摘要
Recently, it has been shown that plants contain homologs to the animal Polycomb repressive complex I （PRC1） components BM11 and RINGIA/B. In Arabidopsis, there are three BMIl-like genes, two of which, AtBMIIA and B, are required during post-embryonic plant growth to repress embryonic traits and allow cell differentiation. However, little is known about the third BMIl-like gene, AtBMIIC. In this work, we show that AtBMIIC is only expressed during endosperm and stamen development. AtBMIIC is an imprinted gene expressed from the maternal allele in the endosperm but bialleli- cally expressed in stamen. We found that the characteristic expression pattern of AtBMIIC is the result of a complex epigenetic regulation that involves CG DNA methylation, RNA-directed non-CG DNA methylation （RdDM）, and PcG activity. Our results show the orchestrated interplay of different epigenetic mechanisms in regulating gene expression throughout development, shedding light on the current hypotheses for the origin and mechanism of imprinting in plant endosperm.
Recently, it has been shown that plants contain homologs to the animal Polycomb repressive complex I （PRC1） components BM11 and RINGIA/B. In Arabidopsis, there are three BMIl-like genes, two of which, AtBMIIA and B, are required during post-embryonic plant growth to repress embryonic traits and allow cell differentiation. However, little is known about the third BMIl-like gene, AtBMIIC. In this work, we show that AtBMIIC is only expressed during endosperm and stamen development. AtBMIIC is an imprinted gene expressed from the maternal allele in the endosperm but bialleli- cally expressed in stamen. We found that the characteristic expression pattern of AtBMIIC is the result of a complex epigenetic regulation that involves CG DNA methylation, RNA-directed non-CG DNA methylation （RdDM）, and PcG activity. Our results show the orchestrated interplay of different epigenetic mechanisms in regulating gene expression throughout development, shedding light on the current hypotheses for the origin and mechanism of imprinting in plant endosperm.
