Polycomb repression of flowering during early plant development

doi:10.1073/pnas.241507798

Polycomb repression of flowering during early plant development

^*Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720; ^‡Section of Plant Biology, Division of Biological Sciences, University of California, Davis, CA 95616; and ^§Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095

Contributed by Robert B. Goldberg

Abstract

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.

Footnotes

↵ † Present address: National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411, Japan.
↵ ¶ To whom reprint requests should be addressed. E-mail: rfischer{at}uclink4.berkeley.edu.
Abbreviations:

FIE,

Fertilization Independent Endosperm;

GFP,

Green Fluorescent Protein;

pFIE∷FIE-GFP,

FIE promoter ligated to FIE and GFP cDNA sequences;

pCaMV∷FIE-GFP,

cauliflower mosaic virus promoter ligated to FIE and GFP cDNA sequences;

GUS,

β-glucuronidase;

LFY∷GUS,

LFY promoter ligated to GUS cDNA;

AG∷GUS,

AG promoter ligated to GUS cDNA;

AP3∷GUS,

AP3 promoter ligated to GUS cDNA;

EMF,

Embryonic Flower