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United States Department of Agriculture

Agricultural Research Service

Research Project: ACQUISITION AND EVALUATION OF CITRUS AND CITRUS RELATIVES IN THE CITRUS VARIETY COLLECTION

Location: National Clonal Germplasm Repository for Citrus & Dates

2009 Annual Report


1a.Objectives (from AD-416)
Maintain high quality of and upgrade citrus variety collection and citrus relative collection.


1b.Approach (from AD-416)
Acquire new potential accessions for the citrus variety collection and citrus relative collection and NCGRCD protected screenhouse collection, evaluate accessions and potential access, update databases appropriately, and maintain collections in good order for efficient utilization. FORMERLY 5310-21000-008-08S (8/08).


3.Progress Report

Characterization and Improved Documentation for Citrus Relative Taxa. The completion of data collection of the 80 different descriptors for the 600 citrus relative trees in 2008 permits us to make available data for relative accessions that lacked descriptor data in the past and to clear up any discrepancies in the identifications of taxa so that we can consolidate the number of trees per taxa. The Repository is currently watermarking photographs of all these Citrus relative taxa and preparing how to upload this large data set into the GRIN system database.

Screening Citrus Germplasm for New Sources of Tolerance to Fusarium solani. In collaboration with ARS and the UC Cooperative Extension, San Diego County, seedling trees of the ‘core’ collection of accessions that represent 90% of diversity in the collection were established and inoculated with Fusarium solani in a greenhouse. To determine the extent of tolerance to F. solani, the amount of healing from girdling and the number of dry root rot lesions was measured on a subjective scale, and the percentage of feeder roots was compared to controls. The results are being analyzed statistically and prepared for incorporation into databases and for publication.

Preservation and Enhancement of the Collection as a Resource. The finding of the Asian citrus psyllid, the vector of huanglongbing (HLB), in San Diego in September 2008 places the UCR Citrus Variety Collection in danger of exposure to the psyllid and HLB. In October, 2008, three California Citrus Nursery companies provided rootstock trees and a crew of individuals who together with the staffs of the Citrus Variety Collection (CVC) and the Repository worked together to propagate 550 different citrus and Citrus relative taxa that were maintained only in the CVC field planting and not in a protected structure. These newly propagated trees are now being maintained in greenhouses that are screened to provide long-term protection from the Asian citrus psyllid for this valuable citrus resource. Funds to screen the existing UCR greenhouses housing these propagated plants were obtained from UCR’s College of Natural and Agricultural Sciences, the Office of Research and the Department of Botany and Plant Sciences.

CVC Accession Records and Website Updates. The CVC database is updated as new accessions and information about these and existing accessions become available. Photographs and information about the source of the accession, parentage, rootstock, season and other notes for each of the relative taxa and other accessions are now posted on the CVC website (http://www.citrusvariety.ucr.edu). We plan to continue to work toward our goal of providing photographs and information about trees of each of the 1000 different accessions in the CVC. We will continue to provide the Repository with our updated records to update their local databases and the USDA ARS GRIN system. ADODR monitored activities by meetings, site visits, e-mail correspondence, and phone calls.


Last Modified: 7/23/2014
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