Genetic Relationships between Loci Controlling the High Stearic and the High Oleic Acid Traits in Sunflower
2000
Pérez-Vich, Bego n ˜ a | Garcés, Rafael | Fernández-Mart ı ´ nez, Jose Mar ı ´ a
Sunflower (Helianthus annuus L.) lines with seed oils containing either high oleic (C18:1) or high stearic (C18:0) acid have been obtained through induced mutagenesis. The combination of the seed oil phenotypes of these lines would result in a novel oil quality of great value for the food industry. The objectives of this study were (i) to determine the genetic relationships between the high C18:0 and the high C18:1 traits, and (ii) to combine both characters. The sunflower lines HAOL-9 (high C18:1), carrying the high C18:1 Ol alleles, and CAS-3 (high C18:0), with the high C18:0 alleles es1 and es2, were reciprocally crossed. The fatty acid content of the F₁, F₂, BC₁F₁ to both parents, and F₃ seeds was analyzed by gas–liquid chromatography (GLC). The segregation patterns for C18:0 (F₂ ratio of 15:1) and C18:1 (F₂ ratio of 1:3 or 7:9) in the F₂ and BC₁F₁ to both parents fit those previously reported when each fatty acid was studied independently. However, a distortion was observed in their combined segregation, indicating that neither character was independently inherited. Furthermore, the analysis of the F₃ generation revealed that F₂ half seeds with the highest C18:0 concentration in a high C18:1 background were still heterozygous for either the C18:0 or the C18:1 levels, suggesting a genetic linkage between the alleles Es2 and Ol These alleles determine a lower C18:0 and a higher C18:1 content, respectively. No F₂ recombination between them was achieved, resulting in the absence of high C18:0/high C18:1 phenotypes. However, some intermediate C18:0/high C18:1 F₂ seeds led to stable F₃ seeds with this phenotype (130 g kg⁻¹ C18:0/790 g kg⁻¹ C18:1).
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