Expression, imprinting, and evolution of rice homologs of the polycomb group genes.
Polycomb group proteins (PcG) play important roles in epigenetic regulation of gene expression. Some core PcG proteins, such as Enhancer of Zeste (E(z)), Suppressor of Zeste (12) (Su(z)12), and Extra Sex Combs (ESC), are conserved in plants. The rice genome contains two E(z)-like genes, OsiEZ1 and OsCLF, two homologs of Su(z)12, OsEMF2a and OsEMF2b, and two ESC-like genes, OsFIE1 and OsFIE2. OsFIE1 is expressed only in endosperm; the maternal copy is expressed while the paternal copy is not active. Other rice PcG genes are expressed in a wide range of tissues and are not imprinted in the endosperm. The two E(z)-like genes appear to have duplicated before the separation of the dicots and monocots; the two homologs of Su(z)12 possibly duplicated during the evolution of the Gramineae and the two ESC-like genes are likely to have duplicated in the ancestor of the grasses. No homologs of the Arabidopsis seed-expressed PcG genes MEA and FIS2 were identified in the rice genome. We have isolated T-DNA insertion lines in the rice homologs of three PcG genes. There is no autonomous endosperm development in these T-DNA insertion lines. One line with a T-DNA insertion in OsEMF2b displays pleiotropic phenotypes including altered flowering time and abnormal flower organs, suggesting important roles in rice development for this gene.
Luo
Ming
M
CSIRO Plant Industry, GPO BOX 1600, ACT 2601, Australia. Electronic address: ming.luo@csiro.au.
Platten
Damien
D
CSIRO Plant Industry, GPO BOX 1600, ACT 2601, Australia; Vitagrain, Uttara Model Town, Dhaka, Bangladesh.
Chaudhury
Abed
A
CSIRO Plant Industry, GPO BOX 1600, ACT 2601, Australia; IRRI, Los Banos, Laguna 4031, Philippines.
Peacock
W J
WJ
CSIRO Plant Industry, GPO BOX 1600, ACT 2601, Australia.
Dennis
Elizabeth S
ES
CSIRO Plant Industry, GPO BOX 1600, ACT 2601, Australia.
D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D018392:Genomic Imprinting / Q000235:genetics*; D008853:Microscopy; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics*; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins / Q000145:classification / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D010940:Plant Proteins; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins