Data from: Fitness dynamics within a poplar hybrid zone: II. Impact of exotic sex on native poplars in an urban jungle.

Trees bearing novel or exotic gene components are poised to contribute to the bioeconomy for a variety of purposes such as bioenergy production, phytoremediation, and carbon sequestration within the forestry sector, but sustainable release of trees with novel traits in large-scale plantations requires the quantification of risks posed to native tree populations. Over the last century, exotic hybrid poplars produced through artificial crosses were planted throughout eastern Canada as ornamentals or windbreaks and these exotics provide a proxy by which to examine the fitness of exotic poplar traits within the natural environment to assess risk of exotic gene escape, establishment, and spread into native gene pools. We assessed postzygotic fitness traits of native and exotic poplars within a naturally regenerated stand in eastern Canada (Quebec City, QC). Pure natives (P. balsamifera and P. deltoides spp. deltoides), native hybrids (P. deltoides × P. balsamifera), and exotic hybrids (trees bearing Populus nigra and P. maximowiczii genetic components) were screened for reproductive biomass, yield, seed germination, and fungal disease susceptibility. Exotic hybrids expressed fitness traits intermediate to pure species and were not significantly different from native hybrids. They formed fully viable seed and backcrossed predominantly with P. balsamifera. These data show that exotic hybrids were not unfit and were capable of establishing and competing within the native stand. Future research will seek to examine the impact of exotic gene regions on associated biotic communities to fully quantify the risk exotic poplars pose to native poplar forests.

携带新型或外源基因组分的林木，有望在林业领域通过多种用途助力生物经济发展，包括生物质能源生产、植物修复以及碳封存；但在大规模人工林可持续释放具有新颖性状的林木，需要量化其对本土林木种群构成的风险。近一个世纪以来，通过人工杂交培育的外源杂交杨树被广泛种植于加拿大东部地区，用作观赏植物或防风林；这些外源树种可作为替代模型，用以研究外源杨树性状在自然环境中的适应性，从而评估外源基因逃逸、定植并扩散至本土基因库的风险。我们针对加拿大东部（魁北克省魁北克市）一处天然更新林分中的本土杨树与外源杨树，评估了其合子后适应性性状。研究对象包括纯本土杨树（美洲杨P. balsamifera与三角杨P. deltoides spp. deltoides）、本土杂交杨树（三角杨×美洲杨P. deltoides × P. balsamifera）以及外源杂交杨树（携带欧洲黑杨P. nigra与日本杨P. maximowiczii遗传组分的林木），对其生殖生物量、结实量、种子萌发率以及真菌病害易感性进行了筛选检测。外源杂交杨树的适应性性状介于两个纯合亲本之间，且与本土杂交杨树无显著差异；它们可产生完全具有活力的种子，且主要以美洲杨P. balsamifera为亲本进行回交。上述数据表明，外源杂交杨树并非适应性低下，且能够在本土林分中定植并竞争生存。未来的研究将聚焦于外源基因区域对相关生物群落的影响，以全面量化外源杨树对本土杨树森林构成的风险。