Involvement of nitrogen and cytokinins in photosynthetic acclimation to elevated CO2 of spring wheat

Acclimation of photosynthetic capacity to elevated CO₂ involves a decrease of the leaf Rubisco content. In the present study, it was hypothesized that nitrogen uptake and partitioning within the leaf and among different aboveground organs affects the down-regulation of Rubisco. Given the interdependence of nitrogen and cytokinin signals at the whole plant level, it is also proposed that cytokinins affect the nitrogen economy of plants under elevated CO₂, and therefore the acclimatory responses. Spring wheat received varying levels of nitrogen and cytokinin in field chambers with ambient (370 μmol mol⁻¹) or elevated (700 μmol mol⁻¹) atmospheric CO₂. Gas exchange, Rubisco, soluble protein and nitrogen contents were determined in the top three leaves in the canopy, together with total nitrogen contents per shoot. Growth in elevated CO₂ induced decreases in photosynthetic capacity only when nitrogen supply was low. However, the leaf contents of Rubisco, soluble protein and total nitrogen on an area basis declined in elevated CO₂ regardless of nitrogen supply. Total nitrogen in the shoot was no lower in elevated than ambient CO₂, but the fraction of this nitrogen located in flag and penultimate leaves was lower in elevated CO₂. Decreased Rubisco: chlorophyll ratios accompanied losses of leaf Rubisco with CO₂ enrichment. Cytokinin applications increased nitrogen content in all leaves and nitrogen allocation to senescing leaves, but decreased Rubisco contents in flag leaves at anthesis and in all leaves 20 days later, together with the amount of Rubisco relative to soluble protein in all leaves at both growth stages. The results suggest that down regulation of Rubisco in leaves at elevated CO₂ is linked with decreased allocation of nitrogen to the younger leaves and that cytokinins cause a fractional decrease of Rubisco and therefore do not alleviate acclimation to elevated CO₂.     

大气CO2浓度升高对春玉米土壤呼吸的影响

为探讨春玉米不同生育期土壤呼吸速率对大气CO₂浓度升高的响应,以黄土高原旱作春玉米为研究对象,通过改进的开顶式气室（OTC）模拟大气CO₂浓度升高的环境,在田间条件下设置自然大气CO₂浓度（CK）、OTC对照（OTC,CO₂浓度同CK）与CO₂浓度升高（OTC+CO₂,OTC系统自动控制CO₂浓度700 μmol/mol）3种处理。研究了旱区覆膜高产栽培春玉米播前（V0）、六叶期（V6）、九叶期（V9）、吐丝期（R1）、乳熟期（R3）、蜡熟期（R5）及完熟期（R6）土壤呼吸速率对大气CO₂浓度升高的响应特征,以及大气CO₂浓度升高对土壤呼吸速率的温度与水分效应的影响。研究发现,OTC+CO₂处理土壤呼吸速率,与CK相比,在R3和R5期分别增加43%、104%（P<0.05）,与OTC相比,R3和R5期分别提升了63%、109%（P<0.05）;OTC处理与CK相比,在整个生育期对土壤呼吸影响不显著;3种处理条件下,土壤温度和水分随生育期变化趋势基本一致,土壤呼吸速率与土壤温度和水分分别呈指数相关和抛物线型相关;结果表明：大气CO₂浓度升高对土壤呼吸的影响因生育期而异,土壤温度和土壤水分是影响旱地农田土壤呼吸的重要因素,CO₂浓度升高会使土壤呼吸温度效应值（Q₁₀）降低,土壤呼吸对土壤水分响应的阈值提高。     

大气CO_2增加对不同生长光强下龙须菜光合生理特性的影响

为了探讨未来大气CO2升高对不同生长光强下大型海藻的影响,选取经济红藻龙须菜为实验材料,研究了其生长速率、光合作用、呼吸作用、叶绿素荧光参数以及光合色素对CO2和光强的响应。实验设置两个CO2浓度,正常空气水平CO2浓度(390μL/L)和高CO2浓度(1000μL/L);两个光强梯度,高光(300μmol m-2s-1)和低光(100μmol m-2s-1)。结果表明,CO2和光强对龙须菜的生长和光合作用有明显的交互作用。大气CO2升高并没有显著影响龙须菜的生长速率,但在不同CO2处理下,龙须菜对光强的响应不同。在空气水平下,光强的变化对其生长速率影响不显著。而在高CO2作用下,高光处理下的藻体有更高的生长速率。CO2显著促进高光生长下龙须菜的呼吸作用速率,但是在低光下作用不明显。而对于光合作用速率来说,低光培养下的藻体CO2表现为负面效应,但对高光下生长的藻体作用不明显。CO2增加没有改变龙须菜生长状态下的电子传递速率,但在高光下,CO2表现为一定的抑制作用。CO2显著降低了龙须菜天线色素藻红蛋白和叶绿素a的含量。这些CO2与光强的结合效应表明,大气CO2的升高对龙须菜光合生理特性的影响随着光强的变化而呈现不同的效应,在未来评估CO2的增加对大型海藻的影响时,要充分考虑其他环境因子的耦合效应。     

Effects of elevated atmospheric CO2 on soil enzyme activities at different nitrogen application treatments

It has been predicted that elevated atmospheric CO₂ will increase enzyme activity as a result of CO₂-induced carbon entering the soil. The objective of this study was to investigate the effects of elevated atmospheric CO₂ on soil enzyme activities under a rice/wheat rotation. This experiment was conducted in Wuxi, Jiangsu, China as part of the China FACE (Free Air Carbon Dioxide Enrichment) Project. Two atmospheric CO₂ concentrations (580±60) and (380±40) μmol·mol^-1) and three N application treatments (low-150, normal-250 and high-350 kg N·hm^-2) were included. Soil samples (0-10 cm) were collected for analysis of β-glucosidase, invertase, urease, acid phosphates and β-glucosaminidase activities. The results revealed that with elevated atmospheric CO₂ β-glucosidase activity significantly decreased (P < 0.05) at low N application rates; had no significant effect with a normal N application rate; and significantly increased (P < 0.05) with a high N application rate. For urease activity, at low and normal N application rates (but not high N application rate), elevated atmospheric CO₂ significantly increased (P < 0.05) it. With acid phosphatase elevated atmospheric CO₂ only had significant higher effects (P < 0.05) at high N application rates. Under different CO₂ concentration, effects of N fertilization are also different. Soil β-glucosidase activity at ambient CO₂ concentration decreased with N fertilization, while it increased at elevated CO₂ concentration. In addition, invertase and acid phosphatase activities at elevated CO₂ concentration, significantly increased (P < 0.05) with N treatments, but there was no effect with the ambient CO₂ concentration. For urease activity, at ambient CO₂ concentration, N fertilization increased it significantly (P < 0.05), whereas at elevated CO₂ concentration it was not significant. Additionally, with β-glucosaminidase activity, there were no significant effects from N application. In general, then, elevated atmospheric CO₂ increased soil enzyme activity, which may be attributed to the following two factors: (1) elevated atmospheric CO₂ led to more plant biomass in the soil, which in turn stimulated soil microbial biomass and activity; and (2) elevated atmospheric CO₂ increased plant photosynthesis, thereby increasing plant-derived soil enzymes.     

Effects of elevated atmospheric CO2 on soil enzyme activities at different nitrogen application treatments

It has been predicted that elevated atmospheric CO₂ will increase enzyme activity as a result of CO₂-induced carbon entering the soil. The objective of this study was to investigate the effects of elevated atmospheric CO₂ on soil enzyme activities under a rice/wheat rotation. This experiment was conducted in Wuxi, Jiangsu, China as part of the China FACE (Free Air Carbon Dioxide Enrichment) Project. Two atmospheric CO₂ concentrations (580±60) and (380±40) μmol·mol^-1) and three N application treatments (low-150, normal-250 and high-350 kg N·hm^-2) were included. Soil samples (0-10 cm) were collected for analysis of β-glucosidase, invertase, urease, acid phosphates and β-glucosaminidase activities. The results revealed that with elevated atmospheric CO₂ β-glucosidase activity significantly decreased (P < 0.05) at low N application rates; had no significant effect with a normal N application rate; and significantly increased (P < 0.05) with a high N application rate. For urease activity, at low and normal N application rates (but not high N application rate), elevated atmospheric CO₂ significantly increased (P < 0.05) it. With acid phosphatase elevated atmospheric CO₂ only had significant higher effects (P < 0.05) at high N application rates. Under different CO₂ concentration, effects of N fertilization are also different. Soil β-glucosidase activity at ambient CO₂ concentration decreased with N fertilization, while it increased at elevated CO₂ concentration. In addition, invertase and acid phosphatase activities at elevated CO₂ concentration, significantly increased (P < 0.05) with N treatments, but there was no effect with the ambient CO₂ concentration. For urease activity, at ambient CO₂ concentration, N fertilization increased it significantly (P < 0.05), whereas at elevated CO₂ concentration it was not significant. Additionally, with β-glucosaminidase activity, there were no significant effects from N application. In general, then, elevated atmospheric CO₂ increased soil enzyme activity, which may be attributed to the following two factors: (1) elevated atmospheric CO₂ led to more plant biomass in the soil, which in turn stimulated soil microbial biomass and activity; and (2) elevated atmospheric CO₂ increased plant photosynthesis, thereby increasing plant-derived soil enzymes.     

The influences of increased CO2 and water supply on growth,biomass allocation and water use efficiency of Sinapis alba L. grown under different wind speeds

We examined how independent and interactive effects of CO₂ concentrations, water supply and wind speed affect growth rates, biomass partitioning, water use efficiency, diffusive conductance and stomatal density of plants. To test the prediction that wind stress will be ameliorated by increased CO₂ and/or by unrestricted water supply we grew Sinapis alba L. plants in controlled chambers under combinations of two levels of CO₂ (350 ppmv, 700 ppmv), two water regimes and two wind speeds (0.3 ms^–1, 3.7 ms^–1). We harvested at ten different dates over a period of 60 days. A growth analysis was carried out to evaluate treatment effects on plant responses. Plants grown both in increased CO₂ and in low wind conditions had significantly greater stem length, leaf area and dry weights of plant parts. Water supply significantly affected stem diameter, root weight and leaf area. CO₂ enrichment significantly increased the rate of biomass accumulation and the relative ratio of biomass increase to leaf area expansion. High wind speed significantly reduced plant growth rates and the rate of leaf area expansion was reduced more than the rate of biomass accumulation. Regression analysis showed significant CO₂ effects on the proportion of leaf and stem dry weight to total dry weight. A marked plant-age effect was dependent on water supply, wind speed and CO₂ concentration. A reduced water supply significantly decreased the stomatal conductance, and water use efficiency significantly increased with a limited water supply, low wind and increased CO₂. We found significant CO₂ x wind effects for water diffusion resistance, adaxial number of stomata and water use efficiencies and significant wind x water effect for water use efficiency. In conclusion, wind stress was ameliorated by growing in unrestricted water but not by growing in increased CO₂.     

剪叶疏花条件下高浓度CO2对汕优63生长和产量的影响

利用稻田FACE(Free Air CO_2Enrichment)系统平台,以杂交稻汕优63为供试材料,二氧化碳设环境CO_2浓度(Ambient)和高CO_2浓度(Ambient+200μmol/mol),抽穗期源库改变设剪叶(剪除剑叶)和疏花处理(相间剪除1次枝梗),以不处理为对照(CK),研究大气CO_2浓度升高对不同源库处理水稻产量形成及物质生产的影响。结果表明:CK条件下,大气CO_2浓度升高使汕优63籽粒产量显著增加32%,这主要与单位面积总颖花量大幅增加(+26%)有关,结实能力亦呈增加趋势但未达显著水平。大气CO_2浓度升高使抽穗期剪叶处理水稻的籽粒产量平均增加55%,明显大于对照水稻,这主要与受精率(+28%)、饱粒率(+23%)和所有籽粒平均粒重(+19%)大幅增加有关。相反,对抽穗期疏花处理水稻而言,高CO_2浓度环境下籽粒产量的增幅(+25%,P=0.07)明显小于对照水稻,这主要与结实能力的响应略有下调有关。与产量响应类似,大气CO_2浓度升高使对照、剪叶和疏花条件下最终生物量分别增加39%、43%和28%,除疏花处理外均达显著水平。抽穗期剪叶和疏花处理本身使水稻籽粒产量分别降低40%和45%,前者主要是结实能力大幅下降所致,而后者与总颖花量减半相关。以上结果表明,大气CO_2浓度升高使杂交水稻生产力大幅增加,人为减小源库比(如剪叶)可增强CO_2肥料效应,而增加源库比(如疏花)则可使这种肥料效应减弱。     

CO2浓度、氮和水分对春小麦光合、蒸散及水分利用效率的影响

研究了不同土壤氮和土壤水分条件下,大气CO₂浓度升高对春小麦光合作用、气孔导度、蒸散和水分利用效率的影响.结果表明,CO₂浓度升高,干旱处理的春小麦(Triticum aestivum L.)叶片光合作用速率幅度增加大于湿润处理,随着氮肥用量增加光合速率相应增加,而不施氮肥增加有限;干旱处理气孔导度幅度减少大于湿润处理,不施氮肥的大于氮肥充足的.CO₂浓度升高,干旱处理的蒸散量减少比湿润处理多,不施氮肥的蒸散量减少较为明显;但干旱处理单叶WUE增加大于湿润处理;随着氮肥用量增加,冠层WUE提高,而不施氮肥的冠层WUE最低.因而CO₂浓度升高、光合速率增加和蒸散量减少会减缓干旱的不利影响,增强作物对干旱胁迫的抵御能力.     

外来入侵植物飞机草和本地植物异叶泽兰对大气CO_2浓度升高的响应

大气CO2浓度升高影响外来植物入侵,研究外来入侵植物和本地植物对大气CO2浓度升高响应的差异,有助于准确预测和管理外来植物入侵。基于封顶式CO2生长室,模拟大气CO2浓度变化(对照和700μmol/mol),比较研究了外来入侵植物飞机草(Chromolaena odorata)和本地植物异叶泽兰(Eupatorium heterophyllum)形态、生长、生物量分配和光合特性对大气CO2浓度升高响应的差异。结果表明:(1)在当前大气CO2浓度下,飞机草总生物量、株高、基径和总叶面积高于异叶泽兰,分枝数低于异叶泽兰;CO2浓度升高,飞机的总生物量、株高、基径、分枝数和总叶面积分别增加了92%、41%、60%、325%和148%,高于异叶泽兰的32%、14%、30%、64%和79%,飞机草生长优势进一步提高。(2)无论在高或低CO2浓度下,飞机草根生物量分数(RMF)都低于异叶泽兰,叶生物量分数(LMF)和茎生物量分数(SMF)都高于异叶泽兰;CO2倍增两种植物RMF均降低,LMF和SMF均升高,但这2个参数对CO2倍增响应的种间差异不显著。(3)无论在高或低CO2浓度下,飞机草和异叶泽兰的净光合速率差异均不显著,CO2倍增对两种植物的净光合速率的促进作用相似。上述结果表明,在未来大气CO2浓度升高的条件下,飞机草的入侵性可能提高,入侵危害将加剧。     

CO2浓度和磷对不同种植方式玉米大豆生长效应研究

通过顶置光源植物生长室控制380和760 μmol·mol-1 2个CO2浓度水平,研究了磷缺乏与正常供磷条件下,CO2浓度升高对玉米/大豆间作、玉米单作和大豆单作3种种植模式下作物株高、茎粗、叶面积及干物质积累的影响.结果表明:(1)CO2浓度升高能显著增加单/间作玉米、大豆的株高、茎粗、叶面积、根干重、地上部干重及总干重.(2)CO2浓度升高对供磷水平下单、间作玉米大豆的株高、茎粗、叶面积及干物质积累量增加的正效应均大于缺磷处理.(3)两种CO2浓度下,间作大豆与单作大豆生长差异不显著,而间作玉米较单作玉米有明显的生长优势,且供磷和CO2浓度的升高均能够促进这种优势.     

Impact of elevated CO2 concentration on ultrastructure of pericarp and composition of grain in three Triticum species of different ploidy levels

Triticum species of three ploidies were grown under ambient (375 μl/l) or elevated (FACE, 550 μl/l) CO₂ concentration [CO₂] to evaluate their response to CO₂ enrichment. The consistent effect of elevated CO₂ was an increase in concentration of starch and decrease in concentration of protein in the grain. Transmission electron micrographs revealed an increase in width and area of chloroplasts, and change in shape from elliptical in ambient to round in elevated [CO₂]. There was a corresponding increase in starch grain size and number in chloroplasts. The large starch grains distributed among thylakoids resulted in separation and distortion of internal membrane system in chloroplasts. The level of response was different in species of different ploidy levels. Maximum increase in starch concentration, and least decrease in protein concentration, was observed in Triticum dicoccoides, which also proved the most suitable species in terms of C:N ratio.     

塔里木河下游胡杨群落CO2通量特征与水分利用效率

以极端干旱环境中的胡杨群落为研究对象,利用涡度相关通量观测系统,研究了胡杨群落CO_2通量与水分利用效率在不同物候期的动态规律。结果表明:胡杨CO_2通量在不同物候期日变化趋势基本一致,但存在明显的季节差异,其中果熟期CO_2通量变化幅度最大,开花期最小,展叶期介于二者之间。相关分析表明,胡杨群落CO_2通量均与显热通量、潜热通量、动量通量、土壤热通量、净辐射以及空气相对湿度呈极显著相关。其中,净辐射、潜热通量和显热通量与CO_2通量的相关系数较大,其变化范围分别为-0.82—-0.88、-0.64—-0.66和-0.63—-0.94,是影响群落CO_2通量的最主要环境因子。胡杨群落水分利用效率(WUE)同样存在明显日变化规律。其时间动态表现为:群落水分利用效率在开花期、叶黄期和落叶期变化幅度大,开花期最高,在展叶期和果熟期WUE最稳定。净辐射和风速是影响群落水分利用效率的两个最关键要素。     

Responses of Gmelina arborea, a tropical deciduous tree species, to elevated atmospheric CO2: Growth, biomass productivity and carbon sequestration efficacy

The photosynthetic response of trees to rising CO₂ concentrations largely depends on source-sink relations, in addition to differences in responsiveness by species, genotype, and functional group. Previous studies on elevated CO₂ responses in trees have either doubled the gas concentration (>700 μmol mol⁻¹) or used single large addition of CO₂ (500-600 μmol mol⁻¹). In this study, Gmelina arborea, a fast growing tropical deciduous tree species, was selected to determine the photosynthetic efficiency, growth response and overall source-sink relations under near elevated atmospheric CO₂ concentration (460 μmol mol⁻¹). Net photosynthetic rate of Gmelina was ∼30% higher in plants grown in elevated CO₂ compared with ambient CO₂-grown plants. The elevated CO₂ concentration also had significant effect on photochemical and biochemical capacities evidenced by changes in F_V/F_M, ABS/CSm, ET₀/CSm and RuBPcase activity. The study also revealed that elevated CO₂ conditions significantly increased absolute growth rate, above ground biomass and carbon sequestration potential in Gmelina which sequestered ∼2100 g tree⁻¹ carbon after 120 days of treatment when compared to ambient CO₂-grown plants. Our data indicate that young Gmelina could accumulate significant biomass and escape acclimatory down-regulation of photosynthesis due to high source-sink capacity even with an increase of 100 μmol mol⁻¹ CO₂.     

Effect of CO2 concentration on the PIC/POC ratio in the coccolithophore Emiliania huxleyi grown under light-limiting conditions and different daylengths

We compared the effect of CO₂ concentration ([CO₂], ranging from ∼5 to ∼34 μmol l⁻¹) at four different photon flux densities (PFD=15, 30, 80 and 150 μmol m⁻² s⁻¹) and two light/dark (L/D) cycles (16/8 and 24/0 h) on the coccolithophore Emiliania huxleyi. With increasing [CO₂], a decrease in the particulate inorganic carbon to particulate organic carbon (PIC/POC) ratio was observed at all light intensities and L/D cycles tested. The individual response in cellular PIC and POC to [CO₂] depended strongly on the PFD. POC production increased with rising [CO₂], irrespective of the light intensity, and PIC production decreased with increasing [CO₂] at a PFD of 150 μmol m⁻² s⁻¹, whereas below this light level it was unaffected by [CO₂]. Cell growth rate decreased with decreasing PFD, but was largely independent of ambient [CO₂]. The diurnal variation in PIC and POC content, monitored over a 38-h period (16/8 h L/D, PFD=150 μmol m⁻² s⁻¹), exceeded the difference in carbon content between cells grown at high (∼29 μmol l⁻¹) and low (∼4 μmol l⁻¹) [CO₂]. However, consistent with the results described above, cellular POC content was higher and PIC content lower at high [CO₂], compared to the values at low [CO₂], and the offset was observed throughout the day. It is suggested that the observed sensitivity of POC production for ambient [CO₂] may be of importance in regulating species-specific primary production and species composition.     

6种草本植物对干旱胁迫和CO2浓度升高交互作用的生长响应

以CO2浓度升高为主要标志的全球气候变化及由其引起的极端气候变化对陆地生态系统产生了重要的影响。利用步入式CO2生长室模拟研究了CO2浓度变化(400和700μL/L)和干旱胁迫(水分充足CK:100%FC(田间持水量);中度干旱MS:40%FC;重度干旱SS:20%FC)的交互作用对草本植物网果酸模(Rumex chalepensis)、野豌豆(Vicia sepium)、泥胡菜(Hemmistepta lyrata)、风轮菜(Clinopodium chinense)、藜(Chenopodium album)和玉米石(Sedum album)生长特性的影响。结果表明:CO2浓度升高总体上刺激了网果酸模、野豌豆、泥胡菜、风轮菜和藜这5种C3植物在任何水分条件下的生长,也刺激了玉米石在水分条件较好下的生长;干旱胁迫总体上抑制了所有6种植物的生长,但中度干旱胁迫有刺激CAM植物玉米石生长的趋势。CO2浓度升高能否缓解干旱的负面影响具有明显的种间差异:CO2浓度升高减缓了干旱胁迫对泥胡菜和风轮菜的负面影响,这种缓解作用在网果酸模和野豌豆中显著降低,对藜没有明显的促进作用,对干旱下的玉米石的生长却起到了抑制作用。CO2浓度升高总体上增加了根质量分数和干物质含量;干旱胁迫明显提高了6种草本植物的根生物量的分配比例,降低了干物质含量;但CO2浓度升高和干旱胁迫的交互作用可导致不同的物种产生不同的响应,说明植物能够通过调节生物量分配和植株本身的水分含量保持能力来适应CO2浓度和干旱胁迫的交互影响,这种调节能力取决于植物在碳的吸收和水分散失之间的平衡"trade-off"。研究结果有助于增进草本植物对未来气候变化的适应性理解,为评估和预测全球气候和水文变化对植物的生理生态影响提供理论依据。     

CO_2浓度升高对杉木幼苗生长及其光合特性和养分含量的影响

以杉木优良无性系‘洋061’幼苗为材料,设置常规CO_2浓度400μL·L~(-1)(对照组)和CO_2加富浓度800μL·L~(-1)(处理组)两个处理,研究CO_2浓度加富对杉木幼苗生长、根系形态特征、光合生理以及养分含量的影响,以明确杉木优良无性系对CO_2浓度升高的响应特征,为杉木苗木高效培育提供理论依据。结果表明:(1)CO_2加富能显著促进杉木幼苗生物量的积累和苗高的生长,并显著促进杉木根系生长,其根长、根系表面积、根系体积和根系直径分别较对照增加14.60%、28.26%、41.98%和14.70%。(2)CO_2加富能促进杉木叶片类胡萝卜素含量显著增加,使杉木叶片净光合速率(P_n)、胞间二氧化碳浓度(C_i)和水分利用效率(WUE)分别较对照显著提高51.03%、14.13%和151.20%,并使气孔导度(G_s)和蒸腾速率(T_r)分别显著下降58.72%和44.00%。(3)CO_2加富使杉木叶片最大荧光(F_m)、可变荧光(F_v)、PSⅡ潜在光化学效率(F_v/F_o)、PSⅡ实际光化学效率(Φ_(PSⅡ))和光化学淬灭系数(qP)分别较对照显著增加11.48%、11.25%、6.33%、20.38%和30.34%,且不同处理间差异显著,非光化学淬灭系数(NPQ)较对照显著下降21.90%(P0.05),但对初始荧光(F_o)和PSⅡ最大光化学效率(F_v/F_m)无显著影响(P0.05)。(4)CO_2加富处理显著增加植株钙元素的含量,并显著降低植株磷元素的含量。研究认为,短期CO_2加富处理可通过增加光合色素含量,提高叶片净光合速率和光能利用效率,进而增强叶片光合能力,同时促进根系生长,增强植物对养分吸收的能力,最终促进杉木幼苗的生长。     

Effects of CO2 and nitrogen supply on the biochemical composition of Ulva rigida with especial emphasis on lipid class analysis

Lipid class composition was analysed in the green macroalga Ulva rigida grown under normal (350 ppm) and high (10,000 ppm) CO₂ levels, and in nitrate saturated and nitrogen limited conditions. A new protocol for the extraction of lipids has been defined. Culture conditions altered the fate of assimilated carbon, and significant changes were observed in protein and total lipid content in particular. A CO₂-enriched atmosphere conditioned the effects of nitrogen limitation on lipid class composition, revealing deep qualitative changes in carbon metabolism. Triglycerides accumulated at high CO₂ and under nitrogen limitation, while chloroplast-related lipids showed an inverse response. Changes in phospholipids could be related to carbon availability as they did not respond to nitrogen limitation. The ratio sterols/acetone-mobile polar lipids followed a negative linear relation with the optimum quantum yield for photosynthetic electron transport (F_v/F_m), and was considered as an index of the «light status» of the cell. The specificity of the response of lipid classes to growth conditions in U. rigida emphasizes the potential role of lipid class analyses as a diagnostic tool for environmental stress.     

大气CO2浓度升高对B型烟粉虱大小、酶活及其寄主的选择性影响

以CO₂浓度升高为作用因子,观测了连续3代饲养在转Bt基因棉(GK-12)和亲本棉泗棉3号(S3)上B型烟粉虱的个体大小、解毒酶活性及第3代烟粉虱的选择性和产卵量。结果表明,CO₂浓度和棉花品种处理对第2、3代烟粉虱卵长、伪蛹大小、雌雄成虫大小的影响均不显著,但CO₂浓度升高使第1代烟粉虱的伪蛹长、雌虫翅展和雌、雄虫长显著低于对照CO₂浓度下生长的烟粉虱;取食S3的伪蛹长、雌虫长和雌虫翅展分别比相应的对照浓度下的低2.81%、2.95%、0.94%,取食GK-12的雌虫翅展和雄虫长均比相应的对照浓度下的低2.08%和2.58%。3种解毒酶的活性测定显示,取食高CO₂浓度处理的转基因棉GK-12上的F3代烟粉虱的谷胱甘肽S转移酶(Glutathione Stransferase, 简称GSTs)活性和取食亲本棉S3的F1代的乙酰胆碱酯酶(Acetylcholinesterase;简称AchE)的活性分别比对照处理的增加45.73%和27.68%;而羧酸酯酶(Carboxylic Ester hydrolase;简称 CarE)在取食4个处理的棉花上烟粉虱的活性均无显著的差异;而取食对照CO₂条件下GK-12棉花的F1代烟粉虱GSTs活性比取食S3棉花低35.12%。对3个因子的交互分析结果显示,C0₂浓度对3种酶活影响均不显著,品种对GSTs的影响显著,世代、CO₂×品种及CO₂×品种×世代间的交互作用对AchE酶活影响显著,各因子对CarE的活性影响均不显著。烟粉虱的选择实验结果表明,4种处理的F3代B型烟粉虱均喜好选择在高CO₂处理的棉花,而且选择高CO₂处理的GK-12的数量多于其他3个处理,其中对照浓度下生长的烟粉虱选择高CO₂的GK-12比高CO₂处理的S3、对照浓度处理的GK-12 和S3分别增加9.175%, 19.89%、27.93%; 而高浓度下生长的烟粉虱选择高CO₂的GK-12比高CO₂处理的S3、对照浓度处理的GK-12 和S3分别增加12.56%,21.05%,28.73%。72h的产卵量检测发现,烟粉虱在高CO₂处理的2种棉花上的产卵量也是多于对照条件下的棉花,对照条件下的棉花相比,高CO₂和对照浓度下生长的烟粉虱的在高CO₂处理的2种棉花上的产卵量分别增加24.55%和19.03%;在高CO₂浓度下生长的F3代烟粉虱更喜好在高CO₂浓度处理的GK-12上产卵,与对照浓度下的GK-12相比增加26.93%,差异达到显著水平。