ARABIDOPSIS MUTANTS DEFINE DOWNSTREAM BRANCHES IN THE PHOTOTRANSDUCTION PATHWAY
ARABIDOPSIS MUTANTS DEFINE DOWNSTREAM BRANCHES IN THE PHOTOTRANSDUCTION PATHWAY
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DOI：
10.1101/gad.8.3.339
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发表时间：
1994-02-01
影响因子：
10.5
通讯作者：
CHORY, J
中科院分区：
文献类型：
--
作者：
LI, HM;ALTSCHMIED, L;CHORY, J
光通过多种途径调控拟南芥幼苗的发育，包括抑制下胚轴生长、促进叶片发育、叶绿体分化、光响应基因表达等。已经描述了从光控制中分离大部分或全部这些反应的突变，例如det1、det2和cop1。为了确定在光调节信号转导通路中定义下游分支的调控成分，只分离了一种光调节反应特异性影响的突变体。通过使用含有两个CAB3启动子-报告子融合的T-DNA结构的转基因系，设计了一种筛选方法来分离在黑暗中过度表达CAB（光系统II型I型叶绿素白蛋白结合蛋白）基因的突变体。分离出8个CAB3启动子均异常表达的突变体，并将其命名为doc突变体（CAB暗过表达）。所有的突变体在黑暗中都有正常的黄化形态。遗传和表型分析表明，大多数突变是隐性的，并且定义了至少三个位点（doc1,doc2, doc3）。det1和det2突变体对CAB和RBCS （RuBP羧化酶的小亚基）表达的影响程度大致相同，但与det1和det2突变体不同，这三种doc突变体在抑制CAB表达方面更具特异性。doc突变体的表型表明，形态变化可以从CAB基因表达的变化中分离出来。此外，CAB基因表达的调控可以与RBCS基因表达的调控进一步分离。上位性研究表明，DOC1和DET3在光传导途径的DET1下游的两个独立分支上起作用。相比之下，DOC2似乎作用于与DET1不同的途径。在短日照条件下，doc1、doc2或doc3的突变也会损害植物的生长。
Light regulates the development of Arabidopsis seedlings in a variety of ways, including inhibition of hypocotyl growth and promotion of leaf development, chloroplast differentiation, and light-responsive gene expression. Mutations that uncouple most or all of these responses from light control have been described, for example, det1, det2, and cop1. To identify regulatory components that define downstream branches in the light-regulated signal transduction pathway, mutants specifically affected in only one light-regulated response were isolated. A screen was designed to isolate mutants that overexpressed the CAB (photosystem II type I chlorophyll alb-binding proteins) genes in the dark, by use of a transgenic line containing a T-DNA construct with two CAB3 promoter-reporter fusions. Eight mutants that showed aberrant expression of both CAB3 promoters were isolated and were designated doc mutants (for dark overexpression of CAB). All of the mutants have normal etiolated morphology in the dark. Genetic and phenotypic analyses indicate that most of the mutations are recessive and define at least three loci (doc1,doc2, doc3). Unlike det1 and det2 mutants, which affect the expression of CAB and RBCS (the small subunit of RuBP carboxylase) to approximately the same extent, all three doc mutations are much more specific in derepressing the expression of CAB. The phenotypes of doc mutants suggest that morphological changes can be genetically separated from changes in CAB gene expression. Moreover, the regulation of CAB gene expression can be separated further from the regulation of RBCS gene expression. Epistasis studies suggest that DOC1 and DET3 act downstream from DET1 on two separate branches in the phototransduction pathway. In contrast, DOC2 appears to act on a distinct pathway from DET1. Mutations in doc1, doc2, or doc3 also impair plant growth under short-day conditions.