A semidwarf phenotype of barley uzu results from a nucleotide substitution in the gene encoding a putative brassinosteroid receptor
A semidwarf phenotype of barley uzu results from a nucleotide substitution in the gene encoding a putative brassinosteroid receptor
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DOI：
10.1104/pp.103.026195
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发表时间：
2003-11-01
期刊：
影响因子：
7.4
通讯作者：
Watanabe, Y
中科院分区：
文献类型：
--
作者：
Chono, M;Honda, I;Watanabe, Y
油菜素内酯（BRs）在植物的整个生长发育过程中发挥着重要作用。尽管阐明谷类作物中油菜素内酯相关生长调节机制很重要，但与油菜素内酯相关的谷类突变体仅在水稻（Oryza sativa）中被鉴定出来。我们之前发现携带“uzu”基因的半矮秆大麦（Hordeum vulgare）品种，在日本被称为“uzu”大麦，对油菜素内酯（BL）无反应。然后我们利用“uzu”基因的等基因系对进行化学和分子分析，以阐明“uzu”矮化的机制。“uzu”品系对BL的反应显著低于其相应的正常品系。对油菜素内酯的测量表明，“uzu”品系会积累油菜素内酯，这与已知的油菜素内酯不敏感突变体相似。水稻和大麦染色体的标记同线性表明，“uzu”基因可能与水稻D61同源，水稻D61是拟南芥油菜素内酯不敏感1（BRI1）的水稻同源基因，编码一种油菜素内酯受体蛋白。利用简并引物分离出了BRI1的大麦同源基因HvBRI1。对“uzu”和正常大麦品种中HvBRI1序列的比较表明，“uzu”表型与一个单核苷酸替换相关。这种替换导致油菜素内酯受体蛋白激酶结构域中一个高度保守的残基发生氨基酸变化。这些结果可能表明“uzu”矮化是由HvBRI1中的错义突变引起的。“uzu”基因作为一种实用的有效矮化基因正在被引入日本所有的无壳大麦品种中，这是关于与油菜素内酯相关的具有重要农艺学意义的突变的首次报道。
Brassinosteroids (BRs) play important roles throughout plant growth and development. Despite the importance of clarifying the mechanism of BR-related growth regulation in cereal crops, BR-related cereal mutants have been identified only in rice (Oryza sativa). We previously found that semidwarf barley (Hordeum vulgare) accessions carrying the "uzu" gene, called "uzu" barley in Japan, are non-responding for brassinolide (BL). We then performed chemical and molecular analyses to clarify the mechanisms of uzu dwarfism using isogenic line pairs of uzu gene. The response of the uzu line to BL was significantly lower than that of its corresponding normal line. Measurement of BRs showed that the uzu line accumulates BRs, similar to known BR-insensitive mutants. The marker synteny of rice and barley chromosomes suggests that the uzu gene may be homologous to rice D61, a rice homolog of Arabidopsis BR-insensitive 1 (BRI1), encoding a BR-receptor protein. A barley homolog of BRI1, HvBRI1, was isolated by using degenerate primers. A comparison of HvBRI1 sequences in uzu and normal barley varieties showed that the uzu phenotype is correlated with a single nucleotide substitution. This substitution results in an amino acid change at a highly conserved residue in the kinase domain of the BR-receptor protein. These results may indicate that uzu dwarfism is caused by the missense mutation in HvBRI1 The uzu gene is being introduced into all hull-less barley cultivars in Japan as an effective dwarf gene for practical use, and this is the first report about an agronomically important mutation related to BRs.