exception of centrosomes in spermatogenesis, the γ-tubulin migrates to broad polar regions and along the spindle fibers, even when it is initially a discrete polar entity. At anaphase it moves poleward, and subsequently migrates from polar regions (distal nuclear surfaces) into the interzone (proximal nuclear surfaces) where interzonal microtubule arrays and phragmoplasts are organized. Following cytokinesis, γ-tubulin becomes associated with nuclear envelopes and organizes radial microtubule systems (RMSs). These may exist only briefly, before establishment of hoop-like cortical arrays in vegetative tissues, or they may be characteristic of interphase in syncytial systems where they serve to organize the common cytoplasm into nuclear cytoplasmic domains (NCDs).