Kinoshita T, Harada J J, Goldberg R B, Fischer R L
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Proc Natl Acad Sci U S A. 2001 Nov 20;98(24):14156-61. doi: 10.1073/pnas.241507798. Epub 2001 Nov 6.
All plants flower late in their life cycle. For example, in Arabidopsis, the shoot undergoes a transition and produces reproductive flowers after the adult phase of vegetative growth. Much is known about genetic and environmental processes that control flowering time in mature plants. However, little is understood about the mechanisms that prevent plants from flowering much earlier during embryo and seedling development. Arabidopsis embryonic flower (emf1 and emf2) mutants flower soon after germination, suggesting that a floral repression mechanism is established in wild-type plants that prevents flowering until maturity. Here, we show that polycomb group proteins play a central role in repressing flowering early in the plant life cycle. We found that mutations in the Fertilization Independent Endosperm (FIE) polycomb gene caused the seedling shoot to produce flower-like structures and organs. Flower-like structures were also generated from the hypocotyl and root, organs not associated with reproduction. Expression of floral induction and homeotic genes was derepressed in mutant embryos and seedlings. These results suggest that FIE-mediated polycomb complexes are an essential component of a floral repression mechanism established early during plant development.
所有植物在其生命周期后期才开花。例如，拟南芥的茎在营养生长的成年阶段后会经历转变并产生生殖花。关于控制成熟植物开花时间的遗传和环境过程，我们已经了解很多。然而，对于在胚胎和幼苗发育期间阻止植物更早开花的机制，我们却知之甚少。拟南芥胚胎花（emf1和emf2）突变体在萌发后不久就开花，这表明在野生型植物中建立了一种花抑制机制，该机制可防止植物在成熟之前开花。在这里，我们表明多梳蛋白家族在植物生命周期早期抑制开花中起核心作用。我们发现，受精独立胚乳（FIE）多梳基因的突变导致幼苗的茎产生花状结构和器官。花状结构也从下胚轴和根产生，而下胚轴和根是与繁殖无关的器官。在突变体胚胎和幼苗中，花诱导基因和同源异型基因的表达被解除抑制。这些结果表明，FIE介导的多梳复合体是植物发育早期建立的花抑制机制的重要组成部分。
