Plant-pest Interactions under Elevated CO2 Concentration in the System Grapevine (Vitis vinifera) – Downy Mildew (Plasmopara Viticola) – Grape Berry Moth (Lobesia Botrana)

Abstract

Plants interact with a wide range of organisms, some of which are harmful, like pathogens and herbivorous insects. These very complex and dynamic biotic interactions can be affected by changes in environmental conditions, such as an elevated concentration of atmospheric CO2 (eCO2) as a consequence of anthropogenic global change. We hypothesize that future eCO2 alters both morphological and genetic features of grapevine plants as well as aggressiveness and pathogenicity of pest organisms, which may result in changes in future pest infestation levels in vineyards. For studying the effects of eCO2 on interactions between grapevine plants and two of their economically most significant pests – the downy mildew pathogen Plasmopara viticola and larvae of the grape berry moth Lobesia botrana – a free-air carbon dioxide enrichment (FACE) system as well as indoor climate chambers are used. The study focuses on possible changes in the biology of P. viticola (e.g. duration of incubation period, vitality of zoospores, germination of soilborne oospores) and in the developmental biology of L. botrana (e.g. hatching rate, duration of development stages, pupal weight, longevity and survival rate, fertility of females). Microscopic studies of pest- relevant morphological characteristics of grapevines (e.g. thickness of berry skin, stomatal density, stomatal aperture) are supposed to provide explanations for possible changes in pest infestation levels under eCO2. Furthermore, the expression levels of relevant defense genes in grapevines are investigated via qPCR to record possible changes in defense reactions of the host plant towards the respective pest organism. The data obtained will contribute to a better understanding of mechanisms in plant- pest interactions under altered environmental conditions.