Grayanotoxin I variation across tissues and species of Rhododendron suggests pollinator-herbivore defence trade-offs

Abstract

Grayanotoxin I (GTX I) is a major toxin in leaves of Rhododendron species, where it provides a defence against insect and vertebrate herbivores. Surprisingly, it is also present in R. ponticum nectar, and this can hold important implications for plant-pollinator mutualisms. However, knowledge of GTX I distributions across the genus Rhododendron and in different plant materials is currently limited, despite the important ecological function of this toxin. Here we characterise GTX I expression in the leaves, petals, and nectar of seven Rhododendron species. Our results indicated interspecific variation in GTX I concentration across all species. GTX I concentrations were consistently higher in leaves compared to petals and nectar. Our findings provide preliminary evidence for phenotypic correlation between GTX I concentrations in defensive tissues (leaves and petals) and floral rewards (nectar), suggesting that Rhododendron species may commonly experience functional trade-offs between herbivore defence and pollinator attraction.

Keywords

Rhododendron; Ericaceae; Plant defence; Functional trade-offs; Phenotypic correlation; Nectar chemicals; Grayanotoxin

Published in

Phytochemistry
2023, Volume: 212, article number: 113707Publisher: PERGAMON-ELSEVIER SCIENCE LTD

SLU Authors

• Egan, Paul

  • Department of Plant Protection Biology, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network


UKÄ Subject classification

Botany
Biochemistry and Molecular Biology


Publication identifier

DOI: https://doi.org/10.1016/j.phytochem.2023.113707

Permanent link to this page (URI)

https://res.slu.se/id/publ/122874