title: Trans-acting small RNA determines dominance relationships in Brassica self-incompatibility.
abstract: A diploid organism has two copies of each gene, one inherited from each parent. The expression of two inherited alleles is sometimes biased by the effects known as dominant/recessive relationships, which determine the final phenotype of the organism. To explore the mechanisms underlying these relationships, we have examined the monoallelic expression of S-locus protein 11 genes (SP11), which encode the male determinants of self-incompatibility in Brassica. We previously reported that SP11 expression was monoallelic in some S heterozygotes, and that the promoter regions of recessive SP11 alleles were specifically methylated in the anther tapetum. Here we show that this methylation is controlled by trans-acting small non-coding RNA (sRNA). We identified inverted genomic sequences that were similar to the recessive SP11 promoters in the flanking regions of dominant SP11 alleles. These sequences were specifically expressed in the anther tapetum and processed into 24-nucleotide sRNA, named SP11 methylation inducer (Smi). Introduction of the Smi genomic region into the recessive S homozygotes triggered the methylation of the promoter of recessive SP11 alleles and repressed their transcription. This is an example showing sRNA encoded in the flanking region of a dominant allele acts in trans to induce transcriptional silencing of the recessive allele. Our finding may provide new insights into the widespread monoallelic gene expression systems.
authors: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0192, Japan.
authors: Yoshiaki
authors: Y
authors: Tarutani
authors: Hiroshi
authors: H
authors: Shiba
authors: Megumi
authors: M
authors: Iwano
authors: Tomohiro
authors: T
authors: Kakizaki
authors: Go
authors: G
authors: Suzuki
authors: Masao
authors: M
authors: Watanabe
authors: Akira
authors: A
authors: Isogai
authors: Seiji
authors: S
authors: Takayama
mesh_terms: D000483:Alleles; D001483:Base Sequence; D001937:Brassica / Q000235:genetics* / Q000502:physiology; D019175:DNA Methylation; D004171:Diploidy; D035264:Flowers / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D020868:Gene Silencing; D005799:Genes, Dominant / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics*; D005808:Genes, Recessive / Q000235:genetics; D006239:Haplotypes / Q000235:genetics; D006579:Heterozygote; D006720:Homozygote; D008969:Molecular Sequence Data; D010641:Phenotype; D051479:Plant Infertility / Q000235:genetics* / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified; D011058:Pollen / Q000235:genetics / Q000378:metabolism; D054817:Pollination / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics*; D022661:RNA, Untranslated / Q000235:genetics*; D012098:Reproduction / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic / Q000235:genetics; D019076:Transgenes / Q000235:genetics
chemical_list: D010940:Plant Proteins; D018749:RNA, Plant; D022661:RNA, Untranslated; C431526:SP11 protein, Brassica