title: Inactivation of a plastid evolutionary conserved gene affects PSII electron transport, life span and fitness of tobacco plants.
abstract: Chloroplasts contain a plastoquinone-NADH-oxidoreductase (Ndh) complex involved in protection against stress and the maintenance of cyclic electron flow. Inactivation of the Ndh complex delays the development of leaf senescence symptoms. Chlorophyll a fluorescence measurements, blue native gel electrophoresis, immunodetection and other techniques were employed to study tobacco (Nicotiana tabacum) Ndh-defective mutants (DeltandhF). The DeltandhF mutants compared with wild-type plants presented: (i) higher photosystem II : photosystem I (PSII : PSI) ratios; (ii) similar or higher levels of ascorbate, carotenoids, thylakoid peroxidase and superoxide dismutase, yield (Phi(PSII)) and maximal photochemical efficiency of PSII levels (F(v)/F(m)) than wild-type plant leaves of the same age; (iii) lower values of nonphotochemical quenching yield (Phi(NPQ)), but not at very high light intensities or during induced leaf senescence; (iv) a similar decrease of antioxidants during senescence; (v) no significant differences in the total foliar area and apical growth rate; and (vi) a production of viable seeds significantly higher than wild-type plants. These results suggest that the Ndh complex is involved in one of the redundant mechanisms that play a safety role in photosynthesis under stress, which has been conserved during evolution, but that its deletion increases fitness when plants are grown under favourable controlled conditions.
authors: Dpto de Biología Vegetal, Universidad de Alcalá, Edificio de Ciencias, Campus Universitario, 28871 Alcalá de Henares, Madrid, Spain.
authors: José Miguel
authors: JM
authors: Zapata
authors: Dpto de Botánica, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Facultad de Biología, Universitat de València, 46100 Burjassot, Valencia, Spain.
authors: Francisco
authors: F
authors: Gasulla
authors: Dpto de Biología Vegetal, Universidad de Alcalá, Edificio de Ciencias, Campus Universitario, 28871 Alcalá de Henares, Madrid, Spain.
authors: Alberto
authors: A
authors: Esteban-Carrasco
authors: Dpto de Botánica, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Facultad de Biología, Universitat de València, 46100 Burjassot, Valencia, Spain.
authors: Eva
authors: E
authors: Barreno
authors: Dpto de Biología Vegetal, Universidad de Alcalá, Edificio de Ciencias, Campus Universitario, 28871 Alcalá de Henares, Madrid, Spain.
authors: Alfredo
authors: A
authors: Guéra
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002734:Chlorophyll / Q000502:physiology; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000378:metabolism*; D004579:Electron Transport / Q000502:physiology; D005453:Fluorescence; D020868:Gene Silencing; D008027:Light; D009245:NADH Dehydrogenase / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D010788:Photosynthesis / Q000502:physiology; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D012098:Reproduction / Q000502:physiology; D013997:Time Factors; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
chemical_list: D000975:Antioxidants; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D002734:Chlorophyll; C489904:NdhF protein, plant; D009245:NADH Dehydrogenase; D000077194:Chlorophyll A