Allelopathy offers a direct opportunity for the host plant to counter development of a parasitic plant by deploying antagonistic secondary metabolites at the early stages of infestation. Little progress has been made in exploiting allelopathy for controlling parasitic plants, largely because of weakened defence secondary metabolism of crop plants as a consequence of breeding for other priorities. However, forage legumes of the genus Desmodium when grown as an intercrop substantially interfere with infestation of maize by Striga spp. through allelopathy. One aspect of the chemistry underpinning this control involves C-glycosylated flavonoids, specifically 6-C-α-l-arabinopyranosyl-8-C-β-d-glucopyranosylapigenin. Currently, the genes for enzymes involved in the crucial step in the biosynthesis of C-glycosylated flavonoids are being identified, with attempts to transfer such genes to cowpea. This approach to exploit allelopathy could potentially produce food crops benefiting directly from this Striga-controlling trait.
KeywordsNuclear Magnetic Resonance Spectroscopy Parasitic Plant Upland Rice Forage Legume Parasitic Weed
This work was funded by the Gatsby Charitable Foundation (UK), Kilimo Trust (East Africa), the Rockefeller Foundation and the Biovision Foundation (Switzerland). Rothamsted Research receives grant-aided support from the Biotechnology and Biological Sciences Research Council (BBSRC) and was funded through the BBSRC/DFID SARID initiative. The authors also acknowledge the assistance provided by icipe field staff, Ministry of Agriculture extension staff and the farmers.
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