Mention watermelon and people immediately think of sweet, juicy, crimson-colored fruit. But watermelons didn't start that way, notes Angela R. Davis of the U.S. Agricultural Research Service. Wild watermelons in their native Africa are white fleshed, the size of softballs, and "hard like softballs," she notes. Bitter and anything but sweet, watermelons hardly started as dessert.

On the other hand, U.S. domesticated watermelons are so sweet that they tend to be off-limits to most of the nation's 20 million people with diabetes. People adhering to low-carb diets also shun the fruit. So, Davis, a melon geneticist and enthusiast, embarked on developing a low-sugar alternative to the standard U.S. supermarket melon. She started by screening a host of noncommercial melons, including many that retained some of their wild traits.

LOOKS THE SAME, BUT. . . These melons may resemble the conventional supermarket versions, but they're far less sweet. That means they would fit well into sugar- or calorie-paring diets. Davis

"The project took a lot longer than we expected," she says. "Because there's a correlation between color and sugar content," low-sugar variants that the researchers initially found—including some wild varieties—had unappetizingly white flesh inside. However, Davis' team eventually ran across one melon that bore yellow flesh and little sugar. Seven generations of crossbreeding progeny of this melon yielded two lines of fruit whose seeds now uniformly grow into pink, low-sugar melons. Another, even redder line produces melons with midlevel sugar content.

Davis' group, based in Lane, Okla., describes these new melons in a pair of papers slated to be published later this year in HortScience.

The new melons may not start out sweet enough to satisfy everyone's taste. However, adding a dash of artificial sweetener usually takes care of the problem, Davis finds. Indeed, in one taste test her group conducted, people eating the melons actually preferred a low-sugar watermelon treated with an artificial sweetener over a conventional supermarket melon.