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Abstract
Necrotrophic effectors play a role in host specialization by influencing pathogenicity and virulence. Corynespora cassiicola, the causal agent of target spot on agricultural crops in the southeastern United States including cotton, tomato and soybean exhibits host specialization through symptom severity on its specific hosts. This study was conducted to identify if secreted effectors such as host-selective toxins and/or metabolites secreted by certain isolates of C. cassiicola are associated with its host specialization, and, if so, to characterize the chemistry of the toxic and host specific compounds. Greenhouse assays using mycelial extracts established that compounds related to phytotoxicity and host specialization are secreted by the cotton and tomato C. cassiicola isolates, but not the soybean fungal isolates. Bioassay guided fractionations demonstrated that phytotoxic compounds have non-proteinaceous components and varying polarities. Potential metabolites were deduced by HPLC-MS. Effector characterization can serve as framework in understanding host-pathogen interactions, subsequently in developing resistant lines against target spot.