Département de Sciences Biologiques, Institut de Recherche en Biologie Végétale, Université de Montréal, Montréal, Canada.
Department of Human Genetics, Canadian Centre for Computational Genomics (C3G), McGill University, Montréal, QC, Canada.
PLoS One. 2022 Jul 19;17(7):e0267540. doi: 10.1371/journal.pone.0267540. eCollection 2022.
Floral adaptations to specific pollinators like corolla shape variation often result in reproductive isolation and thus speciation. But despite their ecological importance, the genetic bases of corolla shape transitions are still poorly understood, especially outside model species. Hence, our goal was to identify candidate genes potentially involved in corolla shape variation between two closely related species of the Rhytidophyllum genus (Gesneriaceae family) from the Antilles with contrasting pollination strategies. Rhytidophyllum rupincola has a tubular corolla and is strictly pollinated by hummingbirds, whereas R. auriculatum has more open flowers and is pollinated by hummingbirds, bats, and insects. We surveyed the literature and used a comparative transcriptome sequence analysis of synonymous and non-synonymous nucleotide substitutions to obtain a list of genes that could explain floral variation between R. auriculatum and R. rupincola. We then tested their association with corolla shape variation using QTL mapping in a F2 hybrid population. Out of 28 genes tested, three were found to be good candidates because of a strong association with corolla shape: RADIALIS, GLOBOSA, and JAGGED. Although the role of these genes in Rhytidophyllum corolla shape variation remains to be confirmed, these findings are a first step towards identifying the genes that have been under selection by pollinators and thus involved in reproductive isolation and speciation in this genus.
花部适应特定传粉者，如花冠形状的变化，往往导致生殖隔离，从而形成物种。但尽管它们具有重要的生态意义，花冠形状转变的遗传基础仍知之甚少，尤其是在模式物种之外。因此，我们的目标是鉴定候选基因，这些基因可能参与安的列斯群岛两个密切相关的 Rhytidophyllum 属（苦苣苔科）物种之间的花冠形状变异，这两个物种具有不同的传粉策略。Rhytidophyllum rupincola 具有管状花冠，仅由蜂鸟传粉，而 R. auriculatum 具有更开放的花朵，由蜂鸟、蝙蝠和昆虫传粉。我们调查了文献，并使用同义与非同义核苷酸替换的比较转录组序列分析，获得了一个可能解释 R. auriculatum 和 R. rupincola 之间花部变异的基因列表。然后，我们使用 F2 杂种群体中的 QTL 映射来测试它们与花冠形状变异的相关性。在测试的 28 个基因中，有三个基因被发现是很好的候选基因，因为它们与花冠形状有很强的相关性：RADIALIS、GLOBOSA 和 JAGGED。尽管这些基因在 Rhytidophyllum 花冠形状变异中的作用仍有待确认，但这些发现是鉴定受传粉者选择并因此参与该属生殖隔离和物种形成的基因的第一步。
