Engineering resistance to maize lethal necrosis: an emerging threat to food security in Africa. Maize lethal necrosis (MLN) is caused by the double infection of maize plants with Maize chlorotic mottle virus (MCMV) and any of the cereal viruses in the Potyviridae group, such as Sugarcane mosaic virus (SCMV), Maize dwarf mosaic virus (MDMV), or Wheat streak mosaic virus (WSMV)1. MCMV or SCMV typically produce milder symptoms when they infect maize alone; in combination, these two viruses rapidly produce a synergistic reaction that seriously damages or kills infected plants. The disease has been found in Kenya and other parts of Africa and there is concern that, without resistant varieties, it could spread.
The aim is to generate GM lines that are resistant to this disease for comparison with conventionally bred varieties. The project will involve working with African partners to characterize the strains of virus responsible for the disease in different regions. Virus will be analysed in samples of infected plant and transgene constructs will be designed so that they are as broadly infected as possible. Maize plants will be transformed with these constructs and the transgenic lines will be tested for resistance in glasshouses and, it is hoped, in the field.
Several types of transgene constructs will produced. Some will be be based on artificial microRNAs and they will be designed so that the RNA silencing of the plants is targeted against the virus2,3. Others will be derivatives of disease resistance genes and they will target the protein-mediated innate immune system of the plant against the causal agents of MLN.
The project will introduce the basic and applied aspects of disease resistance in plants and will be carried out in collaboration with partners in Africa.
- Region, S. R., North, N., South, N. & Gishu, U. Maize lethal necrosis ( MLN ) disease in Kenya and Tanzania : Facts and actions. CIMMYT Rep. (2012).
- Niu, Q.-W. et al. Expression of artificial microRNAs in transgenic Arabidopsis thaliana confers virus resistance. Nat. Biotechnol. 24, 1420–8 (2006).
- Harris, C. J., Slootweg, E. J., Goverse, A. & Baulcombe, D. C. Stepwise artificial evolution of a plant disease resistance gene. Proc. Natl. Acad. Sci. U. S. A. 110, 21189–94 (2013).