Taraxacum kok-saghyz (TKS) carries great potential as alternative natural rubber source. To better inform future breeding efforts with TKS and gain a deeper understanding of its genetic diversity, we utilized de novo sequencing to generate novel genomic simple sequence repeats markers (gSSRs). We utilized 25 gSSRs on a collection of genomic DNA (gDNA) samples from germplasm bank, and two gDNA samples from historical herbarium specimens. PCR coupled with capillary electrophoresis and an array of population genetics tools were employed to analyze the dataset of our study as well as a dataset of the recently published genic SSRs (eSSRs) generated on the same germplasm. Our results using both gSSRs and eSSRs revealed that TKS has low- to- moderate genetic diversity with most of it partitioned to the individuals and individuals within populations, whereas the species lacked population structure. Nineteen of the 25 gSSR markers cross-amplified to other Taraxacum spp. collected from Southeastern United States and identified as T. officinale by ITS sequencing. We used a subset of 14 gSSRs to estimate the genetic diversity of the T. officinale gDNA collection. In contrast to the obligatory outcrossing TKS, T. officinale presented evidence for population structure and clonal reproduction, which agreed with the species biology. We mapped the molecular markers sequences from this study and several others to the well-annotated sunflower genome. Our gSSRs present a functional tool for the biodiversity analyses in Taraxacum, but also in the related genera, as well as in the closely related tribes of the Asteraceae.

Taraxacum koksaghyz, the Russian dandelion, produces latex in its taproots and is an alternative to Hevea brasiliensis as a source for rubber. Studying the inheritance of rubber content and yield as well as breeding of T. koksaghyz could strongly benefit from haploid or doubled haploid techniques. Therefore, this study aimed at establishing the conditions to produce haploid and/or double haploid T. koksaghyz plants. This study focused on gynogenesis because analysis of microsporogenesis showed that very small (young) inflorescences already contain mature pollen and that the development of the microspores is not synchronous in different flowers in one inflorescence. Therefore, a surface disinfection protocol, culture media, and culture conditions were established resulting in shoot formation from ovules. Diploid and triploid Taraxacum officinale were also included in the experiments. Depending on the genotype, 0 to 2.6% of the ovules regenerated shoots via callus. These shoots could be rooted and acclimatized to greenhouse conditions without losses. Eleven plants from ovule cultures were analysed for their ploidy level and compared genetically to the donor material using simple sequence repeats (SSRs) to confirm their origin from either haploid or diploid/triploid donor tissues. All regenerated plants had the same ploidy level and were heterozygous at the same loci as their respective donor plants, and thus originated from somatic tissue.