A cereal crop with enhanced folate: rice transgenic for wheat HPPK/DHPS

Folate is a B-group vitamin critical for normal cellular function and division. It acts in one-carbon transfer systems essential in nucleotide synthesis, methylation and gene expression. Insufficient intake causes megaloblastic anaemia and there are strong linkages to cardiovascular disease, various cancers and cognitive decline. Low levels prenatally can lead to low birth weight and premature infants and catastrophic neural tube defects including spina bifida and anencephaly (1-3). Vertebrates are unable to synthesize folate de novo, accordingly plant foods are the primary source. Cereals unfortunately, which provide over half the worlds population with 80% of their diets are particularly poor in folate. Consequently the majority of developed nations have fortification programmes. In the developing world however, such programmes are logistically far more difficult. A practicable alternative is metabolic engineering, to create a cereal crop plant producing high levels of folate. Folate is produced in a multi-step process from a pterin ring, p-aminobenzoate (pABA) and glutamate residues. Here we show rice plants transgenic for wheat 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase/7,8-dihydropteroate synthase (HPPK/DHPS) which operates at a central point in the production pathway, can give elevated folate levels. Consequently we have a cereal crop transgenic for a single cereal gene expressing enhanced folate levels. Further transgenic plant analysis is ongoing.