ISHS Acta Horticulturae 619: XXVI International Horticultural Congress: Potatoes, Healthy Food for Humanity: International Developments in Breeding, Production, Protection and Utilization
DISEASE RESISTANCE IN POTATO HAPLOIDS |
| Authors: | S.H. Jansky, E.D. Mauritz, J.J. Clark, D.I. Rouse |
| Keywords: | Verticillium wilt, soft rot, common scab, genetics |
| Abstract:
Haploids (2n=4x=24) of the cultivated potato, Solanum tuberosum (2n=4x=48) are commonly used to access the germplasm of wild diploid (2n=4x=24) Solanum species, but are not typically considered to be sources of disease resistance genes. This study was conducted to determine whether haploids exhibit resistance to three major potato diseases, Verticillium wilt (Verticillium dahliae), common scab (Streptomyces scabies) and soft rot (Erwinia carotovora ssp. atroseptica); and to perform a genetic analysis of resistance. Populations of haploid clones derived from the cultivars ‘Atlantic’, ‘Chippewa’, and ‘Merrimack’ were planted in a replicated trial in a field containing high levels of V. dahliae and S. scabies. Plants were scored for symptoms of Verticillium wilt and tubers were evaluated for the presence of scab lesions. Tubers were inoculated with E. c. atroseptica and rated for the diameter of rotted tissue that developed. Within each population, differences among haploid clones were detected for all traits measured. Haploid potato clones with higher levels of disease resistance than their tetraploid parents were identified. Levels of disease resistance also differed among populations, with ‘Atlantic’ haploids expressing the highest levels of disease resistance. Haploids were less vigorous, produced smaller tubers, and expressed more severe Verticillium wilt symptoms than their tetraploid parents. Positive skewness and kurtosis were detected in the distributions of haploid scores for vine maturity and scab resistance, indicating that non-additive genetic variance is important for controlling these traits. Heritability estimates for all traits were less than 0.40. Additive genetic variance appears to be most important for Verticillium wilt and soft rot resistance. This study demonstrates two ways in which haploids may be valuable in breeding programs. First, they may contribute disease resistance genes. In addition, they may be used for genetic analysis of complex traits. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
