Poster: Cell Cycle & Cytokinesis

Abs # 1094: Pre-prophase microtubule band development is not required for cell division plane determination

Presenter:	Cyr, Richard J, rjc8@psu.edu
Authors	Cyr, Richard J (A)   Marcus, Adam I (A)   Dixit, Ram  (A)   Li, Wuxing  (A)   Ma, Hong  (A)
Affiliations:	(A): Penn State

In higher plants, microtubules form a pre-prophase band of microtubules that is hypothesized to provide precise spatial information for accurately determining the plane of cell division. Here we show that PPB development (i.e. narrowing of the PPB) is not necessary for proper division plane determination. Specifically, in ATK1 mutant plants, which lack PPB development, the phragmoplast (the cytokinetic apparatus) still contacts the parental cell wall accurately. In addition, in wild-type cells, where PPB development is inhibited with a reversible microtubule-depolymerizing agent, the phragmoplast can also accurately insert into the proper site. Hence, PPB microtubules do not mark the site of division, per se, rather their presence is a consequence of positional elements which will later serve to guide the growing phragmoplast. Although the PPB microtubules do not mark the division site, they are required for accurate spindle positioning, an activity which presets the future growth trajectory of the phragmoplast and which is necessary for insuring high fidelity cell plate positioning.