Institute of Crop Science, National Agriculture and Food Research Organization (NARO), Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8518, Japan.
Tohoku University, Aoba-ku, Sendai, 980-0845, Japan.
Heredity (Edinb). 2019 Oct;123(4):492-502. doi: 10.1038/s41437-019-0227-x. Epub 2019 May 10.
Common buckwheat (Fagopyrum esculentum) is a heteromorphic self-incompatible (SI) species with two types of floral architecture: thrum (short style) and pin (long style). The floral morphology and intra-morph incompatibility are controlled by a single genetic locus, S. However, the molecular mechanisms underlying the heteromorphic self-incompatibility of common buckwheat remain unclear. To identify these mechanisms, we performed proteomic, quantitative reverse-transcription PCR, and linkage analyses. Comparison of protein profiles between the long and short styles revealed a protein unique to the short style. Amino-acid sequencing revealed that it was a truncated form of polygalacturonase (PG); we designated the gene encoding this protein FePG1. Phylogenetic analysis classified FePG1 into the same clade as PGs that function in pollen development and floral morphology. FePG1 expression was significantly higher in short styles than in long styles. It was expressed in flowers of a short-homostyle line but not in flowers of a long-homostyle line. Linkage analysis indicated that FePG1 was not linked to the S locus; it could be a factor downstream of this locus. Our finding of a gene putatively working under the regulation of the S locus provides useful information for elucidation of the mechanism of heteromorphic self-incompatibility.
普通荞麦（Fagopyrum esculentum）是一种异型自交不亲和（SI）物种，具有两种花型结构：长花柱（短花柱）和短花柱（长花柱）。花型和同型不亲和性由单个遗传位点 S 控制。然而，普通荞麦异型自交不亲和的分子机制尚不清楚。为了鉴定这些机制，我们进行了蛋白质组学、定量逆转录 PCR 和连锁分析。长花柱和短花柱之间的蛋白质图谱比较揭示了一种短花柱特有的蛋白质。氨基酸测序表明它是多聚半乳糖醛酸酶（PG）的截短形式；我们将编码这种蛋白质的基因命名为 FePG1。系统发育分析将 FePG1 归类为与花粉发育和花型功能相同的 PG 簇。FePG1 在短花柱中的表达明显高于长花柱。它在短花柱同型系的花朵中表达，但在长花柱同型系的花朵中不表达。连锁分析表明，FePG1 与 S 位点不连锁；它可能是该位点下游的一个因素。我们发现一个假定在 S 位点调控下工作的基因，为阐明异型自交不亲和的机制提供了有用的信息。
