Roles of Cortical Actin Microfilament Patterning in Division Plane Orientation in Plants

Abstract

In land plant cells, division planes are precisely predicted by the microtubule preprophase band and cortical actin microfilament pattern called the actin-depleted zone or actin microfilament twin peaks. However, the function of cortical actin microfilament patterning is not clear. In this study, we report that treatment with the inhibitor 2,3,5-triiodobenzonic acid (TIBA) or jasplakinolide increased the amount of thick actin microfilaments in tobacco BY-2 cells at interphase. However, during the division of BY-2 cells, these inhibitors did not induce visible alteration of actin microfilament thickness but altered cortical actin microfilament patterning without significant disorganization of the microtubule preprophase band. TIBA treatment induced a single intensity peak of actin microfilament distribution around the cell center, whereas jasplakinolide caused the appearance of triple peaks relative to the distribution of actin microfilament around the cell center, in approximately one-third of the cells at metaphase. Dual observations of microtubules and actin microfilaments revealed that abnormal cortical actin microfilament patterning with single or triple peaks is correlated with oblique mitotic spindles in BY-2 cells. In addition, oblique cell plates were frequently observed in BY-2 cells and Arabidopsis thaliana root cells treated with TIBA or jasplakinolide. These results provide evidence for the critical roles of cortical actin microfilament patterning in spindle and cell plate orientation.

Arabidopsis KCBP interacts with AIR9 but stays in the cortical division zone throughout mitosis via its MyTH4-FERM domain

“…Several previous studies visualizing F-actin, and/or using actindirected drugs, have suggested that F-actin is not only involved in phragmoplast integrity Smertenko et al, 2011) but also in phragmoplast guidance (Lloyd and Traas, 1988;Sano et al, 2005;Kojo et al, 2013). It is not, however, immediately clear how a role for actin in memorizing the division plane (as it must do in occupying the phragmosomal plane during mitosis) is compatible with the absence of F-actin from the narrow cortical ADZ (Cleary, 1995), to which the phragmoplast appears to be attracted.…”

Time-sequential observation of spindle and phragmoplast orientation in BY-2 cells with altered cortical actin microfilament patterning

“…To simultaneously observe microtubules and actin microfilaments in living BY-2 cells, we established BY-YTRF1 cell lines stably expressing yellow fluorescent protein (YFP)-tubulin and tdTomato-ABD2. 15 Using BY-YTRF1 cells, we revealed that altered cortical actin microfilament patterning is strongly correlated with an oblique mitotic spindle orientation at metaphase, suggesting the importance of cortical actin microfilament patterning in regulation of spindle and cell plate orientation. 15 In this study, to further investigate the Precise division plane determination is essential for plant development.…”

“…15 In approximately one-third of BY-GF11 cells treated with TIBA or jasplakinolide, one or three GFP-ABD2 fluorescence intensity peaks were respectively apparent around the cell center. Aniline blue staining revealed that TIBA and jasplakinolide treatments induced significant increases in oblique cell plate orientations compared with a dimethyl sulfoxide (DMSO) control.…”

Cytokinesis defect in BY-2 cells caused by ATP-competitive kinase inhibitors

“…Actin disruption with drugs delays cell plate expansion and causes tilted cell plates, 6 but the underlying mechanisms were yet to be discovered. Indeed, actomyosin complex is essential for division via contractile ring in animal and yeast cells.…”