title: Suppressor of Overexpression of CO 1 Negatively Regulates Dark-Induced Leaf Degreening and Senescence by Directly Repressing Pheophytinase and Other Senescence-Associated Genes in Arabidopsis.
abstract: Although the biochemical pathway of chlorophyll (Chl) degradation has been largely elucidated, how Chl is rapidly yet coordinately degraded during leaf senescence remains elusive. Pheophytinase (PPH) is the enzyme for catalyzing the removal of the phytol group from pheophytina, andPPHexpression is significantly induced during leaf senescence. To elucidate the transcriptional regulation ofPPH, we used a yeast (Saccharomyces cerevisiae) one-hybrid system to screen for its trans-regulators. SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1), a key flowering pathway integrator, was initially identified as one of the putative trans-regulators ofPPHAfter dark treatment, leaves of anSOC1knockdown mutant (soc1-6) showed an accelerated yellowing phenotype, whereas those ofSOC1-overexpressing lines exhibited a partial stay-green phenotype.SOC1andPPHexpression showed a negative correlation during leaf senescence. Substantially, SOC1 protein could bind specifically to the CArG box of thePPHpromoter in vitro and in vivo, and overexpression ofSOC1significantly inhibited the transcriptional activity of thePPHpromoter in Arabidopsis (Arabidopsis thaliana) protoplasts. Importantly,soc1-6 pph-1(aPPHknockout mutant) double mutant displayed a stay-green phenotype similar to that ofpph-1during dark treatment. These results demonstrated that SOC1 inhibits Chl degradation via negatively regulatingPPHexpression. In addition, measurement of the Chl content and the maximum photochemical efficiency of photosystem II ofsoc1-6andSOC1-OEleaves after dark treatment suggested that SOC1 also negatively regulates the general senescence process. SevenSENESCENCE-ASSOCIATED GENES(SAGs) were thereafter identified as its potential target genes, andNONYELLOWING1andSAG113were experimentally confirmed. Together, we reveal that SOC1 represses dark-induced leaf Chl degradation and senescence in general in Arabidopsis.
authors.affiliation: State Key Laboratory of Genetic Engineering and Fudan Center for Genetic Diversity and Designing Agriculture, School of Life Sciences, Fudan University, Shanghai 200438, China.
authors.forename: Junyi
authors.identifier: 0000-0002-0388-2120
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Genetic Engineering and Fudan Center for Genetic Diversity and Designing Agriculture, School of Life Sciences, Fudan University, Shanghai 200438, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Genetic Engineering and Fudan Center for Genetic Diversity and Designing Agriculture, School of Life Sciences, Fudan University, Shanghai 200438, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Genetic Engineering and Fudan Center for Genetic Diversity and Designing Agriculture, School of Life Sciences, Fudan University, Shanghai 200438, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Qiu
authors.affiliation: State Key Laboratory of Genetic Engineering and Fudan Center for Genetic Diversity and Designing Agriculture, School of Life Sciences, Fudan University, Shanghai 200438, China.
authors.forename: Zhongpeng
authors.initials: Z
authors.lastname: Li
authors.affiliation: State Key Laboratory of Genetic Engineering and Fudan Center for Genetic Diversity and Designing Agriculture, School of Life Sciences, Fudan University, Shanghai 200438, China.
authors.forename: Zuokun
authors.identifier: 0000-0002-0794-3330
authors.initials: Z
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Genetic Engineering and Fudan Center for Genetic Diversity and Designing Agriculture, School of Life Sciences, Fudan University, Shanghai 200438, China.
authors.forename: Jiong
authors.initials: J
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Genetic Engineering and Fudan Center for Genetic Diversity and Designing Agriculture, School of Life Sciences, Fudan University, Shanghai 200438, China zhouxin@shnu.edu.cn bkkuai@fudan.edu.cn.
authors.forename: Xin
authors.identifier: 0000-0002-7732-4519
authors.initials: X
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Genetic Engineering and Fudan Center for Genetic Diversity and Designing Agriculture, School of Life Sciences, Fudan University, Shanghai 200438, China zhouxin@shnu.edu.cn bkkuai@fudan.edu.cn.
authors.forename: Benke
authors.identifier: 0000-0003-0523-6381
authors.initials: B
authors.lastname: Kuai
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003624:Darkness; D018506:Gene Expression Regulation, Plant / Q000235:genetics* / Q000528:radiation effects; D006867:Hydrolases / Q000235:genetics* / Q000378:metabolism; D026161:MADS Domain Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010674:Pheophytins / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C419046:AGL20 protein, Arabidopsis; D029681:Arabidopsis Proteins; D026161:MADS Domain Proteins; D010674:Pheophytins; D002734:Chlorophyll; D006867:Hydrolases; D010749:Phosphoprotein Phosphatases; C000589477:SAG113 protein, Arabidopsis