J Integr Plant Biol. ›› 2007, Vol. 49 ›› Issue (8): 1142-1153.DOI: 10.1111/j.1672-9072.2007.00538.x

• Invited Expert Reviews • Previous Articles     Next Articles

The Pleiomorphic Plant MTOC: An Evolutionary Perspective

Roy C. Brown and Betty E. Lemmon   

  • Published:2007-08-04

Abstract: 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).

Key words: angiosperms, bryophytes, cell cycle, life cycle, microtubule, mitosis, γ-tubulin.

Editorial Office, Journal of Integrative Plant Biology, Institute of Botany, CAS
No. 20 Nanxincun, Xiangshan, Beijing 100093, China
Tel: +86 10 6283 6133 Fax: +86 10 8259 2636 E-mail: jipb@ibcas.ac.cn
Copyright © 2021 by the Institute of Botany, the Chinese Academy of Sciences
Online ISSN: 1744-7909 Print ISSN: 1672-9072 CN: 11-5067/Q