Aberrant expression of the Arabidopsis circadian-regulated APRR5 gene belonging to the APRR1/TOC1 quintet results in early flowering and hypersensitiveness to light in early photomorphogenesis.
Aberrant expression of the Arabidopsis circadian-regulated APRR5 gene belonging to the APRR1/TOC1 quintet results in early flowering and hypersensitiveness to light in early photomorphogenesis.
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DOI：
10.1093/pcp/pcf166
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发表时间：
2002-11
影响因子：
4.9
通讯作者：
Eriko Sato;Norihito Nakamichi;T. Yamashino;T. Mizuno
中科院分区：
文献类型：
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作者：
Eriko Sato;Norihito Nakamichi;T. Yamashino;T. Mizuno
在拟南芥中，APRR 1/TOC 1家族基因的转录本在黎明后开始有节奏地积累，并且在连续光照下以APRR 9--> APRR 7--> APRR 5--> APRR 3--> APRR 1/TOC 1的顺序依次积累。然而，除了已充分表征的APRR 1/TOC 1，没有证据表明其他APRR 1/TOC 1家族基因确实与昼夜节律的机制有关。我们在这里试图通过表征组成型表达APRR 5基因的转基因植物来提供这样的证据。由此产生的APRR 5-过表达（APRR 5-ox）植物表现出有趣的特性，不仅昼夜节律，而且控制开花时间和光响应。首先，APRR 5在这样的转基因植物中的异常表达导致关于转录事件的特征表型，其中对于某些昼夜节律调节的基因，包括CCA 1、LHY、APRR 1/TOC 1、其他APRR 1/TOC 1成员、GI和CAB 2，自由运行的节律被显著改变，尽管每个节律甚至在植物被转移到连续光之后也明显持续。关于生物学事件，APRR 5-ox植物开花比野生型植物早得多，或多或少，以独立于光周期的方式（或在短日照条件下）。此外，APRR 5-ox植物显示出SRL（红光下的短下胚轴）表型，其指示在早期光形态建成中对红光的超敏感性。APRR 1-ox和APRR 9-ox植物也显示出相同的表型。因此，APRR 5（连同APRR 1/TOC 1和APRR 9）必须考虑到更好地理解昼夜节律之间的分子联系，通过光周期长日照途径控制开花时间，以及光信号控制植物发育。
In Arabidopsis thaliana, the transcripts of the APRR1/TOC1 family genes each start accumulating after dawn rhythmically and one after another at intervals in the order of APRR9-->APRR7-->APRR5-->APRR3-->APRR1/TOC1 under continuous light. Except for the well-characterized APRR1/TOC1, however, no evidence has been provided that other APRR1/TOC1 family genes are indeed implicated in the mechanisms underlying circadian rhythms. We here attempted to provide such evidence by characterizing transgenic plants that constitutively express the APRR5 gene. The resulting APRR5-overexpressing (APRR5-ox) plants showed intriguing properties with regard to not only circadian rhythms, but also control of flowering time and light response. First, the aberrant expression of APRR5 in such transgenic plants resulted in a characteristic phenotype with regard to transcriptional events, in which free-running rhythms were considerably altered for certain circadian-regulated genes, including CCA1, LHY, APRR1/TOC1, other APRR1/TOC1 members, GI and CAB2, although each rhythm was clearly sustained even after plants were transferred to continuous light. With regard to biological events, APRR5-ox plants flowered much earlier than wild-type plants, more or less, in a manner independent of photoperiodicity (or under short-day conditions). Furthermore, APRR5-ox plants showed an SRL (short-hypocotyls under red light) phenotype that is indicative of hypersensitiveness to red light in early photomorphogenesis. Both APRR1-ox and APRR9-ox plants also showed the same phenotype. Therefore, APRR5 (together with APRR1/TOC1 and APRR9) must be taken into consideration for a better understanding of the molecular links between circadian rhythms, control of flowering time through the photoperiodic long-day pathway, and also light signaling-controlled plant development.