Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo 657-8501, Japan.
J Exp Bot. 2011 Mar;62(6):1887-902. doi: 10.1093/jxb/erq381. Epub 2010 Dec 13.
Most fruit trees in the Rosaceae exhibit self-incompatibility, which is controlled by the pistil S gene, encoding a ribonuclease (S-RNase), and the pollen S gene at the S-locus. The pollen S in Prunus is an F-box protein gene (SLF/SFB) located near the S-RNase, but it has not been identified in Pyrus and Malus. In the Japanese pear, various F-box protein genes (PpSFBB(-α-γ)) linked to the S-RNase are proposed as the pollen S candidate. Two bacterial artificial chromosome (BAC) contigs around the S-RNase genes of Japanese pear were constructed, and 649 kb around S(4)-RNase and 378 kb around S(2)-RNase were sequenced. Six and 10 pollen-specific F-box protein genes (designated as PpSFBB(4-u1-u4, 4-d1-d2) and PpSFBB(2-u1-u5,) (2-d1-d5), respectively) were found, but PpSFBB(4-α-γ) and PpSFBB(2-γ) were absent. The PpSFBB(4) genes showed 66.2-93.1% amino acid identity with the PpSFBB(2) genes, which indicated clustering of related polymorphic F-box protein genes between haplotypes near the S-RNase of the Japanese pear. Phylogenetic analysis classified 36 F-box protein genes of Pyrus and Malus into two major groups (I and II), and also generated gene pairs of PpSFBB genes and PpSFBB/Malus F-box protein genes. Group I consisted of gene pairs with 76.3-94.9% identity, while group II consisted of gene pairs with higher identities (>92%) than group I. This grouping suggests that less polymorphic PpSFBB genes in group II are non-S pollen genes and that the pollen S candidates are included in the group I PpSFBB genes.
大多数蔷薇科果树表现出自交不亲和性，由柱头 S 基因（编码一种核糖核酸酶[S-RNase]）和 S 座位上的花粉 S 基因控制。李属植物的花粉 S 是位于 S-RNase 附近的 F-box 蛋白基因（SLF/SFB），但在梨属和苹果属中尚未鉴定出。在日本梨中，各种与 S-RNase 相关的 F-box 蛋白基因（PpSFBB(-α-γ)）被提议作为花粉 S 候选基因。构建了日本梨 S-RNase 基因周围的两个细菌人工染色体（BAC）连续序列，对 S(4)-RNase 周围的 649kb 和 S(2)-RNase 周围的 378kb 进行了测序。发现了 6 个和 10 个花粉特异性 F-box 蛋白基因（分别命名为 PpSFBB(4-u1-u4, 4-d1-d2)和 PpSFBB(2-u1-u5,)（2-d1-d5)），但 PpSFBB(4-α-γ)和 PpSFBB(2-γ)缺失。PpSFBB(4)基因与 PpSFBB(2)基因的氨基酸同一性为 66.2-93.1%，表明日本梨 S-RNase 附近的单倍型之间相关的多态性 F-box 蛋白基因聚类。系统发育分析将梨属和苹果属的 36 个 F-box 蛋白基因分为两个主要组（I 和 II），并生成了 PpSFBB 基因和 PpSFBB/苹果属 F-box 蛋白基因的基因对。组 I 由具有 76.3-94.9%同一性的基因对组成，而组 II 由具有高于组 I 的同一性（>92%）的基因对组成。这种分组表明，组 II 中较少多态性的 PpSFBB 基因是非 S 花粉基因，花粉 S 候选基因包含在组 I PpSFBB 基因中。
