The low linolenic acid soybean line PI361088B contains a novel GmFAD3A mutation

Characterization of genetic mutations at the molecular level allows for the development of perfect genetic markers and rapid assays to detect those markers, which enables breeders to directly select for desired alleles and accelerate the breeding process. The objectives of this study were to identify genetic lesions found in the GmFAD3A gene in the low linolenic acid soybean [Glycine max (L.) Merr] line PI 361088B, which contains a fan allele, and to develop rapid molecular marker assays that distinguish between the wild-type and PI 361088B alleles. The entire genomic sequence of the GmFAD3A gene was determined for PI 361088B. Two thymine nucleotides are inserted into a run of four thymines from nucleotide position 307 to 310 the GmFAD3A coding sequence, resulting in a frameshift and the introduction of a premature stop codon at nucleotide 328. Two molecular marker assays were developed that rely on polymerase chain reaction (PCR) amplification of the region of interest followed by restriction endonuclease digestion and agarose gel electrophoresis or melting curve analysis. A third assay is an allele-specific PCR-based assay that does not require any endonuclease step and requires only melting curve analysis. In conclusion, the low linolenic acid soybean line PI 361088B contains a coding mutation in GmFAD3A; this allele can easily be distinguished from the corresponding wild-type allele using any, of three rapid molecular marker assays that were developed.