Fungus May Save Crops from Disease and Global Warming

Endophytes that live in plant cells could confer a host of benefits
By Niina Heikkinen and ClimateWire | February 17, 2015

As scientists seek to make crops resilient against disease and the effects of climate change, they are turning to what may seem like an unlikely champion: fungi.
Specifically, they are studying endophytes, a type of fungus (or bacteria) that lives inside plant tissue and has no apparent negative effects on its hosts. Endophytes do, however, provide important protections to plants, which is why researchers are focusing on how the organisms could be used commercially to improve food security.
Although endophytes live within tissues and are ubiquitous in the plant world, it wasn't until relatively recently that scientists even knew of their existence, said Brian Murphy, a botanist at Trinity College in Dublin.
Murphy is currently studying how fungal endophytes could be used to protect barley against disease-causing fungi and recently published some promising results in the journal BioControl.
In the study, Murphy and his collaborators cultivated barley seeds that had not been treated with fungicides to see how effective 10 types of fungal endophytes were at preventing or slowing the onset of disease. The seeds were cultivated in a variety of media, and the endophytes were applied either in a cocktail or individually.
They found that the application of specific types of fungal endophytes, isolated from wild barley growing in Dublin, suppressed the development of seedborne infections in barley, without activating the plants' own defense system. Seeds that were not treated with the fungi developed some of the most devastating varieties of barley pathogens, according to the study.
The type of endophyte that had the greatest ability to suppress pathogen growth was also able to slow the growth of "take-all," a root disease that also affects wheat and oats. This could mean that endophytes have the capacity to serve as more generalized "bio-control agents," but researchers won't know this for sure without further research.
Field tests and a 'compatibility library' The study is gaining interest from European agribusiness, and Murphy's lab is informally working with a major company to make its endophytes commercially available for barley growers. The next step will be to take the research out of the lab and into field trials, which will likely take about three years to complete.
If endophyte use as a disease-fighting agent proves to be viable, it could have wide applicability across the globe, because barley is the fourth most cultivated cereal grain in the world.
"We don't know how these organisms will behave in a field environment," Murphy said. "We hope that one or possibly a cocktail of endophytes will be able to help the plants, but we can't predict outcomes."
"The other big issue is cost," Murphy said. If expanding production is more expensive than producing fungicides, commercialization is unlikely. But if development moves forward, endophyte use could reduce long-term costs.
"Because we are coating each seed individually [with endophytes], we might be able to have a self-sustaining population [of fungi] in the soil," Murphy said.
Out of the 10 fungal endophytes tested, the two best performers came from wild barley growing in sandy, silty soil, with relatively high salinity and low moisture. In the laboratory, endophytes grown in sandy and silty soil cultures performed noticeably better than those cultivated in artificial media.
The research suggests that soil conditions play an important role in endophytes' ability to suppress infection. It also means that endophytes have specific conditions in which they are the most effective, which has important implications for commercializing their use. Fungi that work well on barley in India wouldn't necessarily help barley grown in Ireland, and vice versa.
To get around this limitation, Murphy is hoping to one day develop a "compatibility library" to help producers match the right endophyte with their specific growing conditions and crop varieties.