ARS/SCA: Develop transgenic forage grasses and legumes to alter or knock out biochemical pathways to gain a better understanding of secondary metabolite production and plant persistence

Transgenic approaches can be used in conjunction with biochemical and genetic approaches to dissect biochemical pathways leading to production of compounds of economic importance. Altering expression of endogenous genes or expressing foreign genes could lead to development of novel compounds or compounds with desired components. Presently, transformation of most forage crops, while feasible, is highly inefficient and genotype dependent. Red clover (Trifolium pratense) is an important forage legume in the southeast region. Red clover is particularly rich in isoflavonoid phytoestrogens, secondary metabolites that are beneficial to human health. However, high levels of phytoestrogens have been reported to reduce fertility in sheep and cattle grazing red clover. One goal of this project will be to reduce the total isoflavonoid content in red clover by silencing the isoflavone synthase (IFS)-encoding genes. A second goal of this project will be to suppress or delay the flowering of red clover and tall fescue by expressing the MiRNA-156 gene for the purpose of increasing biomass production.