Plant & Animal Genomes XIV Conference Plant & Animal Genomes XIV ConferenceJanuary 14-18, 2006
Town & Country Convention Center
San Diego, CA
Xueyi Hu , Mandy L. Sullivan-Gilbert , Manju Gupta , Raghav Ram , Steven A. Thompson
The quality of canola oil is determined by its constituent fatty acids such as oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). Most canola cultivars normally produce oil with about 55-65% oleic acid and 8–12% linolenic acid. High concentrations of linolenic acid lead to oil instability and off-type flavor, while high levels of oleic acid increase oxidative stability and nutritional value of oil. Therefore, development of canola cultivars with increased oleic acid and reduced linolenic acid is highly desirable for canola oil quality. In this study, we have mapped one major and one minor locus for high oleic acid and two major QTL loci for low linolenic acid by applying molecular markers to a doubled haploid population. The major locus for high C18:1 was proven to be fatty acid desaturase-2 (fad2) gene and it is located on the linkage group N5; the minor locus is located on N1. One major QTL locus for C18:3 is the fatty acid desaturase-3 gene of the genome C (fad3c) and it is located on N14. The second major QTL locus resides on N4 and could be the second fad3 gene of the A genome (fad3a). We have sequenced genomic clones of the fad2 and fad3 genes amplified from EMS-induced mutants and a wild-type canola cultivar. A comparison of the mutant and wild-type allele sequences of the fad2 and fad3 genes revealed single nucleotide mutations in each of the genes. Detailed sequence analyses suggested mechanisms by which both the mutations can cause altered fatty acid contents in the mutants. Based on the sequence differences between the mutant and wild-type alleles, two single nucleotide polymorphism (SNP) markers, corresponding to the fad2 and fad3 gene mutations, were developed. These markers will be highly useful for direct selection of desirable fad2 and fad3 alleles during marker-assisted trait introgression and breeding of high oleic and low linolenic canola.