ZMBP, Entwicklungsgenetik, Universität Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany.
Nat Cell Biol. 2011 Dec 4;14(1):80-6. doi: 10.1038/ncb2389.
Polarized tip growth is a fundamental cellular process in many eukaryotic organisms, mediating growth of neuronal axons and dendrites or fungal hyphae. In plants, pollen and root hairs are cellular model systems for analysing tip growth. Cell growth depends on membrane traffic. The regulation of this membrane traffic is largely unknown for tip-growing cells, in contrast to cells exhibiting intercalary growth. Here we show that in Arabidopsis, GBF1-related exchange factors for the ARF GTPases (ARF GEFs) GNOM and GNL2 play essential roles in polar tip growth of root hairs and pollen, respectively. When expressed from the same promoter, GNL2 (in contrast to the early-secretory ARF GEF GNL1) is able to replace GNOM in polar recycling of the auxin efflux regulator PIN1 from endosomes to the basal plasma membrane in non-tip growing cells. Thus, polar recycling facilitates polar tip growth, and GNL2 seems to have evolved to meet the specific requirement of fast-growing pollen in higher plants.
极化尖端生长是许多真核生物的基本细胞过程，介导神经元轴突和树突或真菌菌丝的生长。在植物中，花粉和根毛是分析尖端生长的细胞模型系统。细胞生长取决于膜运输。与具有居间生长的细胞相比，对于尖端生长的细胞，这种膜运输的调节在很大程度上是未知的。在这里，我们表明在拟南芥中，GBF1 相关的 ARF GTPases（ARF GEFs）GNOM 和 GNL2 的交换因子分别在根毛和花粉的极性尖端生长中发挥重要作用。当从相同的启动子表达时，GNL2（与早期分泌的 ARF GEF GNL1 相反）能够替代 GNOM，将生长素外排调节剂 PIN1 从内体重新循环到非尖端生长细胞的基底质膜。因此，极性再循环促进极性尖端生长，并且 GNL2 似乎已经进化以满足高等植物中快速生长的花粉的特殊要求。
