Abstract
BackgroundLate blight is the most serious potato disease world-wide. The most effective and environmentally sound way for controlling late blight is to incorporate natural resistance into potato cultivars. Several late blight resistance genes have been cloned recently. However, there is almost no information available about the resistance pathways mediated by any of those genes.ResultsWe previously cloned a late blight resistance gene, RB, from a diploid wild potato species Solanum bulbocastanum. Transgenic potato lines containing a single RB gene showed a rate-limiting resistance against all known races of Phytophthora infestans, the late blight pathogen. To better understand the RB-mediated resistance we silenced the potato Rar1 and Sgt1 genes that have been implicated in mediating disease resistance responses against various plant pathogens and pests. The Rar1 and Sgt1 genes of a RB-containing potato clone were silenced using a RNA interference (RNAi)-based approach. All of the silenced potato plants displayed phenotypically normal growth. The late blight resistance of the Rar1 and Sgt1 silenced lines were evaluated by a traditional greenhouse inoculation method and quantified using a GFP-tagged P. infestans strain. The resistance of the Rar1-silenced plants was not affected. However, silencing of the Sgt1 gene abolished the RB-mediated resistance.ConclusionOur study shows that silencing of the Sgt1 gene in potato does not result in lethality. However, the Sgt1 gene is essential for the RB-mediated late blight resistance. In contrast, the Rar1 gene is not required for RB-mediated resistance. These results provide additional evidence for the universal role of the Sgt1 gene in various R gene-mediated plant defense responses.
Highlights
Late blight is the most serious potato disease world-wide
Genomic DNA was isolated from potato clone K41, which contains the RB gene introgressed from S. bulbocastanum, and was hybridized with the potato Rar1 and Sgt1 gene probes
The Southern hybridization results showed that the haploid potato genome contains only one copy of the Rar1 gene and two copies of the Sgt1 gene, which agree with a similar conclusion reported by Pajerowska et al (2005)
Summary
Late blight is the most serious potato disease world-wide. The most effective and environmentally sound way for controlling late blight is to incorporate natural resistance into potato cultivars. The most effective and environmentally sound way for controlling late blight is to incorporate natural resistance (page number not for citation purposes). The pedigrees of many potato cultivars currently used in different countries include late blight resistant germplasm derived from Solanum demissum, Solanum andigena, and other wild species. Most of the resistance derived from these wild species is controlled by single dominant resistance genes (R genes) These R genes are only effective in preventing the development of late blight if the invading P. infestans race contains the corresponding avirulence genes. This R gene-mediated resistance is often short-lived and is rapidly overcome by new races of the late blight pathogen
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have