| Title: | Simulated folivory increases vertical transmission of fungal endophytes that deter herbivores and alter tolerance to herbivory in Poa autumnalis |
| Author(s): | Gundel PE; Sun P; Charlton ND; Young CA; Miller TEX; Rudgers JA; |
| Address: | "IFEVA-CONICET, Department of Ecology, College of Agronomy, University of Buenos Aires, Buenos Aires, Argentina. Department of Biology, University of New Mexico, Albuquerque, NM, USA. Department of Biosciences, Rice University, Houston, TX, USA. Noble Research Institute LLC, Ardmore, OK, USA" |
| ISSN/ISBN: | 1095-8290 (Electronic) 0305-7364 (Print) 0305-7364 (Linking) |
| Abstract: | "BACKGROUND AND AIMS: The processes that maintain variation in the prevalence of symbioses within host populations are not well understood. While the fitness benefits of symbiosis have clearly been shown to drive changes in symbiont prevalence, the rate of transmission has been less well studied. Many grasses host symbiotic fungi (Epichloe spp.), which can be transmitted vertically to seeds or horizontally via spores. These symbionts may protect plants against herbivores by producing alkaloids or by increasing tolerance to damage. Therefore, herbivory may be a key ecological factor that alters symbiont prevalence within host populations by affecting either symbiont benefits to host fitness or the symbiont transmission rate. Here, we addressed the following questions: Does symbiont presence modulate plant tolerance to herbivory? Does folivory increase symbiont vertical transmission to seeds or hyphal density in seedlings? Do plants with symbiont horizontal transmission have lower rates of vertical transmission than plants lacking horizontal transmission? METHODS: We studied the grass Poa autumnalis and its symbiotic fungi in the genus Epichloe. We measured plant fitness (survival, growth, reproduction) and symbiont transmission to seeds following simulated folivory in a 3-year common garden experiment and surveyed natural populations that varied in mode of symbiont transmission. KEY RESULTS: Poa autumnalis hosted two Epichloe taxa, an undescribed vertically transmitted Epichloe sp. PauTG-1 and E. typhina subsp. poae with both vertical and horizontal transmission. Simulated folivory reduced plant survival, but endophyte presence increased tolerance to damage and boosted fitness. Folivory increased vertical transmission and hyphal density within seedlings, suggesting induced protection for progeny of damaged plants. Across natural populations, the prevalence of vertical transmission did not correlate with symbiont prevalence or differ with mode of transmission. CONCLUSIONS: Herbivory not only mediated the reproductive fitness benefits of symbiosis, but also promoted symbiosis prevalence by increasing vertical transmission of the fungus to the next generation. Our results reveal a new mechanism by which herbivores could influence the prevalence of microbial symbionts in host populations" |
| Keywords: | Endophytes *Epichloe Herbivory *Poa Poaceae Symbiosis Epichloe Defensive mutualism induced response resistance tolerance transgenerational effects; |
| Notes: | "MedlineGundel, Pedro E Sun, Prudence Charlton, Nikki D Young, Carolyn A Miller, Tom E X Rudgers, Jennifer A eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. England 2020/02/06 Ann Bot. 2020 May 13; 125(6):981-991. doi: 10.1093/aob/mcaa021" |
