title: Coexistence of plant and algal energy dissipation mechanisms in the moss Physcomitrella patens.
abstract: Although light is the source of energy for photosynthetic organisms, it causes oxidative stress when in excess. Plants and algae prevent reactive oxygen species (ROS) formation by activation of nonphotochemical quenching (NPQ), which dissipates excess excitation energy as heat. Although NPQ is found in both algae and plants, these organisms rely on two different proteins for its activation, Light harvesting complex stress-related (LHCSR) and Photosystem II subunit S (PSBS). In the moss Physcomitrella patens, both proteins are present and active. Several P. patens lines depleted in or over-expressing PSBS and/or LHCSR at various levels were generated by exploiting the ability of Physcomitrella to undergo homologous recombination. The analysis of the transgenic lines showed that either protein is sufficient, alone, for NPQ activation independently of the other, supporting the idea that they rely on different activation mechanisms. Modulation of PSBS and/or LHCSR contents was found to be correlated with NPQ amplitude, indicating that plants and algae can directly modulate their ability to dissipate energy simply by altering the accumulation level of one or both of these proteins. The availability of a large range of P. patens genotypes differing in PSBS and LHCSR content allowed comparison of their activation mechanisms and discussion of implications for the evolution of photoprotection during land colonization.
authors.affiliation: Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58 B, 35121, Padova, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Gerotto
authors.affiliation: Dipartimento di Biotecnologie, Università di Verona, Strada le Grazie 15, 37134, Verona, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Alboresi
authors.affiliation: Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58 B, 35121, Padova, Italy.
authors.forename: Giorgio M
authors.initials: GM
authors.lastname: Giacometti
authors.affiliation: Dipartimento di Biotecnologie, Università di Verona, Strada le Grazie 15, 37134, Verona, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bassi
authors.affiliation: Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58 B, 35121, Padova, Italy.
authors.forename: Tomas
authors.initials: T
authors.lastname: Morosinotto
mesh_terms: D015153:Blotting, Western; D019068:Bryopsida / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D003470:Culture Media / Q000378:metabolism; D004734:Energy Metabolism; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D005838:Genotype; D059765:Homologous Recombination; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D011523:Protoplasts / Q000378:metabolism; D013045:Species Specificity; D014170:Transformation, Genetic; D024341:Xanthophylls / Q000235:genetics / Q000378:metabolism; D065146:Zeaxanthins
chemical_list: D003470:Culture Media; D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D024341:Xanthophylls; D065146:Zeaxanthins