A New Resistance Gene against Potato Late Blight Originating from Solanum pinnatisectum Located on Potato Chromosome 7

Abstract

Late blight, caused by the pathogen Phytophthora infestans, is one of the most devastating diseases of potato. Here, we describe a new single dominant resistance gene, Rpi2, from the Mexican diploid wild species Solanum pinnatisectum that confers high level and broad spectrum resistance to late blight. The Rpi2 locus confers full resistance to complex isolates of P. infestans, for which race specificity has not yet been demonstrated. This new gene, flanked by the RFLP-derived marker SpT1756 and AFLP-derived marker SpAFLP2 with a minimal genetic distance of 0.8 cM, was mapped to potato chromosome 7. Using the genomic sequence data of potato, we estimated that the physical distance of the nearest marker to the resistance gene was about 27 kb. The map location and other evidence indicated that this resistance locus was different from the previously reported resistance locus Rpi1 on the same chromosome from S. pinnatisectum. The presence of other reported resistance genes in the target region, such as Gro1-4, I-3, and three NBS-LLR like genes, on a homologous tomato genome segment indicates the Rpi2-related region is a hotspot for resistance genes. Comparative sequence analysis showed that the order of nine markers mapped to the Rpi2 genetic map was highly conserved on tomato chromosome 7; however, some rearrangements were observed in the potato genome sequence. Additional markers and potential resistance genes will promote accurate location of the site of Rpi2 and help breeders to introduce this resistance gene into different cultivars by marker-aided selection.

Development of pre-breeding diploid potato germplasm displaying wide phenotypic variations as induced by ethyl methane sulfonate mutagenesis

“…), chemical [ethyl-methane sulfonate (EMS), sodium azide, hydroxylamine, etc.] agents (Jain 2010), or the emerging gene editing enzymatic tools, such as TALEN (Malzahn et al 2017) and CRISPR-Cas9 (Braatz et al 2017;Yang et al 2017b). Gamma rays and EMS are so far the most widely used physical and chemical mutagens for induced mutations (Jain 2010).…”

The potato transcription factor StbZIP61 regulates dynamic biosynthesis of salicylic acid in defense against Phytophthora infestans infection

“…Several defense-related genes, particularly the late blight resistance genes (R genes), have been identified from various potato species. Transgenic potato plants expressing some of these genes display increased resistance to the pathogen (Vleeshouwers et al, 2011;Rodewald and Trognitz, 2013;Jo et al, 2015;Vossen et al, 2016;Yang et al, 2017). Despite these achievements, however, late blight still threatens many potato-growing areas, mainly due to rapid evolution of P. infestans strains that result in ineffectiveness of the race-specific R genes.…”

Analysis of the lineage ofPhytophthora infestansisolates using mating type assay, traditional markers, and next generation sequencing technologies

“…The number of isolates with a sequenced genome is limited; however, genome-wide sequence data of different isolates would provide more detailed phylogenetic information, which would help control isolates that could soon become endemic. Breeding late blight resistant tomato and potato cultivars is a promising strategy to overcome this disease [33, 34]. Characterization of P. infestans will enhance the monitoring of aggressive isolates propagated via infected plant materials from different geographic regions.…”