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United States Department of Agriculture

Agricultural Research Service


item Chung, Davyd
item Ortiz-lopez, Adriana
item Ye, Jim
item Ort, Donald
item Whitmarsh, Clifford

Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/25/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: In canola, an important oil seed crop in North America, the process of chlorophyll degradation in developing seeds is disrupted by mild freezing conditions. The disruption can cause green seed at harvest, which devalues the crop. Pheophorbide an Oxygenase (PaO) appears to be a key step in regulating chlorophyll degradation during leaves sensescence. Pheophorbide a, the substrate of PaO ad other catabolites from seeds accumulate after exposure to freezing conditions. In vitro assays for PaO activity was measured over time using HPLC. Our preliminary observations suggest that PaO activity declines exposure to freezing temperatures. In order to investigate the effect of freezing on expression of this key regulatory step in chlorophyll degradation, work is currently in progress to clone the PaO gene. Arabidopsis is being used as a model system to study low temperature inhibition of chlorophyll degradation during seed development. We are currently investigating chlorophyll degradation in leaf senescene, specifically in canola and Arabidopsis, using fluorescence imaging to observe the distribution of cells at different stages of senescence. Since leaf senscence doesn't occur uniformly, we can use fluorescence imaging to identify uniform regions of leaf senescence as a function of time.

Last Modified: 06/22/2017
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