Strigolactones for the Eradication of Witchweed in Africa

Travis Bayer of Asilomar Bio in the U.S. is developing a low-cost compound that mimics the plant hormone strigolactone to help eradicate the parasitic weed Striga, which is jeopardizing food security and income in smallholder farms across sub-Saharan Africa. Striga lies dormant in arable soil, and is activated by strigolactone produced by plants including staple crops such as maize and rice. Striga then attaches to the plant's roots, steals water and nutrients, and produces toxins, and can completely devastate crops. Striga can be destroyed by applying strigolactone before planting, which induces it to germinate in the absence of a plant to attach to, causing death. However, strigolactone is currently costly to produce at the levels needed to spray all infected areas. To address this, in Phase I, they tested different fermentation methods to produce strigolactone from a genetically-modified industrial yeast. However, the purification step ultimately proved too costly. They also tried a chemical synthesis approach and produced high yields of a potent strigolactone mimic, AB01, at low cost by a simple alkylation reaction with a readily available natural product, sclareolide. They tested AB01 in a field trial in Western Kenya, and found that virtually no Striga emerged in AB01-treated plots, while there was robust parasite growth in control plots. In Phase II, they will determine the feasibility of deploying AB01 to improve smallholder farm productivity across sub-Saharan Africa by optimizing the formulation, performing widespread field trials, evaluating product safety, and quantifying overall production and application costs, and profits from increased yields.