School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea.
Plant Cell Environ. 2011 Dec;34(12):2212-24. doi: 10.1111/j.1365-3040.2011.02416.x. Epub 2011 Sep 28.
An Arabidopsis small GTPase, RabG3b, was previously characterized as a component of autophagy and as a positive regulator for xylem development in Arabidopsis. In this work, we assessed whether RabG3b modulates xylem-associated traits in poplar in a similar way as in Arabidopsis. We generated transgenic poplars (Populus alba × Populus tremula var. glandulosa) overexpressing a constitutively active form of RabG3b (RabG3bCA) and performed a range of morphological, histochemical and molecular analyses to examine xylogenesis. RabG3bCA transgenic poplars showed increased stem growth due to enhanced xylem development. Autophagic structures were observed in differentiating xyelm cells undergoing programmed cell death (PCD) in wild-type poplar, and were more abundant in RabG3bCA transgenic poplar plants and cultured cells. Xylogenic activation was also accompanied by the expression of secondary wall-, PCD- and autophagy-related genes. Collectively, our results suggest that Arabidopsis RabG3b functions to regulate xylem growth through the activation of autophagy during wood formation in Populus, as does the same in Arabidopsis.
拟南芥的一个小分子 GTPase RabG3b 先前被鉴定为自噬的组成部分，也是拟南芥木质部发育的正调控因子。在这项工作中，我们评估了 RabG3b 是否以类似于拟南芥的方式调节杨树中的木质部相关特征。我们生成了过表达组成型激活形式的 RabG3b（RabG3bCA）的转基因杨树（Populus alba×Populus tremula var. glandulosa），并进行了一系列形态学、组织化学和分子分析，以研究木质部的发生。由于木质部发育增强，RabG3bCA 转基因杨树表现出茎生长增加。在野生型杨树中，正在经历程序性细胞死亡（PCD）的分化 xyelm 细胞中观察到自噬结构，并且在 RabG3bCA 转基因杨树植物和培养细胞中更为丰富。木质部的激活也伴随着次生壁、PCD 和自噬相关基因的表达。总的来说，我们的结果表明，拟南芥 RabG3b 通过在杨树的木质部形成过程中激活自噬来调节木质部的生长，这与拟南芥中的情况相同。
