Molecular farming, using the cereal endosperm as bioreactor

Abstract

Seed is an ideal protein production platform because it is the storage organ of the plant and offers appropriate storage compartments for the deposition of foreign proteins. To achieve high foreign protein expression level in the endosperm tissue, the transformation cassette carried the tissue-specific promoter of the wheat high-molecularweight glutenin subunit protein 1Bx17, fused to the first intron of rice actin promoter. Transformation protocols were established and optimized in the laboratory for cereals such as rice, barley and wheat using direct DNA delivery and the Agrobacterium tumefaciens mediated transformation system. Both immature (barley) and mature (rice) embryos, and immature inflorescences (wheat) were used as sources of explants. Subunit edible vaccines were produced to introduce the LTB, CTB and fused LTB-PEDV genes into the rice genome. The PEDV gene was also integrated into the barley genome. A project has recently been started to produce a rabbit-derived enzyme in transgenic wheat endosperm to be used by the pharmaceutical industry.