Fruit Tree Breeding Department. Instituto Valenciano de Investigaciones Agrarias (IVIA). CV-315, Km. 10,7. 46113 Moncada (Valencia), Spain.
Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas. C/Ingeniero Fausto Elio s/n, 46022 Valencia, Spain.
J Exp Bot. 2017 Nov 2;68(18):5069-5078. doi: 10.1093/jxb/erx336.
S-RNase based gametophytic self-incompatibility (SI) is a widespread prezygotic reproductive barrier in flowering plants. In the Solanaceae, Plantaginaceae and Rosaceae gametophytic SI is controlled by the pistil-specific S-RNases and the pollen S-locus F-box proteins but non-S-specific factors, namely modifiers, are also required. In apricot, Prunus armeniaca (Rosaceae), we previously mapped two pollen-part mutations that confer self-compatibility in cultivars Canino and Katy at the distal end of chromosome 3 (M-locus) unlinked to the S-locus. Here, we used high-resolution mapping to identify the M-locus with an ~134 kb segment containing ParM-1-16 genes. Gene expression analysis identified four genes preferentially expressed in anthers as modifier gene candidates, ParM-6, -7, -9 and -14. Variant calling of WGS Illumina data from Canino, Katy, and 10 self-incompatible cultivars detected a 358 bp miniature inverted-repeat transposable element (MITE) insertion in ParM-7 shared only by self-compatible apricots, supporting ParM-7 as strong candidate gene required for SI. ParM-7 encodes a disulfide bond A-like oxidoreductase protein, which we named ParMDO. The MITE insertion truncates the ParMDO ORF and produces a loss of SI function, suggesting that pollen rejection in Prunus is dependent on redox regulation. Based on phylogentic analyses we also suggest that ParMDO may have originated from a tandem duplication followed by subfunctionalization and pollen-specific expression.
基于 S-RNase 的配子体自交不亲和性（SI）是开花植物中广泛存在的合子前生殖障碍。在茄科、车前科和蔷薇科中，配子体 SI 由柱头特异性 S-RNases 和花粉 S 位点 F-box 蛋白控制，但也需要非 S 特异性因子，即修饰因子。在杏树（蔷薇科）中，我们之前在染色体 3 （M 位点）的远端将两个花粉部分突变定位到与 S 位点无关的品种 Canino 和 Katy 中，赋予了它们自交亲和性。在这里，我们使用高分辨率作图将 M 位点定位到包含 ParM-1-16 基因的约 134 kb 片段中。基因表达分析鉴定了四个在花药中优先表达的基因作为修饰基因候选物，ParM-6、-7、-9 和 -14。来自 Canino、Katy 和 10 个自交不亲和品种的 WGS Illumina 数据的变异调用检测到 ParM-7 中的一个 358 bp 微型反向重复转座元件（MITE）插入，仅在自交亲和杏中共享，支持 ParM-7 作为 SI 所必需的强候选基因。ParM-7 编码一个二硫键 A 样氧化还原酶蛋白，我们将其命名为 ParMDO。MITE 插入截断了 ParMDO ORF 并产生 SI 功能丧失，这表明 Prunus 中的花粉排斥依赖于氧化还原调节。基于系统发育分析，我们还提出 ParMDO 可能起源于串联重复，随后发生亚功能化和花粉特异性表达。
