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ARS Home » Pacific West Area » Corvallis, Oregon » National Clonal Germplasm Repository » Research » Publications at this Location » Publication #365635

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

Location: National Clonal Germplasm Repository

Title: Mapping disease resistance in the presence of random meiotic pairing: a case study in rose

item Zurn, Jason
item ZLESAK, DAVID - University Of Wisconsin
item HOLEN, MATTHEW - University Of Minnesota
item BRADEEN, JAMES - University Of Minnesota
item HOKANSON, STAN - University Of Minnesota
item Bassil, Nahla

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2019
Publication Date: 8/3/2019
Citation: Zurn, J.D., Zlesak, D.C., Holen, M., Bradeen, J.M., Hokanson, S.C., Bassil, N.V. 2019. Mapping disease resistance in the presence of random meiotic pairing: a case study in rose. Journal of Plant Health. 2019 Plant Health Conference.

Interpretive Summary: Rose black spot is one of the most devastating diseases 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 controlling the disease. Currently, little is known about resistance found in roses and only four resistance genes have been characterized. One of these genes, Rdr3, was identified by never mapped to a genetic location due to the complex genetics displayed in roses. Because of this we do not know if Rdr3 is a unique gene or a varient of one of the other known genes. New tools have recently been developed that has allowed us to finally map the position of Rdr3. The work presented is an overview of how to map genes in organisms with complex genetics, like roses, and answers the questions surrounding the genetic mapping Rdr3.

Technical Abstract: Genetic mapping in polyploid organisms that undergo random pairing during meiosis is a difficult process. Early genetic maps were constructed using single dose allele markers. These markers cannot be used to identify homoeologous chromosomes. Software capable of identifying allelic dosage for SNP markers and mapping software that allows for the use of higher-dose markers has recently become available, allowing for the creation of high-density maps of segmental allopolyploids, like hybrid roses. The unmapped black spot resistance gene Rdr3 was previously identified in the tetraploid rose ‘George Vancouver’. A mapping population was developed by crossing ‘George Vancouver’ with the susceptible tetraploid ‘Morden Blush’. Phenotyping was conducted via a detached leaf assay with Diplocaron rosae race 8 and the population was genotyped with the WagRhSNP 68K rose Axiom array. Allelic dosage assignment and genetic mapping were conducted using the R packages ‘fitPoly’ and ‘polymapR’, respectively. Rdr3 was mapped to a chromosome 6 homoeolog. To date, three additional black spot resistance genes (Rdr1, Rdr2, and Rdr4) have been mapped. Rdr1 and Rdr2 map to a chromosome 1 homoeolog and Rdr4 maps to a chromosome 5 homoeolog. Rdr3 is a unique gene and not an allele of the other genes as it maps to a different region. Mapping Rdr3 demonstrates how new tools can be used to create high-density maps to begin answering complex genetic questions surrounding polyploids.