Trafficking protein particle (TRAPP) complexes subunit gene AtTrs33 plays an important role in keeping apical meristematic activity and dominance in Arabidopsis. TRAPP complexes, composed of multimeric subunits, are guanine-nucleotide exchange factors for certain Rab GTPases and are believed to be involved in the regulation of membrane trafficking, but the cases in Arabidopsis are largely unknown. Trs33, recently proposed to be a component of TRAPP IV, is non-essential in yeast cells. A single copy of Trs33 gene, AtTrs33, was identified in Arabidopsis. GUS activity assay indicated that AtTrs33 was ubiquitously expressed. Based on a T-DNA insertion line, we found that loss-of-function of AtTrs33 is lethal for apical growth. Knock-down or knock-in of AtTrs33 affects apical meristematic growth and fertility, which indicates that AtTrs33 plays an important role in keeping apical meristematic activity and dominance in Arabidopsis. Analysis of auxin responses and PIN1/2 localization indicate that impaired apical meristematic activity and dominance were caused by altered auxin responses through non-polarized PIN1 localization. The present study reported that AtTrs33 plays an essential role in Arabidopsis cell growth and organization, which is different with its homologue in yeast. These findings provide new insights into the functional divergence of TRAPP subunits.

中文翻译：

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拟南芥 Trs33 在植物顶端分生组织细胞生长和组织中的重要作用。

贩运蛋白颗粒 (TRAPP) 复合亚基基因 AtTrs33 在保持拟南芥顶端分生组织活性和优势方面发挥着重要作用。TRAPP 复合物由多聚体亚基组成，是某些 Rab GTP 酶的鸟嘌呤核苷酸交换因子，被认为与膜运输的调节有关，但拟南芥中的情况在很大程度上是未知的。Trs33，最近被提议作为 TRAPP IV 的一个组成部分，在酵母细胞中是非必需的。在拟南芥中鉴定出Trs33 基因AtTrs33 的单拷贝。GUS 活性测定表明 AtTrs33 普遍表达。基于 T-DNA 插入线，我们发现 AtTrs33 的功能丧失对顶端生长是致命的。AtTrs33 的敲低或敲入影响顶端分生组织生长和生育力，这表明 AtTrs33 在保持拟南芥顶端分生组织活性和优势方面起着重要作用。对生长素反应和 PIN1/2 定位的分析表明，受损的顶端分生组织活性和优势是由通过非极化 PIN1 定位改变的生长素反应引起的。本研究报道 AtTrs33 在拟南芥细胞生长和组织中发挥重要作用，这与其在酵母中的同源物不同。这些发现为 TRAPP 亚基的功能差异提供了新的见解。本研究报道 AtTrs33 在拟南芥细胞生长和组织中发挥重要作用，这与其在酵母中的同源物不同。这些发现为 TRAPP 亚基的功能差异提供了新的见解。本研究报道 AtTrs33 在拟南芥细胞生长和组织中发挥重要作用，这与其在酵母中的同源物不同。这些发现为 TRAPP 亚基的功能差异提供了新的见解。