AtXTH27 plays an essential role in cell wall modification during the development of tracheary elements
AtXTH27 plays an essential role in cell wall modification during the development of tracheary elements
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DOI：
10.1111/j.1365-313x.2005.02395.x
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发表时间：
2005-05-01
期刊：
影响因子：
7.2
通讯作者：
Nishitani, K
中科院分区：
文献类型：
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作者：
Matsui, A;Yokoyama, R;Nishitani, K
木葡聚糖内切转葡糖基酶/水解酶（XTH）是一类能够催化木葡聚糖之间的分子接枝和/或木葡聚糖分子的内型水解的酶。它们由拟南芥中的33个基因编码。虽然最近的研究已经揭示了时间和空间特异性表达谱的个别成员在植物中，其生物学作用仍有待澄清。为了确定该基因家族每个成员的作用，我们研究了每个拟南芥XTH基因被破坏的突变体的表型。这是使用反向遗传方法进行的，并公开了AtXTH 27基因的两个功能丧失突变体，xth 27 -1和xth 27 -2。第一叶的第三脉中出现了短形的导管分子，减少了第一叶的第三脉数量。在该突变体的成熟莲座状叶片中，还观察到黄色的类似病变的斑点。通过将野生型XTH 27基因导入xth 27 -1突变体植物进行遗传互补，三级脉的数量得到恢复，并且病变完全消失。pXTH 27：：GUS融合基因在莲座叶未成熟的导管分子中广泛表达。AtXTH 27 mRNA在莲座叶中的表达水平最高，在叶扩展过程中观察到，当导管元件伸长。这些发现表明AtXTH 27在拟南芥莲座叶中的导管元件的产生过程中起着至关重要的作用。
Xyloglucan endotransglucosylases/hydrolases (XTHs) are a class of enzymes capable of catalyzing the molecular grafting between xyloglucans and/or the endotype hydrolysis of a xyloglucan molecule. They are encoded by 33 genes in Arabidopsis. Whereas recent studies have revealed temporally and spatially specific expression profiles for individual members of this family in plants, their biological roles are still to be clarified. To identify the role of each member of this gene family, we examined phenotypes of mutants in which each of the Arabidopsis XTH genes was disrupted. This was undertaken using a reverse genetic approach, and disclosed two loss-of-function mutants for the AtXTH27 gene, xth27-1 and xth27-2. These exhibited short-shaped tracheary elements in tertiary veins, and reduced the number of tertiary veins in the first leaf. In mature rosette leaves of the mutant, yellow lesion-mimic spots were also observed. Upon genetic complementation by introducing the wild-type XTH27 gene into xth27-1 mutant plants, the number of tertiary veins was restored, and the lesions disappeared completely. Extensive expression of the pXTH27::GUS fusion gene was observed in immature tracheary elements in the rosette leaves. The highest level of AtXTH27 mRNA expression in the rosette leaves was observed during leaf expansion, when the tracheary elements were elongating. These findings indicate that AtXTH27 plays an essential role during the generation of tracheary elements in the rosette leaves of Arabidopsis.