Plant-Animal Interactions

Paul Egan (PhD student)

Research Profile

Chemical ecology of invasive Rhododendron - comparisons between exotic and native habitats and taxa

Grayanotoxins are naturally occurring diterpenoids found in several genera of Ericaceae, and are characterised by a polyhydroxylated tetracyclic skeleton. In the case of Rhododendron ponticum, an introduced alien species which has become highly invasive in Ireland and Britain, the production of these toxic compounds in plants, and in particular in both nectar and pollen, may facilitate invasive spread. The current project will therefore use invasion by R. ponticum as a model system to discover the role of toxic nectar in the invasion process, as it is not clear whether GTX expression has been enhanced or reduced in exotic habitats, in comparison to native Iberian populations (Spain, Portugal). The adaptive benefit of grayanotoxins in nectar and pollen will also be assessed from the perspective of local mutualist pollinators, with identification of floral volatiles and pigments which may serve as attractant/deterrent cues to GTX rich flowers currently on-going. LC and GC-MS analyses will be carried out between TCD and the Royal Botanic Garden, Kew (UK) and will target a wide range of taxa, including non-invasive European species (e.g. R. caucasicum) and North American species with which invasive R. ponticum in Britain is thought to have hybridised (i.e. R. catawbiense, R. maximum). Identifying relative levels of toxicity in different R. ponticum populations, and in closely related, non-invasive taxa, can contribute towards greater understanding of invasion processes and post-invasion selection pressures.

Funded by Science Foundation Ireland.

Publications:
Egan, P.A. Meconopsis autumnalis and M. manasluensis (Papaveraceae); two new species of Himalayan poppy endemic to central Nepal. (submitted to Phytotaxa)
Egan P.A. & Shrestha, S. Meconopsis; Cathcartia (Papaveraceae). In: Watson et al (eds), Flora of Nepal, Vol. 3, Royal Botanic Garden Edinburgh. (in press)
Egan, P.A., van der Kooy, F. & Verpoorte, R. Phytochemistry of the genus Drosera (Droseraceae) and its ethnopharmacological relevance. (submitted to Phytochemistry Reviews)

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