Recent studies show that molecular convergence plays an unexpectedly common role in the evolution of convergent phenotypes. We exploited this phenomenon to find candidate loci underlying resistance to the emerald ash borer (EAB, Agrilus planipennis), the United States’ most costly invasive forest insect to date, within the pan-genome of ash trees (the genus Fraxinus). We show that EAB-resistant taxa occur within three independent phylogenetic lineages. In genomes from these resistant lineages, we detect 53 genes with evidence of convergent amino acid evolution. Gene-tree reconstruction indicates that, for 48 of these candidates, the convergent amino acids are more likely to have arisen via independent evolution than by another process such as hybridization or incomplete lineage sorting. Seven of the candidate genes have putative roles connected to the phenylpropanoid biosynthesis pathway and 17 relate to herbivore recognition, defence signalling or programmed cell death. Evidence for loss-of-function mutations among these candidates is more frequent in susceptible species than in resistant ones. Our results on evolutionary relationships, variability in resistance, and candidate genes for defence response within the ash genus could inform breeding for EAB resistance, facilitating ecological restoration in areas invaded by this beetle.

最近的研究表明，分子趋同在趋同表型的进化中发挥着意想不到的共同作用。我们利用这一现象在白蜡树（白蜡属）的全基因组中寻找对白蜡螟（EAB， Agrilus planipennis ）具有抗性的候选位点，白蜡螟是美国迄今为止最昂贵的入侵森林昆虫。我们发现 EAB 抗性类群出现在三个独立的系统发育谱系中。在这些抗性谱系的基因组中，我们检测到 53 个具有趋同氨基酸进化证据的基因。基因树重建表明，对于其中 48 个候选氨基酸，趋同氨基酸更有可能是通过独立进化产生的，而不是通过杂交或不完全谱系排序等其他过程产生的。其中 7 个候选基因具有与苯丙素生物合成途径相关的假定作用，17 个与草食动物识别、防御信号或程序性细胞死亡有关。这些候选者中功能丧失突变的证据在易感物种中比在抗性物种中更常见。我们对白蜡树属内进化关系、抗性变异性和防御反应候选基因的研究结果可以为 EAB 抗性育种提供信息，促进受这种甲虫入侵的地区的生态恢复。