ARS | Publication request: Role of Pheophorbide a Oxygenase in Chlorophyll Degradation

Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract
Publication Acceptance Date: May 15, 2008
Publication Date: June 23, 2008
Citation: Chung, D.W., Grennan, A.K., Ort, D.R. 2008. Role of Pheophorbide a Oxygenase in Chlorophyll Degradation [abstract]. American Society of Plant Biologists Annual Meeting. Paper No. P20003. Available: http://abstracts.aspb.org/pb2008/public/P20/P20003.html.

Technical Abstract: Degradation of chlorophyll (Chl) is a developmentally regulated cellular process usually related with leaf senescence and fruit ripening. In the plastid of senescing leaves, photoactive Chl is catabolized in a stepwise manor to yield fluorescent chlorophyll catabolites (FCCs). FCCs are then exported from the plastid and ultimately to the vacuole where the acidic pH converts them to colorless breakdown products (NCCs). A key enzyme in the Chl degradation process is the Fe-dependent monooxygenase pheophorbide a oxygenase (PaO), which is responsible for the conversion of Pheide a to red colored catabolite (RCC). The regulation of PaO, a known key regulator of Chl loss, has recently been studied in canola (Brassica napa) seeds where it was shown to be posttranslationally regulated by a phosphorylation/ dephosphorylation mechanism (Chung et al., 2006). A comparative study on the role of PaO in the leaf systems of Arabidopsis (Arabidopsis thaliana) and canola in respect to Chl loss as well as further characterization of PaO through mutant analysis using RNAi has been undertaken. We also describe additional posttranslational modifications, more specifically, the in vitro interaction of PaO and CDPK.