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1.
In this study it has been shown that increased diffusional resistances caused by salt stress may be fully overcome by exposing attached leaves to very low [CO2] (～ 50 µmol mol?1), and, thus a non‐destructive‐in vivo method to correctly estimate photosynthetic capacity in stressed plants is reported. Diffusional (i.e. stomatal conductance, gs, and mesophyll conductance to CO2, gm) and biochemical limitations to photosynthesis (A) were measured in two 1‐year‐old Greek olive cultivars (Chalkidikis and Kerkiras) subjected to salt stress by adding 200 mm NaCl to the irrigation water. Two sets of A–Ci curves were measured. A first set of standard A–Ci curves (i.e. without pre‐conditioning plants at low [CO2]), were generated for salt‐stressed plants. A second set of A–Ci curves were measured, on both control and salt‐stressed plants, after pre‐conditioning leaves at [CO2] of ～ 50 µmol mol?1 for about 1.5 h to force stomatal opening. This forced stomata to be wide open, and gs increased to similar values in control and salt‐stressed plants of both cultivars. After gs had approached the maximum value, the A–Ci response was again measured. The analysis of the photosynthetic capacity of the salt‐stressed plants based on the standard A–Ci curves, showed low values of the Jmax (maximum rate of electron transport) to Vcmax (RuBP‐saturated rate of Rubisco) ratio (1.06), that would implicate a reduced rate of RuBP regeneration, and, thus, a metabolic impairment. However, the analysis of the A–Ci curves made on pre‐conditioned leaves, showed that the estimates of the photosynthetic capacity parameters were much higher than in the standard A–Ci responses. Moreover, these values were similar in magnitude to the average values reported by Wullschleger (Journal of Experimental Botany 44, 907–920, 1993) in a survey of 109 C3 species. These findings clearly indicates that: (1) salt stress did affect gs and gm but not the biochemical capacity to assimilate CO2 and therefore, in these conditions, the sum of the diffusional resistances set the limit to photosynthesis rates; (2) there was a linear relationship (r2 = 0.68) between gm and gs, and, thus, changes of gm can be as fast as those of gs; (3) the estimates of photosynthetic capacity based on A–Ci curves made without removing diffusional limitations are artificially low and lead to incorrect interpretations of the actual limitations of photosynthesis; and (4) the analysis of the photosynthetic properties in terms of stomatal and non‐stomatal limitations should be replaced by the analysis of diffusional and non‐diffusional limitations of photosynthesis. Finally, the C3 photosynthesis model parameterization using in vitro‐measured and in vivo‐measured kinetics parameters was compared. Applying the in vivo‐measured Rubisco kinetics parameters resulted in a better parameterization of the photosynthesis model. 相似文献
2.
Berkley J. Walker Dane C. Skabelund Florian A. Busch Donald R. Ort 《Plant, cell & environment》2016,39(6):1198-1203
Biochemical models of leaf photosynthesis, which are essential for understanding the impact of photosynthesis to changing environments, depend on accurate parameterizations. One such parameter, the photorespiratory CO2 compensation point can be measured from the intersection of several CO2 response curves measured under sub‐saturating illumination. However, determining the actual intersection while accounting for experimental noise can be challenging. Additionally, leaf photosynthesis model outcomes are sensitive to the diffusion paths of CO2 released from the mitochondria. This diffusion path of CO2 includes both chloroplastic as well as cell wall resistances to CO2, which are not readily measurable. Both the difficulties of determining the photorespiratory CO2 compensation point and the impact of multiple intercellular resistances to CO2 can be addressed through application of slope–intercept regression. This technical report summarizes an improved framework for implementing slope–intercept regression to evaluate measurements of the photorespiratory CO2 compensation point. This approach extends past work to include the cases of both Rubisco and Ribulose‐1,5‐bisphosphate (RuBP)‐limited photosynthesis. This report further presents two interactive graphical applications and a spreadsheet‐based tool to allow users to apply slope–intercept theory to their data. 相似文献
3.
Flexas J Diaz-Espejo A Galmés J Kaldenhoff R Medrano H Ribas-Carbo M 《Plant, cell & environment》2007,30(10):1284-1298
The effects of short-term (minutes) variations of CO2 concentration on mesophyll conductance to CO2 (gm) were evaluated in six different C3 species by simultaneous measurements of gas exchange, chlorophyll fluorescence, online carbon isotope discrimination and a novel curve-fitting method. Depending on the species, gm varied from five- to ninefold, along the range of sub-stomatal CO2 concentrations typically used in photosynthesis CO2-response curves (AN)-Ci curves; where AN is the net photosynthetic flux and Ci is the CO2 concentrations in the sub-stomatal cavity), that is, 50 to 1500 micromol CO2 mol(-1) air. Although the pattern was species-dependent, gm strongly declined at high Ci, where photosynthesis was not limited by CO2, but by regeneration of ribulose-1,5-bisphosphate or triose phosphate utilization. Moreover, these changes on gm were found to be totally independent of the velocity and direction of the Ci changes. The response of gm to Ci resembled that of stomatal conductance (gs), but kinetic experiments suggested that the response of gm was actually faster than that of gs. Transgenic tobacco plants differing in the amounts of aquaporin NtAQP1 showed different slopes of the gm-Ci response, suggesting a possible role for aquaporins in mediating CO2 responsiveness of gm. The importance of these findings is discussed in terms of their effects on parameterization of AN-Ci curves. 相似文献
4.
PATRICIA BATTIE‐LACLAU JEAN‐PAUL LACLAU CONSTANCE BERI LAURIANE MIETTON MARTA R.ALMEIDA MUNIZ BRUNA CERSÓZIMO ARENQUE MARISA DE CASSIA PICCOLO LIONEL JORDAN‐MEILLE JEAN‐PIERRE BOUILLET YANN NOUVELLON 《Plant, cell & environment》2014,37(1):70-81
Although vast areas in tropical regions have weathered soils with low potassium (K) levels, little is known about the effects of K supply on the photosynthetic physiology of trees. This study assessed the effects of K and sodium (Na) supply on the diffusional and biochemical limitations to photosynthesis in Eucalyptus grandis leaves. A field experiment comparing treatments receiving K (+K) or Na (+Na) with a control treatment (C) was set up in a K‐deficient soil. The net CO2 assimilation rates were twice as high in +K and 1.6 times higher in +Na than in the C as a result of lower stomatal and mesophyll resistance to CO2 diffusion and higher photosynthetic capacity. The starch content was higher and soluble sugar was lower in +K than in C and +Na, suggesting that K starvation disturbed carbon storage and transport. The specific leaf area, leaf thickness, parenchyma thickness, stomatal size and intercellular air spaces increased in +K and +Na compared to C. Nitrogen and chlorophyll concentrations were also higher in +K and +Na than in C. These results suggest a strong relationship between the K and Na supply to E. grandis trees and the functional and structural limitations to CO2 assimilation rates. 相似文献
5.
YING SUN LIANHONG GU ROBERT E. DICKINSON STEPHEN G. PALLARDY JOHN BAKER YONGHUI CAO FÁBIO MURILO DAMATTA XUEJUN DONG DAVID ELLSWORTH DAVINA VAN GOETHEM ANNA M. JENSEN BEVERLY E. LAW RODOLFO LOOS SAMUEL C. VITOR MARTINS RICHARD J. NORBY JEFFREY WARREN DAVID WESTON KLAUS WINTER 《Plant, cell & environment》2014,37(4):978-994
Worldwide measurements of nearly 130 C3 species covering all major plant functional types are analysed in conjunction with model simulations to determine the effects of mesophyll conductance (gm) on photosynthetic parameters and their relationships estimated from A/Ci curves. We find that an assumption of infinite gm results in up to 75% underestimation for maximum carboxylation rate Vcmax, 60% for maximum electron transport rate Jmax, and 40% for triose phosphate utilization rate Tu. Vcmax is most sensitive, Jmax is less sensitive, and Tu has the least sensitivity to the variation of gm. Because of this asymmetrical effect of gm, the ratios of Jmax to Vcmax, Tu to Vcmax and Tu to Jmax are all overestimated. An infinite gm assumption also limits the freedom of variation of estimated parameters and artificially constrains parameter relationships to stronger shapes. These findings suggest the importance of quantifying gm for understanding in situ photosynthetic machinery functioning. We show that a nonzero resistance to CO2 movement in chloroplasts has small effects on estimated parameters. A non‐linear function with gm as input is developed to convert the parameters estimated under an assumption of infinite gm to proper values. This function will facilitate gm representation in global carbon cycle models. 相似文献
6.
Virtually all current estimates of the maximum carboxylation rate (Vcmax) of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) and the maximum electron transport rate (Jmax) for C3 species implicitly assume an infinite CO2 transfer conductance (gi). And yet, most measurements in perennial plant species or in ageing or stressed leaves show that gi imposes a significant limitation on photosynthesis. Herein, we demonstrate that many current parameterizations of the photosynthesis model of Farquhar, von Caemmerer & Berry (Planta 149, 78–90, 1980 ) based on the leaf intercellular CO2 concentration (Ci) are incorrect for leaves where gi limits photosynthesis. We show how conventional A–Ci curve (net CO2 assimilation rate of a leaf –An– as a function of Ci) fitting methods which rely on a rectangular hyperbola model under the assumption of infinite gi can significantly underestimate Vcmax for such leaves. Alternative parameterizations of the conventional method based on a single, apparent Michaelis–Menten constant for CO2 evaluated at Ci[Km(CO2)i] used for all C3 plants are also not acceptable since the relationship between Vcmax and gi is not conserved among species. We present an alternative A–Ci curve fitting method that accounts for gi through a non‐rectangular hyperbola version of the model of Farquhar et al. (1980 ). Simulated and real examples are used to demonstrate how this new approach eliminates the errors of the conventional A–Ci curve fitting method and provides Vcmax estimates that are virtually insensitive to gi. Finally, we show how the new A–Ci curve fitting method can be used to estimate the value of the kinetic constants of Rubisco in vivo is presented 相似文献
7.
JERONI GALMÉS JOAN MANUEL OCHOGAVÍA JORGE GAGO EMILIO JOSÉ ROLDÁN JOSEP CIFRE MIQUEL ÀNGEL CONESA 《Plant, cell & environment》2013,36(5):920-935
In a previous study, important acclimation to water stress was observed in the Ramellet tomato cultivar (TR) from the Balearic Islands, related to an increase in the water‐use efficiency through modifications in both stomatal (gs) and mesophyll conductances (gm). In the present work, the comparison of physiological and morphological traits between TR accessions grown with and without water stress confirmed that variability in the photosynthetic capacity was mostly explained by differences in the diffusion of CO2 through stomata and leaf mesophyll. Maximization of gm under both treatments was mainly achieved through adjustments in the mesophyll thickness and porosity and the surface area of chloroplasts exposed to intercellular airspace (Sc). In addition, the lower gm/Sc ratio for a given porosity in drought‐acclimated plants suggests that the decrease in gm was due to an increased cell wall thickness. Stomatal conductance was also affected by drought‐associated changes in the morphological properties of stomata, in an accession and treatment‐dependent manner. The results confirm the presence of advantageous physiological traits in the response to drought stress in Mediterranean accessions of tomato, and relate them to particular changes in the leaf anatomical properties, suggesting specific adaptive processes operating at the leaf anatomical level. 相似文献
8.
陆面过程模型添加叶肉导度能有效改善模型模拟的CO2施肥效应精度,但叶肉导度模拟受最大叶肉导度参数取值的影响,优化模型中最大叶肉导度参数是改进陆面过程模型叶肉导度和CO2施肥效应模拟的重要途径。以EALCO（Ecological Assimilation of Land and Climate Observations）模型为例添加叶肉导度,通过人为改变最大叶肉导度值的取值,分析模型输出结果对最大叶肉导度的响应,揭示最大叶肉导度参数在模型中的敏感性,并与已有研究结果或观测数据比较,探讨耦合叶肉导度的陆面过程模型最大叶肉导度参数优化的途径。模拟试验以美国哈佛森林典型温带落叶阔叶林生态监测站（US-Ha1 site, Harvard Forest Environmental Monitoring site）数据为驱动。结果显示：（1）随最大叶肉导度增加,总初级生产力（GPP, Gross Primary Production）模拟精度增加,但最大叶肉导度取值大于1.0 mol m-2 s-1后模拟精度改善有限,最大叶肉导度小于1.0 mol m-2 s-1时GPP模拟精度对最大叶肉导度变化响应敏感;（2）证实了叶肉导度与气孔导度之间存在明显线性关系,最大叶肉导度取值的变化能明显影响这种线性关系的斜率。当最大叶肉导度取值从0.5 mol m-2 s-1增加到1.2 mol m-2 s-1时,气孔导度与叶肉导度的比值从0.75左右降至0.36,这个结果表明,通过明确某一植被功能型叶肉导度与气孔导度比值,可以间接确定模型最大叶肉导度的合理取值范围;（3）证实了陆面过程模型添加叶肉导度能改进CO2施肥效应模拟精度,最大叶肉导度值能影响施肥效应模拟结果,当最大叶肉导度高于0.57 mol m-2 s-1后,随最大叶肉导度增加,模拟GPP随大气CO2浓度增加的增长率呈下降趋势;（4）在月尺度上叶肉导度模拟对最大叶肉导度值的敏感性随不同生长季而不同,在生长盛期的7、8月份最大叶肉导度对叶肉导度模拟结果影响最大,其次是5、6、9月份等生长次盛期,其他月份的影响较小。 相似文献
9.
YONGHONG SU GAOFENG ZHU ZEWEI MIAO QI FENG & ZONGQIANG CHANG 《Plant, cell & environment》2009,32(12):1710-1723
Photosynthesis response to carbon dioxide concentration can provide data on a number of important parameters related to leaf physiology. The genetic algorithm (GA), which is a robust stochastic evolutionary computational algorithm inspired by both natural selection and natural genetics, is proposed to simultaneously estimate the parameters [including maximum carboxylation rate allowed by ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate ( V cmax ), potential light-saturated electron transport rate ( J max ), triose-phosphate utilization (TPU), leaf dark respiration in the light ( R d ) and mesophyll conductance ( g m )] of the photosynthesis models presented by Farquhar, von Caemmerer and Berry, and Ethier and Livingston. The results show that by properly constraining the parameter bounds the GA-based estimate methods can effectively and efficiently obtain globally (or, at least near globally) optimal solutions, which are as good as or better than those obtained by non-linear curve fitting methods used in previous studies. More complicated problems such as taking the g m variation response to CO2 into account can be easily formulated and solved by using GA. The influence of the crossover probability ( P c ), mutation probability ( P m ), population size and generation on the performance of GA was also investigated. 相似文献
10.
J. Mason Earles Thomas N. Buckley Craig R. Brodersen Florian A. Busch F. Javier Cano Brendan Choat John R. Evans Graham D. Farquhar Richard Harwood Minh Huynh Grace P. John Megan L. Miller Fulton E. Rockwell Lawren Sack Christine Scoffoni Paul C. Struik Alex Wu Xinyou Yin Margaret M. Barbour 《Trends in plant science》2019,24(1):15-24
11.
Tholen D Boom C Noguchi K Ueda S Katase T Terashima I 《Plant, cell & environment》2008,31(11):1688-1700
The relationship between chloroplast arrangement and diffusion of CO(2) from substomatal cavities to the chloroplast stroma was investigated in Arabidopsis thaliana. Chloroplast position was manipulated by varying the amount of blue light and by cytochalasin D (CytD) treatment. We also investigated two chloroplast positioning mutants. Chloroplast arrangement was assessed by the surface area of chloroplasts adjacent to intercellular airspaces (S(c)). Although it has been previously shown that long-term acclimation to high light is linked with a large S(c), we found that the short-term chloroplast avoidance response reduces S(c). This effect was not apparent in the blue-light-insensitive phot2 mutant, which did not show the avoidance response. As expected, the smaller S(c) induced by the avoidance response was coupled to a similar decrease in internal conductance. This reduction in internal conductance resulted in an increased limitation of the rate of photosynthesis. The limiting effect of S(c) on internal conductance and photosynthesis was also shown in chup1, a mutant with a constant small S(c) as the result of an unusual chloroplast arrangement. We conclude that chloroplast movements in A. thaliana can rapidly alter leaf morphological parameters, and this has significant consequences for the diffusion of CO(2) through the mesophyll. 相似文献
12.
Structural Adaptation of the Leaf Mesophyll to Shading 总被引：1，自引：0，他引：1
Structural characteristics of the mesophyll were studied in five boreal grass species experiencing a wide range of light and water supply conditions. Quantitative indices of the palisade and spongy mesophyll tissues (cell and chloroplast sizes, the number of chloroplasts per cell, the total cell and chloroplast surface area per unit leaf surface area) were determined in leaves of each of the species. The cell surface area and the cell volume in spongy mesophyll were determined with a novel method based on stereological analysis of cell projections. An important role of spongy parenchyma in the photosynthetic apparatus was demonstrated. In leaves of the species studied, the spongy parenchyma constituted about 50% of the total volume and 40% of the total surface area of mesophyll cells. The proportion of the palisade to spongy mesophyll tissues varied with plant species and growth conditions. In a xerophyte Genista tinctoria, the total cell volume, cell abundance, and the total surface area of cells and chloroplasts were 30–40% larger in the palisade than in the spongy mesophyll. In contrast, in a shade-loving species Veronica chamaedris, the spongy mesophyll was 1.5–2 times more developed than the palisade mesophyll. In mesophyte species grown under high light conditions, the cell abundance and the total cell surface area were 10–20% greater in the palisade mesophyll than in the spongy parenchyma. In shaded habitats, these indices were similar in the palisade and spongy mesophyll or were 10–20% lower in the palisade mesophyll. In mesophytes, CO2 conductance of the spongy mesophyll accounted for about 50% of the total mesophyll conductance, as calculated from the structural characteristics, with the mesophyll CO2 conductance increasing with leaf shading. 相似文献
13.
CHRISTOPHER P. BICKFORD NATE G. MCDOWELL ERIK B. ERHARDT & DAVID T. HANSON 《Plant, cell & environment》2009,32(7):796-810
We present field observations of carbon isotope discrimination (Δ) and internal conductance of CO2 ( g i ) collected using tunable diode laser spectroscopy (TDL). Δ ranged from 12.0 to 27.4‰ over diurnal periods with daily means from 16.3 ± 0.2‰ during drought to 19.0 ± 0.5‰ during monsoon conditions. We observed a large range in g i , with most estimates between 0.04 and 4.0 µ mol m−2 s−1 Pa−1 . We tested the comprehensive Farquhar, O'Leary and Berry model of Δ (Δcomp ), a simplified form of Δcomp (Δsimple ) and a recently suggested amendment (Δrevised ). Sensitivity analyses demonstrated that varying g i had a substantial effect on Δcomp , resulting in mean differences between observed Δ (Δobs ) and Δcomp ranging from 0.04 to 9.6‰. First-order regressions adequately described the relationship between Δ and the ratio of substomatal to atmospheric CO2 partial pressure ( p i / p a ) on all 3 d, but second-order models better described the relationship in July and August. The three tested models each best predicted Δobs on different days. In June, Δsimple outperformed Δcomp and Δrevised , but incorporating g i and all non-photosynthetic fractionations improved model predictions in July and August. 相似文献
14.
15.
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 H2O 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. 相似文献
16.
LAURENT MISSON JEAN‐MARC LIMOUSIN RAQUEL RODRIGUEZ MATTHEW G. LETTS 《Plant, cell & environment》2010,33(11):1898-1910
Global climate change is expected to result in more frequent and intense droughts in the Mediterranean region. To understand forest response to severe drought, we used a mobile rainfall shelter to examine the impact of spring and autumn rainfall exclusion on stomatal (SL) and non‐stomatal (NSL) limitations of photosynthesis in a Quercus ilex ecosystem. Spring rainfall exclusion, carried out during increasing atmospheric demand and leaf development, had a larger impact on photosynthesis than autumn exclusion, conducted at a time of mature foliage and decreasing vapour pressure deficit. The relative importance of NSL increased with drought intensity. SL and NSL were equal once total limitation (TL) reached 60%, but NSL greatly exceeded SL during severe drought, with 76% NSL partitioned equally between mesophyll conductance (MCL) and biochemical (BL) limitations when TL reached 100%. Rainfall exclusion altered the relationship between leaf water potential and photosynthesis. In response to severe mid‐summer drought stress, An and Vcmax were 75% and 72% lower in the spring exclusion plot than in the control plot at the same pre‐dawn leaf water potential. Our results revealed changes in the relationship between photosynthetic parameters and water stress that are not currently included in drought parameterizations for modelling applications. 相似文献
17.
Dongliang Xiong Miquel Nadal 《The Plant journal : for cell and molecular biology》2020,101(4):800-815
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. 相似文献
18.
Water availability is the most limiting factor to global plant productivity, yet photosynthetic responses to seasonal drought cycles are poorly understood, with conflicting reports on which limiting process is the most important during drought. We address the problem using a model‐data synthesis approach to look at canopy level fluxes, integrating twenty years of half hour data gathered by the FLUXNET network across six Mediterranean sites. The measured canopy level, water and carbon fluxes were used, together with an inverse canopy ecophysiological model, to estimate the bulk canopy conductance, bulk mesophyll conductance, and the canopy scale carbon pools in both the intercellular spaces and at the site of carboxylation in the chloroplasts. Thus the roles of stomatal and mesophyll conductance in the regulation of internal carbon pools and photosynthesis could be separated. A quantitative limitation analysis allowed for the relative seasonal responses of stomatal, mesophyll, and biochemical limitations to be gauged. The concentration of carbon in the chloroplast was shown to be a potentially more reliable estimator of assimilation rates than the intercellular carbon concentration. Both stomatal conductance limitations and mesophyll conductance limitations were observed to regulate the response of photosynthesis to water stress in each of the six species studied. The results suggest that mesophyll conductance could bridge the gap between conflicting reports on plant responses to soil water stress, and that the inclusion of mesophyll conductance in biosphere–atmosphere transfer models may improve their performance, in particular their ability to accurately capture the response of terrestrial vegetation productivity to drought. 相似文献
19.
Galmés J Conesa MÀ Ochogavía JM Perdomo JA Francis DM Ribas-Carbó M Savé R Flexas J Medrano H Cifre J 《Plant, cell & environment》2011,34(2):245-260
The physiological traits underlying the apparent drought resistance of 'Tomàtiga de Ramellet' (TR) cultivars, a population of Mediterranean tomato cultivars with delayed fruit deterioration (DFD) phenotype and typically grown under non-irrigation conditions, are evaluated. Eight different tomato accessions were selected and included six TR accessions, one Mediterranean non-TR accession (NTR(M)) and a processing cultivar (NTR(O)). Among the TR accessions two leaf morphology types, normal divided leaves and potato-leaf, were selected. Plants were field grown under well-watered (WW) and water-stressed (WS) treatments, with 30 and 10% of soil water capacity, respectively. Accessions were clustered according to the leaf type and TR phenotype under WW and WS, respectively. Correlation among parameters under the different water treatments suggested that potential improvements in the intrinsic water-use efficiency (A(N)/g(s)) are possible without negative impacts on yield. Under WS TR accessions displayed higher A(N)/g(s), which was not due to differences in Rubisco-related parameters, but correlated with the ratio between the leaf mesophyll and stomatal conductances (g(m)/g(s)). The results confirm the existence of differential traits in the response to drought stress in Mediterranean accessions of tomato, and demonstrate that increases in the g(m)/g(s) ratio would allow improvements in A(N)/g(s) in horticultural crops. 相似文献
20.
Decline in mesophyll conductance (gm) plays a key role in limiting photosynthesis in plants exposed to elevated ozone (O3). Leaf anatomical traits are known to influence gm, but the potential effects of O3-induced changes in leaf anatomy on gm have not yet been clarified. Here, two poplar clones were exposed to elevated O3. The effects of O3 on the photosynthetic capacity and anatomical characteristics were assessed to investigate the leaf anatomical properties that potentially affect gm. We also conducted global meta-analysis to explore the general response patterns of gm and leaf anatomy to O3 exposure. We found that the O3-induced reduction in gm was critical in limiting leaf photosynthesis. Changes in liquid-phase conductance rather than gas-phase conductance drive the decline in gm under elevated O3, and this effect was associated with thicker cell walls and smaller chloroplast sizes. The effects of O3 on palisade and spongy mesophyll cell traits and their contributions to gm were highly genotype-dependent. Our results suggest that, while anatomical adjustments under elevated O3 may contribute to defense against O3 stress, they also cause declines in gm and photosynthesis. These results provide the first evidence of anatomical constraints on gm under elevated O3. 相似文献