Overexpression of OsRAA 1 Causes Pleiotropic Phenotypes in Transgenic Rice Plants , including Altered Leaf , Flower , and Root Development and Root Response to Gravity 1
Overexpression of OsRAA 1 Causes Pleiotropic Phenotypes in Transgenic Rice Plants , including Altered Leaf , Flower , and Root Development and Root Response to Gravity 1
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发表时间：
2004
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通讯作者：
L. Ge;Hui Chen;Jiafu Jiang;Yuan Zhao;Ming-Li Xu;Yunyuan Xu;Ke-hui Tan;Zhi-hong Xu;K. Chong
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作者：
L. Ge;Hui Chen;Jiafu Jiang;Yuan Zhao;Ming-Li Xu;Yunyuan Xu;Ke-hui Tan;Zhi-hong Xu;K. Chong
到目前为止，在水稻中被描述为单子叶模式植物的根基因很少。在这里，OsRAA1(水稻根构型结构相关1)基因已经被分子鉴定。OsRAA1编码一个12.0-kD的蛋白，与拟南芥中的AtFPF1(开花促进因子1)有58%的同源性，而AtFPF1尚未被报道调控根的发育。原位杂交和OsRAA1：：GUS转基因植株的检测结果表明，OsRAA1在顶端分生组织、根尖伸长区、分枝区中柱和幼嫩侧根中特异表达。在玉米(Zea Mays)泛素启动子的控制下，OsRAA1的结构性表达导致水稻幼苗初生根生长减慢，不定根和螺旋初生根数量增加，根系向重反应延迟，这与生长素处理的野生型植株的表型相似。在OsRAA1过表达的情况下，不定根的发生和生长对生长素的处理比对照更敏感，而转基因株系和野生型对9-羟基荧烯-9-羧酸的反应结果相似。在植株发育的最后阶段，OsRAA1的结构性表达也导致了叶片较长和不育小花的形成。对转OsRAA1：：GUS基因植株进行Northern印迹和GUS活性染色分析表明，OsRAA1基因的表达受生长素诱导。同时，OsRAA1的过表达也导致内源性吲哚-3-乙酸量增加。这些数据表明，OsRAA1作为一个新基因在水稻根系发育过程中发挥作用，这种作用是由生长素介导的。OsRAA1对吲哚-3-乙酸代谢的正反馈调节机制可能参与了水稻根系的自然发育。
There are very few root genes that have been described in rice as a monocotyledonous model plant so far. Here, the OsRAA1 (Oryza sativa Root Architecture Associated 1) gene has been characterized molecularly. OsRAA1 encodes a 12.0-kD protein that has 58% homology to the AtFPF1 (Flowering Promoting Factor 1) in Arabidopsis, which has not been reported as modulating root development yet. Data of in situ hybridization and OsRAA1::GUS transgenic plant showed that OsRAA1 expressed specifically in the apical meristem, the elongation zone of root tip, steles of the branch zone, and the young lateral root. Constitutive expression of OsRAA1 under the control of maize (Zea mays) ubiquitin promoter resulted in phenotypes of reduced growth of primary root, increased number of adventitious roots and helix primary root, and delayed gravitropic response of roots in seedlings of rice (Oryza sativa), which are similar to the phenotypes of the wild-type plant treated with auxin. With overexpression of OsRAA1, initiation and growth of adventitious root were more sensitive to treatment of auxin than those of the control plants, while their responses to 9-hydroxyfluorene-9-carboxylic acid in both transgenic line and wild type showed similar results. OsRAA1 constitutive expression also caused longer leaves and sterile florets at the last stage of plant development. Analysis of northern blot and GUS activity staining of OsRAA1::GUS transgenic plants demonstrated that the OsRAA1 expression was induced by auxin. At the same time, overexpression of OsRAA1 also caused endogenous indole-3acetic acid to increase. These data suggested that OsRAA1 as a new gene functions in the development of rice root systems, which are mediated by auxin. A positive feedback regulation mechanism of OsRAA1 to indole-3-acetic acid metabolism may be involved in rice root development in nature.