Search results for "photos"
showing 10 items of 701 documents
The Water to Water Cycles in Microalgae.
2016
In oxygenic photosynthesis, light produces ATP plus NADPH via linear electron transfer, i.e. the in-series activity of the two photosystems: PSI and PSII. This process, however, is thought not to be sufficient to provide enough ATP per NADPH for carbon assimilation in the Calvin-Benson-Bassham cycle. Thus, it is assumed that additional ATP can be generated by alternative electron pathways. These circuits produce an electrochemical proton gradient without NADPH synthesis, and, although they often represent a small proportion of the linear electron flow, they could have a huge importance in optimizing CO2 assimilation. In Viridiplantae, there is a consensus that alternative electron flow comp…
The specific role of plastidial glycolysis in photosynthetic and heterotrophic cells under scrutiny through the study of glyceraldehyde-3-phosphate d…
2016
The cellular compartmentalization of metabolic processes is an important feature in plants where the same pathways could be simultaneously active in different compartments. Plant glycolysis occurs in the cytosol and plastids of green and non-green cells in which the requirements of energy and precursors may be completely different. Because of this, the relevance of plastidial glycolysis could be very different depending on the cell type. In the associated study, we investigated the function of plastidial glycolysis in photosynthetic and heterotrophic cells by specifically driving the expression of plastidial glyceraldehyde-3-phosphate dehydrogenase (GAPCp) in a glyceraldehyde-3-phosphate de…
Leaf anatomy does not explain apparent short-term responses of mesophyll conductance to light and CO2 in tobacco
2018
Mesophyll conductance to CO2 (gm ), a key photosynthetic trait, is strongly constrained by leaf anatomy. Leaf anatomical parameters such as cell wall thickness and chloroplast area exposed to the mesophyll intercellular airspace have been demonstrated to determine gm in species with diverging phylogeny, leaf structure and ontogeny. However, the potential implication of leaf anatomy, especially chloroplast movement, on the short-term response of gm to rapid changes (i.e. seconds to minutes) under different environmental conditions (CO2 , light or temperature) has not been examined. The aim of this study was to determine whether the observed rapid variations of gm in response to variations of…
Mixotrophy in diatoms: Molecular mechanism and industrial potential
2021
Diatoms are microalgae well known for their high variability and high primary productivity, being responsible for about 20% of the annual global carbon fixation. Moreover, they are interesting as potential feedstocks for the production of biofuels and high-value lipids and carotenoids. Diatoms exhibit trophic flexibility and, under certain conditions, they can grow mixotrophically by combing photosynthesis and respiration. So far, only a few species of diatoms have been tested for their mixotrophic metabolism; in some cases, they produced more biomass and with higher lipid content when grown under this condition. Phaeodactylum tricornutum is the most studied diatom species for its mixotroph…
Photoprotection dynamics observed at leaf level from fast temporal reflectance changes
2018
Vegetation dynamically reacts to the available photosynthetically active radiation (PAR) by adjusting the photosynthetic apparatus to either a light harvesting or a photoprotective modus. When activating the photoprotection mechanism, either minor or major pigment-protein interactions may occur at the leaf level, resulting in different light absorption and consequently reflectance intensities. The reflectance changes were measured during sudden illumination transients designed to provoke fast adaptation to high irradiance. Different spectral reflectance change features were observed during different stages of photoprotection activation, extending over part of the visible spectral range (i.e…
Molecular phylogeny and forms of photosynthesis in tribe Salsoleae (Chenopodiaceae).
2016
Evolution of C3–C4 intermediate and C4 lineages are resolved in Salsoleae (Chenopodiaceae), and a model for structural and biochemical changes for the evolution of the Salsoloid form of C4 is considered.
C3cotyledons are followed by C4leaves: intra-individual transcriptome analysis ofSalsola soda(Chenopodiaceae)
2016
The genome of Salsola soda allows a transition from C3 to C4 photosynthesis. A developmental transcriptome series revealed novel genes showing expression patterns similar to those encoding C4 proteins.
Infestation of broad bean (Vicia faba) by the green stink bug (Nezara viridula) decreases shoot abscisic acid contents under well-watered and drought…
2017
The response of broad bean (Vicia faba) plants to water stress alone and in combination with green stink bug (Nezara viridula) infestation was investigated through measurement of: (1) leaf gas exchange; (2) plant hormone titres of abscisic acid (ABA) and its metabolites, and of salicylic acid (SA); and (3) hydrogen peroxide (H2O2) content. Furthermore, we evaluated the effects of experimentally water-stressed broad-bean plants on N. viridula performance in terms of adult host–plant preference, and nymph growth and survival. Water stress significantly reduced both photosynthesis (A) and stomatal conductance (gs), while infestation by the green stink bug had no effects on photosynthesis but s…
Modelling nonlinear dynamics of Crassulacean acid metabolism productivity and water use for global predictions
2021
Crassulacean acid metabolism (CAM) crops are important agricultural commodities in water-limited environments across the globe, yet modeling of CAM productivity lacks the sophistication of widely used C3 and C4 crop models, in part due to the complex responses of the CAM cycle to environmental conditions. This work builds on recent advances in CAM modeling to provide a framework for estimating CAM biomass yield and water use efficiency from basic principles. These advances, which integrate the CAM circadian rhythm with established models of carbon fixation, stomatal conductance, and the soil-plant-atmosphere continuum, are coupled to models of light attenuation, plant respiration, and bioma…
UV-screening and springtime recovery of photosynthetic capacity in leaves of Vaccinium vitis-idaea above and below the snow pack
2019
International audience; Evergreen plants in boreal biomes undergo seasonal hardening and dehardening adjusting their photosynthetic capacity and photoprotection; acclimating to seasonal changes in temperature and irradiance. Leaf epidermal ultraviolet (UV)-screening by flavonols responds to solar radiation, perceived in part through increased ultraviolet-B (UV-B) radiation, and is a candidate trait to provide cross-photoprotection. At Hyytiälä Forestry Station, central Finland, we examined whether the accumulation of flavonols was higher in leaves of Vaccinium vitis-idaea L. growing above the snowpack compared with those below the snowpack. We found that leaves exposed to colder temperature…