title: Perturbations of carotenoid and tetrapyrrole biosynthetic pathways result in differential alterations in chloroplast function and plastid signaling.
abstract: In this study, we used the biosynthetic inhibitors of carotenoid and tetrapyrrole biosynthetic pathways, norflurazon (NF) and oxyfluorfen (OF), as tools to gain insight into mechanisms of photooxidation in rice plants. NF resulted in bleaching symptom on leaves of the treated plants, whereas OF treatment developed a fast symptom of an apparent necrotic phenotype. Both plants exhibited decreases in photosynthetic efficiency, as indicated by Fv/Fm. NF caused severe disruption in thylakoid membranes, whereas OF-treated plants exhibited disruption of chloroplast envelope and plasma membrane. Levels of Lhca and Lhcb proteins in photosystem I (PSI) and PSII were reduced by photooxidative stress in NF- and OF-treated plants, with a greater decrease in NF plants. The down-regulation of nuclear-encoded photosynthesis genes Lhcb and rbcS was also found in both NF- and OF-treated plants, whereas plastid-encoded photosynthetic genes including RbcL, PsaC, and PsbD accumulated normally in NF plants but decreased drastically in OF plants. This proposes that the plastids in NF plants retain their potential to develop thylakoid membranes and that photobleaching is mainly controlled by nuclear genes. Distinct photooxidation patterns between NF- and OF-treated plants developed differential signaling, which might enable the plant to coordinate the expression of photosynthetic genes from the nuclear and plastidic genomes.
authors.affiliation: School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, South Korea.
authors.forename: Joon-Heum
authors.initials: JH
authors.lastname: Park
authors.affiliation: School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, South Korea. Electronic address: sjung@knu.ac.kr.
authors.forename: Sunyo
authors.initials: S
authors.lastname: Jung
mesh_terms: D053898:Biosynthetic Pathways; D002338:Carotenoids / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D002734:Chlorophyll / Q000737:chemistry; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018745:Genome, Plant; D055768:Halogenated Diphenyl Ethers / Q000737:chemistry; D008027:Light; D046529:Microscopy, Electron, Transmission; D012275:Oryza / Q000235:genetics; D018384:Oxidative Stress; D010100:Oxygen / Q000737:chemistry*; D010641:Phenotype; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000737:chemistry; D045332:Photosystem II Protein Complex / Q000737:chemistry; D018087:Plastids / Q000378:metabolism*; D011724:Pyridazines / Q000737:chemistry; D020524:Thylakoids / Q000378:metabolism
chemical_list: D055768:Halogenated Diphenyl Ethers; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D011724:Pyridazines; D002734:Chlorophyll; D002338:Carotenoids; C016027:oxyfluorofen; C008677:norflurazone; D010100:Oxygen; D000077194:Chlorophyll A
keywords: Chloroplast ultrastrucure; Light-harvesting chlorophyll-binding proteins; Norflurazon; Oxyfluorfen; Photooxidation; Photosynthetic genes