The University of California, Riverside says the USDA’s National Institute of Food and Agriculture funded three citrus disease research projects.
The three new grants total more than $11 million, according to a news release.
Huanglongbing, also known as citrus greening, is a bacteria transmitted to citrus trees by the Asian citrus psyllid. Infected trees produce no fruit or fruit that is bitter and small. There is no known cure for the disease, and it has reduced citrus production in Florida by more than 75%, according to the release. Trees with HLB are also in Texas and California.
UC Riverside said the research projects are critical to the citrus industry in the state, noting that it produces 80% of the fresh citrus in the country on 267,000 acres.
The research projects focus on developing a tolerance for the disease through three approaches: below ground, in the rootstocks; above ground, in the shoots and branches; and systemically, with a peptide that moves throughout the tree, according to the university.
Developing new rootstocks
Danelle Seymour, assistant professor of genetics in the botany and plant sciences at UC Riverside, leads a $6.8 million project to breed for HLB-resistant rootstocks. Seymour will collaborate with Kim Bowman, a citrus breeder at the USDA Agricultural Research Service in Ft. Pierce, Fla., according to the release.
“In Florida, nearly every single tree is infected. It’s terrible for growers but wonderful for breeding,” Seymour said in the release. “We can’t do this research at large scale in California because the disease isn’t as widespread here.”
Seymour said it takes 10 to 15 years to evaluate a new generation of trees — crosses made with HLB-resistant traits. Bowman has evaluated more than 10,000 trees and unique hybrids and offers Seymour’s team a chance to look at existing crosses to speed up the process.
UC Riverside said Seymour’s team will also compare the growing habits of these hybrids in different soil types and conditions.
“Can they perform well in response to different salinity levels in the soil, different humidity, as well as other pests and pathogens that we have here? We’ll find out,” Seymour said.
New cultivars
USDA ARS gave Chandrika Ramadugu, a project scientist also in UC Riverside’s department of botany and plant sciences, $3.28 million to develop and analyze second-generation HLB-resistant hybrids, according to the release. The university said Ramadugu’s team used Australian lime genetics as the source of resistance to the disease.
The research team will evaluate 24 novel hybrids in California, Florida and Texas to assess resistance to HLB and fruit quality, the release said.
Peptide research
A $1.36 million project led by Hailing Jin, a professor in microbiology and plant pathology at UC Riverside, will examine the potential of a peptide found in Australian finger limes with known HLB resistance.
“The antimicrobial peptide in the finger limes are more efficient at killing bacteria as compared to antibiotics currently used in the field and much more stable at high temperatures,” Jin said in the release.
Jin’s team will work with Svetlana Folimonova, a professor at the University of Florida, on the project to inject trees with a natural citrus virus carrying the peptide to spread it systemically throughout areas of the tree infected with HLB, according to the release.
“You infect the tree with the virus, and it will spread in areas where the bacteria reside,” Jin said. “It would move systemically through the tree, and it would be very cost-efficient for growers. No need to buy more insecticides.”
