Allelopathy

Abstract

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.