Polyploidy or whole genome duplication is a frequent and recurrent phenomenon in flowering plants that has played a major role in their diversification, adaptation and speciation. The adaptive success of polyploids relates to the different evolutionary fates of duplicated genes. In this study, we explored the impact of the whole genome triplication (WGT) event in the Brassiceae tribe on the genes involved in the self-incompatibility (SI) signalling pathway, a mechanism allowing recognition and rejection of self-pollen in hermaphrodite plants. By taking advantage of the knowledge acquired on this pathway as well as of several reference genomes in Brassicaceae species, we determined copy number of the different genes involved in this pathway and investigated their structural and functional evolutionary dynamics. We could infer that whereas most genes involved in the SI signalling returned to single copies after the WGT event (i.e. ARC1, JDP1, THL1, THL2, Exo70A01) in diploid Brassica species, a few were retained in duplicated (GLO1 and PLDα) or triplicated copies (MLPK). We also carefully studied the gene structure of these latter duplicated genes (including the conservation of functional domains and active sites) and tested their transcription in the stigma to identify which copies seem to be involved in the SI signalling pathway. By taking advantage of these analyses, we then explored the putative origin of a contrasted SI phenotype between two Brassica rapa varieties that have been fully sequenced and shared the same S-allele (S60).

中文翻译：

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全基因组重复对甘蓝型自交不亲和信号通路中涉及的调控基因的进化历史和功能动力学的影响。

多倍体或全基因组重复是开花植物中经常发生的反复现象，在其多样化，适应性和物种形成中起着重要作用。多倍体的适应性成功与重复基因的不同进化命运有关。在这项研究中，我们探讨了芸苔属中的全基因组三倍（WGT）事件对参与自交不亲和（SI）信号传导途径的基因的影响，该机制允许在雌雄同体植物中识别和拒绝自花粉。通过利用在该途径以及十字花科物种中几个参考基因组获得的知识，我们确定了该途径中涉及的不同基因的拷贝数，并研究了它们的结构和功能进化动力学。ARC1，JDP1，THL1，THL2，Exo70A01）在二倍体芸苔属物种，少数是在复制（保留GLO1和PLD α）或三重副本（MLPK）。我们还仔细研究了这些后继重复基因的基因结构（包括功能域和活性位点的保守性），并测试了其在柱头的转录，以确定哪些拷贝似乎与SI信号通路有关。通过利用这些分析，我们然后探索了两个甘蓝型油菜的相反SI表型的推定来源 完全测序并具有相同S-等位基因（S60）的新品种。