1a. Objectives (from AD-416)
1. Identify and prioritize valuable sources of citrus germplasm in Florida which are threatened by HLB or citrus canker. 2. Establish the selected germplasm at USDA ARS Ft. Pierce and subject to standardized thermotherapy procedures. Following thermotherapy of germplasm, test for diseases which should be eliminated, including HLB and citrus canker. 3. Once thermotherapied germplasm has tested free HLB and citrus canker and other pathogens which should be eliminated, budwood would be shipped to NCGRCD, Riverside where it would be subjected to shoot tip grafting, followed by biological and laboratory indexing to ensure elimination of all citrus graft transmissible pathogens as required for release from quarantine in NCGRCD by CDFA and USDA APHIS. 4. Germplasm released from quarantine at NCGRCD would be sent to FL Citrus Introduction Program which will test the repatriated germplasm via protocols established by the “Citrus Passport” protocol, and release to the industry, keeping a clean source in the DPI facility in Chiefland.
1b. Approach (from AD-416)
A committee composed of members from the citrus breeding teams from University of Florida, USDA ARS, Florida Budwood Program, NCGRCD, and members of the Florida Citrus Production Managers Association, Florida Nurserymans’ Association, and Florida Citrus Mutual would identify and prioritize elite germplasm vital for the short and long term survival of the Florida citrus industry and which is threatened by presence of exotic diseases. A technician, under the supervision of an ARS scientist, would establish the plants and conduct the thermotherapy at ARS, Ft. Pierce, FL. Personnel from ARS, Riverside and Florida CIP would conduct laboratory testing on plants at Ft. Pierce following the growout after thermotherapy. Once freedom from HLB and citrus canker is confirmed, budwood would be shipped under quarantine to the Repository, Riverside and some to Florida CIP, Gainesville, where shoot tip grafting followed by full biological indexing would be performed. Following release from quarantine, pathogen-tested budwood would be returned to Florida with a plant maintained in the Protected Collection at the Repository.
3. Progress Report
The purpose of this project is to preserve citrus germplasm in Florida that is threatened by loss due to huanglongbing (HLB) and citrus canker and relates to objective 1 of the parent project. This research is in cooperation with the USDA ARS U.S. Horticultural Research Laboratory, Ft. Pierce, FL and the Florida Citrus Germplasm Introduction Program. Fifty unique accessions from Florida have been propagated in a secure greenhouse, repropagated with buds treated with antibiotics, and appear to be free of HLB. These accessions are being tested for HLB, further therapied as needed and tested for other citrus pathogens. The Repository, Riverside has received 22 accessions from Florida, and 11 are nearly completion of therapy and indexing for release from quarantine status.