Volatilome and proteome responses to Colletotrichum lindemuthianum infection in a moderately resistant and a susceptible bean genotype

We analyzed the changes in the volatilome, proteome, stomatal conductance, salicylic and jasmonic acid contents of a susceptible and a moderately resistant genotype of common bean, Phaseoulus vulgaris L., challenged with Colletotrichum lindemuthianum, the causal agent of fungal anthracnose. Our results indicate differences at both proteome and volatilome levels between the two genotypes, before and after the infection, and different defense strategies. The moderately resistant genotype hindered pathogen infection, invasion, and replication mainly by maintaining epidermal and cell wall structure. The susceptible genotype was not able to limit the early stages of pathogen infection. Rather, stomatal conductance increased in the infected susceptible genotype, and enhanced synthesis of Green Leaf Volatiles and salicylic acid was observed, together with a strong hypersensitive response. Proteomic investigation provided a general framework for physiological changes, whereas observed variations in the volatilome suggested that volatile organic compounds may principally represent stress markers rather than defensive compounds per se.