title: Constitutive expression of pea Lhcb 1-2 in tobacco affects plant development, morphology and photosynthetic capacity.
abstract: Lhcb1-2 from pea was constitutively expressed in transgenic tobacco plants and assessed for functional impact. The successful assembly of the encoded proteins into LHCII trimers was confirmed by electrospray tandem mass spectrometry. Constitutive production of LHCb1-2 led to increased number of thylakoid membranes per chloroplast, increased grana stacking, higher chloroplast numbers per palisade cell and increased photosynthetic capacity at low irradiance, both on a chlorophyll and leaf area basis. The transgenic plants also displayed increased cell volume, larger leaves, higher leaf number per plant at flowering, increased biomass and increased seed weight, when grown under low irradiance levels. Under high irradiance, both transgenic and wild type plants displayed similar photosynthetic rates when tested at 25 degrees C; however, the non-photochemical quenching (NPQ) and qE values increased in the transgenic plants. The exposure of transgenic plants to a photoinhibitory treatment (4 degrees C for 4 h, under continuous illumination) resulted in more detrimental impairment of photosynthesis, since recovery was slower than the non-transgenic plants. These data indicate that constitutive expression of additional Lhcb1-2 transgenes led to a series of changes at all levels of the plant (cellular, leaf and whole organism), and a delay in flowering and senescence. The additional production of the pea protein appears to be accommodated by increasing cellular structures such as the number of thylakoids per chloroplast, organelle volume, organelles per cell, and leaf expansion. The presence of the trimeric pea protein in the tobacco LHCII, however, caused a possible change in the organization of the associated super-complex, that in turn limited photosynthesis at low temperature.
authors.affiliation: Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba-São Paulo, CP 83, CEP 13400-970 Brazil.
authors.forename: Mônica T V
authors.initials: MT
authors.lastname: Labate
authors.forename: Kenton
authors.initials: K
authors.lastname: Ko
authors.forename: Zdenka W
authors.initials: ZW
authors.lastname: Ko
authors.forename: Luciana S R Costa
authors.initials: LS
authors.lastname: Pinto
authors.forename: Maria J U D
authors.initials: MJ
authors.lastname: Real
authors.forename: Marcelo Ribeiro
authors.initials: MR
authors.lastname: Romano
authors.forename: Paulo Roxo
authors.initials: PR
authors.lastname: Barja
authors.forename: Antonio
authors.initials: A
authors.lastname: Granell
authors.forename: Giulia
authors.initials: G
authors.lastname: Friso
authors.forename: Klaas J
authors.initials: KJ
authors.lastname: van Wijk
authors.forename: Enrico
authors.initials: E
authors.lastname: Brugnoli
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Labate
mesh_terms: D000595:Amino Acid Sequence; D050260:Carbohydrate Metabolism; D002245:Carbon Dioxide / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D015151:Immunoblotting; D008027:Light; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010100:Oxygen / Q000494:pharmacology; D018532:Pisum sativum / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010788:Photosynthesis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000235:genetics* / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D021241:Spectrometry, Mass, Electrospray Ionization; D020524:Thylakoids / Q000378:metabolism / Q000648:ultrastructure; D013997:Time Factors; D014026:Nicotiana / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D018749:RNA, Plant; D002245:Carbon Dioxide; D010100:Oxygen