Shoot circumnutation and winding movements require gravisensing cells
Shoot circumnutation and winding movements require gravisensing cells
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DOI：
10.1073/pnas.0504617102
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发表时间：
2005-12-20
影响因子：
11.1
通讯作者：
Takahashi, H
中科院分区：
文献类型：
--
作者：
Kitazawa, D;Hatakeda, Y;Takahashi, H
植物的循环和缠绕是植物普遍的生长运动，使植物能够生存，尽管它们是无根的。然而，控制这些现象的详细分子机制尚不清楚。我们以前发现日本牵牛花（Pharbitis nil或Ipomoea nil）的一个向地性突变体Shidare-asagao （weeping）不仅在环绕上有缺陷，而且在缠绕反应上也有缺陷。这种表型与拟南芥稻草人（SCR）突变体相似。因此，我们研究了牵牛花SCR （PnSCR）是否参与哭泣表型。我们发现，在哭泣型PnSCR中，一个氨基酸插入到高度保守的VHIID基序中；这种突变引起了异常的内胚层分化。我们将突变体或WT PnSCR引入拟南芥scr突变体中进行互补试验。WT的PnSCR，而不是哭泣的PnSCR，挽救了茎部的倾斜和scr的环流。这些结果表明，倾斜异常和抽泣过程中的环流缺陷都是由于PnSCR功能缺失造成的。因此，我们的数据表明，重感内胚层细胞对于茎的环化和缠绕反应是必不可少的，PnSCR是导致哭泣异常表型的原因。
Circumnutation and winding in plants are universal growth movements that allow plants to survive despite their sessile nature. However, the detailed molecular mechanisms controlling these phenomena remain unclear. We previously found that a gravitropic mutant of Japanese morning glory (Pharbitis nil or Ipomoea nil, Shidare-asagao (weeping), is defective not only in circumnutation but also in the winding response. This phenotype is similar to that of the Arabidopsis SCARECROW (SCR) mutant. We therefore investigated whether morning glory SCR (PnSCR) is involved in the weeping phenotype. We found that one amino acid was inserted into the highly conserved VHIID motif in weeping-type PnSCR; this mutation caused abnormal endodermal differentiation. We introduced either the mutant or WT PnSCR into Arabidopsis scr mutants for complementation tests. PnSCR of the WT, but not of weeping, rescued the shoot gravitropism and circumnutation of scr. These results show that both the abnormal gravitropism and the circumnutation defect in weeping are attributable to a loss of PnSCR function. Thus, our data show that gravisensing endodermal cells are indispensable for shoot circumnutation and the winding response and that PnSCR is responsible for the abnormal phenotypes of weeping.