Gene duplication and genetic exchange drive the evolution of S-RNase-based self-incompatibility in Petunia
Gene duplication and genetic exchange drive the evolution of S-RNase-based self-incompatibility in Petunia
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DOI：
10.1038/nplants.2014.5
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发表时间：
2015-01-08
期刊：
影响因子：
18
通讯作者：
Takayama, Seiji
中科院分区：
文献类型：
--
作者：
Kubo, Ken-ichi;Paape, Timothy;Takayama, Seiji
开花植物中的自交不亲和（SI）系统区分自花和非自花花粉以防止近交。虽然其他 SI 系统依赖于特定雄性和雌性决定簇之间的自我识别，但茄科科具有非自我识别系统，导致花粉中表达的 S 位点 F-box 蛋白 (SLF) 的多个雄性决定簇对雌蕊中表达的 S-核糖核酸酶 (S-RNase) 的雌性决定簇进行解毒。目前尚不清楚茄科物种中有多少这种非自我识别系统的 SLF 组件，也不知道它们是如何进化的。我们使用大规模下一代测序和基因组聚合酶链式反应 (PCR) 技术，从总共 168 个 SLF 序列中，在 SI Petunia 的每个 S 单倍型中鉴定了 16-20 个 SLF。我们通过假设特定的 S 等位基因不得具有识别其自身 S-RNase 的保守 SLF 来预测 SLF 的目标 S-RNase，并通过转化实验验证了这些预测。一个简单的数学模型证实 16-20 个 SLF 序列足以识别绝大多数目标 S-RNase。我们发现了基因转换事件的证据，我们认为这对于非自我识别系统的构成至关重要，并且也有助于自相容突变。
Self-incompatibility (SI) systems in flowering plants distinguish self- and non-self pollen to prevent inbreeding. While other SI systems rely on the self- recognition between specific male- and female-determinants, the Solanaceae family has a non-self recognition system resulting in the detoxification of female-determinants of S-ribonucleases (S-RNases), expressed in pistils, by multiple male- determinants of S-locus F-box proteins (SLFs), expressed in pollen. It is not known how many SLF components of this non-self recognition system there are in Solanaceae species, or how they evolved. We identified 16-20 SLFs in each S-haplotype in SI Petunia, from a total of 168 SLF sequences using large-scale next-generation sequencing and genomic polymerase chain reaction (PCR) techniques. We predicted the target S-RNases of SLFs by assuming that a particular S-allele must not have a conserved SLF that recognizes its own S-RNase, and validated these predictions by transformation experiments. A simple mathematical model confirmed that 16-20 SLF sequences would be adequate to recognize the vast majority of target S-RNases. We found evidence of gene conversion events, which we suggest are essential to the constitution of a non-self recognition system and also contribute to self- compatible mutations.