“Huanglongbing can destroy the whole orange industry. If there’s no action, there’s no orange trees in Florida anymore.”
– Feng Luo, School of Computing
“By the end of the grant, we hope to have a very good candidate for trees that can tolerate the disease,” Luo said.
Some diseased trees sprout new branches that have shown tolerance to Huanglongbing, he said. Clemson researchers are using genomics and bioinformatics, both artificial intelligence techniques, to study which genes and pathways make the branches tolerant to the disease.
“If we understand the genes, we can make trees more resistant using gene editing,” Luo said.
Huanglongbing was discovered in southern China in 1919 and has spread quickly in the southern United States since it was first discovered in Florida in 2005.
In a single decade, the disease caused a 72 percent decrease in U.S. production of oranges used for juice and other products, according to a study in the journal Frontiers in Plant Science.
The disease is spread by the Asian citrus psyllid, a winged insect no longer than a grain of rice. The nymphs feed on new shoots and leaves, removing sap from the plant and injecting a pathogen.
The leaves curl and twist, as bacteria hinders growth of new shoots and roots. Once the disease takes hold, the promise of a big, sweet orange ends up small, bitter and lopsided. All citrus trees can be affected, including lemon, lime and grapefruit.
Bo Wu started working on Huanglongbing while a Ph.D. student and has continued as a postdoctoral researcher in Luo’s lab. Wu said the disease evolves quickly but that he likes the challenge.
“My work is to find the mechanism underlying the HLB resistance,” he said. “It feels great, but it is hard work. The mutation is very difficult to identify.”
Other researchers are taking different approaches to combating Huanglongbing, using chemicals and transgenics, Luo said. The advantage to Luo’s approach is that it uses nature’s own solution, he said.
“There would be no regulation problem with our solution,” Luo said. “If we find the tree, we can get it quickly to the farmer.” ✲