Sieburth Leslie E, Muday Gloria K, King Edward J, Benton Geoff, Kim Sun, Metcalf Kasee E, Meyers Lindsay, Seamen Emylie, Van Norman Jaimie M
Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA.
Plant Cell. 2006 Jun;18(6):1396-411. doi: 10.1105/tpc.105.039008. Epub 2006 May 12.
To identify molecular mechanisms controlling vein patterns, we analyzed scarface (sfc) mutants. sfc cotyledon and leaf veins are largely fragmented, unlike the interconnected networks in wild-type plants. SFC encodes an ADP ribosylation factor GTPase activating protein (ARF-GAP), a class with well-established roles in vesicle trafficking regulation. Quadruple mutants of SCF and three homologs (ARF-GAP DOMAIN1, 2, and 4) showed a modestly enhanced vascular phenotype. Genetic interactions between sfc and pinoid and between sfc and gnom suggest a possible function for SFC in trafficking of auxin efflux regulators. Genetic analyses also revealed interaction with cotyledon vascular pattern2, suggesting that lipid-based signals may underlie some SFC ARF-GAP functions. To assess possible roles for SFC in auxin transport, we analyzed sfc roots, which showed exaggerated responses to exogenous auxin and higher auxin transport capacity. To determine whether PIN1 intracellular trafficking was affected, we analyzed PIN1:green fluorescent protein (GFP) dynamics using confocal microscopy in sfc roots. We found normal PIN1:GFP localization at the apical membrane of root cells, but treatment with brefeldin A resulted in PIN1 accumulating in smaller and more numerous compartments than in the wild type. These data suggest that SFC is required for normal intracellular transport of PIN1 from the plasma membrane to the endosome.
为了确定控制叶脉模式的分子机制，我们分析了疤痕脸（sfc）突变体。与野生型植物中相互连接的网络不同，sfc子叶和叶脉在很大程度上是碎片化的。SFC编码一种ADP核糖基化因子GTP酶激活蛋白（ARF-GAP），这一类蛋白在囊泡运输调控中具有既定作用。SFC及其三个同源物（ARF-GAP结构域1、2和4）的四重突变体显示出适度增强的维管表型。sfc与类萜醇以及sfc与gnom之间的遗传相互作用表明SFC在生长素输出调节因子的运输中可能具有功能。遗传分析还揭示了与子叶维管模式2的相互作用，表明基于脂质的信号可能是SFC ARF-GAP某些功能的基础。为了评估SFC在生长素运输中的可能作用，我们分析了sfc根，其对外源生长素表现出夸张的反应且具有更高的生长素运输能力。为了确定PIN1的细胞内运输是否受到影响，我们在sfc根中使用共聚焦显微镜分析了PIN1：绿色荧光蛋白（GFP）的动态变化。我们发现PIN1：GFP在根细胞顶端膜上的定位正常，但用布雷菲德菌素A处理后，PIN1在比野生型更小且更多的区室中积累。这些数据表明SFC是PIN1从质膜到内体正常细胞内运输所必需的。
