Simon R, Igeño M I, Coupland G
John Innes Centre, Norwich, UK.
Nature. 1996 Nov 7;384(6604):59-62. doi: 10.1038/384059a0.
The Arabidopsis floral meristem-identity genes APETALA1 (AP1) and LEAFY (LFY) confer floral identity on developing floral primordia, whereas TERMINAL FLOWER (TFL) is required to repress their expression within shoot and inflorescence meristems. LFY and AP1 are expressed in floral primordia in response to environmental conditions, such as day length, which regulate the onset of flowering, and presumably also in response to the action of genes that influence flowering time. However, the relationship between these flowering-time genes and the floral meristem-identity genes has been difficult to assess because flowering time is determined by several interacting genetic pathways. Here we describe a method to regulate expression of the flowering-time gene CONSTANS (CO) and demonstrate that CO expression is sufficient to trigger flowering, irrespective of day length. In response to CO expression, transcription of LFY and TFL is initiated rapidly, whereas transcription of AP1 occurs much later. We propose that CO acts within a genetic pathway that is sufficient to activate LFY and TFL transcription, but that rapid activation of AP1 requires an additional pathway.
拟南芥花分生组织特征基因APETALA1（AP1）和LEAFY（LFY）赋予发育中的花原基花的特征，而TERMINAL FLOWER（TFL）则在茎尖和花序分生组织中抑制它们的表达。LFY和AP1在花原基中表达，以响应环境条件，如调节开花起始的日长，可能还响应影响开花时间的基因的作用。然而，由于开花时间由几个相互作用的遗传途径决定，这些开花时间基因与花分生组织特征基因之间的关系一直难以评估。在这里，我们描述了一种调节开花时间基因CONSTANS（CO）表达的方法，并证明CO表达足以触发开花，而与日长无关。响应CO表达，LFY和TFL的转录迅速启动，而AP1的转录则发生得晚得多。我们提出，CO在一个足以激活LFY和TFL转录的遗传途径中起作用，但AP1的快速激活需要另一个途径。
