title: Floral Scent Mimicry and Vector-Pathogen Associations in a Pseudoflower-Inducing Plant Pathogen System.
abstract: Several fungal plant pathogens induce 'pseudoflowers' on their hosts to facilitate insect-mediated transmission of gametes and spores. When spores must be transmitted to host flowers to complete the fungal life cycle, we predict that pseudoflowers should evolve traits that mimic flowers and attract the most effective vectors in the flower-visiting community. We quantified insect visitation to flowers, healthy leaves and leaves infected with Monilinia vaccinii-corymbosi (Mvc), the causative agent of mummy berry disease of blueberry. We developed a nested PCR assay for detecting Mvc spores on bees, flies and other potential insect vectors. We also collected volatiles from blueberry flowers, healthy leaves and leaves infected with Mvc, and experimentally manipulated specific pathogen-induced volatiles to assess attractiveness to potential vectors. Bees and flies accounted for the majority of contacts with flowers, leaves infected with Mvc and healthy leaves. Flowers were contacted most often, while there was no difference between bee or fly contacts with healthy and infected leaves. While bees contacted flowers more often than flies, flies contacted infected leaves more often than bees. Bees were more likely to have Mvc spores on their bodies than flies, suggesting that bees may be more effective vectors than flies for transmitting Mvc spores to flowers. Leaves infected with Mvc had volatile profiles distinct from healthy leaves but similar to flowers. Two volatiles produced by flowers and infected leaves, cinnamyl alcohol and cinnamic aldehyde, were attractive to bees, while no volatiles manipulated were attractive to flies or any other insects. These results suggest that Mvc infection of leaves induces mimicry of floral volatiles, and that transmission occurs primarily via bees, which had the highest likelihood of carrying Mvc spores and visited flowers most frequently.
authors.affiliation: Department of Entomology, Cornell University, Ithaca, New York, 14853, United States of America.
authors.forename: Scott H
authors.initials: SH
authors.lastname: McArt
authors.affiliation: School of Natural Sciences, California State University-Monterey Bay, Seaside, California, 93955, United States of America.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Miles
authors.affiliation: Department of Entomology, Philip E. Marucci Center, Rutgers University, Chatsworth, New Jersey, 08019, United States of America.
authors.forename: Cesar
authors.initials: C
authors.lastname: Rodriguez-Saona
authors.affiliation: Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan, 48824, United States of America.
authors.forename: Annemiek
authors.initials: A
authors.lastname: Schilder
authors.affiliation: Department of Biology, University of Massachusetts, Amherst, Massachusetts, 01003, United States of America.
authors.forename: Lynn S
authors.initials: LS
authors.lastname: Adler
authors.affiliation: Department of Entomology, Michigan State University, East Lansing, Michigan, 48824, United States of America.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Grieshop
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology; D029798:Blueberry Plants / Q000382:microbiology*; D004271:DNA, Fungal / Q000032:analysis; D004175:Diptera / Q000502:physiology; D035264:Flowers / Q000382:microbiology*; D054884:Host-Pathogen Interactions / Q000502:physiology*; D006927:Hymenoptera / Q000502:physiology; D018716:Molecular Mimicry; D009812:Odorants / Q000032:analysis*; D018515:Plant Leaves / Q000382:microbiology; D016133:Polymerase Chain Reaction; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D004271:DNA, Fungal; D055549:Volatile Organic Compounds