A New Formulation for Strigolactone Suicidal Germination Agents, towards Successful Striga Management

Abstract

<i>Striga hermonthica</i>, a member of the <i>Orobanchaceae</i> family, is an obligate root parasite of staple cereal crops, which poses a tremendous threat to food security, contributing to malnutrition and poverty in many African countries. Depleting <i>Striga</i> seed reservoirs from infested soils is one of the crucial approaches to minimize subterranean damage to crops. The dependency of <i>Striga</i> germination on the host-released strigolactones (SLs) has prompted the development of the "Suicidal Germination" strategy to reduce the accumulated seed bank of <i>Striga</i>. The success of aforementioned strategy depends not only on the activity of the applied SL analogs, but also requires suitable application protocol with simple, efficient, and handy formulation for rain-fed African agriculture. Here, we developed a new formulation "Emulsifiable Concentration (EC)" for the two previously field-assessed SL analogs Methyl phenlactonoate 3 (MP3) and Nijmegen-1. The new EC formulation was evaluated for biological activities under lab, greenhouse, mini-field, and field conditions in comparison to the previously used Atlas G-1086 formulation. The EC formulation of SL analogs showed better activities on <i>Striga</i> germination with lower EC₅₀ and high stability under Lab conditions. Moreover, EC formulated SL analogs at 1.0 µM concentrations reduced 89-99% <i>Striga</i> emergence in greenhouse. The two EC formulated SL analogs showed also a considerable reduction in <i>Striga</i> emergence in mini-field and field experiments. In conclusion, we have successfully developed a desired formulation for applying SL analogs as suicidal agents for large-scale field application. The encouraging results presented in this study pave the way for integrating the suicidal germination approach in sustainable <i>Striga</i> management strategies for African agriculture.