Molecular farming (also known as bio-pharming) is characterized as the production of proteins or other metabolites that are extremely important as medicine or to industry. This technique only requires an agricultural setting after the desired protein gene is inserted in plants. Usually, plants can synthesize a wide variety of proteins that are free of mammalian toxins and pathogens. Also, plants can produce large amounts of biomass at low cost and require minimum facilities.
Molecular farming is a new source of molecular drugs, such as plasma proteins, hormones, growth factors, vaccines and recombinant antibodies, whose medical uses are known at the molecular level, because plants have long been used as a source of medicinal compounds. It aims to provide pharmaceutical drugs, like vaccines and therapeutic proteins for treating cancer and heart, liver or kidney disease more abundantly and inexpensively.
The technique used in this approach is genetic modulation of plants to produce specific compounds, generally proteins, those needed post-transcriptional modification for activation. After harvesting these products then extracted and purified for application.
Generally, genetic transformation is carried out using Agrobacterium tumefaciens. The protein of interest is often expressed under the control of the cauliflower mosaic virus 35S promoter (CaMV35S), a powerful constitutive promoter for driving expression in plants. Signal localization peptide sequence is attached to the recombinant protein to express in a specific sub-cellular location, such as chloroplasts or vacuoles, in order to improve yields, make simpler purification process, or so that the protein folds properly.
Primarily, Arabidopsis use to study gene expression in plants, but in case of actual and mass production maize, wheat, rice, potatoes, tobacco, flax or safflower are used. Among them, tobacco is the popular organism for the expression of transgenes, as it is easily transformed, produces abundant tissues, and persists well in vitro as well as in greenhouses. On the other hand, the advantage of rice and flax is that they are self-pollinating, and thus gene flow issues are avoided. Besides, human error could still result in pharm crops entering the food supply is a potential risk factor. However, it can be minimized by expressing the recombinant proteins in plants vegetative or producing sterile hybrids, but at a high cost. Another way of reducing the threat is using a minor crop like safflower or tobacco.

Tasnin Khan Eusufzai

Figure: Technique of molecular farming to produce recombinant protein for therapeutic use.