Microtubule Reorganization during Mitosis and Cytokinesis: Lessons Learned from Developing Microgametophytes in Arabidopsis Thaliana

Abstract

In angiosperms, mitosis and cytokinesis take place in the absence of structurally defined microtubule-organizing centers and the underlying mechanisms are largely unknown. In the spindle and phragmoplast, microtubule reorganization depends on microtubule-interacting factors like the γ-tubulin complex. Because of their critical functions in cell division, loss-of-function mutations in the corresponding genes are often homozygous or sporophytic lethal. However, a number of mutations like gem1, gcp2, and nedd1 can be maintained in heterozygous mutants in Arabidopsis thaliana. When mutant microspores produced by a heterozygous parent undergo pollen mitosis I, they are amenable for phenotypic characterization by fluorescence microscopy. The results would allow us to pinpoint at specific functions of particular proteins in microtubule reorganization that are characteristic to specific stages of mitosis and cytokinesis. Conclusions made in the developing microgametophytes can be extrapolated to somatic cells regarding mechanisms that regulate nuclear migration, spindle pole formation, phragmoplast assembly, and cell division plane determination.

Allyl isothiocyanate affects the cell cycle of Arabidopsis thaliana

“…Interestingly, seedlings that had been subjected to the same concentrations for 48 and 60 h displayed bleaching of cotyledons at the time when AITC exposure was stopped, although other chlorophyll containing organs remained green (Figure 1E ). The microtubule cytoskeleton is important for cell division and expansion, both of which are required for plant growth and development (Liu et al, 2011 ). Exposure to vapor of 0.5 M and higher AITC concentrations has previously been shown to disintegrate microtubules in A. thaliana (Øverby et al, 2015a ).…”

Mitotic Spindle Assembly in Land Plants: Molecules and Mechanisms

“…Arabidopsis thaliana is currently the most frequently used plant organism for genetic studies, and the mitotic spindle assembly process has been observed in several Arabidopsis tissues and suspension cells [19,29,30]. The tobacco BY-2 cell line is another popular system for mitosis imaging [31].…”

“…The diagram described here is based on experimental results obtained using reliable methodology such as mutant or RNAi analysis. The knowledge was derived mainly from P. patens , which is a system that allows rapid loss-of-function analysis and high-resolution time-lapse microscopy [108], and Arabidopsis , which has a rich history of mutant collection [29]. However, since genes are well conserved across land plant species, the basic mechanism could be conserved in other plant cell types.…”

Dividing without centrioles: innovative plant microtubule organizing centres organize mitotic spindles in bryophytes, the earliest extant lineages of land plants

“…The spindles of plant cells are generally thought to be anastral and differ in this regard from those of all other eukaryotes (e.g. Liu et al . 2011 ).…”