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Title: CONSTRUCTION OF AN AVOCADO LINKAGE MAP USING VNTR MARKERS.

Author
item SHARON, DROR - ISRAEL
item CREGAN, PERRY
item MHAMEED, SIVH - ISRAEL
item KUHARSKA, MICHEL - ISRAEL
item HILLEL, JOSHI - ISRAEL
item LAHAV, EMIL - ISRAEL
item LAVI, URI - ISRAEL

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Because of the long generation time of tree species such as avocado, the development of new varieties with improved fruit quality or disease resistance is a long process that requires a great deal of time, nursery space, and labor. Thus, if one could select a tree with the proper fruit quality or disease resistance characteristics at the seedling stage, undesirable types could be discarded early in the breeding process and testing could be concentrated on those progeny with the potential to produce new improved varieties. One way to identify desirable trees at the seedling stage is by the use of DNA markers: One first identifies a DNA marker(s) associated with desirable genetic traits and then uses the marker(s) to identify the best seedlings without having to wait until the tree matures. In order to implement such a system one must have a set of DNA markers scattered among the genetic material (genes) of the target species. In this report we document the initial steps in the developmen of such a set of DNA markers in avocado. A total of 35 markers was developed and their positions determined in the DNA of the avocado. This genetic map of the avocado will be useful to avocado breeders for the improvement of avocado and the development of new varieties. This study will also provide basic information to other tree geneticists who are attempting to develop similar genetic maps in other tree species.

Technical Abstract: An avocado genomic DNA library was screened with various microsatellite repeats. (A/T) and (TC/AG) sequences were found to be the most frequent repeats. One hundred and seventy two positive clones were sequenced successfully of which 113 were found to contain simple sequence repeat (SSR) DNA. Primer pairs could be found for 62 clones, almost half of which contained an (A/T) repeat. A GenBank data search for avocado sequences revealed one sequence containing (CT/GA). A total of 93 avocado specific SSR markers were screened for polymorphism using offspring of the cross 'Pinkerton' x 'Ettinger'. Fifty one polymorphic SSR loci, 17 random amplified polymorphic DNA (RAPD), and 23 DNA Fingerprint (DFP) bands were used to construct an avocado genetic map using various computer programs. The analysis resulted in 12 linkage groups with 35 markers (26 SSRs, 3 RAPDs, and 6 DFP bands) covering 357.2 2 centimorgans. This initial map can serve as a basis for a detailed genomic map and for detection of linkage between markers and quantitative trait loci.