How Peppers Proliferated Across the Planet

Paprika is cosmopolitan, a vegetable that occurs in far more varieties than there are nations in the world. One day, you can slice a mild orange pepper to dip in hummus. Or you can roast red peppers and mix them into a dip or your own sauce, such as ajvar or romesco. Poblano peppers can add a bit of spiciness to a dish or even become a meal like chili rellenos. But watch out for those Carolina Reaper peppers.

Common to all of these dishes is the humble pepper plant or Capsicum spp. Hailing from Central and South America, the plant eventually crossed the oceans in the hands of traders, says Pasquale Tripodi of CREA’s Vegetable and Ornamental Plant Research Center in Italy. In a paper published Monday in The Proceedings of the National Academy of Sciences, Dr. Tripodi and European colleagues shared the results of their studies on the genetics of more than 10,000 pepper samples from around the world.

Their results reveal fascinating details about the plant’s worldwide travels, such as how a colonial power’s trading networks spread peppers far and wide, and how some of the plants became sweet and crispy while others gained their fiery pungency.

Millions of seeds rest in a handful of cool, isolated chambers around the world known as plant gene banks. These repositories hold seeds for use by plant breeders and researchers, allowing access to the widest possible variety of traits. A wild eggplant whose roots are mold-resistant, a sturdy tomato that won’t wither in scorching heat, a wheat whose heads stay together in heavy rain – these plants can be grown with tastier varieties in hopes of producing crops for an uncertain future .

Gene banks carefully care for their residents, regularly germinating seeds and collecting fresh ones to ensure that most of their collections remain viable. But relatively few researchers have turned the tools of genetic sequencing onto this ocean of genes.

Since gene banks keep track of where each sample was taken, it should be possible to see where a plant like the bell pepper ended up and whether there are genetic links between certain regions and what happens when they have arrived in a new area and were fresh from influenced pepper lovers.

Dr. Tripodi and his colleagues focused on the most commonly consumed group of peppers, Capsicum annuum, which is grown to make peppers of all colors, cayenne pepper, and jalapeños. The researchers found that Europe and Asia shared a wide variety of species, suggesting that peppers moved along trade routes between east and west. There were also links between Eastern European peppers and those in the Middle East, possibly due to Ottoman trade routes. The team speculates that Portuguese traders who started trading in the 16th

After paprika found admirers in a new location, farmers seem to have made their own choices over the years; Peppers in Eastern Europe were sweeter and less spicy, while East Asian peppers were small and fiery. Researchers discovered genes linked to these and other traits that could be of use to breeders in the future.

The researchers also made a surprising discovery when they checked the data for duplicates – a significant portion of the gene banks’ pepper collections were not unique. This meant that the gene banks unknowingly kept multiple copies of semen, perhaps also because without genetic testing it is difficult to tell whether a new pack of semen is identical to an existing pack. As sequencing becomes cheaper and easier, it can change the way gene banks work.

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