Development and Commercialization of Improved New Disease Resistant Scions and Rootstocks – the Key For a Sustainable and Profitable Florida Citrus Industry

Development and Commercialization of Improved New Disease Resistant Scions and Rootstocks - the Key For a Sustainable and Profitable Florida Citrus Industry

Report Date: 12/12/2016
Project: 15-010   Year: 2016
Category: Plant Improvement
Author: Fred Gmitter
Sponsor: Citrus Research and Development Foundation

Our project is focused on the following objectives: 1. Development of rootstocks that can impart HLB tolerance/resistance to grafted scions. 2. Breeding of HLB tolerant/resistant processing sweet orange-like hybrids. 3. Screening of the UF-CREC germplasm collection to identify and validate HLB tolerant or resistant selections. 4. Advanced field trials, release and commercialization of promising HLB tolerant/resistant scion and rootstock cultivars. DPI Parent Tree Entries: Three �gauntlet� rootstock selections, plus two others already showing evidence of HLB tolerance in field trials. Several scions selections, submitted primarily because of high levels of tolerance to HLB in the field, including Cybrid Dancy (reduced seed); 1 Red pummelo, 1 nearly seedless pink pummelo, and seedless Pummelette ; 3 seedless mandarins; the so-called McTeer Murcott (low seeded and showing HLB tolerance under heavy field pressure); a late maturing true sweet orange exhibiting HLB tolerance in multiple replicates; two HLB tolerant sweet orange-like hybrids; one seedy but extremely high quality mandarin. Gauntlet activities: Several new candidates have been entered into the program, grafted with hot budsticks and their tops propagated. Seventy five candidates were moved from the greenhouse to a psyllid hot house, and another 145 trees were planted in Picos Farm for final field screening, in collaboration with USDA researchers. Transgenic plantings: 198 sweet orange trees and 27 W. Murcott trees, containing a total of 7 different constructs for possible resistance to HLB, were also planted at Picos Farm in collaboration with USDA researchers. Field trials: Meetings were held with our collaborators from Lykes and Cutrale Citrus to review plans and activities in large scale field trials with these companies. Replacement trees were replanted, and seeds for a large trial with Hamlin orange were collected and transferred to the relevant nurseries. Other activities: Meetings were held with CRDF staff to facilitate communications and mutual understanding of our current research agenda. Several interactions took place of our team with recently hired Dr. Catherine Hatcher of CRDF. We have made several field visits to some of our locations in an effort to help her understand the nature and landscape of our citrus breeding program. We feel we have established a good working relationship and anticipate that this will facilitate the more rapid deployment of potential genetic solutions to HLB in the industry. Our field research manager, Dr. Paul Ling, resigned during this time frame and we have begun a search for his replacement. Several meetings and teleconferences were held with collaborators from the USDA, UCR, DPI, and Rucks Nursery to develop and implement plans for two MAC projects aiming to plant several large scale trials in Florida of tolerant rootstock and scion cultivars.

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