The invention relates to crop plants comprising novel seed lipid compositions. Provided are both wild type and mutant nucleic acid molecules encoding Brassica fatty acyl-acyl carrier protein (ACP) thioesterase B proteins (FATB) and the proteins as such. Also provided are Brassica plants, tissue and seeds comprising at least three mutant fatB alleles in their genome, whereby the seed oil fatty acid composition or profile is significantly altered.
