Locascio A, Lucchin M, Varotto S
Department of Environmental Agronomy and Crop Production, University of Padova, Agripolis V. le dell'Università 16, 35020 Legnaro (PD), Italy.
New Phytol. 2009;182(3):630-643. doi: 10.1111/j.1469-8137.2009.02791.x.
In Arabidopsis thaliana, the ability to flower is mainly related to a floral repressor, FLOWERING LOCUS C (FLC), which is regulated through the vernalization pathway. The genes controlling the vernalization pathway seem to be only partially conserved in dicots other than the Brassicaceae. Cichorium intybus (chicory) is a biennial species belonging to the Asteraceae family, and it shows an obligate vernalization requirement for flowering. Cichorium intybus MADS (MCM1, Agamous, Deficiens, SRF) FLC-like (CiMFL) sequences were isolated in C. intybus by RT-PCR and their expression patterns characterized during plant development and in response to vernalization. The biological function of CiMFL was analysed by complementation of A. thaliana FRIGIDA (AtFRI);flc3. Resetting of MFL expression after vernalization was analysed during microsporogenesis. Before vernalization, CiMFL is mainly expressed in the axils of young leaves. Vernalization induced CiMFL down-regulation under a long-day photoperiod but not under a short-day photoperiod. Furthermore, together with a decrease in CiMFL transcripts, cold conditions induced changes in the morphology of the shoot apical meristem and in the transition to flowering. The biological function of CiMFL was found not to be conserved. Our results show that the regulation of CiMFL expression in time and space and in relation to environmental conditions is only partially conserved with respect to FLC isolated from A. thaliana. A model for flowering repression by CiMFL is proposed.
在拟南芥中，开花能力主要与一种开花抑制因子——开花位点C（FLC）相关，该因子通过春化途径受到调控。除十字花科外，控制春化途径的基因在双子叶植物中似乎仅部分保守。菊苣是一种属于菊科的二年生植物，它表现出开花对春化的绝对需求。通过逆转录聚合酶链式反应（RT-PCR）在菊苣中分离出菊苣MADS（MCM1、AGAMOUS、DEFICIENS、SRF）FLC样（CiMFL）序列，并对其在植物发育过程中以及对春化响应时的表达模式进行了表征。通过对拟南芥FRIGIDA（AtFRI）；flc3进行互补分析来研究CiMFL的生物学功能。在小孢子发生过程中分析了春化后MFL表达的重置情况。在春化之前，CiMFL主要在幼叶腋中表达。春化在长日照光周期下诱导CiMFL下调，但在短日照光周期下则不会。此外，随着CiMFL转录本的减少，低温条件诱导了茎尖分生组织形态的变化以及向开花的转变。发现CiMFL的生物学功能并不保守。我们的结果表明，CiMFL表达在时间、空间以及与环境条件相关方面的调控与从拟南芥中分离出的FLC相比仅部分保守。提出了一个CiMFL抑制开花的模型。
