Project Number: 5310-21000-009-00
Project Type: Appropriated

Start Date: Apr 22, 2008
End Date: Apr 21, 2013

Objective:
1) Strategically expand and improve collections of priority genetic resources of citrus and date palm and associated information. 2) Conserve and propagate citrus and date genetic resources efficiently and effectively, and distribute pathogen-tested samples and associated information worldwide. 3) Strategically characterize (¿genotype¿) and evaluate (¿phenotype¿) citrus and date palm genetic resources for priority genetic and horticultural traits. 4) Develop more rapid and accurate diagnostic methods for priority graft-transmissible pathogens of citrus to promote exchange of pathogen-tested stock and efficiently screen for host-plant resistance.

Approach:
New accessions will be acquired through exchange with university breeders, foreign country national programs, botanical gardens, or by plant exploration. New accessions will be quarantined, indexed and therapied before being available for distribution, and they will be characterized using the `Descriptors for Citrus¿ published by IPGRI. In addition to distribution of germplasm, information on the accessions is disseminated via the GRIN website/server and the Repository website. The `genotype¿ and `phenotype¿ of citrus and date palm genetic resources will be characterized for priority genetic and horticultural traits, such as level of antioxidants and the tolerance/resistance to selected diseases. Using SSR markers and by sequence analyses of selected regions of the chromosomal DNA, the genetic variability of core accessions of orange hybrids and major groups will be examined and used to determine ancestral origin. Laboratory-based diagnostic methods will be developed for citrus vein enation and citrus concave gum disease, presently detectable only by biological indexing on indicator plants. Diagnostic tests for huanglongbing disease will be utilized to screen subsets of citrus genetic resources so as to identify new sources of host-plant resistance/tolerance to this disease. Replaces 5310-21000-008-00D (3/08).