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1.
Stable C isotope signals in plant tissues became a key tool in explaining growth responses to the environment. The technique is based on the fundamental assumption that the isotopic composition of a given unit of tissue (e.g. a tree ring) reflects the specific C uptake conditions in the leaf at a given time. Beyond the methodological implications of any deviation from this assumption, it is of physiological interest whether new C is transferred directly from sources (a photosynthesizing leaf) to structural sinks (e.g. adjacent stem tissue), or inherently passes through existing (mobile) C pools, which may be of variable (older) age. Here, we explore the fate of (13)C-labelled photosynthates in the crowns of a 30-35 m tall, mixed forest using a canopy crane. In all nine study species labelled C reached woody tissue within 2-9 h after labelling. Four months later, very small signals were left in branch wood of Tilia suggesting that low mixing of new, labelled C with old C had taken place. In contrast, signals in Fagus and Quercus had increased, indicating more intense mixing. This species-specific mixing of new with old C pools is likely to mask year- or season-specific linkages between tree ring formation and climate and has considerable implications for climate reconstruction using stable isotopes as proxies for past climatic conditions. 相似文献
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John G. Streeter 《Physiologia plantarum》1986,68(2):294-300
When Phaseolus vulgaris L. cv. Kentucky Wonder plants were supplied with various levels of nitrate for 34 days, nodule weight (plant)−1 , acetylene reduction activity (g nodule)−1 , and sugar concentration in nodules were depressed >60% (7.5 m M nitrate vs nil nitrate). Starch concentration in nodules was more than double the sugar concentration and declined only slightly in response to nitrate level. At the highest level of nitrate, sugar concentration in nodules was 50% greater than that in roots and nodule starch was about 6-fold greater than root starch on a fresh weight basis. When plants were grown with 1 m M nitrate and then supplied with 12 m M nitrate for 7 days, the rapid decline in acetylene reduction activity coincided with a decline in sucrose concentration. However, glucose and fructose concentrations declined only after the largest decrease in acetylene reduction had occurred, and the quantitative decrease in glucose and fructose in nodules was small relative to sucrose. Other results showed that the magnitude of the effect of nitrate on some nodule carbohydrate compounds depends on Rhizobium phaseoli strain and on whether plants were grown with or without nitrate prior to experimental treatments. Some of the results are consistent with the carbohydrate-deprivation hypothesis for inhibition of legume nodules by nitrate. However, there are several complications involved in the interpretation of results of this type, and other possible explanations for the results are suggested. 相似文献
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高山分布上限灌木的碳与养分生理碳水化合物不足是高山林线树种生长限制假说之一,国内外以碳水化合物为基础的高山林线研究已有很多,而与高山林线相比,人们对碳水化合物在灌丛线形成中的作用知之甚少。除此之外,土壤养分亦被视为限制高山树种向上分布的重要因素之一。本研究将探究欧亚多种高山灌木不同器官中非结构性碳水化合物(NSCs)、氮(N)和磷(P)在不同季节及高低海拔上的含量变化规律。研究结果显示,除了与夏季相比冬季细根中具有较低的P含量以外,不同海拔与季节对灌木不同器官中的N和P含量均无显著影响。冬季灌木枝条中的NSCs和可溶性糖含量显著高于夏季。海拔与季节对细根中NSCs、淀粉、可溶性糖和糖与淀粉比值的影响均有显著的交互作用。在冬季,灌木细根中的可溶性糖与淀粉含量在海拔上限处要显著低于其在低海拔处;而在夏季,这些指标在高低海拔间均无显著差异。本研究结果表明,与高山林线树种相似,海拔分布上限的灌木冬季细根中较低的非结构性碳水化合物含量可能限制了灌木的向上分布。 相似文献
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Plants that store nonstructural carbohydrates (NSC) may rely on carbon reserves to survive carbon‐limiting stress, assuming that reserves can be mobilized. We asked whether carbon reserves decrease in resource stressed seedlings, and if NSC allocation is related to species' relative stress tolerances. We tested the effects of stress (shade, drought, and defoliation) on NSC in seedlings of five temperate tree species (Acer rubrum Marsh., Betula papyrifera Marsh., Fraxinus americana L., Quercus rubra L., and Quercus velutina Lam.). In a greenhouse experiment, seedlings were subjected to combinations of shade, drought, and defoliation. We harvested seedlings over 32–97 days and measured biomass and NSC concentrations in stems and roots to estimate depletion rates. For all species and treatments, except for defoliation, seedling growth and NSC accumulation ceased. Shade and drought combined caused total NSC decreases in all species. For shade or drought alone, only some species experienced decreases. Starch followed similar patterns as total NSC, but soluble sugars increased under drought for drought‐tolerant species. These results provide evidence that species deplete stored carbon in response to carbon limiting stress and that species differences in NSC response may be important for understanding carbon depletion as a buffer against shade‐ and drought‐induced mortality. 相似文献
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Meghan Blumstein Jessica Gersony Jordi Martínez-Vilalta Anna Sala 《Global Change Biology》2023,29(7):1854-1869
Woody plant species store nonstructural carbohydrates (NSCs) for many functions. While known to buffer against fluctuations in photosynthetic supply, such as at night, NSC stores are also thought to buffer against environmental extremes, such as drought or freezing temperatures by serving as either back-up energy reserves or osmolytes. However, a clear picture of how NSCs are shaped by climate is still lacking. Here, we update and leverage a unique global database of seasonal NSC storage measurements to examine whether maximum total NSC stores and the amount of soluble sugars are associated with clinal patterns in low temperatures or aridity, indicating they may confer a benefit under freezing or drought conditions. We examine patterns using the average climate at each study site and the unique climatic conditions at the time and place in which the sample was taken. Altogether, our results support the idea that NSC stores act as critical osmolytes. Soluble Sugars increase with both colder and drier conditions in aboveground tissues, indicating they can plastically increase a plants' tolerance of cold or arid conditions. However, maximum total NSCs increased, rather than decreased, with average site temperature and had no relationship to average site aridity. This result suggests that the total amount of NSC a plant stores may be more strongly determined by its capacity to assimilate carbon than by environmental stress. Thus, NSCs are unlikely to serve as reservoir of energy. This study is the most comprehensive synthesis to date of global NSC variation in relation to climate and supports the idea that NSC stores likely serve as buffers against environmental stress. By clarifying their role in cold and drought tolerance, we improve our ability to predict plant response to environment. 相似文献
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叶片中非结构性碳水化合物(NSC)不仅是植物维持代谢活动的重要物质基础, 也随凋落物归还土壤并为土壤微生物提供碳源, 对凋落物分解和土壤有机质形成具有重要意义。该研究比较了同质园中11个亚热带代表性树种新鲜叶与凋落叶NSC (可溶性糖、淀粉)含量。结果表明, 所有树种新鲜叶NSC含量均显著高于凋落叶, 新鲜叶中NSC含量为68.7-126.3 mg∙g-1, 而凋落叶中NSC含量为31.4-79.5 mg∙g-1。同时, 可溶性糖含量在新鲜叶和凋落叶中的变化幅度均远大于淀粉: 可溶性糖在新鲜叶中的平均含量是凋落叶的3.3倍; 而淀粉在新鲜叶中的平均含量仅为凋落叶的1.2倍。另外, 对不同功能类群的比较发现, 常绿阔叶树种与落叶阔叶树种NSC含量差异并不显著, 而针叶树种NSC含量明显低于阔叶树种。具体表现为: 在新鲜叶中, 常绿阔叶、落叶阔叶树种NSC含量平均为99.7和96.8 mg∙g-1, 而常绿针叶树种平均为75.4 mg∙g-1; 在凋落叶中, 常绿阔叶、落叶阔叶树种NSC含量平均为47.2和50.7 mg∙g-1, 而常绿针叶树种平均为33.3 mg∙g-1。这些结果表明, NSC作为林木碳代谢组分, 在叶片衰老前可能向新鲜叶转移, 反映了林木叶片碳存储策略。然而, 不管是新鲜叶还是凋落叶, 杉木(Cunninghamia lanceolata)、马尾松(Pinus massoniana)等针叶树种叶片NSC含量显著低于阔叶树种, 这可能降低这些针叶树种凋落叶初始基质质量。 相似文献
7.
Anne L. Maddison Anyela Camargo‐Rodriguez Ian M. Scott Charlotte M. Jones Dafydd M. O. Elias Sarah Hawkins Alice Massey John Clifton‐Brown Niall P. McNamara Iain S. Donnison Sarah J. Purdy 《Global Change Biology Bioenergy》2017,9(7):1264-1278
In perennial energy crop breeding programmes, it can take several years before a mature yield is reached when potential new varieties can be scored. Modern plant breeding technologies have focussed on molecular markers, but for many crop species, this technology is unavailable. Therefore, prematurity predictors of harvestable yield would accelerate the release of new varieties. Metabolic biomarkers are routinely used in medicine, but they have been largely overlooked as predictive tools in plant science. We aimed to identify biomarkers of productivity in the bioenergy crop, Miscanthus, that could be used prognostically to predict future yields. This study identified a metabolic profile reflecting productivity in Miscanthus by correlating the summer carbohydrate composition of multiple genotypes with final yield 6 months later. Consistent and strong, significant correlations were observed between carbohydrate metrics and biomass traits at two separate field sites over 2 years. Machine‐learning feature selection was used to optimize carbohydrate metrics for support vector regression models, which were able to predict interyear biomass traits with a correlation (R) of >0.67 between predicted and actual values. To identify a causal basis for the relationships between the glycome profile and biomass, a 13C‐labelling experiment compared carbohydrate partitioning between high‐ and low‐yielding genotypes. A lower yielding and slower growing genotype partitioned a greater percentage of the 13C pulse into starch compared to a faster growing genotype where a greater percentage was located in the structural biomass. These results supported a link between plant performance and carbon flow through two rival pathways (starch vs. sucrose), with higher yielding plants exhibiting greater partitioning into structural biomass, via sucrose metabolism, rather than starch. Our results demonstrate that the plant metabolome can be used prognostically to anticipate future yields and this is a method that could be used to accelerate selection in perennial energy crop breeding programmes. 相似文献
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森林凋落物(litterfall)是森林植物在其生长发育过程中新陈代谢的产物, 在物质循环和能量流动方面起着重要作用。该文利用已发表的我国主要森林凋落物的研究数据, 分析了不同组分(叶、枝和繁殖器官)凋落物量之间及其与总凋落物量之间的异速比例关系。结果表明: 我国森林叶、枝和繁殖器官的平均凋落物量分别为3 810.34、1 019.07和767.95 kg·hm-2·a-1; 温度、降水量、林龄对森林凋落物量均有一定程度的影响, 其中温度对各组分凋落物量的影响最大。叶凋落物量(LL)与总凋落物量(LT)之间呈等速生长关系(LL ∝ LT0.96), 繁殖器官和枝的凋落物量(分别为LP和LB)与LT之间呈异速比例关系, 分别为LP ∝ LT1.84和LB ∝ LT1.61。不同组分凋落物量之间具有显著的异速比例关系, 其异速指数均小于1.0。不同林型(常绿林和落叶林)各组分凋落物量之间的异速比例关系无显著差异。了解不同组分凋落物量与总凋落物量之间的异速比例关系可以为更加精确地估算森林生产力提供理论依据。 相似文献
11.
Increased chilling tolerance and altered carbon metabolism in tomato leaves following application of mechanical stress 总被引：1，自引：0，他引：1
We investigated the effects of brushing on the chilling tolerance and metabolism of nonstructural carbohydrates (soluble sugars and starch) in tomato leaves before, during and after a chilling stress. Tomato plants ( Lycopersicon esculentum Mill. cv. Caruso) were cultivated either without mechanical stress application (control plants) or with daily brushing treatments for 15 days (brushed plants), prior to a 7-day chilling treatment (8/5°C day/night). Brushing resulted in shorter plants with a 34% reduction in leaf dry weight per area and a 59% reduction of soluble sugars and starch, on a dry weight basis. The sugar to starch ratio was not affected by brushing. A greater chilling tolerance in the brushed plants was demonstrated by the maintenance of a significantly higher PSII efficiency in brushed plants (42%) compared to that of the control plants (30%) after 7 days of chilling treatment, less visible damage to the leaf tissue, and a more rapid resumption of growth during 3 days of recovery as compared to control plants. During the chilling treatment levels of soluble sugars per leaf dry weight increased 15-fold in the brushed plants and 5-fold in control plants. In the present study we have demonstrated that brushing can increase chilling tolerance in tomato plants. The observed differences in chilling tolerance and concentration of soluble sugars in the leaves may indicate an involvement of soluble sugar levels in acclimation to chilling. 相似文献
12.
Soil saccharide extraction and detection 总被引：6，自引：0，他引：6
Extraction of soil saccharides involves the use of reagents effective in breaking hydrogen and covalent bonds between soil
constituents and the saccharides. Of the many extractants proposed for saccharide determination, water is commonly used for
extraction of water-soluble mono- and polysaccharides in soil. Analysis of these water extracts by colorimetric assays (anthrone-sulfuric
acid and phenol-sulfuric acid methods) often show color development indicating that saccharides are present. However, high
performance liquid chromatography (HPLC) and gas chromatography analyses have indicated that these colorimetric assays are
prone to errors due to interferences from inorganic soil constituents such as Cl−, NO3
− and Fe+3. When water extracts (25° or 80°C) are put through deionization resins to remove interferences little to no saccharides are
present when assayed by the phenol-sulfuric acid analysis. The inability of water to extract saccharides from soil or microbial
polymers was confirmed by HPLC analysis. The phenol-sulfuric acid assay was found to be acceptable for saccharide analysis
of soil extracts only after being subjected to resin deionization for interference removal. The anthrone-sulfuric acid method
is not considered acceptable for determining saccharides in soil. 相似文献
13.
Effects of temperature and photoperiod and their interactions on budburst and on the use of carbon reserves were examined in two Mediterranean oaks differing in wood anatomy and leaf habit. Seedlings of Quercus ilex subsp. ballota (evergreen and diffuse-porous wood) and Q. faginea (semi-deciduous and ring-porous wood) were grown under two temperatures (12 and 19 °C) and two photoperiods (10 and 16 h) in a factorial experiment. In the 16 h photoperiod at 19 °C, photosynthesis was suppressed in half of the seedlings by covering leaves with aluminium foil. The concentration of soluble sugars, starch and lipids in leaves, stems and roots was assessed before and after budburst. Under the 12 °C treatment (mean current temperature in early spring in the Iberian Peninsula), budburst in Q. faginea occurred earlier than in Q. ilex . Higher temperature promoted earlier budburst in both species, mostly under the 16 h photoperiod. This response was less pronounced in Q. faginea because its budburst was also controlled by photoperiod, and because this species needs to construct a new ring of xylem before budburst to supply its growth demands. Therefore, dates of budburst of the two species became closer to each other in the warmer treatment, which might alter competitive relations between the species with changing climate. While Q. ilex relied on carbon reserves for budburst, Q. faginea relied on both carbon reserves and current photoassimilates. The different responses of the two Quercus species to temperature and photoperiod related more to xylem structure than to the source of carbon used for budburst. 相似文献
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峨眉山常绿落叶阔叶混交林的生物多样性及植物区系初探 总被引：2，自引：0，他引：2
对峨眉山常绿落叶阔叶混交林的群落结构﹑组成﹑生物多样性及植物区系等几方面进行了研究分析。结果显示峨眉山阔叶混交林由226种维管束植物组成,其中被子植物73科137属207种, 占总种数的91.6%,是峨眉山阔叶混交林的重要组成部分;群落分层现象明显,为乔木层﹑灌木层﹑草本层和层外植物4层,其中草本层发育情况差;科分布型是以热带—亚热带﹑热带—温带为主,各占22.7%, 在属的水平上则以温带分布占绝对优势(52.9%),揭示了峨眉山阔叶混交林的区系性质是以温带为主的亚热带类型;生物多样性指数处于较低的水平,在经过人为干扰后,群落处于稳定的恢复阶段。 相似文献
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林下灌木是亚热带常绿阔叶林重要的构成部分,但林下灌木细根功能性状变异规律及地下生态策略仍不清楚。以福建建瓯万木林自然保护区内9种灌木为研究对象,对细根直径、根长、比根长、组织密度、碳浓度和氮浓度6个细根性状进行研究,采用序级划分法,分析不同树种细根性状序级间的变化特征、常绿和落叶灌木细根性状之间的差异,不同序级细根性状之间的关系以及细根性状变异维度。结果表明:树种和序级对9种灌木细根形态和化学性质有显著影响。直径、根长、根组织密度随着序级的增加而逐渐增加,比根长和氮浓度逐渐减小,碳浓度在序级间的变化趋势不一,未表现出明显的规律。落叶灌木细根直径、根长和氮浓度均显著高于常绿灌木,碳浓度和组织密度显著低于常绿灌木,表明与常绿灌木相比落叶灌木更偏向于资源获取型生态策略,常绿灌木则更偏向于保守型策略。灌木细根在不同序级间的直径与比根长、组织密度,氮浓度与组织密度有较强的相关性,细根其他性状间的关系并不密切或因序级而异。主成分分析结果表明灌木细根性状变异沿一个主成分轴发生变异,该轴表示灌木细根的资源获取和保守的权衡策略。 相似文献
16.
The role of lipids and carbohydrates in the adaptation of Flammulina velutipes to hypothermia (5 to −5°C) in natural environments has been studied for the first time. The main changes are were found to occur in membrane lipids: the levels of sterols and glycolipids decreased, and the proportion of phospholipids with a high degree of nonsaturation (2.2) increased, which was due to predominance of two fatty acids, linoleic (35% of the total) and linolenic (50%). Phosphatidylcholine became the major phospholipid. Under hypothermic conditions, glycerol, known to have antifreeze properties, accumulated in the cell cytosol along with arabitol and trehalose. The significance of this biochemical strategy in the resistance of the fungus to temperatures below zero (i.e., to cryobiotic conditions) is discussed.__________Translated from Mikrobiologiya, Vol. 74, No. 3, 2005, pp. 329–334.Original Russian Text Copyright © 2005 by Tereshina, Memorskaya. 相似文献
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基于地形因子的天童地区常绿树种和落叶树种共存机制研究 总被引：3，自引：0，他引：3
位于亚热带的浙江天童和古田山常绿阔叶林大样地分布有较高比例的落叶树种,那么它们与常绿树种的共存机制是什么?常绿树种和落叶树种生态习性差异较大,二者对生境的选择应有所不同,我们推测生境分化可能是两类植物实现共存的主要机制。为检验该假设,我们以天童20ha动态样地调查数据为依托,选择个体数≥20的55个常绿树种和42个落叶树种作为分析对象,用典范对应分析(CCA)研究了地形因子对二者分布的影响差异,用torus转换检验来分析常绿树种和落叶树种与各类地形生境的关联。结果如下:(1)CCA分析表明地形因子对常绿树种分布的解释量为19.2%,对落叶树种分布的解释量为7.0%。(2)torus转换检验结果表明,与沟谷成正关联的常绿树种和落叶树种的比例分别为16.4%和28.6%,成负关联的比例分别为40%和7%;与山脊成正关联的常绿树种和落叶树种的比例分别为41.8%和4.8%,成负关联的比例分别为10.9%和47.6%;与受干扰生境成正关联的常绿树种和落叶树种的比例分别为16.4%和42.9%。上述结果说明地形对常绿树种分布的影响大于落叶树种;两个植物类群对生境的选择多呈现相反格局,尤其是在沟谷生境和山脊生境,这进一步表明生境分化是常绿树种和落叶树种共存的重要机制之一,生态位理论在一定程度上能较好地解释亚热带常绿阔叶林物种多样性的维持。 相似文献
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Junjun Ding Yuguang Zhang Mengmeng Wang Xin Sun Jing Cong Ye Deng Hui Lu Tong Yuan Joy D. Van Nostrand Diqiang Li Jizhong Zhou Yunfeng Yang 《Molecular ecology》2015,24(20):5175-5185
As two major forest types in the subtropics, broadleaved evergreen and broadleaved deciduous forests have long interested ecologists. However, little is known about their belowground ecosystems despite their ecological importance in driving biogeochemical cycling. Here, we used Illumina MiSeq sequencing targeting 16S rRNA gene and a microarray named GeoChip targeting functional genes to analyse microbial communities in broadleaved evergreen and deciduous forest soils of Shennongjia Mountain of Central China, a region known as ‘The Oriental Botanic Garden’ for its extraordinarily rich biodiversity. We observed higher plant diversity and relatively richer nutrients in the broadleaved evergreen forest than the deciduous forest. In odds to our expectation that plant communities shaped soil microbial communities, we found that soil organic matter quantity and quality, but not plant community parameters, were the best predictors of microbial communities. Actinobacteria, a copiotrophic phylum, was more abundant in the broadleaved evergreen forest, while Verrucomicrobia, an oligotrophic phylum, was more abundant in the broadleaved deciduous forest. The density of the correlation network of microbial OTUs was higher in the broadleaved deciduous forest but its modularity was smaller, reflecting lower resistance to environment changes. In addition, keystone OTUs of the broadleaved deciduous forest were mainly oligotrophic. Microbial functional genes associated with recalcitrant carbon degradation were also more abundant in the broadleaved deciduous forests, resulting in low accumulation of organic matters. Collectively, these findings revealed the important role of soil organic matter in shaping microbial taxonomic and functional traits. 相似文献