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STUDIES ON ROLES OF GENES INVOLVED IN CELL-WALL CONSTRUCTION DURING PLANT MORPHOGENESIS

植物形态发生过程中细胞壁构建相关基因的作用研究

基本信息

批准号：
12440221
负责人：
NISHITANI Kazuhiko
金额：
$ 9.22万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

To gain insight into the functional diversity of the XTH (xyloglucan endotransglucosylase/hydrolase) gene family, we analyzed their expression profiles and obtained the results as followes :1) The two azuki bean VaXTH genes exhibit essentially similar but different tissuespecific expression profiles. Whereas VaXTH1 is expressed in xylem cells in the basal part of the internode, little or no expression of VaXTH2 is found in the xylem. Furthermore, they exhibit spatially divergent expression profiles along the internode, VaXTH1 being expressed nearer to the top of the internode than VaXTH2Auxin up-regulates both of the mRNA levels, however, this effect of auxin on the VaXTH1 gene is nullified in 0.25 M mannitol, which prevents cell expansion without affecting auxin action per se. On the other hand, the auxin-induced up-regulation of the VaXTH2 gene is not affected by mannitol.2) We examined expression profiles of the 33 Arabidopsis AtXTH genes, using quantitative real-time RT-PCR, and revealed that most members exhibit distinct expression profiles in terms of tissue specificity and responses to hormonal signals, with some members exhibiting similar expression patterns. By comparing the flanking sequences of individual genes, we identified four sets of large-segment duplicatoins and two sets of solitary gene duplications.3) We have conducted promoter analysis of the AtXTH17, 18, 19 and 20 and identified cis-acting regions responsible for root specific expression profiles.The results obtained, thus far, support the idea that each member of the XTH gene family is regulated specifically by different sets of plant hormones, and is committed to a certain specific process in a specific tissue, at specific stages of development. Based on these considerations, we advance a hypothesis that the cell wall in a certain cell-type is constructed, maintained and restructured by a series of collaborative actions of a set of enzymes characteristic to the cell-wall type.

为了深入了解XTH （xylo葡聚糖内转糖苷酶/水解酶）基因家族的功能多样性，我们分析了它们的表达谱，得到以下结果：1)两个红豆VaXTH基因表现出本质上相似但不同的组织特异性表达谱。VaXTH1在节间基部木质部细胞中表达，而VaXTH2在木质部细胞中很少或不表达。此外，它们在节间表现出空间上的差异表达谱，VaXTH1比vaxth2更接近节间顶部表达，生长素上调了这两种mRNA水平，然而，生长素对VaXTH1基因的影响在0.25 M甘露醇中被抵消，这可以阻止细胞扩增而不影响生长素本身的作用。另一方面，生长素诱导的VaXTH2基因上调不受甘露醇的影响。2)利用实时定量RT-PCR技术检测了33个拟南芥AtXTH基因的表达谱，发现大多数成员在组织特异性和对激素信号的响应方面表现出不同的表达谱，有些成员表现出相似的表达模式。通过比较单个基因的侧翼序列，我们鉴定出4组大片段重复和2组孤立基因重复。3)我们对AtXTH17、18、19和20进行了启动子分析，确定了负责根特异性表达谱的顺式作用区域。目前所获得的结果支持这样的观点，即XTH基因家族的每个成员都受到不同的植物激素的特异性调节，并在特定的组织中，在特定的发育阶段参与特定的过程。基于这些考虑，我们提出了一种假设，即某种细胞类型的细胞壁是由一组细胞壁类型特有的酶的一系列协同作用而构建、维持和重组的。