ROR1/RPA2A, a putative replication protein A2, functions in epigenetic gene silencing and in regulation of meristem development in Arabidopsis.
We screened for suppressors of repressor of silencing1 (ros1) using the silenced 35S promoter-neomycin phosphotransferase II (Pro(35S):NPTII) gene as a marker and identified two allelic mutants, ror1-1 and ror1-2 (for suppressor of ros1). Map-based cloning revealed that ROR1 encodes a 31-kD protein similar to DNA replication protein A2 (RPA2A). Mutations in ROR1 reactivate the silenced Pro(35S):NPTII gene but not RD29A promoter-luciferase in the ros1 mutant. DNA methylation in rDNA, centromeric DNA, and RD29A promoter regions is not affected by ror1. However, chromatin immunoprecipitation data suggest that histone H3 acetylation is increased and histone H3K9 dimethylation is decreased in the 35S promoter in the ror1 ros1 mutant compared with ros1. These results indicate that release of silenced Pro(35S):NPTII by ror1 mutations is independent of DNA methylation. ROR1/RPA2A is strongly expressed in shoot and root meristems. Mutations in ROR1/RPA2A affect cell division in meristems but not final cell sizes. Our work suggests important roles of ROR1/RPA2A in epigenetic gene silencing and in the regulation of plant development.
Xia
Ran
R
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing.
Wang
Junguo
J
Liu
Chunyan
C
Wang
Yu
Y
Wang
Youqun
Y
Zhai
Jixian
J
Liu
Jun
J
Hong
Xuhui
X
Cao
Xiaofeng
X
Zhu
Jian-Kang
JK
Gong
Zhizhong
Z
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D044127:Epigenesis, Genetic; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D017930:Genes, Reporter; D005816:Genetic Complementation Test; D006801:Humans; D018519:Meristem / Q000166:cytology / Q000254:growth & development*; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D019076:Transgenes; D020798:Two-Hybrid System Techniques
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C509521:ROR1 protein, Arabidopsis; C471271:ROS1 protein, Arabidopsis; D011993:Recombinant Fusion Proteins