Hybridization inPopulusalters the species composition and interactions of root-colonizing fungi: consequences for host plant performance

Abstract

Interactions among plants and soil microbes can significantly influence plant communities, yet we understand little about how hybridization of plant species might alter these interactions. In addition, few studies have explored the effects of different components of soil microbial communities on plant performance. We tested for feedbacks between soil microbes within a Populus hybridizing system using approaches that allowed us to isolate the effects of arbuscular mycorrhizal fungi (AMF) and root endophytes. We found significant differences among the arbuscular mycorrhizal (AM) fungal spore communities cultured from Populus angustifolia James, Populus fremontii S. Watson, and their F 1 hybrids. Populus angustifolia cuttings grew 40% larger when inoculated with AM fungal spores from F 1 hybrids than with spores from P. fremontii, while growth with spores from P. angustifolia was intermediate. However, parental and hybrid inocula promoted growth equally when soil inoculum was used. Roots inoculated with AM fungal spores alone were colonized principally by AMF, while those inoculated with soil were colonized mostly by dark septate endophytes. These results indicate that genetic variation among hybridizing plant species can influence both microbial communities and their interactions with host plants, but these effects depend upon the type of microbe. Furthermore, our results suggest that interactions among fungi during root colonization may alter the composition and function of the plant microbiome.Key words: arbuscular mycorrhizal fungi, interspecific hybrid, dark septate endophyte, plant-soil feedback, Populus spp.Résumé : Les interactions entre les plantes et les microorganismes peuvent influencer significativement les communautés végétales, et pourtant on ne comprend pas bien comment l'hybridation des espèces végétales peut altérer ces interactions. De plus, peu d'études explorent les effets de différentes composantes des communautés microbiennes sur la performance des plantes. Les auteurs ont examiné les rétroactions entre des microorganismes du sol dans un système d'hybridation de Populus, en utilisant des approches permettant d'isoler les effets des champignons mycorhiziens arbusculaires (CMA) et des endophytes racinaires. Ils ont trouvé des différences significatives parmi les communautés sporales des champignons arbusculaires (CA) cultivées à partir des Populus angustifolia James, Populus fremontii S. Watson et leurs hybrides F 1 . Les boutures du P. angustifolia ont montré une augmentation de croissance de 40 % lorsqu'inoculées avec les spores fongiques AM provenant des hybrides F 1 , qu'avec celles provenant du P. fremontii, alors que la croissance avec les spores provenant du P. angustifolia était intermédiaire. Cependant, les inoculums parentaux et hybrides ont exercé la même promotion de croissance lorsque du sol a été utilisé comme inoculum. Les racines inoculées avec des spores fongiques seules ont été colonisées principalement par des CMA, alors que celles inoculées avec le sol ont été colonisées surt...

A Symbiosis Between a Dark Septate Fungus, an Arbuscular Mycorrhiza, and Two Plants Native to the Sagebrush Steppe

“…Studies that have directly investigated these questions are rare and have yielded conflicting results. In Populus, Gehring et al (2013) observed that an increase in DSE fungal colonization was correlated with a decrease in AMF colonization. In contrast, Della Monica et al 2015and Wężowicz et al (2017) showed similar rates of AMF colonization in plants co-inoculated with AMF and DSE than those solely inoculated with AMF.…”