title: 'happy on norflurazon' (hon) mutations implicate perturbance of plastid homeostasis with activating stress acclimatization and changing nuclear gene expression in norflurazon-treated seedlings.
abstract: Various mutant screens have been undertaken to identify constituents involved in the transmission of signals from the plastid to the nucleus. Many of these screens have been performed using carotenoid-deficient plants grown in the presence of norflurazon (NF), an inhibitor of phytoene desaturase. NF-treated plants are bleached and suppress the expression of nuclear genes encoding chloroplast proteins. Several genomes uncoupled (gun) mutants have been isolated that de-repress the expression of these nuclear genes. In the present study, a genetic screen has been established that circumvents severe photo-oxidative stress in NF-treated plants. Under these modified screening conditions, happy on norflurazon (hon) mutants have been identified that, like gun mutants, de-repress expression of the Lhcb gene, encoding a light-harvesting chlorophyll protein, but, in contrast to wild-type and gun mutants, are green in the presence of NF. hon mutations disturb plastid protein homeostasis, thereby activating plastid signaling and inducing stress acclimatization. Rather than defining constituents of a retrograde signaling pathway specifically associated with the NF-induced suppression of nuclear gene expression, as proposed for gun, hon mutations affect Lhcb expression more indirectly prior to initiation of plastid signaling in NF-treated seedlings. They pre-condition seedlings by inducing stress acclimatization, thereby attenuating the impact of a subsequent NF treatment.
authors.affiliation: Institute of Plant Sciences, Plant Genetics, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
authors.forename: Geetanjali
authors.initials: G
authors.lastname: Saini
authors.forename: Rasa
authors.initials: R
authors.lastname: Meskauskiene
authors.forename: Wioletta
authors.initials: W
authors.lastname: Pijacka
authors.forename: Pawel
authors.initials: P
authors.lastname: Roszak
authors.forename: Lars L E
authors.initials: LL
authors.lastname: Sjögren
authors.forename: Adrian K
authors.initials: AK
authors.lastname: Clarke
authors.forename: Marco
authors.initials: M
authors.lastname: Straus
authors.forename: Klaus
authors.initials: K
authors.lastname: Apel
mesh_terms: D000064:Acclimatization; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D005816:Genetic Complementation Test; D006706:Homeostasis; D045342:Light-Harvesting Protein Complexes / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D018384:Oxidative Stress; D011724:Pyridazines / Q000494:pharmacology*; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D018744:DNA, Plant; D045342:Light-Harvesting Protein Complexes; D011724:Pyridazines; C008677:norflurazone