Molecular cloning and expression of a cDNA encoding a microsomal ω-6 fatty acid desaturase from cotton (Gossypium hirsutum)

AcDNA(ghFAD2-1) encoding a seed-specific microsomal omega-6 desaturase was isolated from a cotton (Gossypium hirsutum L. cv. Deltapine-16) embryo cDNA library. The deduced amino acid sequence showed substantial similarity to other plant microsomal omega-6 desaturases. Northern blot analysis indicated that the ghFAD2-1 transcript was specifically induced during embryo development and expression of the transcript could not be detected in leaves. Southern blot analysis using the coding region and 3' untranslated region of ghFAD2-1 revealed that microsomal omega-6 desaturase in cotton is encoded by a small multigene family. There are at least two copies of ghFAD2-1 in two tetraploid cotton species (G. hirsutum L. and G. barbadense L.) and at least one copy in diploid cotton species (G. herbaceum L., G. raimondii Ulbrich and G. robinsonii Mueller).