European scientists, from France and Spain, had previously succeeded in mapping two unconnected sections of the melon DNA sequence.
Now, in a new study published in the Journal of the American Society of Horticultural Sciences, US researchers claim to have joined them up.
According to Dr Kevin Crosby of Texas AgriLife Research, the breakthrough "will help us anchor down some of the desirable genes".
"We can identify specific genes for higher sugar content, disease resistance and even drought tolerance".
The edible curcubits come in a multitude of different varieties but it is their sweet taste that creates the strongest consumer pull. Identifying the genetic markers that trigger fruit sugars, as well as ascorbic acid (vitamin C), is expected to speed development of sweeter, more nutritious fruit.
Method
Crosby, with colleagues Dr Soon Park and Dr Hye Hwang, worked with the Deltex ananas melon and crossed it with a wild melon, known as TGR 1551. Over 100 offspring of the union were grown in greenhouses.
From the leaf tissue of these the team extracted DNA 21 days after planting. This DNA was integrated into the existing genome maps to create a randomly amplified polymorphic DNA marker-based linkage map.
They also mapped quantitative trait loci for sucrose, total soluble solids, ratio of sucrose to total solids, ascorbic acid and the locus for male sterility seen in other crosses.
The results, they said: "will be used to identify quantitative trait loci for fruit sweetness, quality, size, and shape traits, as well as disease resistance".
Source: Journal of the American Society for Horticultural Science 134:67-76 (2009)
A genetic linkage map including loci for male sterility, sugars and ascorbic acid in melon
Authors: Park, S, Hwang, H, Crosby, K