Early Endosomal Trafficking Component BEN2/VPS45 Plays a Crucial Role in Internal Tissues in Regulating Root Growth and Meristem Size in Arabidopsis
Early Endosomal Trafficking Component BEN2/VPS45 Plays a Crucial Role in Internal Tissues in Regulating Root Growth and Meristem Size in Arabidopsis
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DOI：
10.3389/fpls.2020.01027
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发表时间：
2020-07
影响因子：
5.6
通讯作者：
Y. Matsuura;Narumi Fukasawa;Kosuke Ogita;M. Sasabe;T. Kakimoto;Hirokazu Tanaka
中科院分区：
文献类型：
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作者：
Y. Matsuura;Narumi Fukasawa;Kosuke Ogita;M. Sasabe;T. Kakimoto;Hirokazu Tanaka
生长素极性运输参与植物发育的多个方面，包括根生长、侧根分枝、胚胎发生和脉管系统发育。PIN形成的（PIN）生长素流出蛋白在质膜（PM）上表现出不对称分布，并且共同在产生局部生长素积累中发挥关键作用，这是各种生长素依赖性发育过程的基础。在先前的研究中，已经揭示了内体运输组分BEN 1/BIG 5（ARF GEF）和BEN 2/VPS 45（Sec 1/Munc 18蛋白）在拟南芥PIN蛋白的细胞内运输中起作用。BEN 1和BEN 2的突变导致极性PIN定位、生长素响应梯度和根结构的缺陷。在这项研究中，我们试图深入了解这些贩运组件的发展作用。我们发现，虽然生长素分布的遗传或药理学干扰减少了根尖细胞的分裂，并导致根生长减少，同样的操作只有中度影响ben 1; ben 2双突变体。此外，我们建立了转基因株系，其中BEN 2/VPS 45在组织特异性启动子的控制下表达，并证明BEN 2/VPS 45至少在中柱和表皮细胞中以细胞自主的方式调节PIN蛋白的细胞内运输。此外，BEN 2/VPS 45在ben 1; ben 2双突变体的内部组织中表达时挽救了根构型缺陷。这些结果证实了内体运输组分BEN 2/VPS 45在调节生长素依赖的发育过程中的作用，并表明BEN 2/VPS 45是可持续的根生长所需的，最有可能是通过调节根内部组织的生长素向根尖运输。
Polar auxin transport is involved in multiple aspects of plant development, including root growth, lateral root branching, embryogenesis, and vasculature development. PIN-FORMED (PIN) auxin efflux proteins exhibit asymmetric distribution at the plasma membrane (PM) and collectively play pivotal roles in generating local auxin accumulation, which underlies various auxin-dependent developmental processes. In previous research, it has been revealed that endosomal trafficking components BEN1/BIG5 (ARF GEF) and BEN2/VPS45 (Sec1/Munc 18 protein) function in intracellular trafficking of PIN proteins in Arabidopsis. Mutations in both BEN1 and BEN2 resulted in defects in polar PIN localization, auxin response gradients, and in root architecture. In this study, we have attempted to gain insight into the developmental roles of these trafficking components. We showed that while genetic or pharmacological disturbances of auxin distribution reduced dividing cells in the root tips and resulted in reduced root growth, the same manipulations had only moderate impact on ben1; ben2 double mutants. In addition, we established transgenic lines in which BEN2/VPS45 is expressed under control of tissue-specific promoters and demonstrated that BEN2/VPS45 regulates the intracellular traffic of PIN proteins in cell-autonomous manner, at least in stele and epidermal cells. Furthermore, BEN2/VPS45 rescued the root architecture defects when expressed in internal tissues of ben1; ben2 double mutants. These results corroborate the roles of the endosomal trafficking component BEN2/VPS45 in regulation of auxin-dependent developmental processes, and suggest that BEN2/VPS45 is required for sustainable root growth, most likely through regulation of tip-ward auxin transport through the internal tissues of root.