title: Chloroplasts of salt-grown Arabidopsis seedlings are impaired in structure, genome copy number and transcript levels.
abstract: The chloroplast is the most prominent and metabolically active plastid in photosynthetic plants. Chloroplasts differentiate from proplastids in the plant meristem. Plant plastids contain multiple copies of a small circular genome. The numbers of chloroplasts per mesophyll cell and of plastid genome copies are affected by developmental stage and environmental signals. We compared chloroplast structure, gene expression and genome copy number in Arabidopsis seedlings germinated and grown under optimal conditions to those in seedlings germinated and grown in the presence of NaCl. Chloroplasts of the NaCl-grown seedlings were impaired, with less developed thylakoid and granum membranes than control seedlings. In addition, chloroplasts of salt-grown Arabidopsis seedlings accumulated more starch grains than those in the respective control plants. Steady-state transcript levels of chloroplast-encoded genes and of nuclear genes encoding chloroplast proteins were reduced in salt-grown seedlings. This reduction did not result from a global decrease in gene expression, since the expression of other nuclear genes was induced or not affected. Average cellular chloroplast genome copy number was reduced in salt-grown seedlings, suggesting that the reduction in steady-state transcript levels of chloroplast-encoded genes might result from a decrease in template DNA.
authors: Department of Life Sciences and Doris and Bertie Black Center for Bioenergetics in Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel ; Department of Molecular Biology, Division of Biology, Faculty of Science, University of Zagreb, Horvatovac 102a, Zagreb, Croatia.
authors: Petra
authors: P
authors: Peharec Štefanić
authors: Tal
authors: T
authors: Koffler
authors: Guy
authors: G
authors: Adler
authors: Dudy
authors: D
authors: Bar-Zvi
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D018628:Gene Dosage; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D036226:Seedlings / Q000235:genetics / Q000378:metabolism*; D012965:Sodium Chloride; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D012965:Sodium Chloride