1.14.15.17	evolution	AtPaO is a Rieske-type iron–sulfur cluster-containing enzyme that is identical to Arabidopsis accelerated cell death 1 and homologous to lethal leaf spot 1 (LLS1) of maize	676765	
1.14.15.17	evolution	PaO is an evolutionarily conserved protein, and EAS1 is 68% identical to the Arabidopsis ACCERLERATED CELL DEATH (ACD1) protein	-, 736578	
1.14.15.17	malfunction	during the early growth stage (at the 3th leaf stage), eas1 mutants do not show detectable differences compared to wild-type plants. At the heading stage, old leaves of eas1 mutants turn yellowish or brownish, when wild-type plants are still healthy and green. Small chlorotic lesions are first observed near the tip, and then spread down to the entire leaves of eas1 mutants. At the grain filling stage, the leaf senescence phenotype of eas1 is more apparent compared to wild-type, as most eas1 mutant leaves, culms and sheaths turned to dark brown. In addition to the leaf senescence phenotype, the mature eas1 mutant plants also exhibit apparent developmental defects, such as semi-dwarfism, reduced tiller number and partial-filling	-, 736578	
1.14.15.17	malfunction	enzyme inhibition or downregulation leads to accumulation of pheophorbide a, a key intermediate of chlorophyll catabolism, which causes cell death in complete darkness in a transgenic Arabidopsis plant, As-ACD1. When senescence is induced by a continuous dark period, leaves of As-ACD1 plants become dehydrated, phenotype, overview	700721	
1.14.15.17	malfunction	the absence of PAO in mutants or antisense lines from different plant species results in premature cell death. Phototoxicity of Pheide a is considered to trigger the observed cell death phenotype in a light-dependent manner	737013	
1.14.15.17	metabolism	chlorophyll metabolism and proteins (enzymes) involved, including pheophorbide a oxygenase, overview	-, 737240	
1.14.15.17	metabolism	enzyme PaO seems to be a key regulator of chlorophyll catabolism	676765	
1.14.15.17	metabolism	in land plants, chlorophyll is broken down to colorless linear tetrapyrroles in a highly conserved multistep pathway. The pathway is termed the PAO pathway, because the opening of the chlorine macrocycle present in chlorophyll catalyzed by pheophorbide a oxygenase (PAO), the key enzyme of the pathway. The PAO pathway is active during leaf senescence and in ripening fruits. Chlorophyll breakdown does not only occur during leaf senescence and fruit ripening, but also at steady state, during post-harvest and in response to biotic and abiotic stresses, chlorophyll is turned over or degraded, at least to some extent	737013	
1.14.15.17	metabolism	in land plants, chlorophyll is broken down to colorless linear tetrapyrroles in a highly conserved multistep pathway. The pathway is termed the PAO pathway, because the opening of the chlorophyllide macrocycle present in chlorophyll catalyzed by pheophorbide a oxygenase (PAO), the key enzyme of the pathway. The PAO pathway is active during leaf senescence and in ripening fruits. Chlorophyll breakdown does not only occur during leaf senescence and fruit ripening, but also at steady state, during post-harvest and in response to biotic and abiotic stresses, chlorophyll is turned over or degraded, at least to some extent	737013	
1.14.15.17	metabolism	the enzyme is important in the chlorophyll degradation pathway during leaf senescence. The porphyrin macrocycle of pheophorbide is oxygenolytically cleaved by the joint action of pheophorbide, the pheophorbide a oxygenase, PaO, and the red chlorophyll catabolite reductase, RCCR, overview	699270	
1.14.15.17	additional information	catabolites such as hypermodified FCCs and urobilinogenoidic chlorophyll catabolites point to divergent paths of the PAO pathway that might exist in some plant species	737013	
1.14.15.17	physiological function	a close correlation between chlorophyll degradation and enzyme expression exists during broccoli senescence	725808	
1.14.15.17	physiological function	chlorophyll breakdown during senescence is an integral part of plant development and leads to the accumulation of colorless catabolites. The loss of green pigment is due to an oxygenolytic opening of the porphyrin macrocycle of pheophorbide (pheide) a followed by a reduction to yield a fluorescent chlorophyll catabolite. This step is comprised of the interaction of two enzymes, pheide a oxygenase (PaO) and red chl catabolite reductase. Senescence-related activity of PaO	676765	
1.14.15.17	physiological function	gene EAS1 encodes a PaO enzyme containing a putative bipartite chloroplast-targeting peptide, both of which are genetically important for the function of EAS1 during plant growth and development. Pheophorbide a oxygenase (PaO) is a key enzyme for chlorophyll breakdown and involved in chlorophyll degradation during leaf senescence	-, 736578	
1.14.15.17	physiological function	physical interaction between pheophorbide a oxygenase, PAO, and red chlorophyll catabolite reductase, RCCR, required for activity, and interaction with stay-green proteins	737013	
1.14.15.17	physiological function	physical interaction between pheophorbide a oxygenase, PAO, and red chlorophyll catabolite reductase, RCCR, required for activity, and interaction with stay-green proteins, the latter is required for PaO-RCCR interaction. PaO enzyme expression is highly regulated	737013