Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2007
Publication Date: 3/1/2008
Citation: Halterman, D.A., Colton, L., Weilgus, S., Jiang, J. 2008. Rate-Limiting Late Blight Resistance Conferred by the RB Gene in Solanum tuberosum Transgenic Lines Does Not Impact Yield. Plant Disease. 92:339-343. Interpretive Summary: A gene called RB, isolated from wild potato, confers resistance to potato late blight and was previously integrated into four cultivated potato varieties. We have tested whether the integration of this gene has an effect on fitness of the plant, as characterized by tuber yield. We found no significant differences in yield between plants containing the resistance gene and those without it. The plants containing the RB gene remained resistant to late blight even when high concentrations of inoculum were used. However, the tubers of RB-containing plants were not resistant to late blight infection. The results of this paper will influence potato breeders when they consider integration of resistance into breeding lines. Other resistance genes in other plants (i.e. Arabidopsis) can lead to a loss of fitness. However, our results indicate that potato breeders should not worry about the effects of including the RB gene in advanced breeding lines.
Technical Abstract: Late blight of potato, 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 and has been integrated into S. tuberosum using somatic fusions and Agrobacterium-mediated transformation. Plants containing this gene are highly resistant to late blight, even when tested under optimal late blight conditions. In this paper we demonstrate that the addition of the RB resistance gene to multiple S. tuberosum cultivars does not significantly affect plant fitness, as characterized by tuber yield. Additionally, we show that the rate-limiting resistance phenotype conferred by RB is not compromised by an increase in the concentration of sporangia in the inoculum. Although RB-containing tubers did not show increased resistance to P. infestans, all tested RB-containing plants exhibited strong foliar resistance to inoculation under greenhouse conditions.