Title : DArT-based characterisation of genetic diversity in genotypes of Cucumis metuliferus collected from South African Customs Union (SACU)
Abstract:
Cucumis metuliferus E. Mey. ex Naudin (African horned cucumber, 2n = 2x = 24) belongs to the Cucurbitaceae family. It is one of the underexploited and under-researched crop species with the potential to contribute to food security in the Southern African Customs Union (SACU) region (Botswana, Eswatini, Namibia and South Africa) where it grows naturally. It is documented to have phytochemical components which are important in the human daily diet. The crop has also been highlighted to contain genes which may be useful for cucurbit crop improvement by plant breeders. In order to help establish heterotic groups of the SACU C. metuliferus genotypes, Diversity Arrays Technology (DArT) markers were used to investigate the genetic diversity and population structure of 120 SACU African horned cucumber collections. Sequencing provider DArTTM (Canberra) successfully genotyped 10,572 single nucleotide polymorphism (SNP) markers, of which 5,875 were polymorphic. Findings from genetic analyses revealed that samples collected from the same geographical locations did not cluster together genetically. Instead, samples were distributed across different genetic clusters. Principal component analysis (PCA) results revealed the presence of three clusters where PC1 explained 48.5%, PC2 explained 8.8%, and PC3 explained 4.5% of the variance between samples, respectively. The results show that clusters of samples are not determined by the geographical regions in which samples were collected. This indicated that selection of the breeding lines should be based on systematic assessment of the diversity rather than geographical location. Overall, the study provides insights into the genetic diversity of African Horned cucumber for efficient utilization in the improvement endeavors of this crop.
