低温锻炼与CaCl2处理对毛白杨幼苗可溶性总蛋白、CaM及抗冻性的影响

低温锻炼提高了毛白杨幼苗叶片和枝条中钙调素 (CaM)和可溶性总蛋白含量 ,同时也提高了幼苗的抗冻性 .CaCl2 处理对上述低温锻炼的作用有加强的效果 ,体现在明显提高了CaM和可溶性总蛋白含量以及幼苗抗冻性 ;钙离子螯合剂EGTA、钙离子通道阻断剂LaCl3 或钙调素拮抗剂CPZ处理则减弱了低温锻炼的效应 ,表现出CaM和可溶性总蛋白含量以及幼苗抗冻性明显降低 .进一步研究发现 ,CaCl2 处理的低温锻炼不仅能减轻低温胁迫引起的CaM和可溶性总蛋白含量的下降程度 ,而且有利于幼苗在恢复过程中CaM和可溶性总蛋白水平的迅速回升 .这表明Ca2 + CaM可能参与了CaM和可溶性总蛋白的合成及抗冻性的诱导     

CaCl2在毛白杨幼苗抗冻性低温诱导中的作用

不同浓度的CaCl2 处理对毛白杨幼苗抗冻性的提高效应是不同的 ,其中 10mmol·L-1CaCl2 处理更有利于幼苗抗冻性的提高 ,而且处理最适宜时间为 5天 .低温锻炼不仅提高了毛白杨幼苗叶片和枝条中钙调素含量 ,同时也提高了幼苗抗冻性 .CaCl2 处理对低温锻炼的作用有加强效果 ,而钙离子螯合剂EGTA、钙离子通道阻断剂LaCl3 或钙调素拮抗剂CPZ处理则减弱低温锻炼效应 ,表现出CaM含量和幼苗抗冻性明显降低 .这表明Ca2 + CaM可能参与了幼苗抗冻性的诱导     

在低温锻炼中毛白杨幼苗可溶性总蛋白、RNA、DNA、RNase及抗冻性的变化

低温锻炼不仅提高了毛白杨幼苗存活率和抗冻性以及RNA和可溶性总蛋白的含量 ,降低了RNase活性 ,而且能减轻低温胁迫引起的RNA和可溶性总蛋白含量的下降程度和RNase活性的提高 ,有利于幼苗在恢复过程中RNA和可溶性总蛋白水平的迅速回升以及RNase活性的降低 .进一步研究发现 ,DNA含量无论在低温锻炼中还是在低温胁迫下或是在随后的恢复生长期均保持相对稳定 ;低温锻炼所引起的RNA含量的增加 ,与RNase活性的降低呈明显的负相关 ,与可溶性总蛋白含量的增加以及幼苗抗冻性的提高成正相关 .这表明低温锻炼可能抑制RNase活性 ,有效地促进RNA含量的增加 ,而RNA可能参与了可溶性总蛋白的合成及抗冻性的诱导     

甜杨抗冻性低温诱导过程中G6PDHase ,ATPase及蛋白质的变化(英文)

首次研究了低温锻炼对甜杨 (Populussuaveotlens)幼苗抗冻性的效应 ,并对低温锻炼中的G6PDHase ,ATPase及蛋白质的动态变化过程进行了测定 .另外 ,在低温锻炼前用蛋白质合成抑制剂环己亚胺对甜杨幼苗进行预处理 .试验结果表明 ,适当的低温锻炼可明显提高甜杨幼苗的抗冻性 ,但整个低温锻炼过程必须分两个阶段进行 ,第一阶段在 - 10℃的温度下锻炼 6天 ,虽对甜杨幼苗抗冻性的提高效应不明显 ,但它是不可缺少的 ,它可为第二阶段的 - 2 0℃锻炼的进行及抗冻性的完全发育提供基础 .伴随着幼苗枝条中蛋白质含量及G6PDHase和ATPase活性提高的同时 ,也明显提高了幼苗的抗冻性 ;脱锻炼 2天后 ,幼苗抗冻性下降到未锻炼水平 ,而枝条中蛋白质含量及G6PDHase和AT Pase活性虽有下降但略高于未锻炼 .蛋白质合成抑制剂环己亚胺预处理则明显降低了幼苗抗冻性和蛋白质含量 .进一步分析发现 ,低温锻炼中的G6PDHase和ATPase活性及蛋白质含量的变化与幼苗抗冻性的提高密切相关     

低温锻炼对冷胁迫下油茶幼苗光合速率与抗氧化酶活性的影响

以油茶品种"杂优闽1"为试验材料,以未经低温锻炼的油茶幼苗为对照,研究了油茶幼苗在(10±0.5)℃低温锻炼、(2±0.5)℃冷胁迫和常温恢复期间的光合速率和抗氧化酶活性的变化。结果表明:低温锻炼3 d可明显提高油茶幼苗的抗寒性;冷胁迫3 d,经低温锻炼后的油茶幼苗叶片净光合速率和相对含水量明显高于对照;且其在常温下的恢复也较对照迅速。在低温锻炼和冷胁迫期间,油茶幼苗叶片脯氨酸和可溶性糖含量明显增加,且丙二醛(MDA)含量明显低于对照;经低温锻炼的油茶幼苗叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性则均明显高于未经低温锻炼的油茶幼苗,说明渗透调节物质含量增加和保护酶活性增强在低温锻炼诱导油茶幼苗的抗寒性上发挥着重要的作用。     

低温锻炼对翅荚木幼苗抗氧化酶活性和保护物质的影响

采用梯度降温对翅荚木幼苗进行低温锻炼,测定其在低温锻炼过程中抵御低温保护物质的含量和抗氧化酶的活性,结果表明:低温锻炼使POD和SOD活性明显提高;可溶性蛋白、可溶性糖和脯氨酸含量升高;在脱锻炼期间可溶性蛋白、可溶性糖含量和POD、SOD活性仍略高于或接近于对照水平。     

钙-钙调素对中东杨扦插苗的诱导抗冻作用

以零下低温锻炼和结合效应剂（CaCl2、钙离子螯合剂EGTA、钙离子通道阻断剂LaCl3或钙调素拮抗剂CPE）处理的低温锻炼下的中东扬扦插苗为试材，对其体内丙二醛（MDA）及钙调素CaM含量，SOD、POD及线粒体Ca^2-＋ATPase活性分别进行测定。结果表明，低温锻炼不仅在一定程度下提高了幼苗CaM含量，提高了SOD、POD和Ca^2＋-ATPase活性，降低了MDA含量；而且减少了低温胁迫所引起的SOD、POD，Ca^2＋＋ATPase和CaM含量的下降程度以及MDA的增加幅度。在低温锻炼的同时。用CaCl2处理能加强低温锻炼的效果，但这种效应可被EGTA、LaCl3或CPZ处理抑制。经低温锻炼后，幼苗中的CaM含量的增加有助于SOD、POD和线粒体Ca^2＋-ATPase活性的提高，进而对幼苗抗冻性的提高有明显的促进作用。     

落叶松几个抗寒生理指标研究

为研究落叶松对低温的生理反应,探讨其抗寒机制,以华北落叶松（Ｌａｒｉｘ ｐｒｉｎａｐｉａｍ－ｒｕｐｐｒｅｃｈｔｉｉ）幼苗为材料,研究氏温和ＡＢＡ处理对植物可溶性糖含量、水溶性蛋白质含量、脯氨酸含量以及膜稳定性的影响。试验结果表明：低温处理的幼苗,可溶性糖、水溶性蛋白质以及脯氨酸含量均增加,膜的稳定性增强;ＡＢＡ处理的幼苗,水溶性蛋白质的含量明显增加,增强膜的稳定性,对提高幼苗可溶性糖含量和脯氨酸含     

外源硼酸钠对桂花幼苗抗寒性的影响

采用人工气候室模拟低温环境,研究不同浓度的外源硼酸钠对桂花幼苗抗寒性的影响。结果显示:在4℃低温胁迫下,随时间的延长,外源硼酸钠处理桂花叶片MDA含量和可溶性蛋白含量逐渐升高,游离脯氨酸、可溶性糖含量以及SOD、CAT酶活性变化趋势为先上升后下降,POD活性持续上升;外喷0.5%~1%浓度的硼酸钠可显著减少桂花叶片MDA含量,增加游离脯氨酸,促进可溶性蛋白和可溶性糖的积累,提高SOD、POD、CAT抗氧化酶活性;0.5%浓度的硼酸钠可促进植株纵向生长,1%~2%浓度的硼酸钠对低温胁迫下桂花幼苗纵向生长产生一定的抑制作用,且浓度越高抑制性越强。低温胁迫对桂花幼苗产生一定程度的伤害,适当浓度外源硼酸钠处理可以有效缓解低温胁迫对桂花叶片的伤害,提高桂花幼苗的抗寒性。     

脱落酸对低温胁迫下水曲柳幼苗叶片抗寒生理指标的影响

以3a生盆栽水曲柳幼苗为试材,喷施不同浓度的脱落酸,喷后第1d、5d、10d和15d分别采集带叶枝条测定常温和低温胁迫后幼苗叶片质膜相对透性、SOD、POD、可溶性糖含量、水溶性蛋白质含量的变化。进行自然条件下季节性低温处理试验,以验证人工低温试验中所得结论。研究结果表明：10mg／L浓度的ABA增强水曲柳幼苗抗寒性的作用效果最好,能显著降低电导率,显著提高蛋白质含量、SOD活性、POD活性。但对可溶性糖含量的影响无明显变化。30mg／L浓度的ABA预处理有一定的作用效果,但高浓度的60mg／LABA预处理对于增强水曲柳幼苗抗寒性出现了一定的抑制作用。在自然低温条件下,10mg／L浓度的ABA预处理增强水曲柳幼苗抗寒性的作用效果最好,高浓度的无显著作用。     

Effects of cold-hardening on compatible solutes and antioxidant enzyme activities related to freezing tolerance in Ammopiptanthus mongolicus seedlings

Cold acclimation is associated with many metabolic changes that lead to an increase of freezing tolerance. In order to investigate the biochemical process of cold acclimation in Ammopiptanthus mongolicus, seedlings were acclimated at 2℃ under 16-h photoperiod （150 μmol·m^-2·s^-1 photosynthetically active radiation） for 14 d. Freezing tolerance in seedlings increased after 14 d of cold-hardening. Contents of protein, proline and solute carbohydrate in cotyledon increased after cold acclimation. Patterns of isozymes of superoxide dismutase （SOD）, peroxidase, catalase and polyphenol oxidase （PPO） were investigated. The activities of SOD, peroxidase and PPO in cold acclimated plants were increased during cold-hardening. We deduced that compatible solutes and antioxidant enzymes play important roles in development of freezing tolerance during cold acclimation in this evergreen woody plant.     

Influence of ozone on cold acclimation in sugar maple seedlings

During summer 1994, sugar maple (Acer saccharum Marsh.) seedlings were grown in open-top chambers supplied with air containing near ambient ozone concentration (control, low O(3)) or three times the ambient ozone concentration (high O(3)). The rate of CO(2) assimilation was significantly reduced by chronic exposure to a high concentration of ozone during the summer. During fall, seedlings were removed from the open-top chambers and acclimated to cold under natural conditions. In both species during cold acclimation, the starch concentration decreased, whereas the sucrose concentration increased. There was no treatment effect on the freezing tolerance of roots, even though roots in the high-O(3) treatment accumulated higher concentrations of the cryoprotective oligosaccharides raffinose and stachyose than control roots. Cold acclimation occurred earlier and stachyose concentration of stems was higher in high-O(3)-treated seedlings than in low-O(3)-treated seedlings. Cold acclimation was associated with an earlier accumulation of ABA in the xylem sap of high-O(3)-treated seedlings compared with low-O(3)-treated seedlings.     

Different responses of northern and southern ecotypes of Betula pendula to exogenous ABA application

We investigated responses of northern and southern ecotypes of silver birch (Betula pendula Roth) to exogenous abscisic acid (ABA) under controlled environmental conditions to determine the role of ABA in cold acclimation and dormancy development. Abscisic acid was sprayed on the leaves and changes in freezing tolerance, determined by the electrolyte leakage test, and bud dormancy were monitored. Applied ABA induced cold acclimation but had no effect on growth cessation in seedlings grown in long day conditions (LD, 24-h photoperiod at 18 degrees C). It enhanced freezing tolerance and accelerated growth cessation in seedlings grown in short day conditions (SD, 12-h photoperiod at 18 degrees C), and slightly enhanced freezing tolerance in seedlings grown at low temperature (LT, 24-h photoperiod at 4 degrees C) in both ecotypes. There were distinct ecotypic differences in ABA-induced cold acclimation and dormancy development. The northern ecotype was more responsive to applied ABA than the southern ecotype, resulting in more rapid development of freezing tolerance in all treatments, and earlier dormancy development in SD. When plants were grown in a photoperiod just above the critical photoperiod for the ecotype (defined as the longest photoperiod that induces growth cessation), applied ABA caused growth cessation and dormancy development. Compared with ABA-treated seedlings grown in SD, dormancy development was delayed in ABA-treated seedlings exposed to a near-critical photoperiod, but even in this treatment dormancy developed faster in the northern ecotype than in the southern ecotype.     

Differential responses of silver birch (Betula pendula) ecotypes to short-day photoperiod and low temperature

We investigated interrelations of dormancy and freezing tolerance and the role of endogenous abscisic acid (ABA) in the development of silver birch (Betula pendula Roth) ecotypes in controlled environments. Short-day treatment induced growth cessation, bud set and dormancy development, as well as initiation of cold acclimation and an increase in freezing tolerance. Subsequent low temperature and short days (12-h photoperiod) resulted in a significant increase in freezing tolerance, whereas bud dormancy was gradually released. The concentration of ABA increased in response to short days and then remained high, but ABA concentrations fluctuated irregularly when the dormant plants were subsequently exposed to low temperature during short days. Although there was a parallel development of freezing tolerance and bud dormancy in response to short days, subsequent exposure to low temperature had opposite effects on these processes, enhancing freezing tolerance and releasing dormancy. Compared with the southern ecotype, the northern ecotype was more responsive to short days and low temperature, exhibiting earlier initiation of cold acclimation, growth cessation and an increase in ABA concentrations in short days, and higher freezing tolerance, faster dormancy release and greater alteration in ABA concentrations when subsequently exposed to low temperature during short days. The rates and extent of the increases in ABA concentration may be related to increases in freezing tolerance and dormancy development during short days, whereas the extent of the fluctuations in ABA concentration may play an important role in enhancing freezing tolerance and releasing dormancy during a subsequent exposure to low temperature during short days.     

Atmospheric carbon dioxide enrichment reduces carbohydrate and nitrogen reserves in overwintering Picea mariana

Abstract

Elevated levels of atmospheric carbon dioxide (CO₂) can directly affect the cold hardening process in evergreens through their effect on the accumulation of carbon and nitrogen reserves. This study investigated the biochemical responses of black spruce [Picea mariana (Mill.) B.S.P.] seedlings to CO₂ enrichment during growth, cold hardening and dehardening. Seedlings were grown under 350 (ambient) or 710 (elevated) ppm of CO₂ for 12 months in eight mini-greenhouses. Photoperiod and temperature were gradually lowered in autumn to induce cold hardening, and the conditions were reversed in spring to promote dehardening. At regular intervals, cold tolerance was assessed and sugars, starch and amino acid concentrations were measured. The freezing tolerance differed between the two treatments only in early autumn, with seedlings growing under high CO₂ being more tolerant. The northern ecotype was more cold tolerant with concomitant higher concentrations of sucrose, fructose, pinitol, glucose and total soluble sugars. The concentration of soluble sugars increased in needles and roots of black spruce along with cold hardening, and the concentrations of the cryoprotective sugars sucrose and raffinose were lower under elevated CO₂. Amino acid concentrations were also lower under elevated than under ambient CO_2. The lower level of reserve did not translate into a lower level of freezing tolerance.     

4种地锦属植物半致死低温及抗寒生理指标研究

Treated by freezing,1-year-old dormant branches of four Parthenocissus species were used as test materials to determine the electro-conductivities.According to Logistic equation fitting,the semi-lethal low temperatures were calculated.The result showed that the semi-lethal low temperatures and freezing tolerance of the examined species were ranked as: Parthenocissus quinquefolia(-16.63 ℃),P.tricuspidata(-10.78 ℃),P.laetecirens(-10.29 ℃),and P.henryana(-7.72 ℃).By comparing several physiological indexes incl...     

Cold acclimation induced accumulation of phenolic compounds and freezing tolerance in Ammopiptanthus mongolicus

Ammopiptanthus mongolicus, the only freezing tolerant evergreen broad-leaved shrub, local species of the Alashan desert, northwest sand area of China, can survive -30°C or even lower temperature in winter. In the present study, the secondary products phenolics in A. mongolicus cotyledons were determined to study the effects of phenolics on cold tolerance. Cytochemical localization of phenolics in cotyledon cells was observed by electron microscopy and the content of phenolic compounds was assayed by spec-trophotometric measurement. The results showed that the freezing tolerance of A. mongolicus seedlings increased after acclimation at 2-6°C for 14 days, which accompanied the increase of the content of phenolic compounds in cotyledons. Cytochemical observation showed that phenolic deposits were mainly localized in vacuoles and in close proximity to tonoplast, and also in the cytoplasm. The amount and the size of phenolics droplets increased obviously in cytoplasm and vacuoles after cold acclimation, predominantly ag-gregated along membranes of vacuoles and tonoplast. No phenolic deposits were found in cell walls. As hydrogen-or elec-tron-donating agents, phenolics may protect plant cells against reactive oxygen species formed during chilling or freezing stress and improve the freezing tolerance of cold-acclimated A. mongolicus seedlings.