Submitted to: International Society of Citriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/15/2000
Publication Date: 7/15/2003
Citation: BARKLEY, N.A., ROOSE, M.L., KRUEGER, R. ASSESSING GENETIC DIVERSITY IN CITRUS BY UTILIZING MOLECULAR MARKERS. INTERNATIONAL SOCIETY OF CITRICULTURE PROCEEDINGS. 2003. Interpretive Summary: The amount of genetic diversity present in long-established collections, such as the Citrus Variety Collection of the University of California, Riverside, is often not well established. A more complete knowledge of the amount of diversity present in the CVC will provide a more rational basis for management decisions. This report provides an initial look at efforts using simple sequence repeat (SSR) markers to assess the genetic diversity present in the CVC. More advances have been made since the paper was written. A total of 24 markers, 13 of which were developed by the authors, have been used to survey approximately 400 apparently sexually-derived accessions. The results will be analyzed using a number of different and robust tools. Eventually, a 'core' collection will be designated.
Technical Abstract: The Citrus Variety Collection contains 900 accessions in the genus Citrus and related genera in the subfamily Aurantioideae. This collection has been built up over nearly 100 years and the amount of genetic diversity actually present is unclear. Evaluating genetic diversity will lead to designation of a core collection, which will represent the majority of the genetic diversity of the Variety Collection with minimal redundancy. The rationale for constructing a core collection is to simplify management of the collection, allow germplasm users to have easy access to the diversity present in citrus, reduce distribution costs, and to reduce the total number of accessions needed to develop testing procedures. Genetic diversity is being evaluated by utilizing simple sequence repeats (SSR). A total of twenty-four markers have been tested, of which sixteen have produced scorable bands. These microsatellite targeted primers all displayed products within the expected size range. CAC19, TAA33, and TAA45 amplified a ladder of products, which obscured the true alleles. TAA1, TAA52 and CA04 have failed to amplify any products. Approximately twenty polymorphic markers that are well distributed over the genome are needed to adequately determine the diversity of the CVC.