ARS | Publication request: RESISTANCE TO PHYTOPHTHORA INFESTANS IN DIPLOID SOLANUM SPECIES OF MEXICO AND SOUTH AMERICA

Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 1999
Publication Date: N/A

Technical Abstract: Two diploid Solanum species from central Mexico and eight diploid species from northwestern South America were evaluated. Replicated detached leaf assays using the Phytophthora infestans isolate MSU 96 (US-8 A2) were used to score infected leaf area on a scale of 0 to 9. Visual identification of hypersensitive reactions were based on morphological characteristics of the disease reaction. For genetic characterization of a resistant S. pinnatisectum, resistant F1 interspecific hybrid was backcrossed to the susceptible S. cardiophyllum subsp. cardiophyllum parent. According to the segregation data, few loci contribute to resistance in this S. pinnatisectum ccession, which comes from a region of complex and diverse P. infestans populations in Central Mexico. Additional sources of resistance were identified in the distantly related diploid species from the Advanced Rotata (Hawkes) of northwestern South America. Hypersensitive reactions were also identified, concentrated in specific accessions of some of these South American species. This resistance comes from species of a region traditionally not associated with the pathogen P. infestans.