Article (magazine) published 2023.

Roses (Rosa spp. L.) are valuable horticultural crops with global production, markets, and utilization. Cytogenetics of roses can be complicated with variation in ploidy among species and hybrids and occurrence of unreduced gametes, unbalanced (canina) meiosis, and aneuploidy. Most modern rose cultivars are complex, interspecific hybrids with unknown ploidy. Despite most breeding efforts being focused on crossing cultivated varieties, the genome size information is often only available at the generalized species level. The goal of this study was to survey cultivars and breeding lines to determine relative genome sizes and ploidy levels. Flow cytometry was used to determine relative genome size and ploidy levels of 174 accessions of shrub, hybrid tea, grandiflora, floribunda, polyantha, R. chinensis, and R. rugosa cultivars and breeding lines. Chromosome counts were performed to calibrate relative genome size to ploidy level and confirm previously published ploidy reports. 1Cx relative genome size ranged from 0.46 to 0.64 pg and the 2C relative genome size ranged from 0.96 pg to 1.28 pg for diploids, 1.38 to 1.86 pg for triploids, and 1.87 to 2.50 pg for tetraploids when using DAPI fluorochrome and Pisum sativum 'Ctirad' as the internal standard. Chromosome counts further substantiated these ranges and confirmed ploidy of cultivars that were in disagreement with earlier reports for three cultivars. These results provide an extensive database of genome sizes and ploidy for diverse cultivars and breeding lines of rose and establish/validate flow cytometry methods for future applications

Article (website) published 2018.

Roses, which have been cultivated for at least 5000 years, are one of the most important ornamental crops in the world. Because of the interspecific nature and high heterozygosity in commercial roses, the genetic resources available for rose are limited. To effectively identify markers associated with QTL controlling important traits, such as disease resistance, abundant markers along the genome and careful phenotyping are required. Utilizing genotyping by sequencing technology and the strawberry genome (Fragaria vesca v2.0.a1) as a reference, we generated thousands of informative single nucleotide polymorphism (SNP) markers. These SNPs along with known bridge simple sequence repeat (SSR) markers allowed us to create the first high-density integrated consensus map for diploid roses. Individual maps were first created for populations J06-20-14-3דLittle Chief” (J14-3×LC), J06-20-14-3דVineyard Song” (J14-3×VS) and “Old Blush”דRed Fairy” (OB×RF) and these maps were linked with 824 SNPs and 13 SSR bridge markers. The anchor SSR markers were used to determine the numbering of the rose linkage groups. The diploid consensus map has seven linkage groups (LGs), a total length of 892.2 cM, and an average distance of 0.25 cM between 3527 markers. By combining three individual populations, the marker density and the reliability of the marker order in the consensus map was improved over a single population map. Extensive synteny between the strawberry and diploid rose genomes was observed. This consensus map will serve as the tool for the discovery of marker–trait associations in rose breeding using pedigree-based analysis. The high level of conservation observed between the strawberry and rose genomes will help further comparative studies within the Rosaceae family and may aid in the identification of candidate genes within QTL regions.

Article (HMF Ezine) published 1 Oct 2009.

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