Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros

Bases de dados
Ano de publicação
Tipo de documento
Assunto da revista
País de afiliação
Intervalo de ano de publicação
1.
Plant Cell Environ ; 35(9): 1631-46, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22471732

RESUMO

Light and soil water content affect leaf surface area expansion through modifications in epidermal cell numbers and area, while effects on leaf thickness and mesophyll cell volumes are far less documented. Here, three-dimensional imaging was applied in a study of Arabidopsis thaliana leaf growth to determine leaf thickness and the cellular organization of mesophyll tissues under moderate soil water deficit and two cumulative light conditions. In contrast to surface area, thickness was highly conserved in response to water deficit under both low and high cumulative light regimes. Unlike epidermal and palisade mesophyll tissues, no reductions in cell number were observed in the spongy mesophyll; cells had rather changed in volume and shape. Furthermore, leaf features of a selection of genotypes affected in leaf functioning were analysed. The low-starch mutant pgm had very thick leaves because of unusually large palisade mesophyll cells, together with high levels of photosynthesis and stomatal conductance. By means of an open stomata mutant and a 9-cis-epoxycarotenoid dioxygenase overexpressor, it was shown that stomatal conductance does not necessarily have a major impact on leaf dimensions and cellular organization, pointing to additional mechanisms for the control of CO(2) diffusion under high and low stomatal conductance, respectively.


Assuntos
Arabidopsis/anatomia & histologia , Arabidopsis/crescimento & desenvolvimento , Meio Ambiente , Imageamento Tridimensional/métodos , Folhas de Planta/anatomia & histologia , Folhas de Planta/crescimento & desenvolvimento , Arabidopsis/citologia , Arabidopsis/genética , Fenômenos Biomecânicos/efeitos da radiação , Contagem de Células , Forma Celular/efeitos da radiação , Tamanho Celular/efeitos da radiação , Genótipo , Umidade , Luz , Células do Mesofilo/citologia , Células do Mesofilo/efeitos da radiação , Mutação/genética , Especificidade de Órgãos/efeitos da radiação , Fotossíntese/efeitos da radiação , Folhas de Planta/genética , Folhas de Planta/efeitos da radiação , Estômatos de Plantas/anatomia & histologia , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiação , Solo , Amido/metabolismo , Água
2.
Plant Physiol ; 154(1): 357-72, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20631317

RESUMO

Growth and carbon (C) fluxes are severely altered in plants exposed to soil water deficit. Correspondingly, it has been suggested that plants under water deficit suffer from C shortage. In this study, we test this hypothesis in Arabidopsis (Arabidopsis thaliana) by providing an overview of the responses of growth, C balance, metabolites, enzymes of the central metabolism, and a set of sugar-responsive genes to a sustained soil water deficit. The results show that under drought, rosette relative expansion rate is decreased more than photosynthesis, leading to a more positive C balance, while root growth is promoted. Several soluble metabolites accumulate in response to soil water deficit, with K(+) and organic acids as the main contributors to osmotic adjustment. Osmotic adjustment costs only a small percentage of the daily photosynthetic C fixation. All C metabolites measured (not only starch and sugars but also organic acids and amino acids) show a diurnal turnover that often increased under water deficit, suggesting that these metabolites are readily available for being metabolized in situ or exported to roots. On the basis of 30 enzyme activities, no in-depth reprogramming of C metabolism was observed. Water deficit induces a shift of the expression level of a set of sugar-responsive genes that is indicative of increased, rather than decreased, C availability. These results converge to show that the differential impact of soil water deficit on photosynthesis and rosette expansion results in an increased availability of C for the roots, an increased turnover of C metabolites, and a low-cost C-based osmotic adjustment, and these responses are performed without major reformatting of the primary metabolism machinery.


Assuntos
Aclimatação/efeitos dos fármacos , Arabidopsis/enzimologia , Arabidopsis/crescimento & desenvolvimento , Carbono/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Água/farmacologia , Aclimatação/genética , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Biomassa , Metabolismo dos Carboidratos/efeitos dos fármacos , Metabolismo dos Carboidratos/genética , Ácidos Carboxílicos/metabolismo , Análise Multivariada , Osmose/efeitos dos fármacos , Fotoperíodo , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Potássio/metabolismo , Solubilidade/efeitos dos fármacos , Amido/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA