The AP-1 Complex is Required for Proper Mucilage Formation in Arabidopsis Seeds
The AP-1 Complex is Required for Proper Mucilage Formation in Arabidopsis Seeds
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DOI：
10.1093/pcp/pcy158
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发表时间：
2018-08
影响因子：
4.9
通讯作者：
T. Shimada;Tadashi Kunieda;S. Sumi;Y. Koumoto;K. Tamura;K. Hatano;H. Ueda;I. Hara-Nishimura
中科院分区：
文献类型：
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作者：
T. Shimada;Tadashi Kunieda;S. Sumi;Y. Koumoto;K. Tamura;K. Hatano;H. Ueda;I. Hara-Nishimura
衔接蛋白（AP）复合物在后高尔基体运输中的囊泡形成中起着至关重要的作用。陆地植物有5种AP复合物（AP-1 ~ AP-5），每种复合物由2个大亚基、1个中亚基和1个小亚基组成。在这里，我们表明，拟南芥AP-1复合物介导的极化分泌和积累的果胶多糖称为粘液在种皮细胞。以前，AP-1的中亚基AP 1 M2的功能丧失突变体已被证明由于胞质分裂缺陷而显示有害的生长缺陷。为了研究AP-1在分裂间期的功能，我们在ap 1 m2背景下构建了在拟南芥分裂特异性诺勒（KN）启动子控制下表达AP 1 m2-GFP（绿色荧光蛋白）的转基因拟南芥植株。这些转基因植物，命名为pKN系，成功地挽救了胞质分裂缺陷和矮化表型的ap 1 m2。pKN系显示减少的粘液从种皮挤出。此外，在pKN系的最外层珠被细胞的液泡中发现粘液的异常积累。在种子发育过程中，AP 1 M2-GFP在pKN系珠被细胞中的积累大大减少。这些结果表明，反式高尔基体网络（TGN）定位AP-1参与运输的粘液成分的种皮细胞的外表面。我们的研究强调了AP-1在真核细胞极化分选中的进化保守功能。
The adaptor protein (AP) complexes play crucial roles in vesicle formation in post-Golgi trafficking. Land plants have five types of AP complexes (AP-1 to AP-5), each of which consists of two large subunits, one medium subunit and one small subunit. Here, we show that the Arabidopsis AP-1 complex mediates the polarized secretion and accumulation of a pectic polysaccharide called mucilage in seed coat cells. Previously, a loss-of-function mutant of AP1M2, the medium subunit of AP-1, has been shown to display deleterious growth defects because of defective cytokinesis. To investigate the function of AP-1 in interphase, we generated transgenic Arabidopsis plants expressing AP1M2-GFP (green fluorescent protein) under the control of the cytokinesis-specific KNOLLE (KN) promoter in the ap1m2 background. These transgenic plants, designated pKN lines, successfully rescued the cytokinesis defect and dwarf phenotype of ap1m2. pKN lines showed reduced mucilage extrusion from the seed coat. Furthermore, abnormal accumulation of mucilage was found in the vacuoles of the outermost integument cells of pKN lines. During seed development, the accumulation of AP1M2-GFP was greatly reduced in the integument cells of pKN lines. These results suggest that trans-Golgi network (TGN)-localized AP-1 is involved in the trafficking of mucilage components to the outer surface of seed coat cells. Our study highlights an evolutionarily conserved function of AP-1 in polarized sorting in eukaryotic cells.