Van Damme Daniël, Coutuer Silvie, De Rycke Riet, Bouget Francois-Yves, Inzé Dirk, Geelen Danny
Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnologie, Ghent University, B-9052 Gent, Belgium.
Plant Cell. 2006 Dec;18(12):3502-18. doi: 10.1105/tpc.106.040923. Epub 2006 Dec 22.
TPLATE was previously identified as a potential cytokinesis protein targeted to the cell plate. Disruption of TPLATE in Arabidopsis thaliana leads to the production of shriveled pollen unable to germinate. Vesicular compartmentalization of the mature pollen is dramatically altered, and large callose deposits accumulate near the intine cell wall layer. Green fluorescent protein (GFP)-tagged TPLATE expression under the control of the pollen promoter Lat52 complements the phenotype. Downregulation of TPLATE in Arabidopsis seedlings and tobacco (Nicotiana tabacum) BY-2 suspension cells results in crooked cell walls and cell plates that fail to insert into the mother wall. Besides accumulating at the cell plate, GFP-fused TPLATE is temporally targeted to a narrow zone at the cell cortex where the cell plate connects to the mother wall. TPLATE-GFP also localizes to subcellular structures that accumulate at the pollen tube exit site in germinating pollen. Ectopic callose depositions observed in mutant pollen also occur in RNA interference plants, suggesting that TPLATE is implicated in cell wall modification. TPLATE contains domains similar to adaptin and beta-COP coat proteins. These data suggest that TPLATE functions in vesicle-trafficking events required for site-specific cell wall modifications during pollen germination and for anchoring of the cell plate to the mother wall at the correct cortical position.
TPLATE先前被鉴定为一种靶向细胞板的潜在胞质分裂蛋白。拟南芥中TPLATE的破坏会导致产生无法萌发的皱缩花粉。成熟花粉的囊泡区室化发生显著改变，并且在花粉内壁细胞壁层附近积累大量胼胝质沉积物。在花粉启动子Lat52的控制下，绿色荧光蛋白（GFP）标记的TPLATE表达可补充该表型。拟南芥幼苗和烟草（Nicotiana tabacum）BY-2悬浮细胞中TPLATE的下调会导致细胞壁弯曲以及细胞板无法插入母细胞壁。除了在细胞板处积累外，GFP融合的TPLATE还会暂时靶向细胞板与母细胞壁相连的细胞皮层中的一个狭窄区域。TPLATE-GFP还定位于在萌发花粉的花粉管出口位点积累的亚细胞结构。在突变花粉中观察到的异位胼胝质沉积在RNA干扰植物中也会出现，这表明TPLATE与细胞壁修饰有关。TPLATE包含与衔接蛋白和β-COP被膜蛋白相似的结构域。这些数据表明，TPLATE在花粉萌发期间位点特异性细胞壁修饰以及将细胞板锚定在正确皮层位置的母细胞壁所需的囊泡运输事件中发挥作用。
