菠萝叶片绿色组织与贮水组织的腺苷酸及焦磷酸水平的昼夜变化

研究了景天酸代谢（CAM）植物菠萝（Ananas comosus)叶片绿色组织与贮水组织的苹果酸、腺苷酸及焦磷酸含量的昼夜变化。夜间苹果酸的积累仅发生在绿公组织中,而且,其含量也远高于贮水组织,绿色组织中能荷和无机磷含量夜间增高,白天下降,绿色组织中焦磷酸含量夜间增加,在白天的头几个小时迅速下降到低的水平,然后保持稳定,与绿色组织相比,贮水组织中ATP、ADP、无机磷和焦磷酸的含量低得多,且不表现昼夜变化,在贮水组织中没有测到AMP。     

菠萝叶片绿色组织与贮水组织的腺苷酸及焦磷酸水平的昼夜变化

研究了景天酸代谢(CAM)植物菠萝(Ananascomosus)叶片绿色组织与贮水组织的苹果酸、腺苷酸及焦磷酸含量的昼夜变化。夜间苹果酸的积累仅发生在绿色组织中,而且,其含量也远高于贮水组织。绿色组织中能荷和无机磷含量夜间增高,白天下降。绿色组织中焦磷酸含量夜间增加,在白天的头几个小时迅速下降到低的水平,然后保持稳定。与绿色组织相比,贮水组织中ATP、ADP、无机磷和焦磷酸的含量低得多,且不表现昼夜变化,在贮水组织中没有测到AMP。     

菠萝叶片绿色组织与贮水组织中代谢物水平的昼夜变化

研究了景天酸代谢（CAM）植物菠萝叶片绿色组织与贮水组织（WSP）的苹果酸、柠檬酸、异柠檬酸、淀粉、果糖、葡萄糖、蔗糖、葡糖－1－磷酸（G－1－P）、葡糖－6－磷酸（G－6－P）、果糖6－磷酸（F－6－P）、草酰乙酸（OAA）及磷酸烯醇式丙酮酸（PEP）水平的昼夜变化。夜间苹果酸的积累仅发生在绿色组织中,表明只有绿色组织才能进行CAM。可溶性已糖（葡萄糖和果糖）是绿色组织中夜间苹果酸累积的主要碳源。绿色组织G－1－P、G－6－P和F－6－P水平在夜间的初期上升,后期下降,昼间的头3h仍下降,3h后变化不明显。绿色组织中OAA和PEP水平也发生昼夜变化。在贮水组织中没有测到淀粉、蔗糖、OAA和PEP。除葡萄糖和果糖外,WSP中其它代谢物的含量都远低于绿色组织,而且WSP中所有代谢物都无明显的昼夜变化。     

菠萝叶片绿色组织与贮水组织中代谢物水平的昼夜变化

研究了景天酸代谢(CAM)植物菠萝叶片绿色组织与贮水组织(WSP)的苹果酸、柠檬酸、异柠檬酸、淀粉、果糖、葡萄糖、蔗糖、葡糖-1-磷酸(G-1-P)、葡糖-6-磷酸(G-6-P)、果糖-6-磷酸(F-6-P)、草酰乙酸(OAA)及磷酸烯醇式丙酮酸(PEP)水平的昼夜变化。夜间苹果酸的积累仅发生在绿色组织中,表明只有绿色组织才能进行CAM。可溶性已糖(葡萄糖和果糖)是绿色组织中夜间苹果酸累积的主要碳源。绿色组织G-1-P、G-6-P和F-6-P水平在夜间的初期上升,后期下降,昼间的头3h仍下降,3h后变化不明显。绿色组织中OAA和PEP水平也发生昼夜变化。在贮水组织中没有测到淀粉、蔗糖、OAA和PEP。除葡萄糖和果糖外,WSP中其它代谢物的含量都远低于绿色组织,而且WSP中所有代谢物都无明显的昼夜变化。     

植物液泡膜上的焦磷酸酶

本文概述了焦磷酸酶在植物物质和能量代谢过程中的调节作用,并对液泡膜焦磷酸酶的质子泵功能研究现状进行了讨论。     

铝胁迫对小麦根系液泡膜ATP酶,焦磷酸酶活性和膜脂组成的效应

研究了铝胁迫下耐铝性不同的两个小麦品种根细胞液泡膜ＡＴＰ酶、焦磷酸酶活性和膜脂的变化。与对照相比,经２０和１００ｍｏｌ／Ｌ的ＡｌＣｌ３处理后,耐铝品种Ａｌｔａｓ６６的液泡膜Ｈ＾＋－ＡＴＰ和和Ｃａ＾２＋－ＡＴＰ酶活性迅速下降;铝敏感品种Ｓｃｏｕｔ６６液泡膜Ｈ＾＋－ＡＴＰ酶和Ｃａ＾２＋－ＡＴＰ酶活性则在２０μｍｏｌ／Ｌ时增加,１００μｍｏｌ／Ｌ时下降。焦磷酸酶活性在Ａｌ－ｔａｓ６６中下降,在Ｓｃｏｕｔ     

氮素形态对番茄根系液泡膜焦磷酸酶活性的影响

采用超速梯度离心提取液泡膜微囊,研究硝态氮和铵态氮供应情况下番茄（Lycopersicon esculentum L.)根系液泡膜焦磷酸酶活性的变化。结果表明：供应铵态氮番茄根系专一性液泡膜焦磷酸酶活性比供应硝态氮的高37．7％;供应铵态氮根系液泡膜焦磷酸酶转运质子活力也明显高于供应硝态氮根系。Western blot结果表明,供应铵态氮根系液泡膜焦磷酸酶蛋白表达量也明显增加。     

NaCl胁迫对高粱根、叶鞘和叶片液泡膜ATP酶和焦磷酸酶活性的影响

NaCl胁迫初期 ,Na 主要在根和叶鞘中积累。相应地 ,根和叶鞘液泡膜ATP酶和焦磷酸酶水解活性、依赖ATP和PPi的质子泵活性及Na /H 逆向转运活性均明显增加 ,根和叶鞘的生长没有受到抑制。NaCl胁迫后期 ,Na 开始向地上部分运输并在叶片中积累。此时 ,叶片液泡膜质子泵和Na /H 逆向转运活性开始增加 ,根和叶鞘的Na/K比增加 ,其液泡膜ATP酶和焦磷酸酶水解活性、质子泵活性和Na /H 逆向转运活性下降。相应地 ,根和叶鞘的生长也下降。当保温介质中Na/K比超过 1时 ,液泡膜微囊ATP酶和焦磷酸酶活性均随Na/K比的增加而下降。表明非盐生植物液泡膜质子泵在盐胁迫的初期对Na 在液泡内的积累及其耐盐性起重要作用     

灰绿藜液泡膜焦磷酸酶基因的克隆及表达分析

采用同源克隆的方法,获得盐生植物灰绿藜的液泡膜焦磷酸酶基因(VP1)全长cDNA,命名为CgVP1。生物信息学预测分析表明,CgVP1基因包含一个2 292bp的开放阅读框,编码763个氨基酸。CgVP1不仅具有与植物液泡膜焦磷酸酶共有的氨基酸序列DVGADLVGKVE,而且CgVP1与其它植物的VP1相似性达86%。跨膜结构域预测显示,CgVP1氨基酸序列含有12个跨膜螺旋区,可能定位于细胞膜系统上。RT-PCR检测表明,200mmol/L NaCl条件下萌发生长的灰绿藜,再进行800mmol/L NaCl胁迫处理24h后,CgVP1基因表达显著增强。不同浓度KCl、CaCl2、MgCl2分别处理24h,KCl和MgCl2浓度增高,CgVP1基因表达下降,CaCl2则不影响CgVP1基因表达。研究结果表明,灰绿藜CgVP1基因表达对不同种类盐胁迫响应不同,NaCl胁迫可以上调CgVP1基因表达。该研究结果有助于阐明盐胁迫对盐生植物灰绿藜CgVP1基因表达的调控作用。     

铝胁迫对小麦根系液泡膜ATP酶、焦磷酸酶活性和膜脂组成的效应

研究了铝胁迫下耐铝性不同的两个小麦品种根细胞液泡膜ＡＴＰ 酶、焦磷酸酶活性和膜脂的变化。与对照相比,经２０ 和１００μｍｏｌ／Ｌ的ＡｌＣｌ３ 处理后,耐铝品种Ａｌｔａｓ ６６ 的液泡膜Ｈ＋ＡＴＰ 酶和Ｃａ２＋ＡＴＰ 酶活性迅速下降; 铝敏感品种Ｓｃｏｕｔ ６６ 液泡膜Ｈ＋ＡＴＰ酶和Ｃａ２＋ＡＴＰ 酶活性则在２０ μｍｏｌ／Ｌ 时增加,１００ μｍｏｌ／Ｌ时下降。焦磷酸酶活性在Ａｌｔａｓ６６ 中下降,在Ｓｃｏｕｔ ６６ 中增加。与对照相比,在ＡｌＣｌ３ ２０ μｍｏｌ／Ｌ处理时,液泡膜磷脂含量增加,Ａｌｔａｓ ６６ 中的增加比Ｓｃｏｕｔ ６６ 更为明显;１００ μｍｏｌ／Ｌ 时,Ｓｃｏｕｔ ６６ 液泡膜磷脂含量迅速下降,而Ａｌｔａｓ ６６ 下降不显著。两品种小麦在铝处理后根液泡膜糖脂结合半乳糖含量均高于对照,而Ａｌｔａｓ ６６ 中的含量又高于Ｓｃｏｕｔ６６ 。铝处理后,两品种小麦根液泡膜的棕榈酸和油酸含量增加,亚麻酸含量下降, 不饱和指数也随之下降,其中Ｓｃｏｕｔ６６ 下降更为明显。表明Ａｌｔａｓ ６６ 根细胞液泡膜比Ｓｃｏｕｔ６６ 对铝胁迫有更强的适应能力。     

Gas exchange and carbon isotope composition of Ananas comosus in response to elevated CO2 and temperature

Ananas comosus L. (Merr.) (pineapple) was grown at three day/night temperatures and 350 (ambient) and 700 (elevated) μ mol mol^–1 CO₂ to examine the interactive effects of these factors on leaf gas exchange and stable carbon isotope discrimination ( Δ ,‰). All data were collected on the youngest mature leaf for 24 h every 6 weeks. CO₂ uptake (mmol m^–2 d^–1) at ambient and elevated CO₂, respectively, were 306 and 352 at 30/20 °C, 175 and 346 at 30/25 °C and 187 and 343 at 35/25 °C. CO₂ enrichment enhanced CO₂ uptake substantially in the day in all environments. Uptake at night at elevated CO₂, relative to that at ambient CO₂, was unchanged at 30/20 °C, but was 80% higher at 30/25 °C and 44% higher at 35/25 °C suggesting that phosphoenolpyruvate carboxylase was not CO₂-saturated at ambient CO₂ levels and a 25 °C night temperature. Photosynthetic water use efficiency (WUE) was higher at elevated than at ambient CO₂. Leaf Δ -values were higher at elevated than at ambient CO₂ due to relatively higher assimilation in the light. Leaf Δ was significantly and linearly related to the fraction of total CO₂ assimilated at night. The data suggest that a simultaneous increase in CO₂ level and temperature associated with global warming would enhance carbon assimilation, increase WUE, and reduce the temperature dependence of CO₂ uptake by A. comosus .     

Day-night changes of energy-rich compounds in crassulacean acid metabolism (CAM) species utilizing hexose and starch

• Background and Aims Plants with crassulacean acid metabolism (CAM) can be divided into two groups according to the major carbohydrates used for malic acid synthesis, either polysaccharide (starch) or monosaccharide (hexose). This is related to the mechanism and affects energy metabolism in the two groups. In Kalanchoë pinnata and K. daigremontiana, which utilize starch, ATP-dependent phosphofructokinase (tonoplast inorganic pyrophosphatase) activity is greater than inorganic pyrophosphate-dependent phosphofructokinase (tonoplast adenosine triphosphatase) activity, but the reverse is the case in pineapple (Ananas comosus) utilizing hexose. To test the hypothesis that the energy metabolism of the two groups differs, day-night changes in the contents of ATP, ADP, AMP, inorganic phosphate (Pi), phosphoenolpyruvate (PEP) and inorganic pyrophosphate (PPi) in K. pinnata and K. daigremontiana leaves and in pineapple chlorenchyma were analysed.• Methods The contents of energy-rich compounds were measured spectrophotometrically in extracts of tissue sampled in the light and dark, using potted plants, kept for 15 d before the experiments in a growth chamber.• Key Results In the three species, ATP content and adenylate energy charge (AEC) increased in the dark and decreased in the light, in contrast to ADP and AMP. Changes in ATP and AEC were greater in Kalanchoë leaves than in pineapple chlorenchyma. PPi content in the three species increased in the dark, but on illumination it decreased rapidly and substantially, remaining little changed through the rest of the light period. Pi content of Kalanchoë leaves did not change between dark and light, whereas Pi in pineapple chlorenchyma increased in the dark and decreased in the light, and the changes were far greater than in Kalanchoë leaves. Light-dark changes in PEP content in the three species were similar.• Conclusions These results corroborate our hypothesis that day–night changes in the contents of energy-rich compounds differ between CAM species and are related to the carbohydrate used for malic acid synthesis.Key words: Ananas comosus, ATP, chlorenchyma, crassulacean acid metabolism, inorganic pyrophosphate, Kalanchoë daigremontiana, Kalanchoë pinnata, phosphoenolpyruvate     

Daily fluctuations of titratable acidity, content of organic acids (malate and citrate) and soluble sugars of varieties and wild relatives of Ananas comosus L. growing under natural tropical conditions

The genus Ananas has its centre of origin in northern South America. In this area, several varieties of Ananas comosus are widely cultivated, and a number of wild species are found growing under variable conditions of light intensity, soil fertility and water availability. Here we report detailed daily courses of titratable acidity, and malate, citrate and free-sugars content of several cultivated varieties of A. comosus and of A. ananassoides, a closely related species growing on granitic rock-outcrops in southern Venezuela. Day-night oscillations of both malate and citrate were detected in plants growing under full sun, but malate was by far the most important organic anion associated with CAM performance in ail populations sampled. Fructose was the dominant compound in the neutral fraction, but only sucrose showed a consistent inverse relation with the cycle of titratable acidity. The diel oscillations of free sugars measured were not always enough to account for the amount of organic anions accumulated during the night. Plants cultivated under shady conditions always showed a lower night-time increase in titratable acidity and organic acids, and also smaller oscillations in the amount of free sugars than sun exposed plants. In all populations growing under full sun, osmolality increased during the night, but it was not always possible to explain these changes on the basis of variations in molar concentrations of organic acids and sugars. Besides, no diel variations in the cations K⁺, Ca²⁺ and Mg²⁺ were detected. K⁺ was always the dominant cation (K/Ca ratios ～ 19), while Mg²⁺ was always higher than Ca²⁺ (Mg/Ca ～ 2).     

Routes of Ethephon Uptake in Pineapple (Ananas comosus) and Reasons for Failure of Flower Induction

Ethylene-releasing agents such as ethephon (2-chloroethylphosphonic acid) are used widely to induce flowering in pineapples (Ananas comosus (L.) Merrill). However, ethephon treatment is less reliable in summer, particularly if plants are treated on abnormally hot days. [¹⁴C]ethephon was used to follow uptake and translocation in leaf tissues. Up to 30% of the ethephon entered the leaf within 4 h, and up to 60% by 24 h. Uptake was dramatically modified by temperature, relative humidity, solution pH, and the surface on which solution droplets were placed. Entry occurred across the leaf cuticle and probably also by way of stomatal pores, and label was recovered at all depths within the leaf. ¹⁴C label entered more rapidly through the abaxial epidermis than through the adaxial epidermis. Low-volume spray applications to whole plants resulted in rapidly drying droplets mainly on the adaxial, distal epidermis and were rather ineffective at inducing flowering, possibly because little ethephon or ethylene reaches the shoot apex. High-volume sprays may facilitate ethephon entry because solution accumulates in leaf axils and hence remains in prolonged contact with abaxial epidermis of leaf bases close to the shoot apex. When poured into the center of the plant, 20% of a normal commercial ethephon dose induced full flowering even under adverse temperatures. It is suggested that high-volume evening spraying and avoidance of hot days may reduce the incidence of flowering failure. Received March 20, 1998; accepted September 6, 1999     

Light Intensity Affects the Coloration and Structure of Chimeric Leaves of <i>Ananas comosus</i> var<i>. bracteatus</i>

Ananas comosus var. bracteatus is an important ornamental plant because of its green/white chimeric leaves. The accumulation of anthocyanin makes the leaf turn to red especially in the marginal part. However, the red fades away in summer and winter. Light intensity is one of the most important factors affecting leaf color along the seasons. In order to understand the effects of light intensity on the growth and coloration of the chimeric leaves, Ananas comosus var. bracteatus was grown under full sunlight, 50% shade and 75% shade for 75 days to evaluate the concentration of pigments, the color parameters (values L*, a*, b*) and the morpho-anatomical variations of chimeric leaves. The results showed that a high irradiance was beneficial to keep the chimeric leaves red. However, prolonged exposure to high irradiance caused a damage, some of the leaves wrinkled and even burned. Shading instead decreased the concentration of anthocyanin and increased the concentration of chlorophyll, especially in the white marginal part of the leaves. Numerous chloroplasts were observed in the mesophyll cells of the white marginal part of the chimeric leaves under shading for 75 days. The increase in chlorophyll concentration resulted in a better growth of plants. In order to balance the growth and coloration of the leaves, approximately 50% shade is suggested to be the optimum light irradiance condition for Ananas comosus var. bracteatus in summer.     

Membrane Particles,Proteins and ATPase Activity of Tonoplast Vesicles of Mesembryanthemum crystallinum in the C-3 and CAM State*

Dimensions and area densities of membrane particles were studied by electron microscopy of replicas of freeze-fractured suspensions of tonoplast vesicles of Mesembryanthemum crystallinum L. in the C-3 state and after induction of crassulacean acid metabolism (CAM) by salinity. The results are compared with the relative contribution of tonoplast-ATPase protein to total membrane protein obtained from integration of elution profiles in size-exclusion chromatography. Coverage of tonoplast area by globular membrane particles was 20% and 36 % and ATPase in relation to total membrane protein was 33 % and 35 % in C-3 and CAM M. crystallinum, respectively. Thus, by order of magnitude, it is most likely that the particles represent the ATPase. In Kalanchoë daigremontiana Hamet et Perrier de la Bâthie the ATPase also constituted 36% of total tonoplast protein. Induction of CAM in M. crystallinum was associated with an increase in specific ATPase activity of the tonoplast and an increase of the size and area coverage of tonoplast particles, whereas the relative contribution of ATPase protein to total tonoplast protein and the molecular mass of the ATPase holoenzyme, as seen in size-exclusion chromatography, remained almost unchanged.     

CAM activity and day/night changes in the ultrastructure of stem chlorenchyma of Cissus quadrangularis L. as influenced by drought

Abstract Stem chlorenchymatous cells from well-watered and water-stressed plants of Cissus quadrangularis L. were examined to evaluate the effect of drying on cell structure and metabolism. At a stem relative water content as low as 52-58%, cellular integrity was maintained, but some qualitative and quantitative alterations occurred. Chlorophyll coment was higher in stressed plants, and the intact photosynthetic apparatus exhibited an increased degree of thylakoid stacking paralleled by a lower chlorophyll a/h ratio. Overnight malate accumulation was very low. Starch was retained but its day/night fluctuation was practically suppressed. Plastosomes were smaller and fewer, and the range of their daily fluctuation was very reduced. Vacuoles underwent fragmentation and accumulated osmiophilic deposits. The maintenance of the cellular integrity accounts for the ability of C. quadrangularis to recover rapidly from water stress.     

Microhabitats and Water Relations of Epiphytic Cacti and Ferns in a Lowland Neotropical Forest1

The pattern of canopy distribution and some water relations characteristics of the epiphytic cacti Epiphyllum phyllanthus and Rhipsalis baccifera and the epiphytic ferns Polypodium crassifolium and Polypodium phyllitidis were examined in the tropical forest of Barro Colorado Island, Panama. The epiphytic cacti were 6-fold more succulent than the epiphytic ferns, which had a 9-fold higher root: shoot ratio. The four species, especially the cacti, were more abundant on the deciduous trees Ceiba pentandra, Platypodium elegans. and Tabebuia guayacan than on the evergreen Anacardium excelsum. The water-holding capacity of the bark was 2-fold higher for A. excelsum and T. guayacan than for C. pentandra and P. elegans; the main crotches of the latter species intercepted 2-fold more rainfall than those of the former. Well-watered plants of all epiphytic species showed similar total daily transpiration. After 2 weeks of drought, daily transpiration decreased an average of 48 percent for the cacti and 73 percent for the ferns. After 4 weeks of drought, daily transpiration decreased 80 percent for the cacti and was eliminated for the ferns; succulence then decreased an average of 29 percent for the cacti and 98 percent for the ferns, but all species recovered fully within 2 d after rewetting. The epiphytic ferns had a low relative capacitance (0.16 M/Pa), causing these presumably C₃ plants often to be under water stress. A high relative capacitance (0.50 M/Pa) and crassulacean acid metabolism allowed the epiphytic cacti to occur most frequently on the driest sites of this tropical forest.