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United States Department of Agriculture

Agricultural Research Service

Title: Genetic Mapping in Onion: Insight to the Evolution of a Large Diploid Genome

item King, Joseph - FORMER ARS EMPLOYEE
item Havey, Michael

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 18, 1996
Publication Date: N/A

Technical Abstract: The bulb onion, Allium cepa L., is a diploid with an very large nuclear genome. We developed a low-density genetic map with morphological, RAPD, and RFLP markers to examine genome organization, and to study QTL controlling phenotypically correlated bulb quality traits. A mapping population of 58 F3 families was derived from a cross of the inbreds Brigham Yellow Globe 15-23 (BYG) x Alisa Craig 43 (AC). A 112 point map includes 96 RFLPs, 13 RAPDs, a locus controlling complementary red bulb color, and two loci hybridizing with a clone of the enzyme alliinase, which produces the flavors characteristic of Allium species. Duplicated loci were detected by approximately 25% of RFLP probes, and were unlinked, loosely linked (2 to 30 cM), or tightly linked (< 2 cM). This frequency of duplication was comparable to species with polyploid ancestors (paleopolyploids), and higher than that found in most true diploids. However, the distribution of duplicated loci suggests that in contrast to whole genome duplications typical of paleopolyploids, the size and structure of the onion genome may be a product of intrachromosomal duplications and subsequent structural rearrangements.

Last Modified: 4/22/2015
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