Enhanced folate content in bioengineered lettuce stably expressed under field conditions

Folate (vitamin B9) is an essential nutrient that plays a crucial role in various bodily functions. Its deficiency can lead to health issues, such as megaloblastic anemia, neural tube defects in the developing fetus and increased risk of cardiovascular diseases. Consequently, there is interest in increasing folate content in food crops by classical and molecular breeding. Since folate is a water-soluble vitamin that is sensitive to heat, we chose to manipulate its synthesis pathway in lettuce, which is often used for salads and sandwiches, without heat treatment, which makes it a good vehicle for making folate available to the population via biofortification. Transgenic lettuce plants were generated to express the GTP-cyclohydrolase I and aminodeoxychorismate synthase coding sequences from Arabidopsis thaliana. Plants were cultivated under greenhouse conditions and two field trials were carried out. Results have shown that transgenic lines presented up to 3.4 times more folate than the non-transgenic lettuce plants and 1.9 times more folate than spinach, considered one of the plants richest in folates. Advanced generations of homozygous plants were cultivated under field conditions for two years and the results showed that folate-biofortification was stable. A folate-biofortified lettuce serving would provide about 36 to 64% of the recommended daily intake. This technology is a foundation to produce folate-biofortified commercial varieties that can help to reduce hidden hunger, decreasing the number of cases of fetus malformations and other diseases.