Maydell, Daniel; Schwerdt, Johannes; Lehnert, Heike; Pöschl-Grau, Yvonne; Schmutzer, Thomas; Marthe, Frank Population structure, genetic diversity and core set construction of an international collection of 256 Melissa officinalis genotypes Journal Article In: BMC Plant Biology, vol. 26, no. 1, pp. 794, 2026, ISSN: 1471-2229. Abstract | Links | BibTeX | Tags: DiP-DIAMANT, DiP-OptiLamia, Domestication, Gene flow, Gene pool, Genetic diversity, Identification (biology), Melissa officinalis, Officinalis, Population, Subspecies @article{vonmaydell2026population,BackgroundMelissa officinalis (balm) is a perennial medicinal. Climate change and high cultivation costs necessitate the breeding of new cultivars with improved stress tolerance and high metabolite content. However, the high costs of phenotyping large collections limit breeding progress. This study characterized the genetic diversity and population structure of 256 genotypes from 215 international accessions using flow cytometry and genotyping by sequencing (GBS). The primary objective was to identify untapped genetic resources and establish core sets to streamline future breeding and research efforts.ResultsMorphological characterization and flow cytometry revealed a clear division by ploidy and subspecies. The collection comprised 209 diploid and three polyploid genotypes of ssp. officinalis (2C = 1.79 pg) and 44 tetraploid genotypes of ssp. altissima (4C = 3.57 pg). GBS generated 29,307 and 9,909 SNPs for the entire collection and a subset of ssp. officinalis genotypes, respectively. We identified significant genetic differentiation between the subspecies, as confirmed by PCA (PC1 = 69.9%), STRUCTURE, and hierarchical clustering. With 21,770 private alleles and HE = 0.38 subspecies altissima exhibited greater genetic divergence than ssp. officinalis (2,953 private alleles |
