EMBRYONIC FLOWER2, a Novel Polycomb Group Protein Homolog, Mediates Shoot Development and Flowering in Arabidopsis

Abstract

In higher plants, developmental phase changes are regulated by a complex gene network. Loss-of-function mutations in the EMBRYONIC FLOWER genes ( EMF1 and EMF2 ) cause Arabidopsis to flower directly, bypassing vegetative shoot growth. This phenotype suggests that the EMF genes play a major role in repression of the reproductive program. Positional cloning of EMF2 revealed that it encodes a zinc finger protein similar to FERTILIZATION-INDEPENDENT SEED2 and VERNALIZATION2 of Arabidopsis. These genes are characterized as structural homologs of Suppressor of zeste 12 [ Su(z)12 ], a novel Polycomb group gene currently identified in Drosophila. In situ hybridization studies have demonstrated that EMF2 RNA is found in developing embryos, in both the vegetative and the reproductive shoot meristems, and in lateral organ primordia. Transgenic suppression of EMF2 produced a spectrum of early-flowering phenotypes, including emf2 mutant-like phenotype. This result confirms the role of EMF2 in phase transitions by repressing reproductive development.

Constitutive expression of two apple (Malus × domestica Borkh.) homolog genes of LIKE HETEROCHROMATIN PROTEIN1 affects flowering time and whole-plant growth in transgenic Arabidopsis

“…In addition, overexpression of these genes does not aVect the growth phases. These observations suggest that HP1-family and PcG genes are post-transcriptionally regulated (Gaudin et al 2001;Yoshida et al 2001;Hsieh et al 2003;Kotake et al 2003). It was consistent with these observations that the phenotype of transgenic plants with MdLHP1a1/-b1 was not necessarily correlated with the extent of transcription level.…”

“…CURLY LEAF (CLF) was Wrst identiWed as a PcG gene in plant, which represses AGAMOUS (AG) expression (Goodrich et al 1997). The EMBRYONIC FLOWER2 (EMF2) encoding a PcG protein with a zinc Wnger motif is required for maintaining the vegetative development and regulating the development of the inXorescence and Xoral meristem (Yoshida et al 2001). These PcG family proteins form large multimeric complexes and regulate developmental processes by preventing inappropriate expression of target genes (Chanvivattana et al 2004).…”

Conservation, diversification and expansion of C2H2 zinc finger proteins in the Arabidopsis thaliana genome

“…These are VERNALIZATION 2 (VRN2), EMBRYONIC FLOWER2 (EMF2) and FERTILIZATION-INDEPENDENT SEED (FIS2) [12-15]. They belong to the Polycomb group (PcG) and were given the name VEF family.…”

“…The molecular function(s) of their single ZF are unknown, but data from Drosophila Su(z)12 suggest their involvement in specific protein contacts, but not DNA binding. FIS2 [12,13], VRN2 [14] and EMF2 [15] act as repressors in different developmental stages of Arabidopsis (reviewed in [11]). Another conserved AT-ZFP in subset C2 is the protein SERRATE (SE, At2g27100) [17].…”

The WD-repeat protein superfamily in Arabidopsis: conservation and divergence in structure and function

“…Interestingly, this embryonic flowering resembles the phenotype of a mutant for a Su(z)12-like protein designated EMF2 [61], and potentially FIE and EMF2 are components of a distinct Esc-E(z)-like complex. Although FIE has no apparent paralogs within the Arabidopsis proteome, there are multiple Su(z)12-related and E(z)-related proteins (not shown).…”