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Title: SOLANUM TUBEROSUM - S. COMMERSONII SOMATIC HYBRIDS ARE RESISTANT TO BROWN ROT CAUSED BY RALSTONIA SOLANACEARUM

Author
item LAFERRIERE, LOUISE - UNIVERSITY OF WISCONSIN
item Helgeson, John
item ALLEN, CAITILYN - UNIVERSITY OF WISCONSIN

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 7/25/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Bacterial wilt is a serious disease of potatoes in the tropics and subtropics and is becoming a problem in temperate parts of Europe. The wild potato relative S. commersonii is reported to have good wilt resistance but it could not be bred into potatoes using conventional breeding methods because the two species are not sexually compatible. The nuclei of the wild and cultivated potatoes were fused together to form a plant with the genetic information of both species. The result of such a fusion is called a somatic hybrid. The S. tuberosum-S. commersonii somatic hybrids are vigorous and can be crossed with potatoes. We tested the somatic hybrids for resistance to bacterial wilt, and compared them with the wild potato parent and the cultivated potato. The somatic hybrids were all more wilt resistant than potatoes and five of the six somatic hybrids were as wilt resistant as the wild potato. The sixth somatic hybrid had intermediate wilt resistance. We are hopeful that this novel wilt resistance can be bred into potatoes and help protect the United States' multi-billion dollar potato industry against the eventual introduction of the destructive bacterial wilt disease.

Technical Abstract: The wild potato relative Solanum commersonii is reported to have resistance to bacterial wilt caused by Ralstonia (Pseudomonas) solanacearum. S. tuberosum, the cultivated potato, and S. commersonii have different ploidies and endosperm balance numbers, and are therefore sexually incompatible, so they were fused in somatic hybridization. The resultant plants are vigorous, but their resistance level was unknown. We tested the S. commersonii and S. tuberosum source material, cv. Atlantic and six somatic hybrid lines with a virulent strain of R. solanacearum (race 3, biovar 2). As expected, S. commersonii was significantly more wilt resistant than the cultivated potatoes. Five of the six somatic hybrid lines expressed levels of resistance similar to the S. commersonii parent. The resistance level of the sixth somatic hybrid was intermediate, significantly different from both S. commersonii and S. tuberosum. The somatic hybrids are fertile to S. tuberosum and self-compatible.