Location: National Clonal Germplasm Repository for Citrus
Project Number: 2036-21000-012-010-I
Project Type: Interagency Reimbursable Agreement
Start Date: Oct 1, 2023
End Date: Sep 30, 2024
Objective:
Objective 1: Variety Introduction under Quarantine. Citrus germplasm identified by stakeholders or center management will arrive at NCGRCD quarantine facilities and be held under permit.
• Objective 2: Introductory Disease Diagnosis & Pathogen Detection. Laboratory and biological testing of citrus germplasm will be carried out at the NCGRCD facilities prior to therapeutics to assess pathogen status and after therapeutics to determine effectiveness of the therapeutics. New and modified diagnostic protocols will be implemented as they become available.
• Objective 3: Therapy of Citrus Propagative Material. Therapeutics for the elimination of citrus pathogens (shoot-tip grafting, heat therapy) will be carried out at the NCGRCD facilities.
• Objective 4: Foundation Materials. Clean citrus accessions maintained in protective structures will be observed and repropagated as necessary. Trees will be horticulturally managed for optimum health and propagule production. Protected accessions will be retested to meet State and Federal standards and as otherwise determined to be necessary by center management. Seed source trees in the field will be re-tested to meet State standards. When sufficient material is available on newly sanitized, it will be sent to USDA-ARS National Laboratory for Genetic Resource Preservation for secure, long-term cryopreservation. Clean citrus propagative material will be distributed upon request to qualified institutions and individuals.
• Objective 5: NCPN-Citrus-Administrative Activities. The Center Director will participate as a member of the Tier 2 in meetings of that body.
• Objective 6: Education & Outreach Program Coordination. The Center Director is a member of the Education and Outreach Sub-Committee. He also participates in education and outreach activities that present themselves or upon request by NCPN or others.
Approach:
Objective 1. Variety Introduction under Quarantine. Citrus importation and cleanup is performed under PCIP-18-00441 (renewed 2022-08-23, renewal submitted 2023-07-16), which is on file at USDA-APHIS-PPQ Permits Unit. The method followed is summarized as follows: initial pathogen testing to determine incoming pathogen status, followed by therapeutics (shoot-tip grafting or thermotherapy). After therapeutics, the resultant plants are screened by laboratory testing, after which a select plant of each genotype is indexed biologically, followed by final lab tests. Plants testing negative for all known graft transmissible pathogens are petitioned to be released from quarantine.
Objective 2. Introductory Disease Diagnosis & Pathogen Detection. NCGRCD utilizes two basic types of diagnostics: laboratory-based and classical biological indexing. Laboratory tests are mostly qPCR, but ELISA is used for some re-testing purposes and culturing is used for a specific bacterial pathogen, Spiroplasma citri. Complete protocols are on file.
Objective 3. Therapy of Citrus Propagative Material. NCGRCD utilizes two therapeutic methods: shoot-tip grafting (STG) and thermos-therapy. The emphasis is currently on STG but occasionally thermos-therapy is still used.
Objective 4. Foundation Materials. Clean plants are maintained in a PPQ-approved protective structure under compliance agreement HLB-0082. Plants are retested as appropriate by NCGRCD personnel or in the case of HLB, by the California Department of Food & Agriculture Diagnostic Laboratory. Plants are inspected by unit personnel for insect pests and treated, as necessary. Plants are repropagated as needed. Other management practices are taken to ensure vigorous growth and production of budwood. When appropriate, budwood is removed from the trees and sent to NLGRP for long-term preservation under the protocol developed at NLGRP.
Clean plant propagative materials are distributed upon request. All pertinent phytosanitary regulations at all administrative levels are followed and appropriate documentation accompanies each shipment. Further information is available in the NCGRCD Operations Manual draft.
Objective 5 . NCPN-Citrus-Administrative Activities. The Center Director is a member of the Tier 2 board and Education-Outreach Subcommittee. He participates in meetings unless otherwise compromised.
Objective 6. Education & Outreach Program Coordination. The Center Director is a member of the Education and Outreach Committee and participates in meetings unless otherwise compromised. He also participates in other outreach activities that present themselves or upon request.
