Kristina Gostinčar

Background: The genetic diversity and ploidy of apple varieties in Slovenia is not well known so far. In this study, a total of 233 genotypes and 8 reference varieties were analysed with a set of 15 SSR markers in order to estimate the genetic diversity and to determine the genetic structure and relationships among the apple germplasm studied. Results: A total of 228 different alleles were successfully amplified, with an average of 15.2 alleles per locus. All markers were highly discriminating and powerful for varietal identification, with an average power of discrimination of 0.94. The results showed that the germplasm is highly diverse with a mean expected heterozygosity of 0.83 and a mean observed heterozygosity of 0.86. Of the 233 genotypes, 51 were recognised as synonyms and duplicates (22% redundancy), and a total of 182 unique genotypes were identified in the collections. An amount of 23% of the genotypes were identified as triploids by flow cytometry. The UPGMA clustering revealed three main groups. The genetic analysis, which was performed using the Bayesian model, revealed a very strong differentiation into two main groups. The first group comprised 85 genotypes (72% with qI > 0.80), including four reference varieties and seven local varieties. The second group comprised 105 genotypes (65% with qI > 0.80), including 4 reference varieties and two local varieties. In addition, nested Bayesian clustering was applied to these two groups, and four and two sub-groups were found, respectively. Conclusions: Altogether, this study of apple germplasm in the Slovenian landscape indicate a high diversity of apple varieties present and underline the importance of preserving these varieties. The SSR markers used, helped to identify duplicates, synonyms and homonyms within and between collections, which will help us to establish a core collection.

The Rosa genus is characterized by great variability and, consequently, they easily hybridize. The petals of R. pendulina, R. spinosissima and their hybrid Rosa pendulina × spinosissima, collected in western Slovenia, were included in the research. We performed morphometric analysis using keys to determine roses and genetic analysis to determine the genome size. The phenolic compound content in petals of all rose flowers was measured by liquid chromatography and mass spectrometry (HPLC-MS). Using flow cytometry, we could confirm the native hybridization process due to the amount of 2C DNA. The value of R. pendulina was 1.71 pg, of R. spinosissima 1.60 pg and of the hybrid 1.62 pg. The value for the hybrid was close to values measured for parent plants and, at the same time, those values of parent plants significantly differed from each other. Our results showed that the content of phenolic compounds in petals decreased after crossing. We found that the highest total phenolic content (178.9 g/kg FW) was measured in R. spinossisima, the lowest content was analyzed for the hybrid (84.36 g/kg FW) and the content for R. pendulina was between these two values (110.58 g/kg FW). The content of flavanols and flavonols was lowest in the hybrid petals, whereas the content of anthocyanins was highest in the hybrid petals.