P-489 - Do Phytophthora species utilize carbon sources differently? First results using BIOLOG EcoPlates

Members of the genus Phytophthora are among the most aggressive plant pathogens. Despite the enormous ecological and economic impact of Phytophthora spp., relatively few studies focused on the physiological aspects of their growth, different utilization of nutrients, and functional metabolic traits. We used BIOLOG EcoPlates to compare carbon source utilization of four Phytophthora spp. Namely, P. ramorum: causal agent of Sudden Oak Death, a devastating disease of forest trees and ornamental plants in Coastal California and Oregon; P. cactorum: infects a very wide host range worldwide; P. cambivora: mainly a pathogen of forest trees; and P. elongata: a pathogen of Eucalyptus in Western Australia, and recently detected for the first time by our group on Rhododendron in California. The EcoPlates, containing 3 sets of 31 different carbon sources which can be grouped into carbohydrates, carboxylic acids, phenolic acids, amino acids, polymers, and amines, were inoculated with 150 µL zoospores suspensions and incubated at 20ºC for up to 14 days. Color change in wells indicated the utilization of a certain metabolite. Many similarities and some differences were observed in the physiological patterns of the different Phytophthora species. E.g. P. elongata rapidly metabolized carbohydrates and amino acids in the early stages, with polymers in later days, while P. ramorum prioritized amino acid metabolism. Phenolic acids were the least utilized nutrient source. We believe that nutrient utilization might indicate host range preference of pathogens and should be studied in more detail.