Volume 12, Number 3 September 24, 2004

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PhD student discovers new genes

By Amie Lynn Shirkie

The Department of Plant Sciences’ Outstanding PhD Student of the Year has certainly lived up to his title.

Brian Schilling challenged conventional theories of cold acclimation in canola, discovered no fewer than three dozen novel genes, and has laid the groundwork for major developments in spring and winter canola.

Brian Schilling
Brian Schilling

Schilling, who hails from Darfield, B.C., began his doctoral work in 1999. His five-year journey has taken him from a phytotron to the field, to Ventura, Calif. – and there were a few surprises along the way.

Under the supervision of Plant Sciences Prof. Larry Gusta, Schilling aimed to establish a basis for understanding the effects of cold stress on canola. He tested the reigning hypothesis that spring and winter canola acclimate at different rates to different levels of freezing tolerance, and that spring canola is less tolerant of cold temperatures than winter canola.

“ Acclimation,” says Schilling, “refers to the exposure of plants to low, non-freezing temperatures, a process that allows them to develop tolerance to sub-zero temperatures.”

Most of Schilling’s experiments took place in a phytotron, a controlled-growth environment he compares to “a big fridge”. He also collected data from a few outdoor plots.

Schilling studied the level of freezing tolerance achieved by spring and winter canola following a period of cold acclimation. He allowed the plants to deacclimate by warming them to room temperature, and then exposed them to near freezing temperatures once again to test their ability to reacclimate.

Much to his surprise, Schilling discovered that winter and spring varieties of canola acclimated at a similar rate, and showed comparable tolerance to cold stress. “They didn’t behave at all as predicted. It was quite exciting.”

Even more surprising, Schilling found that once the first true leaves of both varieties have emerged, the cotyledons do not acclimate. Schilling says the cotyledons show “similar molecular responses to leaves during cold stress,” a point not yet uncovered in other studies.

Schilling also confirmed that carbohydrates respond similarly to cold stress in both spring and winter canola, though his “biggest result” was in protein analysis: he discovered the protein dehydren to be highly correlated to freezing tolerance in leaves, and prone to accumulation in the cotyledons.

Using micro-array analysis, Schilling searched both varieties for novel genes (of which 170 genes were discovered to be highly correlated to cold acclimation in both spring and winter canola). He found global changes in gene expression during cold acclimation correlate to cold stress. Micro-array as well as Northern analysis were used to help confirm three dozen genes isolated by differential display to be cold responsive.

On the importance of these newly discovered genes, Schilling says, “Some genes were revolutionary because they hadn’t been known to be affected by cold stress.”

The Prairie Genome Project in Western Canada will continue to examine these genes. Schilling adds, “It would be great if these genes provide further insight into cold acclimation. The Genome Project is going to use them to identify molecular pathways in spring and winter canola.”

Schilling presented his results at the Gordon conference in Ventura, Calif., where his research was well received. He also received a Canadian Wheat Board scholarship to help fund his research.

Schilling says he loved “working on a crop that hasn’t been researched much, especially an important crop like canola.” The goal of his research is to understand the molecular pathways involved in cold acclimation and to increase the cold tolerance of both spring and winter canola, an endeavour which will no doubt be carried out by future grad students.

Amie Lynn Shirkie writes graduate student profiles for the College of Graduate Studies & Research.

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

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