Involvement of Arabidopsis thaliana phospholipase Dζ2 in root hydrotropism through the suppression of root gravitropism
Involvement of Arabidopsis thaliana phospholipase Dζ2 in root hydrotropism through the suppression of root gravitropism
复制标题
DOI：
10.1007/s00425-009-1052-x
复制
发表时间：
2009
期刊：
影响因子：
4.3
通讯作者：
Y. Y. Taniguchi-Y.;Masatoshi Taniguchi;T. Tsuge;A. Oka;T. Aoyama
中科院分区：
文献类型：
--
作者：
Y. Y. Taniguchi-Y.;Masatoshi Taniguchi;T. Tsuge;A. Oka;T. Aoyama
根向水性是指在缺水条件下根向水分方向生长的现象。虽然生理和遗传研究已经揭示了根冠参与水分梯度的感应，以及生长素和脱落酸（阿坝）参与不对称根伸长的信号转导，但根向水性的整体机制仍不清楚。结果表明，拟南芥磷脂酶D β 2基因（PLD β 2）的启动子活性定位于根远端伸长区的表皮细胞和与之相邻的侧根帽细胞，外源阿坝增强了PLD β 2基因的启动子活性，并使其作用范围扩大到整个侧根帽。外源阿坝对野生型根向地性的抑制作用在pld β 2突变体根中并不明显，但在pld β 2突变体根中没有观察到。在根系向水性实验中，pld β 2突变显著延迟或干扰了根系的向水性反应。干旱条件下，类似于在一个向水性实验中使用的增强thePLD的启动子在根冠中的活性，外源阿坝。这些结果表明，PLD β 2通过根冠中的阿坝信号响应干旱，并通过抑制根系向重力性来促进根系向水性化。
Root hydrotropism is the phenomenon of directional root growth toward moisture under water-deficient conditions. Although physiological and genetic studies have revealed the involvement of the root cap in the sensing of moisture gradients, and those of auxin and abscisic acid (ABA) in the signal transduction for asymmetric root elongation, the overall mechanism of root hydrotropism is still unclear. We found that the promoter activity of theArabidopsisphospholipase Dζ2 gene (PLDζ2) was localized to epidermal cells in the distal root elongation zone and lateral root cap cells adjacent to them, and that exogenous ABA enhanced the activity and extended its area to the entire root cap. Althoughpldζ2mutant root caps did not exhibit a morphological phenotype in either the absence or presence of exogenous ABA, the inhibitory effect of ABA on gravitropism, which was significant in wild-type roots, was not observed inpldζ2mutant roots. In root hydrotropism experiments,pldζ2mutations significantly retarded or disturbed root hydrotropic responses. A drought condition similar to that used in a hydrotropism experiment enhanced thePLDζ2 promoter activity in the root cap, as did exogenous ABA. These results suggest thatPLDζ2responds to drought through ABA signaling in the root cap and accelerates root hydrotropism through the suppression of root gravitropism.