Characterization of mutations in the FAD2-1B alleles from soybean lines PI 283327 and PI 567189A. A. Schematic of the FAD2-1B gene and the polymorphisms identified in the alleles from PI 283327 and PI 567189A. The horizontal line represents the DNA for FAD2-1B, with the heavier line indicating the intron and lighter lines representing the 5' and 3' untranslated portions of the gene. The dark vertical line represents the portion of exon 1 that contains only the start codon and the darkened rectangle represents exon 2. Numbers beneath the schematic indicate the positions of polymorphisms compared to the Williams 82 reference FAD2-1B coding sequence, with shared missense mutations in bold and non-shared missense mutations underlined. 1 = a105g, silent; 2 = c257t, S86F; 3 = a376g, M126V; 4 = c410g, P137R unique to PI 283327 and PI 210179; 5 = t428c, I143T unique to PI 567189A and PI 578451; 6 = c657t, silent; 7 = t669c, silent; 8 = t682c, silent; 9 = a918g, silent. B. Fatty acid desaturase FAD2-1B amino acid sequence alignment in the region surrounding the mutations in PI 283327 and PI 567189 A. Amino acid positions are indicated at the beginning of each line of the alignment. Identical amino acid residues are highlighted in black, a similar amino acid substitution is highlighted in gray, and the S86F, P137R, and I143T mutations are not highlighted. C. Weblogo output of the amino acid conservation FAD2 enzyme as part of the BLINK feature at NCBI using GI number 197111722. The top 100 best matched sequences were aligned and used as input for sequence LOGO http://weblogo.berkeley.edu/logo.cgi. The logo consists of stacks of symbols, one stack for each position in the amino acid sequence. The overall height of the stack indicates the sequence conservation at that position, while the height of symbols within the stack indicates the relative frequency of each amino acid at that position. Closed arrow indicates residue changed due to the P137R FAD2-1B mutation in PI 283327 and open arrow indicates residue changed due to the I143T FAD2-1B mutation in PI 567189A.