Yasuda Shinsuke, Wada Yuko, Kakizaki Tomohiro, Tarutani Yoshiaki, Miura-Uno Eiko, Murase Kohji, Fujii Sota, Hioki Tomoya, Shimoda Taiki, Takada Yoshinobu, Shiba Hiroshi, Takasaki-Yasuda Takeshi, Suzuki Go, Watanabe Masao, Takayama Seiji
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.
Division of Vegetable Breeding, Institute of Vegetable and Floriculture Science, NARO, Tsu, Mie 514-2392, Japan.
Nat Plants. 2016 Dec 22;3:16206. doi: 10.1038/nplants.2016.206.
In diploid organisms, phenotypic traits are often biased by effects known as Mendelian dominant-recessive interactions between inherited alleles. Phenotypic expression of SP11 alleles, which encodes the male determinants of self-incompatibility in Brassica rapa, is governed by a complex dominance hierarchy. Here, we show that a single polymorphic 24 nucleotide small RNA, named SP11 methylation inducer 2 (Smi2), controls the linear dominance hierarchy of the four SP11 alleles (S > S > S > S). In all dominant-recessive interactions, small RNA variants derived from the linked region of dominant SP11 alleles exhibited high sequence similarity to the promoter regions of recessive SP11 alleles and acted in trans to epigenetically silence their expression. Together with our previous study, we propose a new model: sequence similarity between polymorphic small RNAs and their target regulates mono-allelic gene expression, which explains the entire five-phased linear dominance hierarchy of the SP11 phenotypic expression in Brassica.
在二倍体生物中，表型性状常常受到遗传等位基因之间孟德尔显性-隐性相互作用的影响。编码白菜自交不亲和性雄性决定因子的SP11等位基因的表型表达受复杂的显性等级制度支配。在这里，我们表明，一个单一的多态性24核苷酸小RNA，名为SP11甲基化诱导因子2（Smi2），控制着四个SP11等位基因（S>S>S>S）的线性显性等级。在所有显性-隐性相互作用中，来自显性SP11等位基因连锁区域的小RNA变体与隐性SP11等位基因的启动子区域表现出高度序列相似性，并通过反式作用在表观遗传上沉默它们的表达。结合我们之前的研究，我们提出了一个新模型：多态性小RNA与其靶标之间的序列相似性调节单等位基因表达，这解释了白菜中SP11表型表达的整个五阶段线性显性等级。
