Abstract Detail


Howard, Mia [1], Kao-Kniffin, Jenny [2], Kessler, Andre [3].

Shifts in plant-microbe interactions over ecological succession and their effects on plants’ resistance to herbivores.

Plant herbivore defenses typically escalate over the course of succession, paralleling increasing pressure from herbivores. We have observed increases in the herbivore resistance of a native plant, tall goldenrod, Solidago altissima (Asteraceae), over the first 15 years of oldfield succession in a large-scale field experiment in upstate New York.  While our previous work has suggested that this increase in resistance is at least partially due to rapid microevolutionary shifts in the plant populations, plastic phenotypic shifts in response to changing conditions in the soil environment also contribute. Our field surveys revealed significant shifts in both the biomass and composition of soil microbial communities (bacterial and fungal) in the S. altissima rhizosphere over succession.  We hypothesized that these microbial shifts would functionally affect plant metabolism and thereby at least partially mediate this increase in herbivore resistance that we observed over succession.  In order to assess the capacity of these microbial shifts to alter herbivore resistance, we performed a soil microbiome transplant experiment with S. altissima plants and microbiomes from early (2 years post-agriculture), mid (6 years), and late (15 years) succession, and then characterized their resistance phenotypes through feeding assays with herbivores and analysis of leaf secondary metabolites.  We found that the specialist goldenrod leaf beetle, Trirhabda virgata (Chrysomelidae), strongly preferred to eat leaves from S. altissima plants grown in soil media inoculated with early succession soil microbiomes (2 years) over their later succession (15 years) counterparts in a feeding choice experiment.  This indicates that successional shifts in the soil microbiome can increase resistance to aboveground herbivores, likely contributing to the pattern of decreased herbivory on S. altissima plants we observed at later successional stages in the field.  Moreover, we found that inoculating several crop species with these late succession soil microbiomes generally improved their resistance to Trichoplusia ni, a common agricultural insect pest. These results suggest that manipulating the soil microbiome may be a worthwhile target for improving pest resistance in agriculture and that fallow fields may harbor resistance-conferring soil microbes.

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1 - Cornell University, Plant Biology, 215 Tower Road, E443 Corson Hall, Ithaca, NY, 14853, United States
2 - Cornell University, Horticulture, Plant Science Building, Ithaca, NY, 14853, USA
3 - E445 Corson Hall, Ithaca, NY, 14853, United States

chemical defense
plant resistance
Plant-Animal Interactions
plant-soil feedback

Presentation Type: Oral Paper
Session: ECO7, Ecology 7: Species Interactions
Location: Virtual/Virtual
Date: Friday, July 31st, 2020
Time: 12:45 PM
Number: ECO7002
Abstract ID:335
Candidate for Awards:Ecological Section Best Graduate Student Paper

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