Researchers in Israel have used CRISPR gene editing to deactivate a gene that produces bitter chemicals in grapefruit, potentially making the fruit more appealing to consumers. This innovation could expand the market for citrus and combat the devastating citrus greening disease by enabling cold-hardy, edible varieties. The approach aims to shift citrus farming to temperate regions like northern Europe.
In a bid to make grapefruit less bitter, scientists at the Volcani Center in Rishon LeZion, Israel, have employed CRISPR technology to disable the gene responsible for producing naringin, neohesperidin, and poncirin—the main compounds behind the fruit's sharp taste. "It could expand the market," says Nir Carmi, a researcher on the team. "Kids don’t usually like grapefruit because it’s too bitter for them."
The work addresses multiple challenges facing the citrus industry. A bacterial disease known as citrus greening, or huanglongbing, is ravaging orchards, particularly in subtropical areas like Florida. The insects that transmit the bacteria cannot survive cold winters, limiting farming to warmer climates. However, existing cold-hardy citrus varieties, such as the trifoliate orange, are inedible due to their high bitterness levels.
By editing the enzyme-producing gene, the team created grapefruit trees where these bitter chemicals were undetectable in the leaves, suggesting the fruit will also lack them once mature. Grapefruit trees take several years to bear fruit, so taste tests are pending. The current edited plants include a marker gene, classifying them as transgenic and complicating regulatory approval in many countries. In the US and Japan, simple gene edits without such markers are not considered genetically engineered, easing the path to market.
The researchers plan to repeat the edit without the marker gene, a process described by team member Elena Plesser as "very tedious." They also intend to apply the technique to trifoliate oranges and crossbreed the results with popular varieties like oranges to develop seedless, delicious fruits that tolerate cold weather—a goal that may take many years.
Nir Carmi believes his group's project is the most advanced among similar efforts worldwide. Erin Mulvihill at the University of Ottawa notes that such editing could significantly improve fruit palatability. However, grapefruit's interactions with medications like statins, partly due to naringin, persist; eliminating them fully would require editing multiple genes.
The findings appear in The Plant Journal (DOI: 10.1111/tpj.70654).
