article in Agricultural Research magazine.
Research Sheds Light on Degreening Canola
January 4, 2000
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. Thats what happens in the fall when chlorophyll
disappears and other leaf pigments become visible, creating spectacular fall
In canola plants, freezing temperatures interrupt chlorophyll degradation.
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
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,