The increasing importance of pumpkin (Cucurbita pepo L.) cultivars for seed production has led to considerable breeding efforts for novel high-yielding and disease-resistant cultivars lacking seed coats. Because it is very important to use genetically diverse genotypes for the development of cultivars with a broad genetic and phenotypic base, this study focused on phenotypic and genetic diversity within and among available pumpkin accessions with mutated seed coat phenotypes. Fifty-one accessions were collected from various sources and countries, which showed a wide variety of seed coat types. Genetic analysis with 18 simple sequence repeat (SSR) markers revealed that 37.59% of the total genetic diversity was attributable to interpopulation differentiation and 62.41% to individual differentiation within populations. The average genetic differentiation between accessions (FST) was from 0.030 to 0.760, whereas expected heterozygosity (He) was between 0.048 and 0.491 and observed heterozygosity (Ho) between 0.056 and 0.522. Based on unweighted pair group method with arithmetic mean (UPGMA) analysis, the genetic relationship among accessions reflects the primary geographical origin of accessions. Marker amplification yielded a total of 109 alleles with an average number of alleles per locus of 6.06. Gene diversity per locus varied between 0.027 and 0.879, whereas the polymorphism information content (PIC) varied between 0.027 and 0.867. This is the first report about intra-accession phenotypic and genotypic variability of pumpkins with mutated seedcoats cultivated for their seeds, which are today used in the baking industry, seed oil production, and in traditional and modern medicine.
COBISS.SI-ID: 8109177
The article presents the development of a parthenogenetic haploid induction protocol based on pollination with pollen irradiated with X-ray radiation at 0, 50, 100, 150, 200, 300, and 350 Gy. Various accessions were tested as the female parent or as the pollen donor and large differences were found. The ploidy level of 3,830 putative parthenogenetic embryos was determined using flow cytometry. Four ploidy levels (n, 2n, 3n, and 4n) were found with the majority being diploid. Using selected simple sequence repeat markers on diploid embryos, no spontaneous chromosome doubling could be confirmed. In this study, haploid induction in styrian oil pumpkin was elaborated for the first time. We also showed that X-ray pollen irradiation provides an alternative to gamma radiation treatment, yielding a sufficient percentage of haploid plantlets.
COBISS.SI-ID: 7651449
Discovery of a mutant thin-coated seed phenotype at the end of the 19th century facilitated pumpkin (Cucurbita pepo L.) seed oil production and increased botanic interest in seed coat types and their structures. The main seed coat characteristics were usually analyzed by light and fluorescent microscopy, and more recently, seed coat traits have also been mapped on a C. pepo gene map. The aim of our research was to collect and describe various pumpkin seed types and to analyze, using scanning electron microscopy (SEM), the detailed structure of their seed coats. Seeds of 29 cultivars and landraces were collected and visually evaluated based on seed coat characteristics. Seed samples belonging to different seed types discovered in our collection were transversely sectioned and analyzed by SEM. Twelve seed types were determined, and SEM analysis revealed high variability in their seed coat structures. Using SEM, tissue and cell structures were clearly visible, and novel details of cell and tissue topography were documented. Hypodermal and aerenchyma cells in wild-type seed coats showed fibrous or reticulate secondary cell wall thickening, respectively. In mutant seed types, an absence of different seed coat layers was clearly noted, while the remaining layers were distinctly pronounced. A new completely hull-less seed type was described for the first time. Description of the variability of seed coats in pumpkin was complemented by novel seed coat types, and their structures were analyzed in detail the first time by SEM.
COBISS.SI-ID: 7342457