The staple banana variety available in U.S. supermarkets -- often the ONLY variety -- is threatened by a tropical fungus that is slowly killing it off as it spreads across the globe. The question is whether new, resistant varieties can be found and developed.

"The bananas you find in the average U.S. grocery store are pretty much the same: They're the genetic variety known as Cavendish.

In the market in Mayagüez, Puerto Rico, though, you have choices.

Brian Irish, a scientist who has been working at the U.S. Department of Agriculture's Tropical Agriculture Research Station in Mayagüez, points out our options. There are Cavendish bananas, to be sure, but also red-skinned varieties, miniature ones and others that seem extra plump. Shop owners are also here, buying their bananas from farms on the island."

Dan Charles reports for NPR January 11, 2016. [2]