A Review on the diversity of Melon

The species Cucumis melo L. (melon) is a polymorphic taxon encompassing many botanical and horticultural varieties. Melon fruits exhibit substantial variability in their form, shape, skin characters, flesh color, flesh thickness, sweetness, seed cavity, seed size, etc., which reflects in the market value of melon. This existing diversity in melon germplasm leads botanists to propose different classifications at the specific and infraspecific levels. The majority of classifications are based on morphological and molecular characteristics. Morphologic traits such as flower and fruit characteristics (sex expression, fruit size and shape, fruit skin color, pH, flesh color, taste, aroma, sugar composition, seed size, and shape) were used in the past centuries for melon diversity analysis. Later on, scientists correlate these phenotypic and biochemical traits (Total Soluble Solids, Ascorbic acid content, Titratable acidity, etc.) with genotypic variability by molecular tools. Molecular tools generally used for melon diversity analysis are RAPD, RFLP, AFLP, SSR markers, and Single Nucleotide Polymorphism (SNP). This article emphasizes the progress of studies in the species Cucumis melo L. and its varieties since 1753. Particular attention has been paid to collect data regarding different horticultural groups of the species, and a recent infraspecific classification of the species has also been outlined. Even though the modern molecular techniques provide new insight to melon classification still there is an existing disparity in these classifications, which could be visible to the scientific world.