IDENTIFICATION OF A GENE CONFERRING HIGH-LEVELS OF RESISTANCE TO VERTICILLIUM WILT IN SOLANUM CHACOENSE

Verticillium wilt (Verticillium albo-atrum) is an important disease af fecting potato tuber yield and quality. In North America the major com mercial cultivars are susceptible and management strategies for contro l of the pathogen rely mainly on soil fumigation and crop rotation. In this study 398 genotypes from accessions of Solanum berthaultii, S. c hacoense, and S. tarijense were screened for resistance to Verticilliu m albo-atrum. Resistant genotypes were identified in all but two acces sions; however, results indicate that tolerance is more common than re sistance. We identified two genotypes in S. chacoense (PI 472819) that had low stem-colonization levels and also did not develop wilt sympto ms when inoculated with V. albo-atrum. These genotypes and a susceptib le genotype from PI 472810 (S. chacoense) were studied to determine ge netic inheritance. Segregation ratios in F-1, F-2, and backcross popul ations indicated that resistance in one of the resistant genotypes (18 -21R) was controlled by a single dominant gene. Transfer of the V-c ge ne to tetraploid germ plasm could provide effective and economical con trol of Verticillium wilt.