Identification of a novel chloroplast protein AtNYE1 regulating chlorophyll degradation during leaf senescence in arabidopsis
Identification of a novel chloroplast protein AtNYE1 regulating chlorophyll degradation during leaf senescence in arabidopsis
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DOI：
10.1104/pp.107.100172
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发表时间：
2007-07-01
期刊：
影响因子：
7.4
通讯作者：
Kuai, Benke
中科院分区：
文献类型：
--
作者：
Ren, Guodong;An, Kun;Kuai, Benke
在营养器官衰老和果实成熟期间，叶绿素(Chl)的降解急剧增加。虽然人们很早就提出了Chl降解的生化途径，但对其调控机制却知之甚少。鉴定受Chl降解干扰的突变体并随后分离相关基因将极大地有助于阐明Chl降解的调控。在这里，我们描述了一个不变黄的拟南芥突变体nye1-1，在6-d黑暗孵化结束时，其中保留了50%的Chl，而野生型(Columbia-0)不到10%。然而，Nye1-1的光合作用和衰老相关过程都没有受到显著影响。特征是，在Nye1-1中检测到脱镁叶绿酸a加氧酶活性显著降低。然而，没有观察到叶绿素a或脱镁叶绿酸a的可检测到的积累。正反交试验表明，突变表型是由单基因半显性核突变引起的。我们用位置克隆的方法鉴定了AtNYE1。已鉴定出数十个其推测的同源基因，主要出现在高等植物物种中，其中一些与少数作物物种的Chl降解有关。定量聚合酶链式反应分析表明，AtNYE1受到衰老信号的强烈诱导。AtNYE1的组成性过表达可以产生淡黄色的真叶，甚至白化幼苗。这些结果表明，NYE1通过调节脱镁叶绿酸a加氧酶的活性，在衰老过程中对Chl的降解起着重要的调节作用。
A dramatic increase of chlorophyll (Chl) degradation occurs during senescence of vegetative plant organs and fruit ripening. Although the biochemical pathway of Chl degradation has long been proposed, little is known about its regulatory mechanism. Identification of Chl degradation-disturbed mutants and subsequently isolation of responsible genes would greatly facilitate the elucidation of the regulation of Chl degradation. Here, we describe a nonyellowing mutant of Arabidopsis ( Arabidopsis thaliana), nye1-1, in which 50% Chl was retained, compared to less than 10% in the wild type (Columbia-0), at the end of a 6-d dark incubation. Nevertheless, neither photosynthesis- nor senescence-associated process was significantly affected in nye1-1. Characteristically, a significant reduction in pheophorbide a oxygenase activity was detected in nye1-1. However, no detectable accumulation of either chlorophyllide a or pheophorbide a was observed. Reciprocal crossings revealed that the mutant phenotype was caused by a monogenic semidominant nuclear mutation. We have identified AtNYE1 by positional cloning. Dozens of its putative orthologs, predominantly appearing in higher plant species, were identified, some of which have been associated with Chl degradation in a few crop species. Quantitative polymerase chain reaction analysis showed that AtNYE1 was drastically induced by senescence signals. Constitutive overexpression of AtNYE1 could result in either pale-yellow true leaves or even albino seedlings. These results collectively indicate that NYE1 plays an important regulatory role in Chl degradation during senescence by modulating pheophorbide a oxygenase activity.