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1.
Photosynthesis in intact leaves of C3 plants: Physics,physiology and rate limitations 总被引:1,自引:0,他引:1
Thomas D. Sharkey 《The Botanical review》1985,51(1):53-105
The instantaneous rate of photosynthetic CO2 assimilation in C3 plants has generally been studied in model systems such as isolated chloroplasts and algae. From these studies and from theoretical analyses of gas exchange behavior it is now possible to study the biochemistry of photosynthesis in intact leaves using a combination of methods, most of which are nondestructive. The limitations to the rate of photosynthesis can be divided among three general classes: (1) the supply or utilization of CO2, (2) the supply or utilization of light, and (3) the supply or utilization of phosphate. The first limitation is most readily studied by determining how the CO2 assimilation rate varies with the partial pressure of CO2 inside the leaf. The second limitation can be studied by determining the quantum requirement of photosynthesis. The third limitation is most easily detected as a loss of O2 sensitivity of photosynthesis. Measurement of fluorescence from intact leaves can give additional information about the various limitations. These methods are all non-destructive and so can be observed repeatedly as the environment of a leaf is changed. In addition, leaves can be quick-frozen and metabolite concentrations then measured to give more information about the limitations to intact leaf photosynthesis rates. In this review the physics and biochemistry of photosynthesis in intact C3 leaves, and the interface between physiology and photosynthesis—triose phosphate utilization—are discussed. 相似文献
2.
Declining net primary production (NPP) with forest age is often attributed to a corresponding decline in gross primary production (GPP). We tested two hypotheses explaining the decline of GPP in ageing stands (14–115 years old) of Pinus taeda L.: (1) increasing N limitation limits photosynthetic capacity and thus decreases GPP with increasing age; and (2) hydraulic limitations increasingly induce stomatal closure, reducing GPP with increasing age. We tested these hypotheses using measurements of foliar nitrogen, photosynthesis, sap‐flow and dendroclimatological techniques. Hypothesis (1) was not supported; foliar N retranslocation did not increase and declines were not observed in foliar N, leaf area per tree or photosynthetic capacity. Hypothesis (2) was supported; declines were observed in light‐saturated photosynthesis, leaf‐ and canopy‐level stomatal conductance, concentration of CO2 inside leaf air‐spaces (corroborated by an increase in wood δ13C) and specific leaf area (SLA), while stomatal limitation and the ratio of sapwood area (SA) to leaf area increased. The sensitivity of radial growth to inter‐annual variation in temperature and drought decreased with age, suggesting that tree water use becomes increasingly conservative with age. We conclude that hydraulic limitation increasingly limits the photosynthetic rates of ageing loblolly pine trees, possibly explaining the observed reduction of NPP. 相似文献
3.
随着全球气候变化的加剧,陆地生态系统中植物光合作用限制影响程度的增加已成为降低全球植被净初级生产力的主要因素。系统了解植物光合作用限制因素是科学评估植被生产力的重要前提,也是缓解植物光合作用限制,增加植物光合碳同化能力的先决条件。对植物光合作用限制因素进行了系统解析,分析了光合作用三种限制因素生化限制(Biochemical limitation,lb)、气孔限制(Stomatal limitation,ls)、叶肉限制(Mesophyll limitation,lm)的环境响应,重点讨论了叶肉限制及其影响机理,述评了光合作用限制定量分析方法及改善措施,最后以提高植被生产力为驱使目标,对未来植物光合作用限制因素研究提出以下内容:(1)基因工程技术与系统生物学数据相结合提高植被生产力;(2)气孔响应速度对植物光合作用的影响机制;(3)水通道蛋白(Aquaporin, AQPs)和碳酸酐酶(Carbonic anhydrase, CAs)感知环境信号变化的驱动基因。以期为未来气候变化背景下,深入认识和降低植物光合作用限制,提... 相似文献
4.
Photosynthetic limitation of several representative subalpine species in the Catalan Pyrenees in summer
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Information on the photosynthetic process and its limitations is essential in order to predict both the capacity of species to adapt to conditions associated with climate change and the likely changes in plant communities. Considering that high‐mountain species are especially sensitive, three species representative of subalpine forests of the Central Catalan Pyrenees: mountain pine (Pinus uncinata Mill.), birch (Betula pendula Roth) and rhododendron (Rhododendron ferrugineum L.) were studied under conditions associated with climate change, such as low precipitation, elevated atmospheric [CO2] and high solar irradiation incident at Earth's surface, in order to detect any photosynthetic limitations. Short‐term high [CO2] increased photosynthesis rates (A) and water use efficiency (WUE), especially in birch and mountain pine, whereas stomatal conductance (gs) was not altered in either species. Birch showed photosynthesis limitation through stomatal closure related to low rainfall, which induced photoinhibition and early foliar senescence. Rhododendron was especially affected by high irradiance, showing early photosynthetic saturation in low light, highest chlorophyll content, lowest gas exchange rates and least photoprotection. Mountain pine had the highest A, photosynthetic capacity (Amax) and light‐saturated rates of net CO2 assimilation (Asat), which were maintained under reduced precipitation. Furthermore, maximum quantum yield (Fv/Fm), thermal energy dissipation, PRI and SIPI radiometric index, and ascorbate content indicated improved photoprotection with respect to the other two species. However, maximum velocity of carboxylation of RuBisco (Vcmax) indicated that N availability would be the main photosynthetic limitation in this species. 相似文献
5.
Carbon source–sink limitations differ between two species with contrasting growth strategies
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Angela C. Burnett Alistair Rogers Mark Rees Colin P. Osborne 《Plant, cell & environment》2016,39(11):2460-2472
Understanding how carbon source and sink strengths limit plant growth is a critical knowledge gap that hinders efforts to maximize crop yield. We investigated how differences in growth rate arise from source–sink limitations, using a model system comparing a fast‐growing domesticated annual barley (Hordeum vulgare cv. NFC Tipple) with a slow‐growing wild perennial relative (Hordeum bulbosum). Source strength was manipulated by growing plants at sub‐ambient and elevated CO2 concentrations ([CO2]). Limitations on vegetative growth imposed by source and sink were diagnosed by measuring relative growth rate, developmental plasticity, photosynthesis and major carbon and nitrogen metabolite pools. Growth was sink limited in the annual but source limited in the perennial. RGR and carbon acquisition were higher in the annual, but photosynthesis responded weakly to elevated [CO2] indicating that source strength was near maximal at current [CO2]. In contrast, photosynthetic rate and sink development responded strongly to elevated [CO2] in the perennial, indicating significant source limitation. Sink limitation was avoided in the perennial by high sink plasticity: a marked increase in tillering and root:shoot ratio at elevated [CO2], and lower non‐structural carbohydrate accumulation. Alleviating sink limitation during vegetative development could be important for maximizing growth of elite cereals under future elevated [CO2]. 相似文献
6.
MEGAN BECKETT FRANCESCO LORETO VIOLETA VELIKOVA CECILIA BRUNETTI MARTINA DI FERDINANDO MASSIMILIANO TATTINI CARLO CALFAPIETRA JILL M. FARRANT 《Plant, cell & environment》2012,35(12):2061-2074
We investigated the photosynthetic limitations occurring during dehydration and rehydration of Xerophyta humilis, a poikilochlorophyllous resurrection plant, and whether volatile and non‐volatile isoprenoids might be involved in desiccation tolerance. Photosynthesis declined rapidly after dehydration below 85% relative water content (RWC). Raising intercellular CO2 concentrations during desiccation suggest that the main photosynthetic limitation was photochemical, affecting energy‐dependent RuBP regeneration. Imaging fluorescence confirmed that both the number of photosystem II (PSII) functional reaction centres and their efficiency were impaired under progressive dehydration, and revealed the occurrence of heterogeneous photosynthesis during desiccation, being the basal leaf area more resistant to the stress. Full recovery in photosynthetic parameters occurred on rehydration, confirming that photosynthetic limitations were fully reversible and that no permanent damage occurred. During desiccation, zeaxanthin and lutein increased only when photosynthesis had ceased, implying that these isoprenoids do not directly scavenge reactive oxygen species, but rather protect photosynthetic membranes from damage and consequent denaturation. X. humilis was found to emit isoprene, a volatile isoprenoid that acts as a membrane strengthener in plants. Isoprene emission was stimulated by drought and peaked at 80% RWC. We surmise that isoprene and non‐volatile isoprenoids cooperate in reducing membrane damage in X. humilis, isoprene being effective when desiccation is moderate while non‐volatile isoprenoids operate when water deficit is more extreme. 相似文献
7.
Diffusional limitations explain the lower photosynthetic capacity of ferns as compared with angiosperms in a common garden study
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M. CARRIQUÍ H. M. CABRERA M. À. CONESA R. E. COOPMAN C. DOUTHE J. GAGO A. GALLÉ J. GALMÉS M. RIBAS‐CARBO M. TOMÁS J. FLEXAS 《Plant, cell & environment》2015,38(3):448-460
Ferns are thought to have lower photosynthetic rates than angiosperms and they lack fine stomatal regulation. However, no study has directly compared photosynthesis in plants of both groups grown under optimal conditions in a common environment. We present a common garden comparison of seven angiosperms and seven ferns paired by habitat preference, with the aims of (1) confirming that ferns do have lower photosynthesis capacity than angiosperms and quantifying these differences; (2) determining the importance of diffusional versus biochemical limitations; and (3) analysing the potential implication of leaf anatomical traits in setting the photosynthesis capacity in both groups. On average, the photosynthetic rate of ferns was about half that of angiosperms, and they exhibited lower stomatal and mesophyll conductance to CO2 (gm), maximum velocity of carboxylation and electron transport rate. A quantitative limitation analysis revealed that stomatal and mesophyll conductances were co‐responsible for the lower photosynthesis of ferns as compared with angiosperms. However, gm alone was the most constraining factor for photosynthesis in ferns. Consistently, leaf anatomy showed important differences between angiosperms and ferns, especially in cell wall thickness and the surface of chloroplasts exposed to intercellular air spaces. 相似文献
8.
Wataru Yamori Kensuke Kusumi Koh Iba Ichiro Terashima 《Plant, cell & environment》2020,43(5):1230-1240
A close correlation between stomatal conductance and the steady-state photosynthetic rate has been observed for diverse plant species under various environmental conditions. However, it remains unclear whether stomatal conductance is a major limiting factor for the photosynthetic rate under naturally fluctuating light conditions. We analysed a SLAC1 knockout rice line to examine the role of stomatal conductance in photosynthetic responses to fluctuating light. SLAC1 encodes a stomatal anion channel that regulates stomatal closure. Long exposures to weak light before treatments with strong light increased the photosynthetic induction time required for plants to reach a steady-state photosynthetic rate and also induced stomatal limitation of photosynthesis by restricting the diffusion of CO2 into leaves. The slac1 mutant exhibited a significantly higher rate of stomatal opening after an increase in irradiance than wild-type plants, leading to a higher rate of photosynthetic induction. Under natural conditions, in which irradiance levels are highly variable, the stomata of the slac1 mutant remained open to ensure efficient photosynthetic reaction. These observations reveal that stomatal conductance is important for regulating photosynthesis in rice plants in the natural environment with fluctuating light. 相似文献
9.
Electron transport is the functional limitation of photosynthesis in field-grown Pima cotton plants at high temperature 总被引:19,自引:4,他引:15
Restrictions to photosynthesis can limit plant growth at high temperature in a variety of ways. In addition to increasing photorespiration, moderately high temperatures (35–42 °C) can cause direct injury to the photosynthetic apparatus. Both carbon metabolism and thylakoid reactions have been suggested as the primary site of injury at these temperatures. In the present study this issue was addressed by first characterizing leaf temperature dynamics in Pima cotton (Gossypium barbadense) grown under irrigation in the US desert south‐west. It was found that cotton leaves repeatedly reached temperatures above 40 °C and could fluctuate as much as 8 or 10 °C in a matter of seconds. Laboratory studies revealed a maximum photosynthetic rate at 30–33 °C that declined by 22% at 45 °C. The majority of the inhibition persisted upon return to 30 °C. The mechanism of this limitation was assessed by measuring the response of photosynthesis to CO2 in the laboratory. The first time a cotton leaf (grown at 30 °C) was exposed to 45 °C, photosynthetic electron transport was stimulated (at high CO2) because of an increased flux through the photorespiratory pathway. However, upon cooling back to 30 °C, photosynthetic electron transport was inhibited and fell substantially below the level measured before the heat treatment. In the field, the response of assimilation (A) to various internal levels of CO2 (Ci) revealed that photosynthesis was limited by ribulose‐1,5‐bisphosphate (RuBP) regeneration at normal levels of CO2 (presumably because of limitations in thylakoid reactions needed to support RuBP regeneration). There was no evidence of a ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) limitation at air levels of CO2 and at no point on any of 30 A–Ci curves measured on leaves at temperatures from 28 to 39 °C was RuBP regeneration capacity measured to be in substantial excess of the capacity of Rubisco to use RuBP. It is therefore concluded that photosynthesis in field‐grown Pima cotton leaves is functionally limited by photosynthetic electron transport and RuBP regeneration capacity, not Rubisco activity. 相似文献
10.
Phylogenetic analyses show that C4 grasses typically occupy drier habitats than their C3 relatives, but recent experiments comparing the physiology of closely related C3 and C4 species have shown that advantages of C4 photosynthesis can be lost under drought. We tested the generality of these paradoxical findings in grass species representing the known evolutionary diversity of C4 NADP‐me and C3 photosynthetic types. Our experiment investigated the effects of drought on leaf photosynthesis, water potential, nitrogen, chlorophyll content and mortality. C4 grasses in control treatments were characterized by higher CO2 assimilation rates and water potential, but lower stomatal conductance and nitrogen content. Under drought, stomatal conductance declined more dramatically in C3 than C4 species, and photosynthetic water‐use and nitrogen‐use efficiency advantages held by C4 species under control conditions were each diminished by 40%. Leaf mortality was slightly higher in C4 than C3 grasses, but leaf condition under drought otherwise showed no dependence on photosynthetic‐type. This phylogenetically controlled experiment suggested that a drought‐induced reduction in the photosynthetic performance advantages of C4 NADP‐me relative to C3 grasses is a general phenomenon. 相似文献
11.
Samuel H. Taylor Douglas J. Orr Elizabete Carmo-Silva Stephen P. Long 《Plant, cell & environment》2020,43(11):2623-2636
Interventions to increase crop radiation use efficiency rely on understanding of how biochemical and stomatal limitations affect photosynthesis. When leaves transition from shade to high light, slow increases in maximum Rubisco carboxylation rate and stomatal conductance limit net CO2 assimilation for several minutes. However, as stomata open intercellular [CO2] increases, so electron transport rate could also become limiting. Photosynthetic limitations were evaluated in three important Brassica crops: Brassica rapa, Brassica oleracea and Brassica napus. Measurements of induction after a period of shade showed that net CO2 assimilation by B. rapa and B. napus saturated by 10 min. A new method of analyzing limitations to induction by varying intercellular [CO2] showed this was due to co-limitation by Rubisco and electron transport. By contrast, in B. oleracea persistent Rubisco limitation meant that CO2 assimilation was still recovering 15 min after induction. Correspondingly, B. oleracea had the lowest Rubisco total activity. The methodology developed, and its application here, shows a means to identify the basis of variation in photosynthetic efficiency in fluctuating light, which could be exploited in breeding and bioengineering to improve crop productivity. 相似文献
12.
Photosynthesis is the basis of all life on Earth. Surprisingly, until very recently, data on photosynthesis, photosynthetic efficiencies, and photosynthesis limitations in terrestrial land plants other than spermatophytes were very scarce. Here we provide an updated data compilation showing that maximum photosynthesis rates (expressed either on an area or dry mass basis) progressively scale along the land plant’s phylogeny, from lowest values in bryophytes to largest in angiosperms. Unexpectedly, both photosynthetic water (WUE) and nitrogen (PNUE) use efficiencies also scale positively through the phylogeny, for which it has been commonly reported that these two efficiencies tend to trade‐off between them when comparing different genotypes or a single species subject to different environmental conditions. After providing experimental evidence that these observed trends are mostly due to an increased mesophyll conductance to CO2 – associated with specific anatomical changes – along the phylogeny, we discuss how these findings on a large phylogenetic scale can provide useful information to address potential photosynthetic improvements in crops in the near future. 相似文献
13.
Salinity is one of the main environmental stress for crops such as tomato which is widely spread in the Mediterranean region. It is now widely considered that in plant adaptation to salts, the time scale of the response is essential. During the initial phase of response to salinity, when the osmotic effect predominates, plant response to salts is regulated by hormones, and between them abscisic acid plays a crucial role. We showed that on tomato crops during the first phase (osmotic one) low CO2 conditioning treatment before photosynthetic response to carbon dioxide concentration (A–Ci curve) is not applicable because diffusional limitations to photosynthesis is not removed by low CO2 air concentration. Conditioning at low CO2 is not sufficient to remove diffusional limitation of photosynthesis in salt stressed tomatoes during osmotic phase. 相似文献
14.
Lack of fructose 2,6‐bisphosphate compromises photosynthesis and growth in Arabidopsis in fluctuating environments
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Alistair J. McCormick Nicholas J. Kruger 《The Plant journal : for cell and molecular biology》2015,81(5):670-683
The balance between carbon assimilation, storage and utilisation during photosynthesis is dependent on partitioning of photoassimilate between starch and sucrose, and varies in response to changes in the environment. However, the extent to which the capacity to modulate carbon partitioning rapidly through short‐term allosteric regulation may contribute to plant performance is unknown. Here we examine the physiological role of fructose 2,6‐bisphosphate (Fru‐2,6‐P2) during photosynthesis, growth and reproduction in Arabidopsis thaliana (L.). In leaves this signal metabolite contributes to coordination of carbon assimilation and partitioning during photosynthesis by allosterically modulating the activity of cytosolic fructose‐1,6‐bisphosphatase. Three independent T‐DNA insertional mutant lines deficient in 6‐phosphofructo‐2‐kinase/fructose‐2,6‐bisphosphatase (F2KP), the bifunctional enzyme responsible for both the synthesis and degradation of Fru‐2,6‐P2, lack Fru‐2,6‐P2. These plants have normal steady‐state rates of photosynthesis, but exhibit increased partitioning of photoassimilate into sucrose and have delayed photosynthetic induction kinetics. The F2KP‐deficient plants grow normally in constant environments, but show reduced growth and seed yields relative to wildtype plants in fluctuating light and/or temperature. We conclude that Fru‐2,6‐P2 is required for optimum regulation of photosynthetic carbon metabolism under variable growth conditions. These analyses suggest that the capacity of Fru‐2,6‐P2 to modulate partitioning of photoassimilate is an important determinant of growth and fitness in natural environments. 相似文献
15.
The dynamics of leaf photosynthesis in fluctuating light affects carbon gain by plants. Mesophyll conductance (gm) limits CO2 assimilation rate (A) under the steady state, but the extent of this limitation under non-steady-state conditions is unknown. In the present study, we aimed to characterize the dynamics of gm and the limitations to A imposed by gas diffusional and biochemical processes under fluctuating light. The induction responses of A, stomatal conductance (gs), gm, and the maximum rate of RuBP carboxylation (Vcmax) or electron transport (J) were investigated in Arabidopsis (Arabidopsis thaliana (L.)) and tobacco (Nicotiana tabacum L.). We first characterized gm induction after a change from darkness to light. Each limitation to A imposed by gm, gs and Vcmax or J was significant during induction, indicating that gas diffusional and biochemical processes limit photosynthesis. Initially, gs imposed the greatest limitation to A, showing the slowest response under high light after long and short periods of darkness, assuming RuBP-carboxylation limitation. However, if RuBP-regeneration limitation was assumed, then J imposed the greatest limitation. gm did not vary much following short interruptions to light. The limitation to A imposed by gm was the smallest of all the limitations for most of the induction phase. This suggests that altering induction kinetics of mesophyll conductance would have little impact on A following a change in light. To enhance the carbon gain by plants under naturally dynamic light environments, attention should therefore be focused on faster stomatal opening or activation of electron transport.Gas diffusional and biochemical processes impose significant limitations to CO2 assimilation during photosynthetic induction. 相似文献
16.
Partitioning controls on Amazon forest photosynthesis between environmental and biotic factors at hourly to interannual timescales
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Jin Wu Kaiyu Guan Matthew Hayek Natalia Restrepo‐Coupe Kenia T. Wiedemann Xiangtao Xu Richard Wehr Bradley O. Christoffersen Guofang Miao Rodrigo da Silva Alessandro C. de Araujo Raimundo C. Oliviera Plinio B. Camargo Russell K. Monson Alfredo R. Huete Scott R. Saleska 《Global Change Biology》2017,23(3):1240-1257
Gross ecosystem productivity (GEP) in tropical forests varies both with the environment and with biotic changes in photosynthetic infrastructure, but our understanding of the relative effects of these factors across timescales is limited. Here, we used a statistical model to partition the variability of seven years of eddy covariance‐derived GEP in a central Amazon evergreen forest into two main causes: variation in environmental drivers (solar radiation, diffuse light fraction, and vapor pressure deficit) that interact with model parameters that govern photosynthesis and biotic variation in canopy photosynthetic light‐use efficiency associated with changes in the parameters themselves. Our fitted model was able to explain most of the variability in GEP at hourly (R2 = 0.77) to interannual (R2 = 0.80) timescales. At hourly timescales, we found that 75% of observed GEP variability could be attributed to environmental variability. When aggregating GEP to the longer timescales (daily, monthly, and yearly), however, environmental variation explained progressively less GEP variability: At monthly timescales, it explained only 3%, much less than biotic variation in canopy photosynthetic light‐use efficiency, which accounted for 63%. These results challenge modeling approaches that assume GEP is primarily controlled by the environment at both short and long timescales. Our approach distinguishing biotic from environmental variability can help to resolve debates about environmental limitations to tropical forest photosynthesis. For example, we found that biotically regulated canopy photosynthetic light‐use efficiency (associated with leaf phenology) increased with sunlight during dry seasons (consistent with light but not water limitation of canopy development) but that realized GEP was nonetheless lower relative to its potential efficiency during dry than wet seasons (consistent with water limitation of photosynthesis in given assemblages of leaves). This work highlights the importance of accounting for differential regulation of GEP at different timescales and of identifying the underlying feedbacks and adaptive mechanisms. 相似文献
17.
In this study, we tested for the temporal occurrence of photosynthetic acclimation to elevated [CO2] in the flag leaf of two important cereal crops, rice and wheat. In order to characterize the temporal onset of acclimation and the basis for any observed decline in photosynthetic rate, we characterized net photosynthesis, gs, gm, Ci/Ca, Ci/Cc, Vcmax, Jmax, cell wall thickness, content of Rubisco, cytochrome (Cyt) f, N, chlorophyll and carbohydrate, mRNA expression for rbcL and petA, activity for Rubisco, sucrose phosphate synthase (SPS) and sucrose synthase (SS) at full flag expansion, mid‐anthesis and the late grain‐filling stage. No acclimation was observed for either crop at full flag leaf expansion. However, at the mid‐anthesis stage, photosynthetic acclimation in rice was associated with RuBP carboxylation and regeneration limitations, while wheat only had the carboxylation limitation. By grain maturation, the decline of Rubisco content and activity had contributed to RuBP carboxylation limitation of photosynthesis in both crops at elevated [CO2]; however, the sharp decrease of Rubisco enzyme activity played a more important role in wheat. Although an increase in non‐structural carbohydrates did occur during these later stages, it was not consistently associated with changes in SPS and SS or photosynthetic acclimation. Rather, over time elevated [CO2] appeared to enhance the rate of N degradation and senescence so that by late‐grain fill, photosynthetic acclimation to elevated [CO2] in the flag leaf of either species was complete. These data suggest that the basis for photosynthetic acclimation with elevated [CO2] may be more closely associated with enhanced rates of senescence, and, as a consequence, may be temporally dynamic, with significant species variation. 相似文献
18.
The reduction of photosynthetic rates with tree age has been proposed as a major driver of the productivity declination along
ontogeny. It is not clear, however, how environmental humidity affects stomatal conductance and biochemical potential of photosynthesis
in trees belonging to different age-classes. We assessed daily cycles of gas exchange on leaves of juvenile and mature individuals
of the tropical high-elevation tree Alnus jorullensis Kunth (Betulaceae), at two sites with contrasting precipitation in the Venezuelan Andes. Photosynthesis and stomatal conductance
were higher in juvenile trees during the morning and at noon in the mesic site, and were in general similar between age-classes
in the wet site. Under light-saturating conditions, the net photosynthetic rate was similar between the age-classes at the
wet site and higher for juvenile trees at the mesic site, whereas stomatal conductance did not differ between age-classes
and was higher at the wet site. Daily cycles of gas exchange and a type II regression model between photosynthesis and intercellular
CO2 concentration indicated that the better performance of juvenile trees at the mesic site was due to lower non-stomatal limitations.
These results support the proposal that non-stomatal limitations—rather than stomatal ones—are involved in the decay of photosynthesis
in mature trees, and suggest that such limitations may be evident only under drier conditions. 相似文献
19.
J. C. Ramalho Z. S. Zlatev A. E. Leitão I. P. Pais A. S. Fortunato F. C. Lidon 《Plant biology (Stuttgart, Germany)》2014,16(1):133-146
The impact of moderate water deficit on the photosynthetic apparatus of three Phaseolus vulgaris L. cultivars, Plovdiv 10 (P10), Dobrudjanski Ran (DR) and Prelom (Prel), was investigated. Water shortage had less impact on leaf hydration, RWC (predawn and midday) and predawn water potential in Prel. RWC and Ψp were more reduced in P10, while there was no osmotic adjustment in any cultivar. Although drought drastically reduced stomatal opening in P10 and DR, reduced Amax indicated non‐stomatal limitations that contributed to the negligible Pn. These limitations were on potential thylakoid electron transport rates of PSI and II, pointing to photosystem functioning as a major limiting step in photosynthesis. This agrees with decreases in actual photochemical efficiency of PSII (Fv′/Fm′), quantum yield of photosynthetic non‐cyclic electron transport (?e) and energy‐driven photochemical events (qP), although the impact on these parameters would also include down‐regulation processes. When compared to DR, Prel retained a higher functional state of the photosynthetic machinery, justifying reduced need for photoprotective mechanisms (non‐photochemical quenching, zeaxanthin, lutein, β‐carotene) and maintenance of the balance between energy capture and dissipative pigments. The highest increases in fructose, glucose, arabinose and sorbitol in Prel might be related to tolerance to a lower oxidative state. All cultivars had reduced Amax due to daytime stomatal closure in well‐watered conditions. Under moderate drought, Prel had highest tolerance, higher leaf hydration and maintenance of important photochemical use of energy. However, water shortage caused appreciable non‐stomatal limitations to photosynthesis linked to regulation/imbalance at the metabolic level (and growth) in all cultivars. This included damage, as reflected in decreased potential photosystem functioning, pointing to higher sensitivity of photosynthesis to drought than is commonly assumed. 相似文献
20.
Tsu-Wei Chen Michael Henke Pieter H. B. de Visser Gerhard Buck-Sorlin Dirk Wiechers Katrin Kahlen Hartmut Stützel 《Annals of botany》2014,114(4):677-688