2019 ASHS Annual Conference

Plant architecture, which is determined by both genetic and environmental effects, greatly affects the appearance and desirability of ornamental plants, including roses. Cultivars with full, compact plant architecture are preferred, but phenotyping for architecture traits is time-consuming and complex. Thus, molecular markers associated with rose plant architecture traits are desirable. To that end, 84 diploid cultivars were phenotyped for five architecture traits—number of primary shoots, apical dominance as determined by the ratio of number of secondary shoots to the length of the primary shoot, growth habit, plant height, and plant volume—in spring and winter 2018 in College Station, Texas. Statistical analyses were conducted in JMP v4. The cultivars were also genotyped for single nucleotide polymorphisms via genotyping by sequencing, resulting in approximately 8000 markers that were considered useful for subsequent analyses. STRUCTURE and GAPIT were used to determine population structure and perform a genome-wide association analysis, respectively. The cultivars were found to form five subpopulations. A significant SNP on chromosome 1 was found for number of primary shoots in spring (LOD=6). Though not strictly significant, SNPs of interest were also identified for growth habit (chromosome 3), plant height (chromosome 3), and plant volume (chromosomes 2, 3, and 5). While further studies are needed, this indicates that developing markers for plant architecture in roses is a feasible goal.