Polycomb Group Gene EbEZ from Apomictic Eulaliopsis binata Ectopic Expressed in Rice and Regulate Seed Development by Interacting with the OsFIE1 Protein.

Polycomb group (PcG) protein MEDEA (MEA), one of the Enhancer of Zeste [E(z)], represses endosperm development in Arabidopsis until fertilization occurs. The Eulaliopsis binata is an apomictic species that forms endosperm asexually. Up to now, little is known about their homologs in apomictic plants. Here, E(z)-like genes EbEZ1 and EbEZ2 were cloned from Eulaliopsis. The EbEZs were ubiquitously expressed in vegetative and reproductive organs while their high mRNAs were accumulated in seed. In addition, up-regulated expression of EbEZ1 in mature seed was in accompanied with hypomethylation of the promoter. Transgenic EbEZ1 rice lines produced decreased seed setting and abnormal endosperm and embryo. Moreover, the expression level of genes which were co-expressed with OsCLF (a homolog of EbEZ1) were up-regulated, indicating that EbEZ1 may integrate into the regulatory network of rice endogenous PcG complex which was supported by EbEZ1 interaction in vitro with the rice FERTILIZATION INDEPENDENT ENDOSPERM 1 (FIE1) PcG protein. [ABSTRACT FROM AUTHOR]