Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: July 15, 2000
Publication Date: N/A
Technical Abstract: Canola is an important oil seed crop in North America with annual yields exceeding seven million metric tons. Under normal field conditions canola seeds produce chloroplasts during early seed development and then catabolize the photosynthetic machinery during seed maturation, producing seeds that are essentially free of chlorophyll. However, an untimely frost during seed development can disrupt the chlorophyll degradation process causing green seed at harvest and devaluing the crop. Because little is known about chlorophyll degradation in seeds, much of our experimental approach relies on results from senescent leaves. Our preliminary results indicate that pheophorbide a oxygenase (PaO) plays a key role in chlorophyll degradation. We identified products of chlorophyll degradation by spectrofluorometry and found accumulation of chlorophyllide a and pheophorbide a in seeds of plants exposed to freezing temperature. These findings indicate that the activity of pheophorbide a oxygenase declines after freezing temperatures.