title: Delayed degradation of chlorophylls and photosynthetic proteins in Arabidopsis autophagy mutants during stress-induced leaf yellowing.
abstract: Plant autophagy, one of the essential proteolysis systems, balances proteome and nutrient levels in cells of the whole plant. Autophagy has been studied by analysing Arabidopsis thaliana autophagy-defective atg mutants, but the relationship between autophagy and chlorophyll (Chl) breakdown during stress-induced leaf yellowing remains unclear. During natural senescence or under abiotic-stress conditions, extensive cell death and early yellowing occurs in the leaves of atg mutants. A new finding is revealed that atg5 and atg7 mutants exhibit a functional stay-green phenotype under mild abiotic-stress conditions, but leaf yellowing proceeds normally in wild-type leaves under these conditions. Under mild salt stress, atg5 leaves retained high levels of Chls and all photosystem proteins and maintained a normal chloroplast structure. Furthermore, a double mutant of atg5 and non-functional stay-green nonyellowing1-1 (atg5 nye1-1) showed a much stronger stay-green phenotype than either single mutant. Taking these results together, it is proposed that autophagy functions in the non-selective catabolism of Chls and photosynthetic proteins during stress-induced leaf yellowing, in addition to the selective degradation of Chl-apoprotein complexes in the chloroplasts through the senescence-induced STAY-GREEN1/NYE1 and Chl catabolic enzymes.
authors: Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea sakuraba0425@gmail.com ncpaek@snu.ac.kr.
authors: Yasuhito
authors: Y
authors: Sakuraba
authors: Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea.
authors: Sang-Hwa
authors: SH
authors: Lee
authors: Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea.
authors: Ye-Sol
authors: YS
authors: Kim
authors: Department of Life Sciences, Korea University, Seoul 136-701, Korea.
authors: Ohkmae K
authors: OK
authors: Park
authors: Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland.
authors: Stefan
authors: S
authors: Hörtensteiner
authors: Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea sakuraba0425@gmail.com ncpaek@snu.ac.kr.
authors: Nam-Chon
authors: NC
authors: Paek
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects / Q000235:genetics; D000071187:Autophagy-Related Protein 5; D002734:Chlorophyll / Q000378:metabolism*; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D003624:Darkness; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D010858:Pigmentation / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D000071187:Autophagy-Related Protein 5; D045342:Light-Harvesting Protein Complexes; D002734:Chlorophyll; D012965:Sodium Chloride; C518662:Atg5 protein, Arabidopsis; D010744:Phosphoric Monoester Hydrolases
keywords: Abiotic stress; Arabidopsis thaliana; atg5; autophagy; chlorophyll degradation; leaf senescence; stay-green.