Plant research improves drought tolerance

Plant researchers in Canada are inching closer to commercializing what might be considered the Holy Grail of drought tolerance in agricultural crops.

Julian Northey, an adjunct professor at the University of Ontario Institute of Technology, and Marcus Samuel, an associate professor of plant biology at the University of Calgary, are part of a team that is studying a natural physiological process linked to improved drought tolerance.

Early reports suggest the process, if deployed in new drought tolerant crop cultivars, could boost yields by as much as 30 percent under moderate to severe drought conditions.

“When a plant is under stress, this phytohormone known as abscisic acid or ABA, is the main hormone (that confers drought tolerance),” said Northey.

“Basically, when a plant becomes more sensitive to this phyto-hormone, then it (the plant) becomes more drought resistant.”

“We haven’t done a complete physiological overview … to understand all of the mechanisms that are responding … but (ABA) is the major one.”

Northey, a molecular geneticist who studied at the University of Toronto, dedicated his doctoral research to understanding ABA and its relationship to drought tolerance.

Using arabidopsis as a test species, he determined that drought tolerance is influenced through an interaction of two plant hormones — abscisic acid or ABA and brassinosteroids.

Researchers have determined that there is an inverse relationship between ABA and brassinosteroids. If brassinosteroid levels in the plant are elevated, then ABA levels are reduced, meaning the plant is less tolerant of abiotic stress caused by drought or excessive heat.

Similarly, if brassinosteroid levels are reduced, then ABA responses are generally observed at higher levels, giving plants more tolerance to drought and stress conditions.

Northey and Samuel are now using various techniques to either suppress brassinosteroid production or hypersensitize plants to the presence of ABA.

Northey recently formed a biotechnology company called Frontier Agri-Science Inc., to develop and commercialize technologies associated with the management of ABA levels or ABA hypersensitivity.

Northey is focusing on using non-genetically modified platforms, mutagenesis and traditional plant selection, to identify experimental cultivars that contain a natural genetic hypersensitivity to ABA.

Experimental mutagenic cultivars of bread wheat were field tested in the United States this year.

Ideally, selections from those trials could result in the registration new drought tolerant bread wheat lines within a few years.

A non-GM application would be less expensive to commercialize and more readily accepted by consumers concerned about genetically modified organisms.

At the University of Calgary, Samuel said ABA research could greatly increase agricultural productivity in areas that are prone to drought-related yield loss.

Samuel’s group is focusing on developing canola lines that could tolerate severe drought conditions for a longer period of time, without significantly impacting plant performance.

“This could lead to a generation of crop plants that are drought-tolerant, particularly in Canada,” Samuel said in a news release.

“Our findings can be translated into a technology for canola, and possibly wheat, to make these crops more drought-tolerant. Under water-stressed conditions, crop yield could be improved by at least 20 percent.”

Samuel’s research in canola hinges on a process known as protein farnesylation.

Essentially, a lipid or fatty acid modification of a specific enzyme or protein molecule, called CYP85A2, is required for BR production.

The loss of either the specific enzyme, or the lipid modification of the enzyme, can reduce brassinolide hormone accumulation and clear the way for improved ABA–induced responses.

The trick is to reduce brassinosteroid levels without significantly impacting plant growth.

“We figured out the mechanism behind this molecular pathway and how this operates, and how this can be translated into canola,” Samuel said. “Drought is a major problem, even in Alberta where most canola depends on rainfall rather than irrigation.”

Samuel’s research is funded by the Natural Sciences and Engineering Research Council of Canada. The work is also supported by Alberta Crop Industry Development Fund Ltd.

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