a very-long-chain acyl-CoA + H(+) + malonyl-CoA = a very-long-chain 3-oxoacyl-CoA + CO2 + CoA Lipid metabolism; fatty acid biosynthesis. Expressed in siliques. Repressed by herbicides such as flufenacet and benfuresate. Belongs to the thiolase-like superfamily. Chalcone/stilbene synthases family.