Exploring the genetic diversity and population structure of little-pod false flax (Camelina microcarpa: Brassicaceae) in Ukraine

Taxa of the genus Camelina faced numerous hybridization and allopolyploidy events during their evolutionary history. Little-pod false flax, C. microcarpa, a direct wild progenitor of the cultivated oilseed crop C. sativa, is one of the most widespread representatives of the genus. Due to several genetic bottleneck events and subsequent domestication, C. sativa now exhibits low genetic diversity, which significantly complicates its breeding. Camelina microcarpa wild germplasm seems to be a valuable pool of genetic diversity that could be effectively used for gene introgression in C. sativa and overcoming its genetic paucity. However, the genetic diversity and population structure of C. microcarpa remain insufficiently understood, particularly in Ukraine, which is considered among Camelina’s genetic diversity hotspots. Here, we used a combination of TBP/cTBP and SSR markers to assess the genetic diversity and population structure of C. microcarpa in Ukraine and partially in adjacent Western European regions. Three distinct genetic populations have been identified: Southern Ukrainian (predominantly occurring in the Steppe zone), Northwestern Ukrainian (occurring in the Forest-Steppe zone and Precarpathian region, particularly in Lviv Region), and Western European (Poland, Hungary, Germany). Our findings suggest that the Southern Ukrainian population exhibits the highest genetic diversity, possibly representing an ancestral gene pool, while the Northwestern Ukrainian and Western European populations demonstrate evidence of a high gene flow with the Southern Ukrainian population of C. microcarpa. Our phylogenetic analysis confirmed strong differentiation of these three populations, while the population structure analysis further indicated a high rate of admixtures between the populations. These findings enhance our under­standing of the evolutionary relationships and geographic distribution of C. microcarpa. The observed high heterozygosity and complex population structure highlight the potential of C. microcarpa (especially the Southern Ukrainian population) to be used as a germplasm donor for C. sativa breeding programs. Our study provides new insights into hexaploid Camelina species evolution and genetic diversity, establishing foundations for future development of wild germplasm utilization strategies and cultivated false flax breeding improvement.