Data and publications from the Andre Kessler lab

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    Metabolic Integration of Spectral and Chemical Cues Mediating Plant Responses to Competitors and Herbivores
    (Plants, 2022)
    Light quality and chemicals in a plant’s environment can provide crucial information about the presence and nature of antagonists, such as competitors and herbivores. Here, we evaluate the roles of three sources of information—shifts in the red:far red (R:FR) ratio of light reflected off of potentially competing neighbors, induced metabolic changes to damage by insect herbivores, and induced changes to volatile organic compounds emitted from herbivore-damaged neighboring plants—to affect metabolic responses in the tall goldenrod, Solidago altissima. We address the hy-pothesis that plants integrate the information available about competitors and herbivory to opti-mize metabolic responses to interacting stressors by exposing plants to the different types of en-vironmental information in isolation and combination. We found strong interactions between the exposure to decreased R:FR light ratios and damage on the induction of secondary metabolites (volatile and non-volatile) in plants. Similarly, the perception of VOCs emitted from neighboring plants was altered by the simultaneous exposure to spectral cues from neighbors. These results suggest that plants integrate spectral and chemical environmental cues to change the production and perception of volatile and non-volatile compounds and highlight the role of plant con-text-dependent metabolic responses in mediating population and community dynamics.
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    Chautá, Alexander; Kumar, Arvind; Mejia, Jessica; Stashenko, Elena; Kessler, Andre (TBD, 2022)
    Stickiness of vegetative tissues has evolved multiple times in different plant families but is rare and understudied in flowers. While stickiness in general is thought to function primarily as a defense against herbivores, it can compromise mutualistic interactions (such as those with pollinators) in reproductive tissues. Here, we test the hypothesis that stickiness on flower petals of the High-Andean plant, Bejaria resinosa (Ericaceae), functions as a defense against florivores. We address ecological consequences and discuss potential trade-offs associated with a repellant trait expressed in flowers that mediate mutualistic interactions. In surveys and manipulative experiments, we assess florivory and resulting fitness effects on plants with sticky and non-sticky flowers in different native populations of B. resinosa in Colombia. In addition, we analyze the volatile and non-volatile components in sticky and non-sticky flower morphs to understand the chemical information context within which stickiness is expressed. We demonstrate that fruit set is strongly affected by floral stickiness but also varies with population. While identifying floral stickiness as a major defensive function, our data also suggest that the context-dependency of chemical defense functionality likely arises from differential availability of primary pollinators and potential trade-offs between chemical defense with different modes of action.
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    Shifts in plant–microbe interactions over community succession and their effects on plant resistance to herbivores
    Howard, Mia; Kao-Kniffin, Jenny; Kessler, Andre (New Phytologist, 2020)
    Soil microorganisms can influence the development of complex plant phenotypes, including resistance to herbivores. This microbiome-mediated plasticity may be particularly important for plant species that persist in environments with drastically changing herbivore pressure, for example over community succession. We established a 15-yr gradient of old-field succession to examine the herbivore resistance and rhizosphere microbial communities of Solidago altissima plants in a large-scale field experiment. To assess the functional effects of these successional microbial shifts, we inoculated S. altissima plants with microbiomes from the 2nd, 6th and 15th successional years in a glasshouse and compared their herbivore resistance. The resistance of S. altissima plants to herbivores changed over succession, with concomitant shifts in the rhizosphere microbiome. Late succession microbiomes conferred the strongest herbivore resistance to S. altissima plants in a glasshouse experiment, paralleling the low levels of herbivory observed in the oldest communities in the field. While many factors change over succession and may contribute to the shifts in rhizosphere communities and herbivore resistance we observed, our results indicated that soil microbial shifts alone can alter plants’ interactions with herbivores. Our findings suggest that changes in soil microbial communities over succession can play an important role in enhancing plant resistance to herbivores.