In our study, we used the rich biodiversity of peppers in the Balkan region and characterized 63 pepper accessions from five cultivar types (Pungent; Sweet; Pumpkin; Kapia; For powder), in view of their phytochemical composition and antioxidant activity. The obtained results showed high variation in the compositional profiles between studied cultivar groups, as well within individual groups. Based on fresh weight (FW), the most abundant sugar in the studied accessions was glucose (0.36–3.79%), followed by fructose (0.16–2.98%). The accessions from “For powder” group were the richest source of uronic acids—0.77%, followed by accessions from “Pungent” group—0.64%. In four of the five groups, citric acid was the predominant organic acid, whereas only in the “Sweet” group, malic acid was the major representative of organic acid. The highest amount of ascorbic acid (Vitamin C) was found in a genotype CAPS-7, which is in the group of “Pungent” accessions. The polyphenol content varied in a broad range from 42 mg/100 g FW to 266 mg/100 g FW. The differences in the flavonoid content were even more significant reaching 60-fold difference—from 1.0 mg/100 g FW to 64.3 mg/100 g FW. The accessions from the “For powder” group were leaders in regards to their total polyphenol and total flavonoid contents, as well as for their antioxidant activity, measured by ORAC and HORAC assays. This variation in fruit composition might be manipulated via plant breeding to create new pepper varieties with improved nutritional value of their fruits.

The Balkan pepper breeding program aims to use in vitro embryogenesis (anther culture) to develop doubled haploid pepper lines with valuable traits. We analyzed the effectiveness of microspore embryogenesis on 17 pepper genotypes comprised of varieties, breeding lines, and F₁hybrids of different varietal types (conical, bell shape, and kapia) and characterized the agronomic traits of newly generated doubled haploid lines. The highest androgenic potential was observed in the variety Stryama and breeding line 560/06 with 9.55 and 13.00% reacted anthers, respectively. Of the 186 regenerated plants, 147 were successfully adapted with a survival index of 79.03%. Flow cytometry analysis showed that the haploid:diploid ratio of regenerants was 1.5:1. All diploid plants were confirmed to be androgenic in origin. There were significant differences in terms of quantitative fruit characteristics of length, width, weight, pericarp weight, pericarp thickness, and productivity per plant among the diploid lines. Also, androgenic lines 21, 23, and 74 derived from Stryama and line 55 obtained from Zlaten medal 7 were distinguished with higher values of some fruit traits compared to initial genotypes. Additionally, several androgenesis lines (Stryama lines 21, 23, and 74, and Zlaten medal 7 line 55) scored higher for some fruit traits compared to the initial genotype. These results show that anther culture is a promising tool for the creation of Balkan pepper breeding lines with improved traits.

There were investigated and compared the in vitro response in anther culture of 16 Bulgarian pepper (Capsicum annuum L.) genotypes: six lines, six varieties and four hybrids developed in Maritsa Vegetable Crops Research Institute, Plovdiv. The anthers reacted with induction of direct embryogenesis or callusogenesis. Only in two of the studied genotypes (line N145 and variety Zlaten medal) the anthers have shown indirect organogenesis. There were established genotypes with good embryogenic ability—varieties Zlaten medal, Albena, Stryama, Hebur, Kourtovska kapiya, F1 hybrids N1647 X N668, N1647 X N1962 and lines N1312, N145 and N668. The embryoids obtained from anthers of line N145 and varieties Stryama and Kourtovska kapiya developed to regenerants with formed roots and cotyledons. The results from this study proved that for the first time is achieved a successful induction of embryogenesis in vitro and obtaining plant-regenerants, with microspore origin, of Bulgarian pepper genotypes.

Information about the genetic variation among cultivars of vegetable crops is of vital importance for improvement of plant breeding programmes worldwide. The objectives of this study were to group 19 pepper (Capsicum annuum L.) cultivars from the collection of Maritsa Vegetable Crops Research Institute, Plovdiv, Bulgariainto clusters according to their distances as estimated by agronomic traits and 9 di-and tri -nucleotide inter simple sequence repeat polymorphism (ISSR) markers and to assess the relationships between them. The phenotypic characterization during 3 consecutive years revealed significant differences among Bulgarian cultivars for the studied 13 phenotypic traits. The biplot analysis of quantitative traits showed that the most strongly correlating traits with the first axis (55.6% of variance) were fruit width, fruit weight and pericarp thickness (in the negative direction of the axis), and plant height (PH) (in the positive direction). The most discriminative traits, considering the second axis (22.6% of variance) were fruit length (FL) and to a lesser extent the stem height (StH). The correspondence analysis of the qualitative traits showed that the intensity of the colour of the fruit (before and at maturity), fruit colourbefore maturity and fruit shape in longitudinal section were the most discriminative characteristics for the first two dimensions. The agronomic traits data and 7 dinucleotide ISSR primers were used to estimate the pairwise genetic distances. Higher mean phenotypic distance (0.414) in comparison to the genotypic ones (0.214) among the cultivars was observed, indicating higher phenotypic diversity among them. A highly signi?cant, positive correlation between the agronomic data and ISSR marker-based matrices (r=0.41, p=0.001)was detected. This indicates that ISSR distance tended to re?ect that of the agronomics ones. However, additional molecular studies and large collection of highly diverse genotypes are needed to reveal associations between the marker loci and specific QTLs. The research initiated is a base for more precise estimation of genetic distances between pepper genotypes from the available large collection of landraces, local and modern cultivars including large number of highly polymorphic markers.