Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2005
Publication Date: 6/1/2006
Citation: Frost, K., Jansky, S.H., Rouse, D. 2006. Transmission of Verticillium wilt resistance to tetraploid potato via unilateral sexual polyploidization. Euphytica. 149:281-287. Interpretive Summary: Verticillium wilt is a serious disease of potato caused by a soil-borne fungus. It causes early death of potato plants and can result in dramatic yield reductions. The fungus is found in all major potato growing regions and can survive in the soil for a decade or more. Consequently, Verticillium wilt is a problem for most potato growers every year. The only effective method of control is soil fumigation, which is expensive and can be harmful to the environment. The development of Verticillium wilt resistant varieties offers a cost-effective and environmentally-friendly alternative control method. Major varieties in the United States are not resistant to the fungus. In previous studies, we identified two partially wild potato plants with very high levels of Verticillium wilt resistance. These plants can not be crossed readily with the cultivated potato, which has twice as many chromosomes. We effectively doubled the chromosome number of the resistant plants and crossed them to the cultivated potato. Some of the offspring are highly resistant to Verticillium wilt, indicating that Verticillium wilt resistance genes from the wild relatives were transferred to the cultivated potato. This germplasm will be useful to potato breeders for the development of Verticillium wilt resistant varieties.
Technical Abstract: Verticillium wilt is a serious disease of potato and is caused by the soil-borne fungi Verticillium dahliae and V. albo-atrum. No major cultivar is resistant to this disease. Two diploid interspecific potato clones, C287 and C545, were previously identified with consistently high levels of Verticillium wilt resistance and are thought to have the same genotype for the loci that confer resistance to V. dahliae stem colonization. The purpose of this study was to determine if resistance to V. dahliae stem colonization could be transferred to the tetraploid level in potato via unilateral sexual polyploidization (USP). To do this, three replications of 142 progeny in eight families obtained by crossing C287 and C545 to two tetraploid breeding clones, S438 and S440, and the cultivar ‘Atlantic’ were planted in a V. dahliae-infested field and a field without a significant V. dahliae infestation. Vine maturity, V. dahliae stem colonization, disease, and yield were evaluated for each plot. Resistance was evaluated relative to C545 and C287. There were differences among families for maturity, stem colonization, and yield. No differences between the mean stem colonization of C545 and C287 progeny were detected. Family differences due to the tetraploid parents indicate that they contributed resistance to the progeny. Stem colonization data from this experiment were consistent with the proposed complementary two-gene model for Verticillium wilt resistance in the diploid parents. Unilateral sexual polyploidization is an effective method for transferring V. dahliae stem colonization resistance to the tetraploid level.