Volume 9, Number 17 May 10, 2002

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Grad student’s research finds GM plants’ impact on microorganisms in soil is ‘minor and temporary’

Kari Dunfield

By Elizabeth Frogley

Genetically modified crops are being grown all across Canada, but there is still research to be done on how they affect the environment.

Kari Dunfield, who recently completed her PhD in soil science, studied the way genetically modified canola affects the land it’s grown on – and in particular its effect on the tiny microorganisms in the soil around plant’s roots.

“My thesis was concerned with these communities of microorganisms because of the important relationship that exists between plants and microorganisms in the soil,” Dunfield says.

Microorganisms flourish in the area of soil that surrounds plant roots, where they receive nutrients from plants, and may stimulate or inhibit plant growth. They play a key role in soil ecosystems, transforming nutrients and decomposing organic matter.

If genetically modified plants affect the microorganisms in the soil, they could influence plant growth and health and ultimately ecosystem sustainability.

“More than half of the canola grown in Saskatchewan is genetically modified to be herbicide resistant, and at the time that genetically modified canola was approved for growth in Canada, little was known about how to properly assess the soil microbial community,” says Dunfield.

Her study is one of the first comprehensive, multiple-field-site and multiple-field-year studies examining the effects of genetically modified plants on microorganisms in the soil.

The study examined eight canola varieties, four of which are genetically modified to be herbicide resistant.

Plants are referred to as genetically modified if they contain genes that have been inserted in a lab. A new gene which will give a plant desired qualities is introduced using either particle bombardment, where new genes are shot into the cell, or the “Agrobacterium method” in which a type of soil-dwelling bacteria transfers the new gene to the plant. Plants can also gain new genes, and therefore new properties, through more traditional methods of domestication and controlled breeding.

Dunfield’s research is important to the future sale of canola and other genetically modified crops.

“There are a number of countries throughout the world, such as most European countries, that have not approved the commercial release of genetically modified crops,” Dunfield says. These countries are very interested the results of studies like Dunfield’s, so they can be sure that using genetically modified crops won’t damage the ecosystem where they grow.

Dunfield’s research showed that microorganisms surrounding plant roots are affected by plant genetics. This means the microorganisms around the plant’s roots varied among the different varieties of genetically modified canola, and were different from the microorganisms around the roots of conventional canola varieties. 

But Dunfield also found these differences are temporary and dependent on the presence of the plant: they do not carry forward to the next season.  As well, the genetically modified canola affected microorganisms in the soil differently in different fields.

“This research shows that genetically modified crops can influence the composition and diversity of the microorganisms associated with their roots,” she says.

“However, these differences are temporary, and minor in comparison to the changes created by other commonly accepted agricultural practices, such as cultivation.”

“Changes in the diversity of microorganisms associated with genetically modified plants don’t necessarily indicate changes to ecosystem functioning and sustainability,” she concludes.

Dunfield became interested in soil science after completing a M.Sc. in plant science and an undergraduate degree in biology.

She says she likes the interdisciplinary focus of soil science. Soil microbiology can involve a variety of researchers, including crop scientists and engineers, and can range from genetic research on microorganisms, to enhancing plant growth, to bioremediation of contaminated sites.

Dunfield has just started a position as a post-doctoral research associate at the University of Maine, and hopes to eventually obtain a faculty position at a Canadian university.

For more information, contact communications.office@usask.ca

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