Maize resistance to witchweed through changes in strigolactone biosynthesis.

Abstract

Maize (<i>Zea mays</i>) is a major staple crop in Africa, where its yield and the livelihood of millions are compromised by the parasitic witchweed <i>Striga</i>. Germination of <i>Striga</i> is induced by strigolactones exuded from maize roots into the rhizosphere. In a maize germplasm collection, we identified two strigolactones, zealactol and zealactonoic acid, which stimulate less <i>Striga</i> germination than the major maize strigolactone, zealactone. We then showed that a single cytochrome P450, ZmCYP706C37, catalyzes a series of oxidative steps in the maize-strigolactone biosynthetic pathway. Reduction in activity of this enzyme and two others involved in the pathway, ZmMAX1b and ZmCLAMT1, can change strigolactone composition and reduce <i>Striga</i> germination and infection. These results offer prospects for breeding <i>Striga</i>-resistant maize.