Scientists have improved the metabolism of an oilseed plant to mimic the molecular structure of the human milk. Their technique made the oilseed plant accumulate triacylglycerol with most of the fatty acid in the middle of its molecular structure, instead of in the outer parts. This can potentially lead to a new plant-based source of milk fat substitute that infants can easily digest.

Formula milk sold for infant nutrition use milk fats from plants. However, the molecular structure of the plant-derived fat makes it hard to digest for infants. Its stereoisomeric structure consists of saturated fatty acids in the outer position that makes it less suitable to infants' digestion. This led to studies to find a human milk substitute that resembles the structure of actual human milk.

A team from the Rothamsted Research in the United Kingdom introduced a mutation to the plant Arabidopsis thaliana, a type of oilseed plant related to mustard. The mutation allowed the scientists to change the location of an enzyme responsible for processing fat. This resulted to saturated fatty acid palmitate being accumulated in the middle part of the stereoisomeric structure which is similar to human milk. The method can possibly help in the mass production of fat molecules similar to that of a human milk's using oil-rich plants like sunflower and oilseed rape, without making the synthesizing process extremely expensive.

See the full article in PNAS.

Fig. 1.

A simplified diagram illustrating the cytosolic and chloroplastic pathways for de novo glycerolipid biosynthesis in Arabidopsis. Three modifications enabled palmitoyl (C16:0) groups (white bars) to be incorporated into the sn-2 (or β) position of TAG in developing seeds. (1) Retargeting of LPAT1 to the ER, (2) knock down of LPAT2 and (3) knock out of PDCT. C18:x, long-chain mono-, or polyunsaturated fatty acyl groups (black bars); C16:0 and C18:x groups (hatched bars); CoA, CoenzymeA; ACP, acyl carrier protein; G3P, glycerol-3-phosphate; 1-LPA, sn-1 lysophosphatidic acid; PA, phosphatidic acid, DAG, diacylglycerol, TAG, triacylglycerol; PC, phosphatidylcholine; 1-LPC, sn-1 lysophosphatidylcholine; FFA, free fatty acid; LPAT, 1-LPA acyltransferase; PDCT, PC:DAG cholinephosphotransferase.