Region-specific local landraces represent a germplasm diversity adapted and acclimatized to local conditions, and are ideal to breed for targeted market niches while maintaining the variability of heirloom traits. A collection of 180 pepper accessions, collected from 62 diverse locations across six Balkan countries, were characterized and evaluated for phenotypic and biochemical variation during a multi-year environment. An assortment of 32 agro-morphological, fruit quality, and virus resistance traits were evaluated, and the top 10% accessions were identified. A wide range of trait variation concerning plant architecture, inflorescence and fruit traits, yield and fruit quality was observed, and appreciable variation was noticed. According to hierarchical clustering, six distinct clusters were established based on pre-defined varietal groups. Divergence among accessions for phenotypic and fruit compositional variability was analyzed, and eight principal components were identified that contributed~71% of the variation, with fruit shape, width, wall thickness, weight, and fruit quality traits being the most discriminant. Evaluation of the response to tobacco mosaic virus (TMV) and pepper mild mottle mosaic virus (PMMoV) showed that 24 and 1 accession were resistant, respectively while no tomato spotted wilt virus (TSWV) resistance was found. Considerable diversity for agro-biomorphological traits indicates the Balkan pepper collection as good gene sources for prebreeding and cultivar development that are locally adapted.

For years, the main emphasis of industrial pepper production has been the creation of large-fruited high-yielding varieties. This has led to the exploitation of pepper (Capsicum annuum L.) varieties with a significantly narrow genetic background. The Balkan region has a range of valuable local landraces that are noticeably decreasing in prevalence and may be lost. In this study, we utilized Tomato Analyzer (TA) to characterize the intra-and intervarietal type fruit diversity using 50 different fruit shape, size, and color descriptors of a Balkan pepper collection. The collection comprised of 168 diverse accessions and collected from 62 locations and 31 districts in six different Balkan countries. Fruit shape was the main trait used for visual accession grouping into 5 different varietal groupings of elongated, round, conical, bell, and pumpkin shape, respectively. Beyond visual grouping, hierarchical cluster analysis grouped the evaluated accessions into eight distinct clusters based on fruit shape, size, surface, and color. In total, 47 TA descriptors were identified to contribute to the total variation, with first two components explaining 54% of variation, and 90% of variation contained in 12 components. Among TA descriptors, fruit size and proximal/distal fruit end shape contributed to component 1 variation whereas fruit perimeter, area and color contributed to component 2. We hope that this research will assist pepper breeding and genetic resources communities to better understand Balkan pepper fruit diversity and develop pepper varieties with desirable fruit traits. Quantification of fruit diversity could be crucial for further investigation into the genetic determinants of fruit shape and size by a genome-wide association study.

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 N1647Χ N668, N1647 Χ 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, Bulgaria into 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 colour before 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 higher phenotypic diversity among them. A highly significant, 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 reflect 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.

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