title: Misexpression of a chloroplast aspartyl protease leads to severe growth defects and alters carbohydrate metabolism in Arabidopsis.
abstract: The crucial role of carbohydrate in plant growth and morphogenesis is widely recognized. In this study, we describe the characterization of nana, a dwarf Arabidopsis (Arabidopsis thaliana) mutant impaired in carbohydrate metabolism. We show that the nana dwarf phenotype was accompanied by altered leaf morphology and a delayed flowering time. Our genetic and molecular data indicate that the mutation in nana is due to a transfer DNA insertion in the promoter region of a gene encoding a chloroplast-located aspartyl protease that alters its pattern of expression. Overexpression of the gene (oxNANA) phenocopies the mutation. Both nana and oxNANA display alterations in carbohydrate content, and the extent of these changes varies depending on growth light intensity. In particular, in low light, soluble sugar levels are lower and do not show the daily fluctuations observed in wild-type plants. Moreover, nana and oxNANA are defective in the expression of some genes implicated in sugar metabolism and photosynthetic light harvesting. Interestingly, some chloroplast-encoded genes as well as genes whose products seem to be involved in retrograde signaling appear to be down-regulated. These findings suggest that the NANA aspartic protease has an important regulatory function in chloroplasts that not only influences photosynthetic carbon metabolism but also plastid and nuclear gene expression.
authors.affiliation: PlantLab, Institute of Life Sciences, Scuola Superiore Sant'Anna, 56127 Pisa, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Paparelli
authors.forename: Silvia
authors.initials: S
authors.lastname: Gonzali
authors.forename: Sandro
authors.initials: S
authors.lastname: Parlanti
authors.forename: Giacomo
authors.initials: G
authors.lastname: Novi
authors.forename: Federico M
authors.initials: FM
authors.lastname: Giorgi
authors.forename: Francesco
authors.initials: F
authors.lastname: Licausi
authors.forename: Monika
authors.initials: M
authors.lastname: Kosmacz
authors.forename: Regina
authors.initials: R
authors.lastname: Feil
authors.forename: John E
authors.initials: JE
authors.lastname: Lunn
authors.forename: Henrike
authors.initials: H
authors.lastname: Brust
authors.forename: Joost T
authors.initials: JT
authors.lastname: van Dongen
authors.forename: Martin
authors.initials: M
authors.lastname: Steup
authors.forename: Pierdomenico
authors.initials: P
authors.lastname: Perata
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D057055:Aspartic Acid Proteases / Q000235:genetics / Q000378:metabolism*; D050260:Carbohydrate Metabolism / Q000187:drug effects; D002736:Chloroplasts / Q000187:drug effects / Q000201:enzymology*; D002940:Circadian Rhythm / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010788:Photosynthesis / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D012333:RNA, Messenger; D013395:Sucrose; D013213:Starch; D057055:Aspartic Acid Proteases