Title : Morpho-agronomic characterization and Simple Sequence Repeats (SSRS) analysis of sweet melon (cucumis melo l.) germplasm in Nigeria
Abstract:
Sweet melon (Cucumis melo L.) is a commercially important fruit crop with diverse genetic resources. This study aimed to assess the genetic diversity and phenotypic variation of sweet melon germplasm in Nigeria, using a combination of molecular and morphological characterisation techniques. A total of 30 sweet melon ecotypes were evaluated for morpho-agronomic traits, including plant growth habit, leaf shape, fruit shape, size, colour and maturity period. Significant variations (p≤0.05) were observed among the ecotypes for most of the traits studied, indicating a wide range of phenotypic diversity. To further explore the genetic diversity, Simple Sequence Repeat (SSR) markers were employed to analyse the DNA of the melon genotypes. A total of five (5) SSR markers (CM16 F/CM16 R, ECM133 F/ECM133 R, GCM303 F/GCM303 R, CMAT141 F/CMAT141 R and CMBR F/CMBR R) were used, which generated more monomorphic bands (71.4%) than polymorphic (28.6%) with an average of two bands per marker. The polymorphism information content (PIC) values ranged from 200 to 300bp, indicating a high level of genetic diversity among the genotypes. Cluster analysis based on SSR markers grouped the genotypes into two distinct clusters, with Geidam distinct, while the other nine ecotypes formed a major cluster (figure 5). The genetic diversity observed among the genotypes could be attributed to natural selection, genetic drift, environment and human selection. Integrating morphological and molecular data provided a comprehensive understanding of the genetic relationships and phenotypic diversity within the sweet melon germplasm. The identification of unique genotypes with desirable traits, such as disease resistance, early maturity and high fruit quality, has significant implications for sweet melon breeding programmes in Calabar. The results of this study highlight the potential of SSR markers for assessing genetic diversity and identifying superior genotypes in sweet melon. The information generated from this study can be utilized to develop improved cultivars adapted to the local environment and to promote sustainable melon production in the region.
Keywords: Sweet melon (Cucumis melo L.), Genetic Diversity, Phenotypic Variation, Simple Sequence Repeat (SSR) Markers, Breeding Programs
