摘要：

In both plants and animals Polycomb group (PcG) genes act to maintain silencing of key developmental genes. A number of PcG genes have been identified in through independent genetic screens. These can be placed in three groups based upon strong homology with the proteins E(z), ESC and SU(Z)12. contains multiple homologues of E(z) and these have evolved to act in different pathways (represses flowering in the immature plant; prevents certain aspects of seed development in the absence of fertilisation; and has recently been shown to be partially redundant to ). Despite the high level of conservation between CLF and MEA proteins, I have shown that they are not equivalent. is unable to rescue a when expressed under either the endogenous promoter or the constitutative 35S promoter. In it has been shown that E(Z) acts in multimeric protein complexes with the PcG proteins ESC and SU(Z)12. Through yeast-two hybrid assays I have shown that CLF physically interacts with both the SU(Z)12 homologue EMF2 and the ESC homologue FIE, providing evidence of a similar complex acting to repress flowering in the immature plant. I have mapped the domains to which these interactions mediate. Of particular interest is the interaction between EMF2 and CLF; this region maps to the VEFS box of EMF2 and the C5 region of CLF. Embryos carrying a maternal inherited allele abort during deed development, making it impossible to observe the role of post seed development. I have created a transgenic steroid-inducible line, which I have used to rescue - embryos. The resulting plants show severe developmental abnormalities, with highly disorganised organ growth.

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