preferred_name: 1-(9Z,12Z-octadecadienoyl)-2-acyl-3-[beta-D-galactosyl]-sn-glycerol + 2 reduced [2Fe-2S]-[ferredoxin] + O2 + 2 H(+) = 1-(9Z,12Z,15Z-octadecatrienoyl)-2-acyl-3-[beta-D-galactosyl]-sn-glycerol + 2 oxidized [2Fe-2S]-[ferredoxin] + 2 H2O