ARS | Publication request: A LOW DENSITY GENETIC MAP OF ONION PROVIDES EVIDENCE FOR DUPLICATION AND REARRANGEMENT DURING EVOLUTION OF A LARGE DIPLOID GENOME

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 1995
Publication Date: N/A

Technical Abstract: The bulb onion, Allium cepa L., is the second most valuable vegetable worldwide, and a member of the Liliaceae, a family of monocots in which very large genomes are common. The onion genome is huge and distributed among 8 large metacentric chromosomes. We are developing a low density genetic map with phenotypic, RAPD and RFLP markers to facilitate selection and analysis of traits such as disease resistance and restoration of male fertility, and to examine the organization of a large plant genome. A mapping population of 58 F3 families was derived from a cross of the inbreds Bringham Yellow Globe 15-23 (BYG) x Alisa Craig 43 (AC). A 126-point map includes 112 RFLPs, 12 RAPDs, and loci controlling complementary red bulb color and the enzyme alliinase which hydrolyzes alkyl cysteine sulphoxides to produce the odor characteristic of Allium species. Approximately 25% of RFLP probes detected duplicate loci occurring as unlinked, linked, but separate on a linkage group and tightly linked gene families. Evolutionary models suggested by these data include tandem duplications followed by rearrangements, but not ancestral polyploidy.