Active on saturated acyl-CoAs up to C22. Mediates the synthesis of VLCFAs from 20 to 26 carbons in length (e.g. C20:1, C20, C24, C26). a very-long-chain acyl-CoA + H(+) + malonyl-CoA = a very-long-chain 3-oxoacyl-CoA + CO2 + CoA Inhibited by K3 herbicides such as alachlor, allidochlor, anilofos, cafenstrole, fentrazamide and flufenacet (PubMed:15277688). Strongly inhibited by metazachlor (PubMed:22284369). Lipid metabolism; fatty acid biosynthesis. Expressed in flowers. Repressed by herbicides such as flufenacet and benfuresate. Belongs to the thiolase-like superfamily. Chalcone/stilbene synthases family.