Genetic Linkage between the Trigenic Male‐Female Sterility and Oil Quality Alleles in Safflower

Abstract

Several studies have shown that the proportions of oleic and linoleic acid in the seed oil of safflower (Carthamus tinctorius L.) are governed by two alleles at the ol locus. In some studies, however, fewer plants than expected had the olol genotype. The deviation from the expected ratio could have been caused by a genetic linkage between sterility and oleic or linoleic acid content. Although male‐female sterile plants appeared in the F2 of such studies, sterile plants were not used in measurements of fatty acid composition. The objective of this investigation was to detect possible genetic association between sterility and oil quality genes. We examine data from a cross of US‐10 with genotype OlOl (high linoleic acid) to 57–147, an introduction from India with genotype olol (high oleic acid). This cross gave sterile plants the F2. We measured the iodine value (IV) in bulk seeds from 217 selfed, fertile F2 plants and found a distorted ratio due to fewer than expected plants with low IV (genotype olol). Using the half‐seed technique to determine the fatty acid composition of 342 (fertile and sterile) F2 seeds from selfed F1 plants, there was no deficiency in the expected number of olol genotypes. The difference in the ratios of the F2 plants grown from half‐seeds and those used in fatty acid measurements indicate linkage between sterility and the ol locus. Of the genes involved in sterility, where sterile genotypes are s1s1s2s2S3—, s1s1S2—s3s3, and s1s1s2s2s3s3, a statistically significant deviation was detected due to linkage between the s1 and ol loci. This information should be considered by breeders of safflower who systematically use introductions from a multitude of gene centers in their breeding programs.