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1.
Plant J ; 101(4): 800-815, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31677190

RESUMO

For land plants, water is the principal governor of growth. Photosynthetic performance is highly dependent on the stable and suitable water status of leaves, which is balanced by the water transport capacity, the water loss rate as well as the water capacitance of the plant. This review discusses the links between leaf water status and photosynthesis, specifically focussing on the coordination of CO2 and water transport within leaves, and the potential role of leaf capacitance and elasticity on CO2 and water transport.

2.
J Exp Bot ; 69(22): 5599-5609, 2018 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-30189099

RESUMO

The leaf economics spectrum (LES) is an ecophysiological concept describing the trade-offs of leaf structural and physiological traits, and has been widely investigated on multiple scales. However, the effects of the breeding process on the LES in crops, as well as the mechanisms of the trait trade-offs underlying the LES, have not been thoroughly elucidated to date. In this study, a dataset that included leaf anatomical, biochemical, and functional traits was constructed to evaluate the trait covariations and trade-offs in domesticated species, namely rice (Oryza species). The slopes and intercepts of the major bivariate correlations of the leaf traits in rice were significantly different from the global LES dataset (Glopnet), which is based on multiple non-crop species in natural ecosystems, although the general patterns were similar. The photosynthetic traits responded differently to leaf structural and biochemical changes, and mesophyll conductance was the most sensitive to leaf nitrogen (N) status. A further analysis revealed that the relative limitation of mesophyll conductance declined with leaf N content; however, the limitation of the biochemistry increased relative to leaf N content. These findings indicate that breeding selection and high-resource agricultural environments lead crops to deviate from the leaf trait covariation in wild species, and future breeding to increase the photosynthesis of rice should primarily focus on improvement of the efficiency of photosynthetic enzymes.


Assuntos
Oryza , Fotossíntese , Folhas de Planta , Células do Mesofilo/química , Células do Mesofilo/citologia , Células do Mesofilo/fisiologia , Oryza/anatomia & histologia , Oryza/química , Oryza/fisiologia , Fenótipo , Folhas de Planta/anatomia & histologia , Folhas de Planta/química , Folhas de Planta/fisiologia
3.
J Exp Bot ; 69(16): 4033-4045, 2018 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-29788146

RESUMO

Understanding the physiological responses of crops to drought is important for ensuring sustained crop productivity under climate change, which is expected to exacerbate the frequency and intensity of periods of drought. Drought responses involve multiple traits, and the correlations between these traits are poorly understood. Using a variety of techniques, we estimated the changes in gas exchange, leaf hydraulic conductance, and leaf turgor in rice (Oryza sativa) in response to both short- and long-term soil drought. We performed a photosynthetic limitation analysis to quantify the contributions of each limiting factor to the resultant overall decrease in photosynthesis during drought. Biomass, leaf area, and leaf width significantly decreased during the 2-week drought treatment, but leaf mass per area and leaf vein density increased. Light-saturated photosynthetic rate declined dramatically during soil drought, mainly due to the decrease in stomatal conductance (gs) and mesophyll conductance (gm). Stomatal modeling suggested that the decline in leaf hydraulic conductance explained most of the decrease in stomatal closure during the drought treatment, and may also trigger the drought-related decrease of stomatal conductance and mesophyll conductance. The results of this study provide insight into the regulation of carbon assimilation under drought conditions.


Assuntos
Oryza/fisiologia , Folhas de Planta/fisiologia , Estômatos de Plantas/fisiologia , Secas
4.
Physiol Plant ; 163(1): 45-58, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29055043

RESUMO

Salinity significantly limits leaf photosynthesis but the factors causing the limitation in salt-stressed leaves remain unclear. In the present work, photosynthetic and biochemical traits were investigated in four rice genotypes under two NaCl concentration (0 and 150 mM) to assess the stomatal, mesophyll and biochemical contributions to reduced photosynthetic rate (A) in salt-stressed leaves. Our results indicated that salinity led to a decrease in A, leaf osmotic potential, electron transport rate and CO2 concentrations in the chloroplasts (Cc ) of rice leaves. Decreased A in salt-stressed leaves was mainly attributable to low Cc , which was determined by stomatal and mesophyll conductance. The increased stomatal limitation was mainly related to the low leaf osmotic potential caused by soil salinity. However, the increased mesophyll limitation in salt-stressed leaves was related to both osmotic stress and ion stress. These findings highlight the importance of considering mesophyll conductance when developing salinity-tolerant rice cultivars.


Assuntos
Dióxido de Carbono/metabolismo , Oryza/fisiologia , Fotossíntese/fisiologia , Cloroplastos/fisiologia , Difusão , Células do Mesofilo/fisiologia , Osmose , Folhas de Planta/fisiologia , Estômatos de Plantas/fisiologia , Salinidade , Cloreto de Sódio/metabolismo , Solo/química , Estresse Fisiológico
5.
Plant Cell Environ ; 41(2): 436-450, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29220546

RESUMO

Stomatal conductance (gs ) and mesophyll conductance (gm ) represent major constraints to photosynthetic rate (A), and these traits are expected to coordinate with leaf hydraulic conductance (Kleaf ) across species, under both steady-state and dynamic conditions. However, empirical information about their coordination is scarce. In this study, Kleaf , gas exchange, stomatal kinetics, and leaf anatomy in 10 species including ferns, gymnosperms, and angiosperms were investigated to elucidate the correlation of H2 O and CO2 diffusion inside leaves under varying light conditions. Gas exchange, Kleaf , and anatomical traits varied widely across species. Under light-saturated conditions, the A, gs , gm , and Kleaf were strongly correlated across species. However, the response patterns of A, gs , gm , and Kleaf to varying light intensities were highly species dependent. Moreover, stomatal opening upon light exposure of dark-adapted leaves in the studied ferns and gymnosperms was generally faster than in the angiosperms; however, stomatal closing in light-adapted leaves after darkening was faster in angiosperms. The present results show that there is a large variability in the coordination of leaf hydraulic and gas exchange parameters across terrestrial plant species, as well as in their responses to changing light.


Assuntos
Células do Mesofilo/fisiologia , Folhas de Planta/fisiologia , Estômatos de Plantas/fisiologia , Transpiração Vegetal/fisiologia , Luz , Fotossíntese , Filogenia , Folhas de Planta/anatomia & histologia , Plantas/metabolismo , Água/metabolismo
6.
Sci Rep ; 7(1): 5782, 2017 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-28720786

RESUMO

The photosynthetic, biochemical, and anatomical traits of accumulation and replication of chloroplasts (arc) mutants of Arabidopsis thaliana were investigated to study the effects of chloroplast size and number on photosynthesis. Chloroplasts were found to be significantly larger, and the chloroplast surface area exposed to intercellular air spaces (S c) significantly lower in the mutants than in their wild-types. The decreased S c and increase cytoplasm thickness in the mutants resulted in a lower mesophyll conductance (g m) and a consequently lower chloroplast CO2 concentration (C c). There were no significant differences between the mutants and their wild-types in maximal carboxylation rate (V cmax), maximal electron transport (J cmax), and leaf soluble proteins. Leaf nitrogen (N) and Rubisco content were similar in both Wassilewskija (Ws) wild-type (Ws-WT) and the Ws mutant (arc 8), whereas they were slightly higher in Columbia (Col) wild-type (Col-WT) than the Col mutant (arc 12). The photosynthetic rate (A) and photosynthetic N use efficiency (PNUE) were significantly lower in the mutants than their wild-types. The mutants showed similar A/C c responses as their wild-type counterparts, but A at given C c was higher in Col and its mutant than in Ws and its mutant. From these results, we conclude that decreases in g m and C c are crucial to the reduction in A in arc mutants.


Assuntos
Arabidopsis/genética , Cloroplastos/genética , Mutação , Fotossíntese/genética , Arabidopsis/metabolismo , Dióxido de Carbono/metabolismo , Cloroplastos/metabolismo , Luz , Microscopia Eletrônica de Transmissão , Nitrogênio/metabolismo , Fotossíntese/efeitos da radiação , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura
7.
New Phytol ; 213(2): 572-583, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27653809

RESUMO

Leaf hydraulic conductance (Kleaf ) and mesophyll conductance (gm ) both represent major constraints to photosynthetic rate (A), and previous studies have suggested that Kleaf and gm is correlated in leaves. However, there is scarce empirical information about their correlation. In this study, Kleaf , leaf hydraulic conductance inside xylem (Kx ), leaf hydraulic conductance outside xylem (Kox ), A, stomatal conductance (gs ), gm , and anatomical and structural leaf traits in 11 Oryza genotypes were investigated to elucidate the correlation of H2 O and CO2 diffusion inside leaves. All of the leaf functional and anatomical traits varied significantly among genotypes. Kleaf was not correlated with the maximum theoretical stomatal conductance calculated from stomatal dimensions (gsmax ), and neither gs nor gsmax were correlated with Kx . Moreover, Kox was linearly correlated with gm and both were closely related to mesophyll structural traits. These results suggest that Kleaf and gm are related to leaf anatomical and structural features, which may explain the mechanism for correlation between gm and Kleaf .


Assuntos
Dióxido de Carbono/metabolismo , Células do Mesofilo/fisiologia , Oryza/fisiologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/fisiologia , Água/metabolismo , Difusão , Genótipo , Células do Mesofilo/ultraestrutura , Oryza/genética , Fotossíntese , Folhas de Planta/ultraestrutura , Estômatos de Plantas/fisiologia , Xilema/fisiologia
8.
Ann Bot ; 117(6): 963-71, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-27017586

RESUMO

BACKGROUND AND AIMS: Leaf mass per area (LMA) is an important leaf trait; however, correlations between LMA and leaf anatomical features and photosynthesis have not been fully investigated, especially in cereal crops. The objectives of this study were (a) to investigate the correlations between LMA and leaf anatomical traits; and (b) to clarify the response of LMA to nitrogen supply and its effect on photosynthetic nitrogen use efficiency (PNUE). METHODS: In the present study, 11 rice varieties were pot grown under sufficient nitrogen (SN) conditions, and four selected rice cultivars were grown under low nitrogen (LN) conditions. Leaf anatomical traits, gas exchange and leaf N content were measured. KEY RESULTS: There was large variation in LMA across selected rice varieties. Regression analysis showed that the variation in LMA was more closely related to leaf density (LD) than to leaf thickness (LT). LMA was positively related to the percentage of mesophyll tissue area (%mesophyll), negatively related to the percentage of epidermis tissue area (%epidermis) and unrelated to the percentage of vascular tissue area (%vascular). The response of LMA to N supplementation was dependent on the variety and was also mainly determined by the response of LD to N. Compared with SN, photosynthesis was significantly decreased under LN, while PNUE was increased. The increase in PNUE was more critical in rice cultivars with a higher LMA under SN supply. CONCLUSIONS: Leaf density is the major cause of the variation in LMA across rice varieties and N treatments, and an increase in LMA under high N conditions would aggravate the decrease in PNUE.


Assuntos
Nitrogênio/metabolismo , Oryza/fisiologia , Folhas de Planta/química , Folhas de Planta/fisiologia , Genótipo , Células do Mesofilo , Oryza/genética , Folhas de Planta/citologia , Proteínas de Plantas/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo
9.
Sci Rep ; 5: 13389, 2015 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-26303807

RESUMO

Chlorophyll meters are widely used to guide nitrogen (N) management by monitoring leaf N status in agricultural systems, but the effects of environmental factors and leaf characteristics on leaf N estimations are still unclear. In the present study, we estimated the relationships among SPAD readings, chlorophyll content and leaf N content per leaf area for seven species grown in multiple environments. There were similar relationships between SPAD readings and chlorophyll content per leaf area for the species groups, but the relationship between chlorophyll content and leaf N content per leaf area, and the relationship between SPAD readings and leaf N content per leaf area varied widely among the species groups. A significant impact of light-dependent chloroplast movement on SPAD readings was observed under low leaf N supplementation in both rice and soybean but not under high N supplementation. Furthermore, the allocation of leaf N to chlorophyll was strongly influenced by short-term changes in growth light. We demonstrate that the relationship between SPAD readings and leaf N content per leaf area is profoundly affected by environmental factors and leaf features of crop species, which should be accounted for when using a chlorophyll meter to guide N management in agricultural systems.


Assuntos
Clorofila/análise , Produtos Agrícolas/química , Monitoramento Ambiental/métodos , Nitrogênio/análise , Folhas de Planta/química , Tecnologia de Sensoriamento Remoto/métodos , Meio Ambiente , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Análise Espectral/métodos
10.
Plant Cell Environ ; 38(12): 2541-50, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25923314

RESUMO

Photosynthesis in C3 plants is significantly limited by mesophyll conductance (gm ), which can vary with leaf anatomical traits and nitrogen (N) supplements. Several studies have investigated the response of gm to N supplements; however, none examined the implications of N supplements on the response of gm to rapid environmental changes. Here we investigated the effect of N supplement on gm and the response of gm to change of CO2 , temperature and irradiance in rice. High N supplement (HN) increased mesophyll cell wall surface area and chloroplast surface area exposed to intercellular airspace per leaf area, and reduced cell wall thickness. These changes resulted in increased gm . The gm of leaves with HN was more sensitive to changes in CO2 concentration, temperature and irradiance. The difference in leaf structural features between low N supplement and HN indicates that a rapid change in gm is related to the regulation of diffusion through biological membranes rather than leaf structural features. These results will contribute to an understanding of the determinants of gm response to rapid changes in environmental factors.


Assuntos
Nitrogênio/farmacologia , Oryza/efeitos dos fármacos , Dióxido de Carbono/farmacologia , Cloroplastos/metabolismo , Difusão , Células do Mesofilo/efeitos dos fármacos , Células do Mesofilo/fisiologia , Células do Mesofilo/efeitos da radiação , Oryza/fisiologia , Oryza/efeitos da radiação , Fotossíntese/efeitos dos fármacos , Fotossíntese/efeitos da radiação , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Transpiração Vegetal/efeitos dos fármacos , Transpiração Vegetal/fisiologia , Transpiração Vegetal/efeitos da radiação , Temperatura Ambiente
11.
J Exp Bot ; 66(3): 741-8, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25429002

RESUMO

Leaf hydraulic conductance (K leaf) is a major determinant of photosynthetic rate in plants. Previous work has assessed the relationships between leaf morpho-anatomical traits and K leaf with woody species, but there has been very little focus on cereal crops. The genus Oryza, which includes rice (Oryza sativa) and wild species (such as O. rufipogon cv. Griff), is ideal material for identifying leaf features associated with K leaf and gas exchange. Leaf morpho-anatomical traits, K leaf, leaf N content per leaf area, and CO2 diffusion efficiency were investigated in 11 Oryza cultivars. K leaf was positively correlated with leaf thickness and related traits, and therefore positively correlated with leaf mass per area and leaf N content per leaf area, and negatively with inter-veinal distance. K leaf was also positively correlated with leaf area and its related traits, and therefore negatively correlated with the proportion of minor vein length per area. In addition, coordination between K leaf and CO2 diffusion conductance in leaves was observed. We conclude that leaf morpho-anatomical traits and N content per leaf area strongly influence K leaf. Our results suggest that more detailed anatomical and structural studies are needed to elucidate the impacts of leaf feature traits on K leaf and gas exchange in grasses.


Assuntos
Dióxido de Carbono/metabolismo , Nitrogênio/metabolismo , Oryza/anatomia & histologia , Oryza/fisiologia , Transpiração Vegetal , Folhas de Planta/anatomia & histologia , Folhas de Planta/fisiologia , Especificidade da Espécie
12.
Biotechnol Lett ; 36(7): 1407-20, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24658743

RESUMO

Rice diseases (bacterial, fungal, or viral) threaten food productivity. Host resistance is the most efficient, environmentally friendly method to cope with such diverse pathogens. Quantitative resistance conferred by quantitative trait loci (QTLs) is a valuable resource for rice disease resistance improvement. Although QTLs confer partial but durable resistance to many pathogen species in different crop plants, the molecular mechanisms of quantitative disease resistance remain mostly unknown. Quantitative resistance and non-host resistance are types of broad-spectrum resistance, which are mediated by resistance (R) genes. Because R genes activate different resistance pathways, investigating the genetic spectrum of resistance may lead to minimal losses from harmful diseases. Genome studies can reveal interactions between different genes and their pathways and provide insight into gene functions. Protein­protein interaction (proteomics) studies using molecular and bioinformatics tools may further enlighten our understanding of resistance phenomena.


Assuntos
Embaralhamento de DNA , Resistência à Doença , Oryza/imunologia , Oryza/fisiologia , Doenças das Plantas/prevenção & controle , Oryza/genética , Locos de Características Quantitativas
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