Tan Xiaoyun, Cao Kun, Liu Feng, Li Yingxin, Li Pengxiang, Gao Caiji, Ding Yu, Lan Zhiyi, Shi Zhixuan, Rui Qingchen, Feng Yihong, Liu Yulong, Zhao Yanxue, Wu Chengyun, Zhang Qian, Li Yan, Jiang Liwen, Bao Yiqun
College of Life Sciences, Nanjing Agricultural University, Nanjing, People's Republic of China.
School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
PLoS Genet. 2016 Jul 22;12(7):e1006140. doi: 10.1371/journal.pgen.1006140. eCollection 2016 Jul.
Spatially and temporally regulated membrane trafficking events incorporate membrane and cell wall materials into the pollen tube apex and are believed to underlie the rapid pollen tube growth. In plants, the molecular mechanisms and physiological functions of intra-Golgi transport and Golgi integrity maintenance remain largely unclear. The conserved oligomeric Golgi (COG) complex has been implicated in tethering of retrograde intra-Golgi vesicles in yeast and mammalian cells. Using genetic and cytologic approaches, we demonstrate that T-DNA insertions in Arabidopsis COG complex subunits, COG3 and COG8, cause an absolute, male-specific transmission defect that can be complemented by expression of COG3 and COG8 from the LAT52 pollen promoter, respectively. No obvious abnormalities in the microgametogenesis of the two mutants are observed, but in vitro and in vivo pollen tube growth are defective. COG3 or COG8 proteins fused to green fluorescent protein (GFP) label the Golgi apparatus. In pollen of both mutants, Golgi bodies exhibit altered morphology. Moreover, γ-COP and EMP12 proteins lose their tight association with the Golgi. These defects lead to the incorrect deposition of cell wall components and proteins during pollen tube growth. COG3 and COG8 interact directly with each other, and a structural model of the Arabidopsis COG complex is proposed. We believe that the COG complex helps to modulate Golgi morphology and vesicle trafficking homeostasis during pollen tube tip growth.
时空调控的膜运输事件将膜和细胞壁物质整合到花粉管顶端，据信这是花粉管快速生长的基础。在植物中，高尔基体内运输和高尔基体完整性维持的分子机制及生理功能仍 largely 不清楚。保守的寡聚高尔基体（COG）复合体在酵母和哺乳动物细胞中参与逆行高尔基体内囊泡的拴系。利用遗传和细胞学方法，我们证明拟南芥 COG 复合体亚基 COG3 和 COG8 中的 T-DNA 插入导致绝对的、雄性特异性的传递缺陷，分别可由来自 LAT52 花粉启动子的 COG3 和 COG8 的表达互补。在这两个突变体的小孢子发生过程中未观察到明显异常，但体外和体内花粉管生长存在缺陷。与绿色荧光蛋白（GFP）融合的 COG3 或 COG8 蛋白标记高尔基体。在两个突变体的花粉中，高尔基体呈现出改变的形态。此外，γ-COP 和 EMP12 蛋白与高尔基体失去紧密结合。这些缺陷导致花粉管生长过程中细胞壁成分和蛋白质的错误沉积。COG3 和 COG8 直接相互作用，并提出了拟南芥 COG 复合体的结构模型。我们认为 COG 复合体有助于在花粉管顶端生长过程中调节高尔基体形态和囊泡运输稳态。
