Both plant genotype and herbivory shape aspen endophyte communities

Abstract

Salicinoid phenolic glycosides are common defence substances in salicaceous trees and specialist leaf beetles use these compounds for their own defence against predators. Salicinoids vary qualitatively and qualitatively in aspen (Populus tremula) and this variation has a genetic basis. The foliar endophyte mycobiome is plentiful and we hypothesised that it is related to plant genotype, potentially mediated by salicinoid composition, and that interactions with the leaf beetle Chrysomela tremula may alter this relationship. We studied these three-way interactions in controlled greenhouse experiments. Endophytic fungi were isolated from sterilised leaf tissues with and without beetle damage, and from beetles. We confirmed that endophyte composition was influenced by host genotype. Beetle activity added generalist morphs to the mycobiome that overrode the initial host association. Yeast-like genera (Cryptococcus and Rhodotorula) were isolated only from beetle-damaged tissues and from beetles, whereas fast-growing filamentous fungi dominated beetle-free control plants. Competition experiments between filamentous fungi of plant origin and beetle-related yeasts suggested interaction of both stimulating and inhibiting modes of action amongst the fungi. As a result, we detected examples of amensalism, commensalism, parasitism and competition between the morphs tested, but we found no evidence of mutualism, and consequently no co-evolutionary relationship could be demonstrated, between yeasts carried by beetles, host genotype and associated filamentous morphs. Endophyte studies are method-dependent and high-throughput sequencing technology best define the fungal mycobiome, culturing however continues to be a cheap way to provide fundamental ecological insights and it is also required for experimental studies.Electronic supplementary materialThe online version of this article (10.1007/s00442-018-4097-3) contains supplementary material, which is available to authorized users.

Defining the twig fungal communities of Fraxinus species and Fraxinus excelsior genotypes with differences in susceptibility to ash dieback

“…This suggests that the twig fungal communities of F. excelsior genotypes responded differently to the seasonal variables, which could be due to certain fungal taxa governing resistance to ash dieback in the resistant genotypes or vice versa. This is similar to previous findings in other tree species, for example, aspen (Populus tremula) (Albrectsen et al, 2018), narrowleaf cottonwood (P. angustifolia) (Lamit et al, 2014) and coffee (Coffea arabica) (Saucedo-Garcia et al, 2014). Furthermore, we also detected a significant effect of susceptibility to ash dieback on the twig fungal communities of F. excelsior genotypes.…”

Forest Tree Microbiomes and Associated Fungal Endophytes: Functional Roles and Impact on Forest Health

“…Rajala et al [60] demonstrated variations in the communities of endophytes between Norway spruce clones, which suggests a potential influence of the host tree genotype. Albrectsen et al [146] further confirmed that the foliar endophyte composition of Populus tremula L. is influenced by the host genotype. These observations indicate that foliar endophytes communities vary not only among diverse host species [86,135,138], but also among genotypes of the same species [60,146].…”

From plants to herbivores: novel insights into the ecological and evolutionary consequences of plant variation

“…Lastly, there has been increasing interest in the effects of chemical variation on plant-herbivore-microbe interactions (Tabata 2018), and here Albrectsen et al (2018) show that the composition of tree endophytic fungi is influenced by both host tree genotype and leaf beetle herbivory. It is notable that herbivory enriches fungal assemblages without relation to the plant genotype.…”

“…The studies of this special topic cover a broad range of plant life forms, from marine algae in an aquatic system (Ledet et al 2018) to terrestrial herbs (Calf et al 2018;Chiriboga et al 2018;Cuny et al 2018;Howard et al 2018;Humphrey et al 2018;Kergunteuil et al 2018;Quintero and Bowers 2018), to shrubs (Nell et al 2018;Ochoa-López et al 2018), to long-lived trees (Albrectsen et al 2018;Bagchi et al 2018;Cipollini and Peterson 2018;Coley et al 2018;Falk et al 2018;Lämke and Unsicker 2018). In twelve case studies and four review papers, selected aspects of the huge variation in phenomena and underlying mechanisms are highlighted and new research questions opened, which may inspire further research in this exciting field.…”

“…Likewise, variation within and among plant individuals and across landscapes are critical for plant-herbivore interactions, but not fully explored. Micro-or macro-scale spatial heterogeneity in the abiotic and biotic environment can generate significant within-and among-plant variation (e.g., Schaeffer et al 2018), and recent studies have provided novel insights into how plant chemistry impacts herbivores, microbes and natural enemies (Albrectsen et al 2018;Calf et al 2018;Coley et al 2018;Cuny et al 2018). Moreover, the effects of plant chemical traits are often considered in isolation, but they may act together with other features of growth and defense to form distinct trait combinations or syndromes (Coley et al 2018;Kergunteuil et al 2018;Tewes and Müller 2018).…”