DEFINE: a multidisciplinary research project to investigate the effects of exotic plant pathogenic fungi and insects on native ecosystems.

The effects of biological invasions have been mostly studied in terms of financial losses and ecological impact on native species. However, there is a lack of information on the extent to which invasive organisms may determine physiological and genetic changes in native components of ecosystems. A research project named DEFINE (Deciphering the Effects of invasive Fungi and Insects on Native Ecosystems) was recently granted by MIUR, within the FIRB program. The project aims at investigating the potential impact of invasions by fungal plant pathogens and phytophagous insects on the main components of the native ecosystems: plants, their pathogens, pests and symbionts. Three model systems are studied, each including either an exotic pathogen or an exotic insect in Europe (the tree pathogen Heterobasidion irregulare and the phytophagous insects Hyphantria cunea and Bagrada hilaris) and its main host in the invasion area (Pinus pinea, Populus nigra, Brassica oleracea). Effects of invasive organisms on a range of native components, including infected/infested hosts and neighbouring healthy plants (inter-plant signalling), are determined by conducting comparative inoculation/infestation experiments with native host-associated pathogens and insects. Host responses are assessed by analysing Volatile Organic Compounds (VOCs) and gene transcripts in plant tissues. Effects are also investigated on occurrence and gene expression of native ecto- and endo-mycorrhizal fungi, and on genomics of native species that may have experienced allelic introgression from the invasive organism. For this purpose, whole-genome genotyping of 15 Heterobasidion isolates is in progress in order to clarify allelic introgression between invasive and native species.