Development of herbicide-tolerant cassava via a high-throughput chemical mutagenesis platform

Cassava (Manihot esculenta), grown primarily for its starchy storage root, is a leading food source across tropical regions of South America, Africa and Asia. Weed management is a significant problem for commercial production but also smallholder farming families, particularly in Africa, in which hand weeding is performed mainly by women and children. Hand weeding is physically difficult, time consuming and often ineffective, resulting in yield losses estimated between 20-80%. Introduction of an integrated weed management system is likely to have significant economic and social benefits for cassava farming in Africa. Key to weed control is the development of herbicide-tolerant farmer-preferred cassava varieties. We have newly developed and optimized a tissue culture-based platform for high-throughput chemical mutagenesis and screening of cassava friable embryogenic callus. Herbicide tolerant mutants, as well as proof-of-concept transgenics, have been generated and verified in glasshouse trials in our model cassava variety. The mutagenesis platform is currently being used to generate acetolactate synthase (ALS) herbicide-tolerant cassava with a focus on farmer-preferred varieties commonly grown in Nigeria, which is the world’s largest cassava producer. In future, these non-GM ALS herbicide-tolerant cassava plants will be made available to cassava breeding programs and Nigerian smallholder farmers via the International Institute of Tropical Agriculture (IITA).

Dr Emily McMallum

Emily McCallum completed her PhD in plant molecular biology and plant-insect interactions under Prof. Jimmy Botella and Prof. Myron Zalucki at the University of Queensland. Moving to the CNRS Institut de Biologie Moléculaire des Plantes in Strasbourg, France, she contributed to research studying the role of chromatin dynamics in plant development and stress responses in Arabidopsis. With a strong interest in plant biotechnology, Emily joined the cassava research group in the lab of Prof. Wilhelm Gruissem at the ETH Zurich in 2010 and currently manages a Bill and Melinda Gates Foundation funded project to generate herbicide-tolerant cassava varieties through random mutagenesis.