Research Sheds Light on Degreening Canola Seeds

In the world of plants, green is usually good--except in canola seeds. Freezing temperatures stop the normal breakdown of chlorophyll in canola seeds, causing them to stay green. An early frost can cost North American canola growers as much as $150 million.

Agricultural Research Service scientists in Urbana, Ill., are looking for ways to alter canola plants for better tolerance to freezing temperatures. Many plants break down chlorophyll even after a freeze, according to C. John Whitmarsh, an ARS plant physiologist in Urbana, Ill. That’s what happens in the fall when chlorophyll disappears and other leaf pigments become visible, creating spectacular fall foliage.

In canola plants, freezing temperatures interrupt chlorophyll degradation. That’s why

Adriana Ortiz-Lopez, a post-doctoral research scientist who works with Whitmarsh, is studying the effect of freezing temperatures on Arabidopsis--a close relative of canola. Her work with chlorophyll fluorescence has illuminated one stage in the breakdown of chlorophyll that is blocked in plants that have been exposed to freezing temperatures. The next step is to identify which proteins and genes are involved in the blockage. Once the genes responsible for freeze tolerance are identified, the scientists can clone the genes with the aim of producing genetically modified canola that is insensitive to mildly freezing temperatures.

Canola is an oilseed crop grown mainly in parts of western Canada, with some acreage in Ontario and the Pacific Northwest, north central, and southeastern United States. Its yellow flowers produce pea-shaped pods that contain tiny seeds harvested for their oil. Canola oil contains omega 3 fatty acids, acclaimed for improving human immune and vascular systems.

An article describing this work appears in the January issue of Agricultural Research, ARS’ monthly magazine. Click here to view it on the web.

ARS is the chief research agency of the U.S. Department of Agriculture.

Scientific contact: C. John Whitmarsh, ARS Photosynthesis Research Unit, Urbana, Ill., phone (217) 333-2947, fax (217) 244-4419, johnwhit@life.uiuc.edu.