Broad-Spectrum and Phenotypically Stable Resistance to Neotropical Phytophthora capsici Isolates in Solanum lycopersicum and Solanum habrochaites Accessions

Phytophthora capsici can induce severe economic losses in the tomato (Solanum lycopersicum) crop. However, broad-spectrum and phenotypically stable sources of resistance to this highly variable pathogen are not yet identified in Solanum (section Lycopersion) germplasm. We evaluated, in three bioassays, the reaction of Solanum (Lycopersicon) accessions against seven P. capsici isolates. All isolates across all bioassays induced severe symptoms in the susceptible control Capsicum annuum ‘Tico’. The Ralstonia solanacearum-resistant tomato ‘Hawaii-7996’ displayed superior levels of resistance to four isolates, whereas S. habrochaites ‘WIR-7924’ displayed resistance to five isolates. The resistant/susceptible reactions of the accessions were not coincident, indicating the presence of isolate-specific resistance factors as well as potential pathogen pathotypes. Large-spectrum genetic resistance to P. capsici isolates is essential for sustainable management of this pathogen. Hence, combining resistance factors from ‘Hawaii-7996’ and S. habrochaites ‘WIR-7924’ into a single cultivar would be a promising breeding strategy aiming to develop tomatoes with resistance to a wide array of P. capsici isolates.