Arabidopsisα Aurora Kinases Function in Formative Cell Division Plane Orientation

Abstract

To establish three-dimensional structures/organs, plant cells continuously have to adapt the orientation of their division plane in a highly regulated manner. However, mechanisms underlying switches in division plane orientation remain elusive. Here, we characterize a viable double knockdown mutant in Arabidopsis thaliana group a Aurora (AUR) kinases, AUR1 and AUR2, (aur1-2 aur2-2), with a primary defect in lateral root formation and outgrowth. Mutant analysis revealed that aur1-2 aur2-2 lateral root primordia are built from randomly oriented cell divisions instead of distinct cell layers. This phenotype could be traced back to cytokinesis defects and misoriented cell plates during the initial anticlinal pericycle cell divisions that give rise to lateral root primordia. Complementation assays showed that the Arabidopsis a group Aurora kinases are functionally divergent from the single b group member AUR3 and that AUR1 functions in division plane orientation prior to cytokinesis. In addition to defective lateral root patterning, aur1-2 aur2-2 plants also show defects in orienting formative divisions during embryogenesis, divisions surrounding the main root stem cell niche, and divisions surrounding stomata formation. Taken together, our results put forward a central role for a Aurora kinases in regulating formative division plane orientation throughout development.

Lateral root morphogenesis is dependent on the mechanical properties of the overlaying tissues

“…Plates were then incubated in a near-vertical position at 23°C in 150 μmol photons·m −2 ·sec −1 with a cycle of 18 h light/6 h dark. The aur1-2;2-2-pPIN1::PIN1-GFP transgenic and mutant lines were described previously (20). Details about constructions of the other lines can be found in SI Materials and Methods.…”

“…plate in LRPs following mitosis (20). This results in a chaotic pattern of cell plate deposition in LRPs (Fig.…”

Phosphorylation of MAP65-1 by Arabidopsis Aurora Kinases Is Required for Efficient Cell Cycle Progression

“…Caenorhabditis elegans (Schumacher et al, 1998a;1998b), Drosophila melanogaster (Glover et al, 1995), Xenopus laevis (Roghi et al, 1998;Adams et al, 2000), and Oryza sativa and Physcomitrella patens (Demidov et al, 2005;Guo et al, 2009)] or three homologs [e.g. mammals (Crane et al, 2004), Arabidopsis (Demidov et al, 2005;Van Damme et al, 2011)]. Mammalian Aurora kinases, designated A, B, and C, have very high sequence similarity, but different subcellular localization and substrate specificity (Vader and Lens, 2008;Carmena et al, 2009).…”

“…Aurora C, on the other hand, is highly expressed in testis and tumor cells, where it localizes to spindle poles from anaphase to cytokinesis (Kimura et al, 1999). Arabidopsis (Arabidopsis thaliana) Auroras have been divided into an a-group (comprising Aurora 1 and 2) and b-group (Aurora 3) based on their functional diversity and targeting patterns (Demidov et al, 2005;Kawabe et al, 2005;Van Damme et al, 2011). Aurora 1 and 2 associate with spindle microtubules (MTs) and the forming cell plate, whereas Aurora 3 is present at centromeres in metaphase (Van Damme et al, 2004aDemidov et al, 2005).…”

“…Down-regulation of alpha Auroras in Arabidopsis leads to multiple phenotypic aberrations, likely due to hypo-phosphorylation of their substrates. Namely, the double alpha Aurora knockdown mutant aur1/aur2 exhibits defects in orienting formative cell divisions (Van Damme et al, 2011), while RNAi silencing displays impaired cytokinesis with defective cell plate formation (Petrovská et al, 2012). The preferential phosphorylation of the microtubule-associated protein TPX2 by Arabidopsis Aurora 1 (Tomaštíková et al, 2015) and the colocalization of TPX2 and Aurora 1 on MTs (Petrovská et al, 2012) hint toward a role of alpha Aurora kinases in the regulation of cytoskeletal dynamics.…”