An urgent need for new ways to protect crops from fungal disease
A rapidly rising global population is placing increased pressure on food security. This is exacerbated by climate change, which is not only increasing extreme weather events such and flood and drought but may also be increasing crop loss due to fungal plant disease. Current control strategies include host resistance, fungicides, and management practices such as crop rotation.
Unfortunately, such strategies often do not offer adequate protection or lead to environmental damage. Furthermore, many fungal pathogens have shown a remarkable ability to evolve resistance against conventional pathogen control strategies, which can lead to devastating disease outbreaks. Therefore, there is an urgent need to add develop novel tools for pathogen control.
Investigating natural gene drives as a potential means of pathogen control
All current control strategies look at changing the plant (e.g., breeding for more resistant plants) or farming practices (e.g. chemical fungicides or crop rotation). However, a major paradigm shift would be to manipulate the pathogens themselves.
Until recently such an approach was in the realms of science fiction. But gene drive technology may make manipulation of pathogens in agronomic settings feasible. Gene drives are genetic elements that bias sexual reproduction in such a way that they are transmitted to the next generation at a higher-than-expected frequency. This means that even elements which are deleterious to the pathogen can rapidly spread through a population.
We have been investigating ways to engineer a gene drive element to reduce pathogenicity. If successful, in theory this should be able to spread throughout the pathogen population and reduce the disease burden on crops without the use of environmentally damaging chemicals. Before such possibilities can be realised a greater scientific understanding of how gene drives work in fungi is required.
A greater understanding of a naturally occurring gene drive
We have recently transferred a known gene drive element from a non-pathogenic species into the wheat pathogenic fungus Fusarium graminearum and shown that it is functional in this species. Furthermore, by inserting the drive element in a locus necessary for F. graminearum pathogenicity we are able to “drive out” pathogenicity in a laboratory population.
Because a deeper understanding of the biology underlying gene drives will be crucial for their future deployment, we have also made fundamental scientific discoveries into the mechanistic basis of this drive including that the drive acts through DNA damage to kill non-inheriting progeny.