Contributes to fatty acids elongation (By similarity). Plays a role in controlling leaf anatomy and plant architecture (Ref.5). a very-long-chain acyl-CoA + H(+) + malonyl-CoA = a very-long-chain 3-oxoacyl-CoA + CO2 + CoA Highly expressed in leaf sheaths (Ref.5). Expressed in leaves, flag leaves and panicles (Ref.5). Belongs to the thiolase-like superfamily. Chalcone/stilbene synthases family.