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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #377369
Research Project: Maximizing the Impact of Potato Genebank Resources: Development and Evaluation of a Wild Species Genotype Diversity Panel

Location: Vegetable Crops Research

Title: Characterization of a late blight resistance gene homologous to R2 in potato variety Payette Russet

Author
item Karki, Hari
item Halterman, Dennis
item ENDELMAN, JEFF - University Of Wisconsin

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/2020
Publication Date: 1/5/2021
Citation: Karki, H.S., Halterman, D.A., Endelman, J. 2021. Characterization of a late blight resistance gene homologous to R2 in potato variety Payette Russet. American Journal of Potato Research. (2021) 98:78–84. https://doi.org/10.1007/s12230-020-09811-2.
DOI: https://doi.org/10.1007/s12230-020-09811-2

Interpretive Summary: Potato is one of the most important crops in the world. Late blight of potato caused by the Phytophthora infestans is a major yield limiting factor. Payette Russet is among the few late blight resistant cultivated potatoes available in the US. We have found that disease resistance in Payette Russet is conferred by a gene located within an area of the potato genome that was previously known to contain multiple resistance genes. The sequence of the gene from Payette Russet shows that it is the same as the Rpi-abpt gene. Using the sequence information from this gene, we developed a genetic marker that can be used by breeders to track resistance within populations without the need for pathogen inoculation assays.

Technical Abstract: Breeding for late blight resistance has traditionally relied on phenotypic selection, but as the number of characterized R genes has grown, so have the possibilities for genotypic selection. One challenge for russet varieties is the lack of information about the genetic basis of resistance in this germplasm group. Based on observations of strong resistance by 'Payette Russet' to genotype US-23 of P. infestans in inoculated experiments, we deduced the variety must contain at least one major R gene. To identify the gene(s), 79 F1 progeny were screened using a detached leaf assay and classified as resistant vs. susceptible. Linkage mapping using markers from the potato SNP array revealed a single resistant haplotype on the short arm of chromosome group 4, which coincides with the R2/Rpi-abpt/Rpi-blb3 locus. PCR amplification and sequencing of the gene in Payette revealed it is homologous to R2, and infiltration experiments with N. benthamiana confirmed its recognition of the Avr2 effector. Multiple sequence alignment of a small diversity panel revealed a haplotype-specific SNP conserved among R2 homologs, which was converted to a KASP marker that showed perfect prediction accuracy in the F1 population and diversity panel. Although many genotypes of P. infestans are virulent against R2, even when defeated this gene may be valuable as one component of a multi-genic approach to quantitative resistance.