title: The NAC transcription factor ANAC046 is a positive regulator of chlorophyll degradation and senescence in Arabidopsis leaves.
abstract: Chlorophyll (Chl) degradation occurs during leaf senescence, embryo degreening, bud breaking, and fruit ripening. The Chl catabolic pathway has been intensively studied and nearly all the enzymes involved are identified and characterized; however, the molecular regulatory mechanisms of this pathway are largely unknown. In this study, we performed yeast one-hybrid screening using a transcription factor cDNA library to search for factors controlling the expression of Chl catabolic genes. We identified ANAC046 as a common regulator that directly binds to the promoter regions of NON-YELLOW COLORING1, STAY-GREEN1 (SGR1), SGR2, and PHEOPHORBIDE a OXYGENASE. Transgenic plants overexpressing ANAC046 exhibited an early-senescence phenotype and a lower Chl content in comparison with the wild-type plants, whereas loss-of-function mutants exhibited a delayed-senescence phenotype and a higher Chl content. Microarray analysis of ANAC046 transgenic plants showed that not only Chl catabolic genes but also senescence-associated genes were positively regulated by ANAC046. We conclude that ANAC046 is a positive regulator of Arabidopsis leaf senescence and exerts its effect by controlling the expression of Chl catabolic genes and senescence-associated genes.
authors.affiliation: National Agriculture and Food Research Organization (NARO), Institute of Floricultural Science, Tsukuba, Ibaraki 305-8519, Japan.|Research Fellow of Japanese Society for the Promotion of Science (JSPS), Tokyo 102-0083, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Oda-Yamamizo
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Mitsuda
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Sakamoto
authors.affiliation: Horticultural Experiment Center, Wakayama Prefectural Agricultural Research Station, Gobo, Wakayama 644-0024, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ogawa
authors.affiliation: Institute for Environmental Science and Technology (IEST), Saitama University, Saitama, Saitama 338-8570, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Ohme-Takagi
authors.affiliation: National Agriculture and Food Research Organization (NARO), Institute of Floricultural Science, Tsukuba, Ibaraki 305-8519, Japan.
authors.forename: Akemi
authors.initials: A
authors.lastname: Ohmiya
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002734:Chlorophyll / Q000378:metabolism*; D020869:Gene Expression Profiling / Q000379:methods; D018506:Gene Expression Regulation, Plant; D053858:Metabolic Networks and Pathways / Q000235:genetics; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D010740:Phospholipases / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000145:classification / Q000235:genetics / Q000378:metabolism*
chemical_list: C493660:ANAC055 protein, Arabidopsis; D029681:Arabidopsis Proteins; D014157:Transcription Factors; D002734:Chlorophyll; D010740:Phospholipases; C455511:SGR2 phospholipase, Arabidopsis