Biologicals offer new opportunities to make plants and soils thrive

Wednesday, March 18, 2020

This U of Guelph researcher looks to wild relatives and ancient varieties of crops to identify biologicals from the plant microbiome that might help today's agricultural systems

by Jackie Clark
Staff Writer
Better Farming

Dr. Manish Raizada and his team of graduate students and researchers in the plant agriculture department at the University of Guelph are studying endophytes to find potential biological growth promotors or biological pest controls.

Endophytes are microbes that live inside plants without causing disease, and that may benefit the plant, Raizada tells Better Farming.

"We look for a plant that has our trait of interest," he explains. That trait might be stress tolerance, or resistance to a certain disease.

To find plants with the desired trait, the Raizada lab team "will often look at indigenous knowledge and ancient landraces or wild relatives or crop species," he says. A landrace is a local cultivar that was improved through traditional methods. Since these varieties usually grow with minimal chemical inputs, the plants may have selected for more beneficial traits.

Raizada has a lot of "respect for Indigenous farmers. They often will point to things that are very interesting," he says.

Through consulting traditional knowledge, Raizada's team finds species and varieties of plants with the beneficial trait that the researchers are interested in. Then, they investigate that plant's microbiome.

"We focus on seed-associated microbes because of the thought that, for the most important, the plant has a strong selection to carry those microbes through the seed," Raizada explains.

Then, the researchers culture the microbes in the lab and conduct some in vitro testing to see which may promote the trait of interest.

Once the scientists have a species of microbe they think might be beneficial, they can test it with new plants.

"We have three delivery methods," Raizada explains. "Coating onto seeds, spraying onto soil early in the season, and a late-season spray directly onto the target tissue as biocontrol.

"Not a lot of people have had luck with coating bacteria onto seed," he adds.

The scientists will do greenhouse testing to see if the microbe, in one of those formulations, can benefit crops as a biological amendment. The next step is field trials, but the researchers must first clear some regulatory requirements.

"At some point we'll sequence the microbe to make sure it's safe," Raizada says.

They will look for any obvious toxicity or virulent genes. The scientists will also conduct the Ames test for bacterial mutagenesis (to ensure the microbe isn't likely to cause mutations in DNA of other species), and insect studies as a proxy for human health effects.

"We need some of those to get regulatory permits to do a field trial," Raizada explains.

It may take several years to discover an endophyte that has potential as a biological, conduct the testing, and finally have a product that may be ready for the commercialization process.

"The minimum pipeline is about five years," Raizada says, although he has studied some endophytes for more than a decade. BF