A team of researchers has discovered the mechanisms that protect finger millet, an important cereal crop, from a toxic fungus. The findings may be used to develop similar protections for other crops, including wheat and corn. The details are in a paper that was just published in the journal Nature Microbiology.
Fusarium graminearum is the asexual reproductive stage, also called an anamorph, of the Gibberella zeae fungus. F. graminearum damages crops by changing the amino acid composition, which also results in the production of mycotoxins. These mycotoxins are harmful to both livestock and people. Mycotoxin contamination is an especially dangerous type of food poisoning, causing liver damage, fevers, vomiting, and diarrhea in humans. Crop losses attributed to F. graminearum cost the agriculture industry billions of dollars each year.
Interestingly, finger millet (Eleusine coracana) is immune to F. graminearum. Finger millet is a cereal crop grown throughout Asia and Africa. The seeds are resistant to both fungal and insect attacks, making it a relatively safe crop to grow and store. Finger millet is still a staple food in many parts of the world. For the first time, researchers investigated the unique resistance mechanisms of the crop.
The research team exposed finger millet to F. graminearum and observed the plant’s roots under a microscope. They found a symbiotic relationship between the plant and a type of beneficial bacteria called M6. M6 lives in the plant’s roots but emerges into the soil when it senses F. graminearum pathogens. The bacteria rapidly multiply, forming a barrier that prevents the fungus from gaining entry to the roots. The root hairs then begin growing, helping to reinforce the barrier. Finally, M6 releases compounds that kill the fungus.
The team believes M6 can be used to protect other crops. Corn and wheat are already being tested with the microbe. The findings have the potential to prevent crop losses while also reducing the risk of mycotoxin contamination.
Walaa K. Mousa et al. Root-hair endophyte stacking in finger millet creates a physicochemical barrier to trap the fungal pathogen Fusarium graminearum. Nature Microbiology (2016).