ARS | Publication request: Identification and Characterization of RB Orthologous Genes from the Late Blight Resistant Wild Potato Species Solanum verrucosum

Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 23, 2007
Publication Date: October 1, 2006
Citation: Halterman, D.A., Liu, Z. 2006. Identification and Characterization of RB Orthologous Genes from the Late Blight Resistant Wild Potato Species Solanum verrucosum. Physiological and Molecular Plant Pathology. 69:230-239.

Interpretive Summary: Late blight, caused by the hemibiotrophic oomycete pathogen Phytophthora infestans, is one of the most devastating plant pathogens of potato. A major late blight resistance gene, called RB, was previously identified in the wild potato species Solanum bulbocastanum. Another wild potato species, S. verrucosum also contains resistance to late blight. Using greenhouse inoculation assays, we have tested the late blight resistance levels in eight S. verrucosum accessions. Resistance among the accessions varied between moderate and high levels. Using a two-step, homology-based cloning approach, we have isolated transcribed RB orthologs from the eight S. verrucosum accessions. The RB-like gene from one of these accessions encodes a full-length protein and was transferred to susceptible S. tuberosum using Agrobacterium-mediated transformation. These resultant transgenic lines exhibit high levels of resistance in greenhouse assays confirming the functionality of this gene. This resistance gene offers to potato breeders an additional genetic resource for late blight resistance.

Technical Abstract: Late blight is one of the most devastating plant pathogens of potato. A major late blight resistance gene, called RB, was previously identified in the wild potato species Solanum bulbocastanum. Another wild potato species, S. verrucosum also contains resistance to late blight. We have now identified a gene similar, but not identical, to RB in S. verrucosum. This gene also confers resistance to late blight when put into normally susceptible cultivated potato. The availability of this gene to potato breeders will benefit their breeding programs and add to our “arsenal” of resistance to late blight.