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Research Project: Management of Temperate-Adapted Fruit, Nut, and Specialty Crop Genetic Resources and Associated Information

Location: National Clonal Germplasm Repository

Title: Mapping a new black spot resistance locus in rose [abstract]

Author
item Zurn, Jason
item Zlesak, David - University Of Wisconsin
item Bradeen, James - University Of Minnesota
item Hokanson, Stan - University Of Minnesota
item Bassil, Nahla

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 10/27/2017
Publication Date: 1/13/2018
Citation: Zurn, J.D., Zlesak, D.C., Bradeen, J., Hokanson, S.C., Bassil, N.V. 2018. Mapping a new black spot resistance locus in rose [abstract]. Plant and Animal Genome Conference. January 13-17, 2018, San Diego, California.

Interpretive Summary: Rose black spot is one of the most devistating disseases of cultivated roses for both the home and commercial market. The use of genetic resistance is the most economic and environmentally friendly management strategy for controling the disease. Currently, little is known about resistance found in roses and only three resistance genes have been mapped and characterized. The variey Brite Eyes has been found to be resistant to all but one strain of the pathogen which causes black spot. To better characterize the resistance in Brite Eyes a population was developed by crossing it with the susceptible variety Morden Blush. The offspring of the cross segregated 1:1 for resistance to susceptibility suggesting the resistance is controlled by a single resistance gene. Subsequent genetic mapping indentified a single resistance gene. The previously mapped reistance genes do not map to this location and do not provide resistance to many of the pathogen strains the Brite Eyes gene does. Therefore the resistance gene in Brite Eyes is a new gene.

Technical Abstract: Rose black spot, caused by Diplocarpon rosae, is one of the most devastating foliar diseases of cultivated roses (Rosa hybrida). The pathogen is globally distributed and has the potential to cause large economic losses in the outdoor rose industry. Genetic resistance is the most economical disease management strategy for black spot and many breeding programs are focused on creating cultivars with durable resistance. The tetraploid cultivar Brite EyesTM (‘RADbrite’) is resistant all D. rosae races except race 12. Because of this broad resistance, a 94 individual F1 mapping population was developed by crossing Brite EyesTM to the susceptible tetraploid ‘Morden Blush’. The population was phenotyped with four races (8, 9, 10, and 11) and a genetic map was constructed using the WagRhSNP 68K Axiom array. The F1 individuals were either resistant or susceptible to all races evaluated and segregated 1:1, suggesting resistance is mediated by a single locus. Preliminary mapping places the Brite EyesTM resistance locus on a single linkage group in a 14 cM region delimited by AX-86760042 and AX-86782856. This linkage group is homeologous to chromosome 5 of the diploid integrated consensus map. Prior to this experiment, three resistance loci have been mapped (Rdr1, Rdr2, and Rdr3). Both Rdr1 and Rdr2 are located on a chromosome 1 homeolog and the equivalent chromosomal location of Rdr3 is unknown. However, races 3 and 9 are virulent on Rdr3, suggesting the resistance in Brite EyesTM is novel. Future efforts will focus on developing a diagnostic test for marker assisted selection.