BIN2, a new brassinosteroid-insensitive locus in Arabidopsis
BIN2, a new brassinosteroid-insensitive locus in Arabidopsis
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DOI：
10.1104/pp.127.1.14
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发表时间：
2001-09-01
期刊：
影响因子：
7.4
通讯作者：
Chory, J
中科院分区：
文献类型：
--
作者：
Li, JM;Nam, KH;Chory, J
油菜素内酯（BR）在植物发育过程中发挥着重要作用。尽管已鉴定出许多参与 BR 生物合成的基因，但拟南芥中的遗传方法仅鉴定出一种基因 BRI1，它编码 BR 的膜受体。为了扩展我们对植物类固醇信号传导分子机制的了解，我们分析了从之前的遗传筛选中收集的许多矮化和半矮化突变体，并鉴定了一种对外源 BR 处理几乎没有反应的半矮化突变体。 bin2 (BR-INSENSITIVE 2) 突变体的遗传分析表明，BR 不敏感矮化表型是由于 BIN2 基因的半显性突变所致，该基因映射到 IV 号染色体中间标记 CH42 和 AG 之间。对类似半矮化突变体的直接筛选导致了 BIN2 基因的第二个等位基因的鉴定。尽管在 bin2/+ 突变体中观察到一些新的表型，但纯合 bin2 突变体与 BR 感知有缺陷的充分表征的 bri1 突变体几乎相同。除了 BR 不敏感的矮化表型外，bin2 突变体在根部生长抑制和 CPD 基因表达的反馈抑制分析中还表现出 BR 不敏感性。此外，bin2突变体表现出对脱落酸过敏的表型，该表型与bri1和BR缺陷突变体共享红色。使用三倍体植物进行的基因剂量实验表明，bin2 表型可能是由 BIN2 基因中的新形或超形功能获得性突变引起的。因此，两个 bin2 突变定义了一个新的基因位点，其基因产物可能在 BR 信号传导中发挥作用。
Brassinosteroids (BRs) play important roles throughout plant development. Although many genes have been identified that are involved in BR biosynthesis, genetic approaches in Arabidopsis have led to the identification of only one gene, BRI1, that encodes a membrane receptor for BRs. To expand our knowledge of the molecular mechanism(s) of plant steroid signaling, we analyzed many dwarf and semidwarf mutants collected from our previous genetic screens and identified a semidwarf mutant that showed little response to exogenous BR treatments. Genetic analysis of the bin2 (BR-INSENSITIVE 2) mutant indicated that the BR-insensitive dwarf phenotype was due to a semidominant mutation in the BIN2 gene that mapped to the middle of chromosome IV between the markers CH42 and AG. A direct screening for similar semidwarf mutants resulted in the identification of a second allele of the BIN2 gene. Despite some novel phenotypes observed with the bin2/+ mutants, the homozygous bin2 mutants were almost identical to the well-characterized bri1 mutants that are defective in BR perception. In addition to the BR-insensitive dwarf phenotype, bin2 mutants exhibited BR insensitivity when assayed for root growth inhibition and feedback inhibition of CPD gene expression. Furthermore, bin2 mutants displayed an abscisic acid-hypersensitive phenotype that is sh a-red by the bri1 and BR-deficient mutants. A gene dosage experiment using triploid plants suggested that the bin2 phenotypes were likely caused by either neomorphic or hypermorphic gain-of-function mutations in the BIN2 gene. Thus, the two bin2 mutations define a novel genetic locus whose gene product might play a role irt BR signaling.