RESUMEN
Large trees in plantations generally produce more wood per unit of resource use than small trees. Two processes may account for this pattern: greater photosynthetic resource use efficiency or greater partitioning of carbon to wood production. We estimated gross primary production (GPP) at the individual scale by combining transpiration with photosynthetic water-use efficiency of Eucalyptus trees. Aboveground production fluxes were estimated using allometric equations and modeled respiration; total belowground carbon fluxes (TBCF) were estimated by subtracting aboveground fluxes from GPP. Partitioning was estimated by dividing component fluxes by GPP. Dominant trees produced almost three times as much wood as suppressed trees. They used 25 ± 10% (mean ± SD) of their photosynthates for wood production, whereas suppressed trees only used 12 ± 2%. By contrast, dominant trees used 27 ± 19% of their photosynthate belowground, whereas suppressed trees used 58 ± 5%. Intermediate trees lay between these extremes. Photosynthetic water-use efficiency of dominant trees was c. 13% greater than the efficiency of suppressed trees. Suppressed trees used more than twice as much of their photosynthate belowground and less than half as much aboveground compared with dominant trees. Differences in carbon partitioning were much greater than differences in GPP or photosynthetic water-use efficiency.
Asunto(s)
Carbono , Eucalyptus , Fotosíntesis , Árboles , Agua , Madera , Eucalyptus/fisiología , Eucalyptus/metabolismo , Carbono/metabolismo , Árboles/fisiología , Árboles/metabolismo , Agua/metabolismo , Madera/fisiología , Transpiración de Plantas/fisiología , Modelos BiológicosRESUMEN
Sucrose metabolism is important for most plants, both as the main source of carbon and via signaling mechanisms that have been proposed for this molecule. A cleaving enzyme, invertase (INV) channels sucrose into sink metabolism. Although acid soluble and insoluble invertases have been largely investigated, studies on the role of neutral invertases (A/N-INV) have lagged behind. Here, we identified a tomato A/N-INV encoding gene (NI6) co-localizing with a previously reported quantitative trait locus (QTL) largely affecting primary carbon metabolism in tomato. Of the eight A/N-INV genes identified in the tomato genome, NI6 mRNA is present in all organs, but its expression was higher in sink tissues (mainly roots and fruits). A NI6-GFP fusion protein localized to the cytosol of mesophyll cells. Tomato NI6-silenced plants showed impaired growth phenotype, delayed flowering and a dramatic reduction in fruit set. Global gene expression and metabolite profile analyses of these plants revealed that NI6 is not only essential for sugar metabolism, but also plays a signaling role in stress adaptation. We also identified major hubs, whose expression patterns were greatly affected by NI6 silencing; these hubs were within the signaling cascade that coordinates carbohydrate metabolism with growth and development in tomato.
Asunto(s)
Frutas/fisiología , Solanum lycopersicum , beta-Fructofuranosidasa , Citosol , Solanum lycopersicum/enzimología , Solanum lycopersicum/genética , Sacarosa , beta-Fructofuranosidasa/genéticaRESUMEN
Glucitol, also known as sorbitol, is a major photosynthetic product in plants from the Rosaceae family. This sugar alcohol is synthesized from glucose-6-phosphate by the combined activities of aldose-6-phosphate reductase (Ald6PRase) and glucitol-6-phosphatase. In this work we show the purification and characterization of recombinant Ald6PRase from peach leaves. The recombinant enzyme was inhibited by glucose-1-phosphate, fructose-6-phosphate, fructose-1,6-bisphosphate and orthophosphate. Oxidizing agents irreversibly inhibited the enzyme and produced protein precipitation. Enzyme thiolation with oxidized glutathione protected the enzyme from insolubilization caused by diamide, while incubation with NADP+ (one of the substrates) completely prevented enzyme precipitation. Our results suggest that Ald6PRase is finely regulated to control carbon partitioning in peach leaves.
Asunto(s)
Aldehído Reductasa/metabolismo , Hojas de la Planta/enzimología , Proteínas de Plantas/metabolismo , Prunus domestica/enzimología , Aldehído Reductasa/antagonistas & inhibidores , Aldehído Reductasa/genética , Fructosadifosfatos/metabolismo , Fructosadifosfatos/farmacología , Fructosafosfatos/metabolismo , Fructosafosfatos/farmacología , Glucofosfatos/metabolismo , Glucofosfatos/farmacología , Disulfuro de Glutatión/metabolismo , Hexosafosfatos/metabolismo , Hexosafosfatos/farmacología , Immunoblotting , Cinética , Modelos Biológicos , NADP/metabolismo , Oxidantes/metabolismo , Oxidantes/farmacología , Fosfatos/metabolismo , Fosfatos/farmacología , Filogenia , Hojas de la Planta/genética , Proteínas de Plantas/clasificación , Proteínas de Plantas/genética , Prunus domestica/genética , Proteínas Recombinantes/metabolismo , Especificidad por Sustrato , Compuestos de Sulfhidrilo/metabolismoRESUMEN
The rates of increase in yield of the main commercial crops have been steadily falling in many areas worldwide. This generates concerns because there is a growing demand for plant biomass due to the increasing population. Plant yield should thus be improved in the context of climate change and decreasing natural resources. It is a major challenge which could be tackled by improving and/or altering light-use efficiency, CO2 uptake and fixation, primary metabolism, plant architecture and leaf morphology, and developmental plant processes. In this review, we discuss some of the traits which could lead to yield increase, with a focus on how natural genetic variation could be harnessed. Moreover, we provide insights for advancing our understanding of the molecular aspects governing plant growth and yield, and propose future avenues for improvement of crop yield. We also suggest that knowledge accumulated over the last decade in the field of molecular physiology should be integrated into new ideotypes.
Asunto(s)
Producción de Cultivos , Variación Genética/fisiología , Desarrollo de la Planta/genética , Hojas de la Planta/anatomía & histología , Variación Genética/genética , Fotosíntesis/genética , Fotosíntesis/fisiología , Desarrollo de la Planta/fisiología , Hojas de la Planta/fisiología , Transpiración de Plantas/genéticaRESUMEN
Growth and polymer synthesis were studied in a recombinant E. coli strain carrying phaBAC and phaP of Azotobacter sp. strain FA8 using different carbon sources and oxygen availability conditions. The results obtained with glucose or glycerol were completely different, demonstrating that the metabolic routes leading to the synthesis of the polymer when using glycerol do not respond to environmental conditions such as oxygen availability in the same way as they do when other substrates, such as glucose, are used. When cells were grown in a bioreactor using glucose the amount of polymer accumulated at low aeration was reduced by half when compared to high aeration, while glycerol cultures produced at low aeration almost twice the amount of polymer synthesized at the higher aeration condition. The synthesis of other metabolic products, such as ethanol, lactate, formate and acetate, were also affected by both the carbon source used and aeration conditions. In glucose cultures, lactate and formate production increased in low agitation compared to high agitation, while poly(3-hydroxybutyrate) synthesis decreased. In glycerol cultures, the amount of acids produced also increased when agitation was lowered, but carbon flow was mostly redirected towards ethanol and poly(3-hydroxybutyrate). These results indicated that carbon partitioning differed depending on both carbon source and oxygen availability, and that aeration conditions had different effects on the synthesis of the polymer and other metabolic products when glucose or glycerol were used.