A reappraisal of the natural and experimental host range of Neotropical Phytophthora capsici isolates from Solanaceae, Cucurbitaceae, Rosaceae, and Fabaceae

Abstract

The knowledge about the array of host and non-host plant species of the cosmopolitan soil-borne pathogen Phytophthora capsici is potentially useful in establishing efficient crop rotation systems. In the present work, pathogenicity bioassays were carried out aiming to re-examine the host range of P. capsici using 4 isolates obtained from taxonomically distinct species: snap bean, strawberry, bell-pepper and squash. Ninety-six plant accessions (72 species within 40 genera and 17 botanical families) were inoculated at seedling stage with zoospore suspensions. Reaction of fruits, pods, tubers, roots, or bulbs of 25 plant species was also determined. Twenty-two species were found to be susceptible to P. capsici at the seedling stage, and 20 species displayed varying levels of fruit/pod/tuber/bulb susceptibility. We report one Cucurbitaceae (Sicana odorifera) and eight Solanaceae species: Physalis angulata, Solanum aethiopicum var. gilo, S. betaceum (former Cyphomandra betaceae), S. chilense, S. paniculatum, S. torvum, Capsicum praetermissum and Nicotiana benthamiana as novel experimental hosts of P. capsici at seedling stage. We also present the first formal report of Solenostemon autranii (Lamiaceae) as a new experimental host at seedling stage. Infection by at least one P. capsici isolate was also reported for the first time in pods of cowpea (Vigna unguiculata) and in potato (S. tuberosum) tubers. Sechium edule (chayote) and Cucumis anguria (gherkin) were identified as novel cucurbitaceous hosts at the fruit stage, but these species were not infected by all isolates at seedling stage. An updated list of all currently reported hosts is provided.