Identification of sources of resistance in tomato to Phytophthora infestans at Mexico

Abstract

Late blight caused by Phytophthora infestans, devastating disease in tomato (Solanum lycopersicum L.) worldwide. The present study was carried out to identify sources of resistance in wild genotypes of Solanum lycopersicum var. cerasiforme collected in Mexico, and experimental varieties. San Marzano and Rio Grande were susceptible controls, and the resistant control, accession LA2533 pimpinellifollium. Field and greenhouse trials were established for exposure to natural infections. Incidence and severity of the disease and the area under the curve of the disease (AUDPC) were estimated. In laboratory, leaf samples were inoculated with six pathogen strains isolated from potato plants, from Valle de México. It was calculated necrotic area percentage (NAP), sporulation degree (SD) and index disease (ID). Wild populations V115, 319 and 327 had similar behavior to resistant control, followed by experimental genotypes 1-1, 3-1, 1-12, 2-29, 3-31 and 2-14. In separated leaflets inoculated test with Toluca´s strains , V115 highlighted, followed by 3-3, 1-12, 2-29, 3-6, 1-1, 2-14 and 319 and moderated resistance were showed by 3-1, 3-31, LA2533, 3-33 and 327. Susceptible control San Marzano obtained higher values for AUDPC, NA, SD and ID.