A principal role for AtXTH18 in Arabidopsis thaliana root growth:: a functional analysis using RNAi plants
A principal role for AtXTH18 in Arabidopsis thaliana root growth:: a functional analysis using RNAi plants
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DOI：
10.1007/s10265-006-0262-6
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发表时间：
2006-03-01
影响因子：
2.8
通讯作者：
Nishitani, K
中科院分区：
文献类型：
--
作者：
Osato, Y;Yokoyama, R;Nishitani, K
纤维素微纤丝在细胞壁基质中的重排被认为是调节植物细胞扩张方向和程度的最关键步骤之一。木葡聚糖内切转葡萄糖基酶/水解酶（XTH）是一类介导纤维素微纤维之间承重交联的构建和重组的酶。拟南芥XTH基因AtXTH 17、18、19和20在遗传学上彼此密切相关，并且优先在根中表达。然而，它们在根内表现出不同的表达谱，并且对激素信号的反应不同。为了研究它们在根生长中的功能，我们使用T-DNA插入系和RNAi植物检测了这些基因的功能丧失突变体的表型。这些功能分析揭示了AtXTH 18基因在主根伸长中的主要作用。在四个XTH基因中，AtXTH 18表现出最高水平的mRNA表达。我们还确定了这些基因的生长素信号通路，使用AXR 2/IAA 7基因缺陷的突变体，发现AtXTH 19在根的伸长/成熟区域的表达是在AXR 2/IAA 7信号通路的控制下。
Rearrangement of cellulose microfibrils within cell-wall matrices is considered one of the most critical steps in the regulation of both the orientation and extent of cell expansion in plants. Xyloglucan endotransglucosylase/ hydrolases (XTHs) are a family of enzymes that mediate the construction and restructuring of load-bearing cross links among cellulose microfibrils. The Arabidopsis thaliana XTH genes AtXTH17, 18, 19, and 20 are phylogenetically closely related to one another and are preferentially expressed in the roots. However, they exhibit different expression profiles within the root and respond to hormonal signals differently. To investigate their functions in root growth, we examined phenotypes of loss-of-function mutants for these genes using T-DNA insertion lines and RNAi plants. These functional analyses disclosed a principal role for the AtXTH18 gene in primary root elongation. Of the four XTH genes, AtXTH18 exhibits the highest level of mRNA expression. We also determined auxin-signaling pathways for these genes using a mutant with a defect in the AXR2/IAA7 gene and found that the expression of AtXTH19 in the elongation/maturation region of the root is under the control of the AXR2/IAA7 signaling pathway.