Meet the Honeysweet Plum: A virus-resistant plum that ARS hopes to bring to market soon. They are large and oblong with a very sweet, flavorful taste.
ARS created the Honeysweet variety using RNAi, a biotechnology method that makes them immune to the plum pox virus. Plum pox infects stone fruit trees: plums, peaches, apricots and cherries. Once infected, the fruit discolors and falls from the tree prior to maturation. There is no natural, genetic resistance to the virus.
Plum pox is devastating, according to Dr. Chris Dardick, molecular plant biologist and lead scientist at the ARS Appalachian Fruit Research Laboratory in Kearneysville, WV. Eradicating the virus is costly: infected trees are identified and destroyed, and all trees in a 500-meter area around the infected tree are also destroyed to prevent virus spread.
Growers in the U.S. fear Sharka disease. According to Dardick, “The U.S. prune industry is almost entirely in California. They have the largest, highest quality fruit and they export about 50% of the world’s supply. They don’t have plum pox, but they’re terrified they’re going to get it."
RNAi technology could stop plum pox completely. “Trials in the U.S. and Europe since the 1990s show that these experimental trees are completely resistant to the virus,” said Dardick.
To deploy RNAi technology in Honeysweet, a gene from the plum pox virus was spliced into the plum plant. “This spliced gene acts as sort of antigen against the virus,” said Dardick. “Basically, it’s a genetic vaccine. It’s very effective.”
For more information: tellus.ars.usda.gov