Submitted to: International Society of Citriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/15/2000
Publication Date: 7/15/2003
Citation: KRUEGER, R., GULSEN, O., ROOSE, M.L. USE OF MOLECULAR MARKERS IN MANAGEMENT OF CITRUS GERMPLASM RESOURCES. INTERNATIONAL SOCIETY OF CITRICULTURE PROCEEDINGS. 2003. Interpretive Summary: With the development of various types of molecular markers over the last decade, their use in the management of collections of genetic resources has become more common. Most reports in this area have dealt with the assessment of the amount of genetic diversity present in collections of seed-propagated crops. Use of molecular markers in the management of clonally-propagated crops is somewhat different. Particularly in the case of citrus, it is possible to use markers in other ways than the simple assessment of diversity. Since certain types of citrus are apomictic, it is possible with markers to identify nucellar seedlings and thus eliminate duplications within seedling populations and to a lesser extent between existing accessions. Some other uses are also described in this paper. Notably, the importance of high-quality pathogen-tested germplasm is a priority for clonal crops and markers for certain pathogens are useful for assessing their pathogen status. All of these uses are currently being carried out at the National Clonal Germplasm Repository for Citrus & Dates in Riverside, California.
Technical Abstract: Molecular markers have been used in the management of plant genetic resources for some time. Their use in the management of genetic resources of perennial crops, particularly citrus, is somewhat different than for seed crops. The use of molecular markers has been initiated in the management of citrus genetic resources maintained in Riverside, California, by the US Dept of Agriculture and the University of California. Molecular markers have been used to identify nucellar seedlings (representing the type) for accessions received as seed; reduce the number of trees maintained by identifying redundancies; identify accessions for which the identification had been lost; and screen for pathogens. Examples of these uses are given. Ongoing projects include surveying of the field collection and assessing the amount of genetic diversity actually present. This will permit designation of a core collection, prioritization of accessions for evaluation and other activities, and indicate redundancies and gaps in the collection. The markers utilized have been SSR and ISSR, which offer several advantages over other types of markers in these applications. Other potential uses and benefits of molecular markers in the maintenance and management of citrus genetic resources are discussed.