Purpose

The health benefits of soy are central to the large growth of soybean based food market. Many are aware that Asian populations, who regularly consume soy, suffer six times fewer cases of breast cancer and twelve times fewer prostate cancers than Western populations.

Isoflavone content is a major factor in soybean's nutritional value. Due to their chemical structure, isoflavones such as genistein and daidzein act as phyto-estrogens by binding estrogen receptors and exerting a weak estrogenic activity.

Isoflavone content in non-legume crops, such as corn, are not readily accessible by those who consume them. Since corn, or maize, is much more associated with Western diets, it would be beneficial, both nutritionally and economically, to metabolically engineer isoflavonoid biosynthesis in corn.

Project

This project seeks to find ways to synthesize isoflavones in maize. In legumes, isoflavone synthase acts as a metabolic branch-point by converting flavanones to isoflavones. Expression of soybean IFA leads to tissue-specific production of small amounts of isoflavones in tobacco and maize, species that do not normally synthesize isoflavones.

Current data suggests that accumulation of isoflavones in non-legume plants depends on phenylpropanoid activity for providing substrates. At the same time, the flavonoid pathway competes for flavanone intermediates and has a significant effect on isoflavone production.

Therefore, the objects of the program are: 1)Reduce flavonoid biosynthesis in maize BMS cultures and transgenic plants; and 2) Engineer isoflavone production in maize.

Impact

The current project is unique because engineering high levels of isoflavone in maize will increase the nutritional value of the crop and improve pathogen resistance. The outcome of this project (isoflavone corn) offers an alternative to soy products as a source of dietary isoflavones.