Inactivation of a plastid evolutionary conserved gene affects PSII electron transport, life span and fitness of tobacco plants.
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.
Zapata
José Miguel
JM
Dpto de Biología Vegetal, Universidad de Alcalá, Edificio de Ciencias, Campus Universitario, 28871 Alcalá de Henares, Madrid, Spain.
Gasulla
Francisco
F
Dpto de Botánica, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Facultad de Biología, Universitat de València, 46100 Burjassot, Valencia, Spain.
Esteban-Carrasco
Alberto
A
Dpto de Biología Vegetal, Universidad de Alcalá, Edificio de Ciencias, Campus Universitario, 28871 Alcalá de Henares, Madrid, Spain.
Barreno
Eva
E
Dpto de Botánica, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Facultad de Biología, Universitat de València, 46100 Burjassot, Valencia, Spain.
Guéra
Alfredo
A
Dpto de Biología Vegetal, Universidad de Alcalá, Edificio de Ciencias, Campus Universitario, 28871 Alcalá de Henares, Madrid, Spain.
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*
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