QUANTITATIVE TRAIT LOCUS ANALYSIS OF FATTY-ACID CONCENTRATIONS IN MAIZE

A study was conducted to determine the number and chromosomal location of quantitative trait loci (QTL) influencing the concentration of fiv e fatty acids in 200 F2S1 lines derived from an Illinois High Oil (IHO ) by Illinois Low Oil (Early Maturity) (ILO(EM)) cross. Restriction fr agment length polymorphism (RFLP) analysis was performed on the 200 S- 1 lines and concentrations of palmitic (16:0), stearic (18:0), oleic ( 18:1), linoleic (18:2), and linolenic (18:3) acids were determined in self-pollinated kernels harvested from plants grown in replicated fiel d trials during 1992 and 1993. A series of 74 cDNA and genomic clones were used and these revealed 80 polymorphic loci spaced, on average, 2 4 cM apart throughout the maize genome. Analysis of variance detected significant (p < 0.05) associations between several RFLP loci and the concentration of each fatty acid. A total of 15 RFLP loci clustered in 12 chromosomal regions were associated with the concentration of 16:0 , 17 loci clustered in 10 regions were associated with the concentrati on of 18:0, 12 loci clustered in eight regions were associated with th e concentration of 18:1 and 18:2, and 17 loci clustered in eight regio ns were associated with the concentration of 18:3. Multiple linear reg ression models consisting of four RFLP loci explained 24 and 62% of th e total phenotypic and genotypic variation (R(2)) among the 200 F2S1 l ines for 16:0, five loci explained 51 and 71% of the variation for 18: 0, three loci explained 67 and 79% of the variation for 18:1, two loci explained 67 and 81% of the variation for 18:2, and seven loci explai ned 52 and 78% of the variation for 18:3 in these 200 F2S1 lines. The ratio of 18:1 to 18:2 was tightly interrelated as the same QTL were as sociated with the concentrations of 18:1 and 18:2. A quantitative trai t locus that explained 63% of the phenotypic variation in the ratio of 18:1 to 18:2 is tightly linked to umc65 on chromosome 6 in the region of the linoleic acidl locus.