A NEW CLASS OF ARABIDOPSIS CONSTITUTIVE PHOTOMORPHOGENIC GENES INVOLVED IN REGULATING COTYLEDON DEVELOPMENT
A NEW CLASS OF ARABIDOPSIS CONSTITUTIVE PHOTOMORPHOGENIC GENES INVOLVED IN REGULATING COTYLEDON DEVELOPMENT
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DOI：
10.1105/tpc.5.3.329
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发表时间：
1993-03-01
期刊：
影响因子：
11.6
通讯作者：
DENG, XW
中科院分区：
文献类型：
--
作者：
HOU, YM;VONARNIM, AG;DENG, XW
光信号对拟南芥幼苗下胚轴和子叶的形态发生有深远的影响，但光信号的转导和整合控制这些过程的机制尚不清楚。我们在这里报告了一类新的结构性光形态发生(COP)突变体，COP2，COP3和COP4，其中暗生长的幼苗具有类似于光生长的野生型幼苗的开放和扩大的子叶。这三个突变与以前描述的光敏色素缺失突变的上位关系表明，COP2、COP3和COP4可能在光调节途径中作用于光敏色素的下游。这三个基因座上的突变都缓解了在黑暗生长的野生型苗子叶中观察到的对细胞类型分化、细胞扩大和横向细胞分裂的正常抑制，但不影响叶绿体的分化。COP4突变还导致核基因的高水平暗表达，但不是叶绿体编码的光诱导基因。我们进一步证明，对于编码光合作用捕光复合体的叶绿素a/b结合蛋白的核Cab1基因，在暗培养的Cop4突变体中，激活是通过调节启动子的活性实现的。有趣的是，COP4通过一条不同于COP1和COP9的途径来调节CAB1启动子的活性。此外，COP4突变体在根和地上部的向重反应中都存在缺陷，这表明COP4基因可能同时参与光信号和重力感应过程。
Light signals have profound effects on morphogenesis of hypocotyls and cotyledons of Arabidopsis seedlings, but the mechanisms by which light signals am transduced and integrated to control these processes are poorly understood. We report here the identification of a new class of constitutive photomorphogenic (cop) mutants, cop2, cop3, and cop4, in which dark-grown seedlings have open and enlarged cotyledons resembling those of light-grown wild-type seedlings. The epistatic relationships of these three mutations to previously characterized phytochrome-deficient mutations suggest that COP2, COP3, and COP4 may act downstream of phytochrome in the light regulatory pathway. Mutations in each of the three loci alleviate the normal inhibition of cell-type differentiation, cell enlargement, and lateral cell division observed in cotyledons of dark-grown wild-type seedlings, but do not affect plastid differentiation. The cop4 mutation also leads to high-level dark expression of nuclear, but not plastid-encoded, light-inducible genes. We further show that for the nuclear cab1 gene encoding a chlorophyll a/b binding protein of the photosynthetic light-harvesting complex, activation in dark-grown cop4 mutants is achieved by modulation of promoter activity. Interestingly, COP4 modulates cab1 promoter activity through a pathway distinct from that of COP1 and COP9. Furthermore, cop4 mutants are defective in both root and shoot gravitropic responses, indicating that the COP4 locus may be involved in both light-signaling and gravity-sensing processes.