Fatty acid desaturase involved in the production of chloroplast-specific phosphatidylglycerol molecular species containing 16:1(3E). Catalyzes the formation of a trans double bond introduced close to the carboxyl group of palmitic acid, which is specifically esterified to the sn-2 glyceryl carbon of phosphatidylglycerol. a 1-acyl-2-hexadecanoyl-glycerolipid + 2 H(+) + O2 + 2 reduced [2Fe-2S]-[ferredoxin] = a 1-acyl-2-[(3E)-hexadec-3-enoyl]-glycerolipid + 2 H2O + 2 oxidized [2Fe-2S]-[ferredoxin] Lipid metabolism; fatty acid metabolism. The histidine box domains are involved in binding the catalytic metal ions. No visible phenotype, but missing a chloroplast-specific phosphatidylglycerol molecular species that carries a delta 3-trans-hexadecenoic acid in the sn-2 position of its core glyceryl moiety. Belongs to the fatty acid desaturase CarF family. Truncated N-terminus.