Delta(12) fatty acid desaturase converting palmitoleic acid (16:1(9)) to hexadecadienoic acid (16:2(9,12)). No detectable Delta(12)linoleate desaturase activity. Involved in the biosynthesis of the aliphatic side chain of sorgoleone, a phytotoxic secondary metabolite playing a direct role in allelopathic interactions. Lipid metabolism; polyunsaturated fatty acid biosynthesis. Highly expressed in root hair cells. Barely detected in panicle, shoot apex, stems and leaves. Up-regulated upon auxin treatment (PubMed:22087851). Up-regulated by jasmonate and methyl jasmonate (PubMed:23702703). The histidine box domains may contain the active site and/or be involved in metal ion binding. Belongs to the fatty acid desaturase type 1 family.