The present invention relates to mutant Δ8 desaturase genes, which have the ability to convert eicosadienoic acid [20:2 ω-6, EDA] to dihomo-γ-linolenic acid [20:3, DGLA] and / or eicosatrienoic acid [20:3 ω-3, ETrA] to eicosatetraenoic acid [20:3 ω-3, ETA]. Isolated nucleic acid fragments and recombinant constructs comprising such fragments encoding Δ8 desaturase along with methods of making long-chain polyunsaturated fatty acids (PUFAs) using these mutant Δ8 desaturases in plants and oleaginous yeast are disclosed.