The rice brassinosteroid-deficient dwarf2 mutant, defective in the rice homolog of Arabidopsis DIMINUTO/DWARF1, is rescued by the endogenously accumulated alternative bioactive brassinosteroid, dolichosterone
The rice brassinosteroid-deficient dwarf2 mutant, defective in the rice homolog of Arabidopsis DIMINUTO/DWARF1, is rescued by the endogenously accumulated alternative bioactive brassinosteroid, dolichosterone
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DOI：
10.1105/tpc.105.030973
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发表时间：
2005-08-01
期刊：
影响因子：
11.6
通讯作者：
Matsuoka, M
中科院分区：
文献类型：
--
作者：
Hong, Z;Ueguchi-Tanaka, M;Matsuoka, M
我们鉴定了一个油菜素内酯（BR）缺失的水稻突变体，即BR缺失矮秆2（brd 2）. brd 2基因座在Dim/dwf 1的编码区中含有单碱基缺失，Dim/dwf 1是拟南芥DIM/DWARF 1（DIM/DWF 1）的同源物。将野生型Dim/dwf 1基因导入brd 2恢复了正常表型。过度生产和阻遏的Dim/dwf 1导致形成鲜明对比的表型，阻遏物模仿brd 2表型和overproducers具有大的身材，花和种子的数量增加。虽然brd 2含有低水平的常见6-氧代型BR，但brd 2表型的严重程度比brd 1突变体轻得多，并且与d2和d11最相似，后者在幼苗阶段显示出半矮生表型.定量分析表明，在brd 2中，24-亚甲基BR生物合成途径被激活，并产生不常见的BR，长甾酮（DS）。DS提高了水稻叶片关节弯曲角，挽救了brd 1矮化表型，抑制了根伸长，表明DS是一种具有生物活性的BR。基于这些观察结果，我们讨论了一种替代BR生物合成途径，当Dim/dwf 1有缺陷时产生DS。
We have identified a rice ( Oryza sativa) brassinosteroid ( BR)- deficient mutant, BR- deficient dwarf2 ( brd2). The brd2 locus contains a single base deletion in the coding region of Dim/ dwf1, a homolog of Arabidopsis thaliana DIMINUTO/ DWARF1 ( DIM/ DWF1). Introduction of the wild- type Dim/ dwf1 gene into brd2 restored the normal phenotype. Overproduction and repression of Dim/ dwf1 resulted in contrasting phenotypes, with repressors mimicking the brd2 phenotype and overproducers having large stature with increased numbers of flowers and seeds. Although brd2 contains low levels of common 6- oxo- type BRs, the severity of the brd2 phenotype is much milder than brd1 mutants and most similar to d2 and d11, which show a semidwarf phenotype at the young seedling stage. Quantitative analysis suggested that in brd2, the 24- methylene BR biosynthesis pathway is activated and the uncommon BR, dolichosterone ( DS), is produced. DS enhances the rice lamina joint bending angle, rescues the brd1 dwarf phenotype, and inhibits root elongation, indicating that DS is a bioactive BR in rice. Based on these observations, we discuss an alternative BR biosynthetic pathway that produces DS when Dim/ dwf1 is defective.