FaFAD1 structure. The FaFAD1 gene, noted also as gene24414, is located in a region corresponding to linkage group 3 (LG3) in the F. vesca genome. Simple sequence repeat regions are noted by the large black arrows, and the small black arrows represent primers used to test for amplification within this region in parental lines and progeny. The letters A and B denote the primers used for marker amplification. The asterisk denotes a potential allele introducing a stop codon into the FaFAD1 sequence.