University of Guelph plant scientists have shown for the first time how an ancient crop teams up with a beneficial microbe to protect against a devastating fungal infection, a discovery that may benefit millions of subsistence farmers and livestock in developing countries.
Their discovery may also point the way toward a natural treatment to thwart the pathogen in other important crops grown worldwide including corn and wheat, said plant agriculture professor Manish Raizada.
He’s senior author of a paper published today in Nature Microbiology. He worked with lead author and former PhD student Walaa Mousa, current graduate student Charles Shearer, Ridgetown Campus scientist Victor Limay-Rios and researchers in California.
The paper describes a novel defence mechanism allowing crop plants to work with bacteria called endophytes living in their roots to ward off Fusarium graminearum.
This fungus makes a toxin that can sicken livestock and people.
The M6 microbe lives in the roots of finger millet, a cereal crop grown by subsistence farmers in Africa and South Asia. Millions of people rely on the crop, first domesticated in East Africa in about 5,000 BC.
The crop has long been known to be resistant to fungal disease.
Through microscope observations, Mousa learned how the mechanism works.
Sensing the pathogen near the plant roots, the microbe enters the soil and multiplies to millions of cells that form a protective barrier on the root surface.
Even more striking, Raizada said, the plant’s root hairs grow to many times their normal length. Like layers in lasagna, the root hairs and the bacterial cells form a dense mat that traps the fungus.
Mousa found that natural products of these endophytic bacteria then kill the fungus.
“This appears to be a new defence mechanism for plants,” said Raizada.
He likens it to the human immune system, with immobile plant cells “recruiting” mobile microbes to seek out and destroy pathogens.
The researchers believe this defence evolved in a kind of evolutionary arms race in the African ancestors of finger millet and Fusarium. The fungus can make an antibiotic against M6 for which the bacterium has developed resistance in turn, Raizada said.
“We think subsistence farmers in East Africa over generations may have selected for this special microbe through breeding.”
He said the findings may help agricultural companies develop seed treatments using M6 to protect more susceptible and widely grown crops such as corn and wheat against the fungus.
Farmers spend tens of millions of dollars fighting crop diseases such as Fusarium.
U of G has licensed the lab’s results to an agricultural startup company for potential use in those crops. The microbe is now being tested in Canadian corn and wheat.
The team found that M6 also protects against other fungi.
He said the study shows the importance of indigenous farming knowledge and practices. “These crops should be explored and valued.”
Learn more: U of G Discovery May Benefit Farmers Worldwide
An international research team is developing nanotechnology-based applications of hexanal, a natural plant extract that extends the storage life of harvested fruit.
Bananas, mangoes and papayas: these tender tropical fruits are in high demand in export markets and an important livelihood source for producers. But freshness is key because these fruits spoil quickly and damage easily. The challenge is especially daunting where refrigeration is lacking. Estimates suggest that up to 40% of produce in tropical countries is lost in post-harvest handling.
Breakthrough research by Canadian, Indian, and Sri Lankan partners points to a promising innovation: nanotech applications of a natural plant extract called hexanal can be used to delay fruit ripening. Hexanal inhibits a plant enzyme that is responsible for breaking cell membranes during a fruit’s ripening process.
In initial research in India and Sri Lanka, scientists used a hexanal-impregnated formula to test the product on mangoes. Spraying orchards with a low concentration of the compound slowed fruit ripening by three weeks. The team is also developing “smart packaging” systems, made from materials such as banana fibre, that slowly release hexanal to extend storage life after fruit is harvested.
These applications can boost farmers’ incomes. “Let’s say a mango farmer sprays half or one third of the orchard with the formulation,” explains Jay Subramanian, a professor at Canada’s University of Guelph. “He gets that same mango production but spread out over a three- to four-week window instead of just one week, which causes a major rush and a glut in the market, leading to low prices.”
In field trials, farmers were able to earn up to 15% more for their crop. Once harvested, the sprayed mangoes remained fresh for up to 26 days in cold storage and 17 days at room temperature.
The University of Guelph (U of G) is a comprehensive public research university in Guelph, Ontario, Canada.
It was established in 1964 after the amalgamation of Ontario Agricultural College, the Macdonald Institute, and the Ontario Veterinary College, and has since grown to an institution of more than 28,000 students and academic staff. It currently offers over 94 undergraduate degrees, 48 graduate programs, and 6 associate degrees in many different disciplines.
The University of Guelph is consistently ranked as a top comprehensive university in Canada by Maclean’s magazine, and given top marks for student satisfaction among medium-sized universities in Canada by The Globe and Mail. It has held these rankings with its reputation, innovative research-intensive programs, and lively campus life cited as particular strengths. The University of Guelph has also been ranked 50th by Times Higher Education in their list of the top 100 universities under 50 years old. The university has a key focus on life science and has ranked 76-100 in the world by ARWU.
Currently, the faculty at the University of Guelph hold 39 Canada Research Chair positions in the research areas of natural sciences, engineering, health sciences and social sciences. Recent academic achievements include the first scientific validation of water on Mars, Alpha particle X-ray spectrometer (APXS) on board the Mars Exploration Rovers, and the Barcode of Life project for species identification.
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An almost entirely accidental discovery by University of Guelph researchers could transform food and biofuel production and increase carbon capture on farmland.
By tweaking a plant’s genetic profile, the researchers doubled the plant’s growth and increased seed production by more than 400 per cent.
The findings were published in the March 2016 issue of Plant Biotechnology Journal.
The team studied Arabidopsis, a small flowering plant often used in lab studies because of its ease of use and its similarity to some common farm crops. They found that inserting a particular corn enzyme caused the plant’s growth rate to skyrocket.
“Even if the effects in a field-grown crop were less, such as only a tenth of what we’ve seen in the lab, that would still represent an increase in yield of 40 to 50 per cent, compared with the average one to two per cent a year that most breeding programs deliver,” said Prof. Michael Emes, Department of Molecular and Cellular Biology (MCB).