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Auxin-dependent gene expression of ascorbate oxidase and cell-elongation in plants.

植物中抗坏血酸氧化酶的生长素依赖性基因表达和细胞伸长。

基本信息

批准号：
10660090
负责人：
ESAKA Muneharu
金额：
$ 1.98万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10660090/
关键词：
ascorbate oxidase gene expression auxin transgenic plant cell elongation cell division proloplast シス因子転写調節

项目摘要

The biological function of ascorbate oxidase (AAO) has not been clarified yet, although AAO has been suggested to be involved in cell growth. We investigated AAO expression during non-synchronous, synchronous and elongation cultures of tobacco BY-2 cells. In non-synchronous culture, AAO mRNA was abundant in logarithmic growth phase. In synchronous division culture, AAO mRNA was detected in all phases but the levels were quite low in G1 phase. In elongation culture, the levels of AAO mRNA increased during elongation of cells. AAO activity in the culture medium, as well as ascorbate and dehydroascorbate contents in the cells, also increased during the elongation. We propose that AAO expression and production of dehydroascorbate is under the control of cell cycle, and that AAO may function as an ascorbate oxidizer apoplastically in the process of cell elongation. When pumpkin AAO cDNA was introduced into tobacco BY-2 (Nicotiana tabacum L. cv. Bright Yellow No. 2) cultured cells by Agrobacterium-mediated transformation, the transgenic cells expressed and secreted the recombinant pumpkin AAO into the culture medium. These transgenic cells showed no morphological difference from wild-type cells. However, in the presence of applied hormones protoplasts prepared from the transgenic cells elongated more rapidly than those of wild-type cells. We propose that AAO may play a key role in the regulation of cell expansion perhaps by controlling transport processes through plasma membrane, but not by affecting the cell wall.

尽管抗坏血酸氧化酶(AAO)被认为参与细胞生长，但其生物学功能尚不清楚。我们研究了Aao在烟草BY-2细胞非同步、同步和伸长培养过程中的表达。在非同步化培养中，Aao基因在对数生长期大量表达。在同步分裂培养中，Aao基因在各时相均有表达，但在G1期的表达水平较低。在伸长培养中，随着细胞伸长，Aao基因的表达水平逐渐升高。在伸长过程中，培养液中的Aao活性以及细胞中抗坏血酸和脱氢抗坏血酸的含量也有所增加。我们认为AAO的表达和脱氢抗坏血酸的产生受细胞周期的控制，在细胞伸长过程中可能作为抗坏血酸氧化剂发挥作用。将南瓜Aao基因导入烟草BY-2(Nictiana tabacum L.cv.)通过农杆菌介导法转化南瓜AAO细胞，表达并分泌重组南瓜AAO到培养基中。这些转基因细胞与野生型细胞在形态上没有差异。然而，在施加激素的情况下，转基因细胞制备的原生质体比野生型细胞伸长得更快。我们认为，AAO可能通过控制细胞膜的运输过程，而不是通过影响细胞壁，在调节细胞扩张方面发挥关键作用。