NaCl胁迫对菜用大豆种子多胺代谢的影响

采用蛭石栽培,在100 mmol·L-1NaCl胁迫下,对耐盐性不同的两个品种菜用大豆种子的丙二醛(MDA)含量和多胺(PAs)代谢进行了研究.结果表明:NaCl胁迫显著增加了菜用大豆种子的MDA含量,但耐盐品种‘绿领特早’(LL)的增幅低于盐敏感品种‘理想高产95-1’(LX).与LX相比,LL种子在整个NaCl胁迫期间均维持了相对较高的游离态精胺(Spm)、结合态Spm、结合态亚精胺(Spd)、束缚态Spd和束缚态腐胺(Put)含量,较高的(Spd +Spm )/Put 和(cPAs+bPAs)/fPAs值及较低的Put/PAs值,在胁迫中、后期(9～15 d)维持了相对较高的游离态Spd含量;胁迫期间,LL的精胺酸脱羧酶(ADC)长时期(6～15 d)保持相对较高的活性,而多胺氧化酶(PAO)则长时期(6～15 d)维持相对较低的活性.综上,LL具有较强的多胺合成能力及较强的Put向Spd和Spm以及游离态多胺向结合态和束缚态多胺转化的能力,进而有效抑制了细胞的膜脂过氧化,这可能是其耐盐性较强的重要原因之一.     

Regulation of exogenous spermidine on the reactive oxygen species level and polyamine metabolism in <Emphasis Type="Italic">Alternanthera philoxeroides</Emphasis> (Mart.) Griseb under copper stress

Effects of exogenous spermidine (Spd) on the reactive oxygen species level and polyamine metabolism against copper (Cu) stress in Alternanthera philoxeroides (Mart.) Griseb leaves were investigated. Cu treatment induced a marked accumulation of Cu and enhanced contents of malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and the generation rate of O₂ ^·−. It also significantly increased putrescine (Put) levels but lowered spermidine (Spd) and spermine (Spm) levels. The activities of arginine decarboxylase (ADC), ornithine decarboxylase (ODC) and polyamine oxidase (PAO) were all elevated with the increase of Cu concentration. However, application of exogenous Spd effectively decreased H₂O₂ content and the generation rate of O₂ ^·−, prevented Cu-induced lipid peroxidation and reduced Cu accumulation. Moreover, it declined level of endogenous Put and increased levels of Spd and Spm. Activities of ADC, ODC and PAO were all inhibited by exogenous Spd. The results indicated that application of exogenous Spd could enhance the tolerance of A. philoxeroides to Cu stress by reducing the reactive oxygen level and balancing polyamine metabolism.     

Involvement of polyamines in the drought resistance of rice

This study investigated whether and how polyamines (PAs) in rice (Oryza sativa L.) plants are involved in drought resistance. Six rice cultivars differing in drought resistance were used and subjected to well-watered and water-stressed treatments during their reproductive period. The activities of arginine decarboxylase, S-adenosyl-L-methionine decarboxylase, and spermidine (Spd) synthase in the leaves were significantly enhanced by water stress, in good agreement with the increase in putrescine (Put), Spd, and spermine (Spm) contents there. The increased contents of free Spd, free Spm, and insoluble-conjugated Put under water stress were significantly correlated with the yield maintenance ratio (the ratio of grain yield under water-stressed conditions to grain yield under well-watered conditions) of the cultivars. Free Put at an early stage of water stress positively, whereas at a later stage negatively, correlated with the yield maintenance ratio. No significant differences were observed in soluble-conjugated PAs and insoluble-conjugated Spd and Spm among the cultivars. Free PAs showed significant accumulation when leaf water potentials reached -0.51 MPa to -0.62 MPa for the drought-resistant cultivars and -0.70 MPa to -0.84 MPa for the drought-susceptible ones. The results suggest that rice has a large capacity to enhance PA biosynthesis in leaves in response to water stress. The role of PAs in plant defence to water stress varies with PA forms and stress stages. In adapting to drought it would be good for rice to have the physiological traits of higher levels of free Spd/free Spm and insoluble-conjugated Put, as well as early accumulation of free PAs, under water stress.     

Exogenous polyamines enhance copper tolerance of Nymphoides peltatum

The protective effects of polyamines (PAs) against copper (Cu) toxicity were investigated in the leaves of Nymphoides peltatum. Cu treatment increased the putrescine (Put) level and lowered spermidine (Spd) and spermine (Spm) levels, thereby reducing the (Spd+Spm)/Put ratio in leaves. Exogenous application of Spd or Spm markedly reversed these Cu-induced effects for all three PAs and partially restored the (Spd+Spm)/Put ratio in leaves. It also significantly enhanced the level of proline, retarded the loss of soluble protein, decreased the rate of O2*- generation and H2O2 content, and prevented Cu-induced lipid peroxidation. Furthermore, exogenous Spd and Spm reduced the accumulation of Cu and effectively maintained the balance of nutrient elements in plant leaves under Cu stress. These results suggest that exogenous application of Spd or Spm can enhance the tolerance of N. peltatum to Cu by increasing the levels of endogenous Spd and Spm as well as the (Spd+Spm)/Put ratio.     

Physiological and biochemical responses induced by lead stress in Spirodela polyrhiza

The effects of increasing lead concentration on the activities of superoxide dismutase (SOD), peroxides (POD) and catalase (CAT), levels of ascorbate (AsA), reduced glutathione (GSH), Pb accumulation and its influence on nutrient elements, polyamines (PAs) content, as well as activities of polyamine oxidase (PAO) and ornithine decarboxylase (ODC), were investigated in Spirodela polyrhiza. POD and CAT activities increased progressively followed by a decline, while SOD activity gradually fell. The effect of Pb application on AsA content was similar to that seen for POD and CAT activities. GSH content initially rose but then declined. A significant enhancement in Pb accumulation was observed, except in the 25?μM Pb treatments. Nutrient elements were also affected. Moreover, Pb stress induced a considerable decrease in total spermidine (Spd), while the levels of total putrescine (Put) and spermine (Spm) initially increased at 25?μM Pb but then declined. Free and perchloric acid soluble conjugated (PS-conjugated) PAs contents changed in a similar way to total PAs. In addition, Pb stress induced a continuous accumulation of perchloric acid insoluble bound (PIS-bound) Spm and an initial accumulation of PIS-bound Put and Spd. The ratio of free (Spd?+?Spm)/Put significantly declined whereas the ratio of total (Spd?+?Spm)/Put rose at low Pb concentrations (25 and 50?μM). PAO activity rose gradually with an increase in Pb concentration, reaching peak values at 100?μM, while ODC activity first increased at 25?μM Pb and then declined. The results indicated that the tolerance of S. polyrhiza to Pb stress was enhanced by activating the antioxidant system, preventing the entry of the Pb ion and altering the content of polyamines.     

γ-氨基丁酸对低氧胁迫下甜瓜幼苗多胺代谢的影响

以‘西域一号’甜瓜为试验材料,采用营养液水培法,研究了低氧胁迫下外源添加γ-氨基丁酸(GABA)对甜瓜幼苗多胺代谢的影响.结果表明：与通气对照相比,低氧胁迫处理的甜瓜幼苗谷氨酸脱羧酶(GAD)活性和GABA含量显著提高,同时多胺合成酶活性提高诱导多胺含量显著增加,但二胺氧化酶(DAO)和多胺氧化酶(PAO)活性也显著提高;根系精氨酸脱羧酶(ADC)活性提高幅度较大,导致根系游离态腐胺含量较高,而叶片鸟氨酸脱羧酶(ODC)和S-腺苷甲硫氨酸脱羧酶(SAMDC)活性提高幅度较大,导致叶片游离态亚精胺(Spd)含量较高;根系游离态DAO和PAO活性显著低于叶片,其细胞壁结合态PAO活性显著高于叶片.与低氧胁迫处理相比,低氧胁迫下外源添加GABA处理的甜瓜幼苗叶片和根系中GABA和谷氨酸含量均显著提高,而GAD活性显著降低;精氨酸、鸟氨酸、甲硫氨酸含量的提高促使多胺合成酶活性显著提高,从而诱导多胺含量显著增加,DAO和PAO活性显著降低.     

Exogenous spermidine enhances Hydrocharis dubia cadmium tolerance

The effects of exogenous spermidine (Spd) on arginine decarboxylase (ADC), ornithine decarboxylase (ODC), polyamine oxidase (PAO), and diamine oxidase (DAO) activities, the rate of superoxide radical (O ₂ ^·? ) generation and polyamine (PA), malondialdehyde (MDA), and H₂O₂ contents in Hydrocharis dubia (Bl.) Backer leaves under cadmium (Cd) toxicity were studied after 6-day treatment. Cd stress increased putrescine (Put) level and lowered spermidine (Spd) and spermine (Spm) levels. In addition, the activities of ADC, DAO, and PAO were increased, while that of ODC was decreased. Exogenous application of Spd markedly reversed these Cd-induced effects. It also significantly reduced the generation of O ₂ ^·? and H₂O₂ and prevented lipid peroxidation. These results suggest that exogenous Spd can enhance the tolerance of H. dubia to Cd. The maintenance of PA homeostasis was necessary for plant metal tolerance.     

外源多胺对铜胁迫下水鳖叶片多胺代谢、抗氧化系统和矿质营养元素的影响

采用营养液水培的方法,研究了外源亚精胺(Spd)和精胺(Spm)对Cu胁迫下水鳖叶片3种形态多胺(PAs)、抗氧化系统及营养元素的影响。结果表明:(1)Cu胁迫使水鳖叶片腐胺(Put)急剧积累,Spd和Spm明显下降,从而使(Spd+Spm)/Put比值也随之下降。外源Spd和Spm显著或极显著逆转Cu诱导的PAs变化,抑制Put的积累,缓解Spd和Spm的下降,从而提高了(Spd+Spm)/Put比值。(2)外源Spd和Spm抑制了Cu胁迫诱导的多胺氧化酶(PAO)的增加,缓解了二胺氧化酶(DAO)的下降。(3)与单一Cu胁迫相比,Spd和Spm显著或极显著提高了超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、游离脯氨酸(Pro)含量,从而降低了超氧阴离子(O2.-)产生速率和过氧化氢(H2O2)含量,极显著降低了丙二醛(MDA)含量,缓解了Cu诱导的氧化胁迫。(4)外源Spd和Spm显著或极显著缓解了Cu胁迫下矿质营养元素吸收平衡的紊乱。以上结果均说明了外施Spd和Spm可增加水鳖对Cu胁迫的耐受性。     

多胺与香蕉抗寒性的关系的研究

人工气候箱中模拟寒潮对香蕉苗造成低温伤害,低温胁迫前用1 mmol·L-1多胺(PAs)和D-精氨酸(D-Arg)喷洒香蕉叶片。结果表明,低温胁迫后香蕉叶片内源腐胺(Put)含量下降,亚精胺(Spd)含量明显增多,精胺(Spm)比较稳定;D-Arg处理的内源多胺总量明显降低。外源Spd和Spm可以提高受冷胁迫的香蕉叶片中过氧化物酶(POD)活性、降低电解质渗漏率、增加可溶性糖和脯氨酸的含量,有助于提高香蕉的抗寒力;Put对香蕉抗寒力没有明显影响;D-Arg则有不利作用。     

Spermidine biosynthesis as affected by osmotic stress in oat leaves

A new assay for the evaluation of spermidine (Spd) synthase activity was developed. It involves a coupled reaction and avoids the use of decarboxylated S-adenosylmethionine, which is unstable and not easily available. This assay was applied to assess changes in enzyme activity in oat leaves subjected to osmotic stress in the dark. The results indicate that osmotically-induced putrescine (Put) accumulation in cereals results not only from the activation of the arginine decarboxylase pathway, but also from the inhibition of the activity of Spd synthase, the enzyme which catalyzes the transformation of Put to Spd. Other possibilities which could contribute to the decline of Spd and spermine levels under osmotic stress are also discussed.Abbreviations ADC arginine decarboxylase - Dap diaminopropane - DFMA -difluoromethylarginine - MGBG methylglyoxal-bis-guanylhydrazone - MTA 5-deoxy-5-methylthioadenosine - ODC ornithine decarboxylase - PA polyamines - PAO polyamine oxidase - PCA perchloric acid - PLP pyridoxal phosphate - Put putrescine - SAM S-adenosylmethionine - dSAM decarboxylated S-adenosylmethionine - SAMDC S-adenosylmethionine decarboxylase - Spd spermidine - Spm spermine     

低氧胁迫下24-表油菜素内酯对黄瓜幼苗叶片光合特性及多胺含量的影响

采用1/2 Hoagland营养液培养,研究了低氧胁迫下24-表油菜素内酯(EBR)对黄瓜幼苗叶片光合特性及多胺含量的影响.结果表明：低氧胁迫下黄瓜幼苗的净光合速率(P_n)、气孔导度(g_s)、蒸腾速率(T_r)、胞间CO₂浓度(C_i)显著下降,而叶绿素含量显著提高,幼苗生长受抑;低氧胁迫显著提高了黄瓜幼苗叶片的腐胺(Put)、亚精胺(Spd)、精胺(Spm)、多胺(PAs)含量和Put/PAs,但降低了(Spd+Spm) /Put.低氧胁迫下,外源EBR不仅显著提高了黄瓜幼苗的P_n、g_s、T_r及叶绿素含量,也显著提高了黄瓜幼苗叶片的游离态Spm、结合态Spd、Spm及束缚态Put、Spd、Spm含量,促进了PAs的进一步积累,且降低了Put/PAs,提高了(Spd+Spm)/Put．可见,外源EBR调节了黄瓜幼苗内源多胺含量及形态的变化,维持了较高的光合性能,促进了叶面积和干物质量的显著增加,缓解了低氧胁迫对黄瓜幼苗的伤害.     

氯化钠胁迫对嫁接黄瓜叶片多胺含量的影响

以日本耐盐品种‘帝王新土佐’南瓜为砧木,以’新泰密刺’黄瓜为接穗,在100 mmol·L^-1 NaCl胁迫下,对黄瓜嫁接和自根植株不同时期叶片中不同形态多胺含量的变化进行了研究.结果表明：NaCl胁迫下黄瓜嫁接植株游离态腐胺（Put）含量在胁迫2 d时与自根植株无显著差异,其余时间均显著高于自根植株;游离态亚精胺（Spd）和游离态精胺（Spm）含量在整个胁迫期间均显著高于自根植株;游离态多胺总量（PAs）在胁迫第4天出现峰值;嫁接植株游离态Put/PAs值在胁迫4 d时与自根植株无显著差异,其余胁迫时间均显著低于自根植株,而(Spd+Spm)/Put值在整个胁迫期间均显著高于自根植株;嫁接植株结合态和束缚态Put、Spd和Spm含量在整个胁迫期间均显著高于自根植株,结合态和束缚态PAs在胁迫第6天出现峰值;结合态多胺的Put/PAs值和(Spd+Spm)/Put值变化趋势与游离态多胺一致;嫁接植株束缚态Put/PAs值在胁迫6 d时与自根植株无显著差异,其余时间均显著低于自根植株,而(Spd+Spm)/Put值在整个胁迫期间均显著高于自根植株.表明黄瓜嫁接植株表现出较强的耐盐特征.     

盐胁迫下大麦幼苗多胺的种类和状态与多胺氧化酶活性的关系

200 mmol/L的NaCl胁迫8 d大麦幼苗叶片和根系中的三种形态多胺都有不同程度地下降,其中游离态多胺含量的下降幅度最大;高氯酸不溶性结合态多胺含量变化较小.根系中PAO的活性先上升后下降,而叶片中PAO的活性先下降后上升.游离态多胺中,亚精胺和精胺(Spd Spm)的含量变化与相应部位PAO的活性变化趋势相反,表明PAO在盐胁迫下可能调节了游离态多胺的含量从而影响高氯酸可溶结合态与高氯酸不溶结合态多胺的含量.     

Involvement of polyamines, abscisic acid and anti-oxidative enzymes in adaptation of Blue Panicgrass (Panicum antidotale Retz.) to saline environments

A hydroponic experiment was conducted to assess the possible involvement of polyamines (PAs), abscisic acid (ABA) and anti-oxidative enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in adaptation of six populations of Panicum antidotale Retz. to selection pressure (soil salinity) of a wide range of habitats. Plants of six populations were collected from six different habitats with ECe ranging from 3.39 to 19.23 dS m⁻¹ and pH from 7.65 to 5.86. Young tillers from 6-month-old plants were transplanted in plastic containers each containing 10 l of half strength Hoagland's nutrient solution alone or with 150 mol m⁻³ NaCl. After 42 days growth, contents of polyamines (Put, Spd and Spm) and ABA, and the activities of anti-oxidative enzymes (SOD, POD and CAT) of all populations generally increased under salt stress. The populations collected from highly saline habitats showed a greater accumulation of polyamines and ABA and the activities of anti-oxidative enzymes as compared to those from mild or non-saline habitats. Moreover, Spm/Spd and Put/(Spd + Spm) ratios generally increased under salt stress. However, the populations from highly saline environments had significantly higher Spm/Spd and Put/(Spd + Spm) ratios as compared to those from mild or non-saline environments. Similarly, the populations adapted to high salinity accumulated less Na⁺ and Cl⁻ in culm and leaves, and showed less decrease in leaf K⁺ and Ca²⁺ under salinity stress. Higher activities of anti-oxidative enzymes and accumulation of polyamines and ABA, and increased Spm/Spd and Put/(Spm + Spd) ratios were found to be highly correlated with the degree of adaptability of Panicum to saline environment.     

Changes in content of free,conjugated and bound polyamines and osmotic adjustment in adaptation of vetiver grass to water deficit

Osmotic adjustment and alteration of polyamines (PAs) have been suggested to play roles in plant adaptation to water deficit/drought stress. In this study, the changes in cell intactness, photosynthesis, compatible solutes and PAs [including putrescine (Put), spermidine (Spd) and spermine (Spm) each in free, conjugated and bound forms] were investigated in leaves of vetiver grass exposed to different intensity of water deficit stress and subsequent rewatering. The results showed that, when vetiver grass was exposed to the moderate (20% and 40% PEG-6000 solutions) and severe (60% PEG solution) water deficit for 6 days, the plant injury degree (expressed as the parameters of plant growth, cell membrane integrity, water relations and photosynthesis) increased and contents of free and conjugated Put decreased with the rise of PEG concentration. Under the moderate water deficit, the plants could survive by the reduced osmotic potential (ψ_s), increased free and conjugated Spd and Spm in leaves. After subsequent rewatering, the osmotic balance was re-established, most of the above investigated physiological parameters were fully or partly recovered to the control levels. However, it was not the case for the severely-stressed and rewatering plants. It indicates that, vetiver grass can cope well with the moderate water deficit/drought stress by using the strategies of osmotic adjustment and maintenance of total contents of free, conjugated and bound PAs in leaves.     

Stress-dependent accumulation of spermidine and spermine in the halophyte Mesembryanthemum crystallinum under salinity conditions

We studied the effects of chloride salinity (300 and 500 mM NaCl) on the content of free polyamines (PAs) from putrescine (Put) family in Mesembryanthemum crystallinum L. leaves and roots. The contents of Put and spermidine (Spd) in leaves increased temporarily, achieving the highest values on the third day of salinity treatment; thereafter (by days 7–14), they dropped sharply. The content of spermine (Spm) increased gradually, and its high level was maintained until the end of experiment. The dynamics of Spm accumulation in leaves under salinity conditions resembled that of phosphoenolpyruvate carboxylase (PEPC), a key enzyme of the water-saving CAM pathway of photosynthesis. This indicates indirectly the involvement of Spm in the common ice plant adaptation to salinity. A decrease in the molar ratios of Spd to Spm in the leaves under salinity conditions could point to the acceleration of Spm biosynthesis (accumulation) during plant adaptation, whereas the levels of Spm precursors, Put and Spd, did not increase. This phenomenon could be explained by an accelerated conversion of Spd into Spm, an active liberation of free Spm from its conjugates, or changes in the rates of studied PA biosynthesis and degradation under salinity. At the same time, the intracellular concentration of ethylene rose under these conditions. It was supposed and then demonstrated, that the pathway of ethylene biosynthesis and that of the synthesis of Put family PAs compete under severe salinity conditions. This competition might be based on the disturbances in sulfur metabolism and a decrease in the methionine content, an immediate precursor of S-adenosyl-L-methionine.     

枣品种耐盐性与叶片生物膜结合态多胺水平和H~＋-ATP酶活性的关系

120mmol·L^-1NaCl胁迫30d,耐盐性强的‘金丝小枣’叶片细胞质膜、液泡膜共价结合态腐胺（Put）、亚精胺（Spd）、精胺（Spm）含量及多胺（PAs）总水平与对照无显著性差异,但耐盐性弱的‘冬枣’叶片质膜共价结合态Put、Spd、Spm含量和PAs总水平及液泡膜Spd含量均显著降低;‘金丝小枣’叶片类囊体膜共价结合态Put含量、PAs总水平较对照显著降低,‘冬枣’则是Put、Spd、Spm含量及PAs总水平均显著降低。盐胁迫下,‘金丝小枣’叶片细胞质膜、液泡膜、类囊体膜非共价结合态Put、Spd、Spm含量及PAs总水平下降,但其中仅类囊体膜Spd含量显著低于对照,而‘冬枣’的3种膜上非共价结合态的这些多胺及其总水平均显著低于对照。与对照相比,盐胁迫下耐盐性不同的2个枣品种,叶片细胞质膜、液泡膜和类囊体膜H＋-ATP酶活性均降低,但降低幅度因枣品种和生物膜种类不同而异,且H＋-ATP酶活性与相应膜结合态多胺水平存在极紧密的正相关关系。结果表明,膜结合态多胺参与枣品种耐盐性的表达,调节盐胁迫下枣叶细胞中溶质的跨膜运输。     

‘神马’菊花花芽分化与内源多胺的关系

用薄层层析-荧光法测定菊花'神马'花芽分化期间顶芽和叶片中多胺的动态变化,分析了菊花花芽分化与多胺的关系.结果表明,花芽分化起始期顶芽中的腐胺(Put)含量急剧下降,此后在低水平上波动;叶片内Put则于总苞鳞片分化初期大幅上升,其后各阶段处于较低的水平.顶芽中精胺(Spm)与亚精胺(Spd)含量呈平行波动上升趋势,顶芽中Spin在小花原基分化初期直到花冠分化中期处于优势地位,而顶芽中Spd并无明显变化.顶芽、叶片中的Spin变化趋势相反,顶芽中Spm、Spd的含量变化趋势十分相似,但叶片中却呈交替性变化.结果显示,菊花花芽分化过程中,Put含量的降低有利于启动菊花花芽分化,后期Spm的增加有利于小花的分化,叶片可能向顶芽提供Spm,顶芽和叶片中的Spd与小花原基分化有密切关系.     

Polyamines content and physiological and biochemical responses to ladder concentration of nickel stress in Hydrocharis dubia (Bl.) Backer leaves

Influence of ladder concentration of nickel (Ni) on the leaves of Hydrocharis dubia were studied after 3 days treatment. The accumulation of Ni, the content of polyamines, proline, malondialdehyde (MDA) and soluble protein, as well as the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in the leaves were investigated. The result indicated that the toxicity of Ni manifested in respective aspect of physiological and biochemical characters. Significant increase of Ni concentration in the leaf tissue was observed, which was concentration dependent. Visible symptoms of Ni toxicity: chlorosis and necrosis occurred following the 3rd day. Meantime, treatment with Ni resulted in the increase in the generation rate of O₂^•− in the leaves. SOD and CAT activities decreased significantly in response to Ni treatment, it was possibly the reason of accumulation of O₂^•−. However, a several-fold decrease in POD activities was found. Our results indicated that because of prolonged increases in O₂^•− level, oxidative damage, measured as the level of lipid peroxidation, occured in the leaves of Ni treated fronds. The changes of the content of polyamines (PAs) were also investigated in the leaves of Hydrocharis dubia. Ni treatment significantly increased the putrescine (Put) level and lowered spermidine (Spd) and spermine (Spm) levels, thereby significantly reducing the ratio of free (Spd + Spm)/Put in leaves, which has been considered as the signal under stress. Although the trend that PS-conjugated PAs and PIS-bound PAs changed the same as free PAs, they changed in more less extent.