预吸胀对绿豆种子脱水耐性的影响

绿豆 (Vignaradiata)种子的吸水曲线未出现明显的“平稳期”。种子萌发 5 0 %的时间和热时间分别为 11h和 11 5度天。在吸胀初期 ,种子的相对电导率迅速增加 ,然后下降。随着脱水时间的延长 ,预吸胀不同时间的绿豆种子的含水量和存活率、由存活种子产生的幼苗鲜重、胚根和下胚轴长度明显下降 ;而且随着预吸胀时间的增加 ,种子对脱水的敏感性显著加强 ;预吸胀种子的相对渗漏率在脱水初期缓慢增加 ,然后迅速增加 ,且预吸胀时间愈长 ,相对渗漏率增加的幅度愈大。结果表明预吸胀的绿豆种子的脱水耐性是逐渐丧失的 ;吸胀的能萌发的正常性种子的脱水敏感性可以作为研究种子顽拗性的一种模式系统     

豌豆种子吸胀过程中脱水耐性变化的时间模式

研究了豌豆种子吸胀过程中脱水耐性的变化模式。种子在吸胀初期迅速吸收水分,然后缓慢吸收直到平台期。电解质渗漏速率在吸胀初期增加直到11h,然后随着吸胀下降。在吸胀过程中,种子的萌发率逐渐增加,种子和胚轴的脱水耐性逐渐丧失,10％和50％的种子和胚轴被脱水致死的含水量明显增加。赤霉素和脱落酸处理改变豌豆种子的萌发特性,提高胚轴的脱水耐性。研究结果表明,吸胀的豌豆种子脱水耐性的丧失是一种数量性状,正常性种子吸胀后脱水耐性的变化能够作为种子顽拗性研究的模式系统。     

萌发玉米种子脱水耐性与胚根细胞超微结构的变化

玉米种子脱水试验表明,25℃下萌发24h种子脱水耐性开始丧失,丧失50％和100％的时间分别为33h、58h。萌发过程中随着吸胀时间增加,玉米种子脱水耐性逐步丧失。显微观察显示,种子吸胀过程中,胚根细胞的贮藏物质逐步减少,线粒体等细胞器的分化程度则不断提高,尤其是脂类物质的分解程度与脱水耐性变化的关系似乎更明显。     

假槟榔种子脱水耐性的发育变化

对假槟榔（Archontophoenix alexandrae）种子和胚发育过程中脱水耐性的变化、不同脱水速率对脱水耐性的影响及种子的萌发和贮藏特性进行了研究。种子含水量在花后55～70d逐步降低,随后不再变化,并保持在较高水平（37％）;花后90d的种子获得最大干重。花后60d后种子获得萌发能力,花后70d达到最大值。在交替光照下（14h光照,10h黑暗,12μnmol m^-2s^-1）,种子在15℃～40℃下均能萌发,其萌发的适宜温度范围为30℃～35℃;但光照对种子的萌发有较大的抑制作用。种子和胚在花后55～90d,脱水耐性逐渐增强;花后90d种子和胚的脱水耐性最强,此时种子和胚的半致死含水量分别为0．18g／g和0．3g／g。脱水至相同含水量,快速脱水的种子的存活率明显高于慢速脱水。无论是否进行脱水处理,-18℃下贮藏1个月后,种子均丧失萌发能力;在4℃,10℃和15℃下,适度脱水能延长种子的贮藏寿命。假槟榔种子不耐脱水,不适合在低温、低含水量条件下长期贮藏,属顽拗性种子。     

盐分、温度及其互作对羊草种子发芽率和幼苗生长的影响

羊草是多年生优质牧草,也是中国松嫩平原的优势建群植物。研究了羊草种子在8种浓度（0、50、100、150、200、300、400和500mmol／L）NaCl胁迫及将胁迫解除后在3种变温（16／28℃、5／28℃和5／35℃）条件下的发芽率以及幼苗的生长变化。双因素方差分析表明,NaCl胁迫解除前后盐浓度、温度及其互作均极显著影响羊草种子萌发和幼苗生长。胁迫解除前,在3种温度下,羊草种子发芽率最高出现在没有盐胁迫的条件下,随着NaCl浓度的增加,发芽率呈下降趋势。5／28℃下,NaCl溶液对种子萌发抑制最小,浓度达到200mmol／L时,仍有25．3％的种子萌发;在5／35℃下,对种子萌发抑制作用最大,浓度超过100mmol／L时,种子萌发被完全抑制;16／28℃的处理介于二者之间。胁迫解除后,羊草种子在3种温度下发芽趋势不同。16／28℃下表现为NaCl浓度较大的处理发芽率较高,5／28℃下则呈先上升（0～150mmol/L）后基本保持不变趋势;5／35℃下则呈先上升后下降趋势。盐胁迫下,羊草幼苗在16／28℃变温下生长最好,其次为5／28℃,5／35℃生长最差。盐胁迫解除后,16／28℃和5／28℃下,0～100mmol／LNaCl处理的幼苗根长和苗长随浓度增加而显著上升,大于此浓度变化较小;在5／35℃下,100mmol/LNaCl处理的幼苗根长和苗长最大,而浓度大于100mmol／L时,则随着NaCl浓度增加呈下降趋势。     

NaCl胁迫对2种表型盐地碱蓬种子萌发的渗透效应和离子效应研究

采用高低2个浓度的NaCl、LiCl及等渗甘露醇溶液处理紫红色表型(紫色型)和绿色表型(绿色型)盐地碱蓬种子,通过测定它们的种子萌发率、吸胀速率和胚内离子含量,研究NaCl胁迫对2种表型种子萌发的离子效应和渗透效应.结果表明:(1)2种表型盐地碱蓬种子萌发率在高浓度(300 mmol/L)和低浓度(100 mmol/L)NaCl处理下均显著降低,紫色型种子萌发率在低浓度下显著低于绿色型,而在高浓度下却显著高于绿色型;绿色型种子萌发率在高浓度(30 mmol/L)和低浓度(10 mmol/L)LiCl处理下均未受到显著影响,但紫色型种子萌发率却均极显著降低;2种表型盐地碱蓬种子萌发率在低浓度等渗甘露醇处理下均极显著低于低浓度NaCl处理,而高浓度等渗甘露醇处理却均与高浓度NaCl处理无显著差异.(2)2表型种盐地碱蓬种子的吸胀速率在低浓度NaCl处理下没有受到显著影响,但高浓度NaCl处理及与之等渗的高浓度甘露醇处理下都显著降低,而且紫色型种子的吸胀速率在等渗甘露醇处理时显著高于绿色型.(3)2种表型盐地碱蓬种子胚中的Na 含量和Na /K 在对照和低浓度NaCl处理下无显著差异,但紫色型种子胚中的Na 、K 含量在高浓度NaCl处理时都显著高于对照,且K 含量增加的幅度远大于Na 含量,导致紫色型种子胚中的Na /K 显著低于绿色型.研究发现,盐地碱蓬种子萌发在低浓度NaCl胁迫下主要受离子效应抑制,而高浓度NaCl胁迫下则主要受渗透效应抑制,紫色型种子萌发率在高浓度NaCl胁迫下高于绿色型的原因之一是前者能维持更低的Na /K 比.     

腺苷减少豚鼠心室肌细胞内游离钙浓度

目的：研究腺苷对豚鼠心室肌细胞内游离钙浓度（[Ca^2＋]i）的影响并探讨其可能机制。方法：用激光共聚焦显微镜探测细胞内游离钙浓度,结果用相对荧光强度（（FI-FI0）／FI0,％;FI0：对照;FI：给药）表示。结果：①在正常台氏液和无钙台氏液中,腺苷（10,50,100μmol／L）浓度依赖性地降低[Ca^2＋];。②含30mmol／L KCl的台氏液（高钾台氏液）能够增加[Ca^2＋]i。腺苷（10,50,100μmol／L）能够显著抑制KCl引起的[Ca^2＋]i的增加。③预先应用选择性腺苷AI受体拮抗剂DPCPX（1μmol／L）,可大部分取消腺苷（100μmol／L）在高钾台氏液中的作用。腺苷（100μmol／L）在高钾台氏液的作用也可被预先应用一氧化氮（No）合酶抑制剂L-NAME（1mmol／L）所部分减弱。④腺苷（100μmol／L）能明显抑制无钙台氏液中由低浓度ryanodine引起的[Ca^2＋];增加。⑤当细胞外液钙浓度由1mmol／L增加到10mmol／L而诱发心室肌细胞钙超载时,部分心室肌细胞产生可传播的钙波,腺苷（100μmol／L）可降低钙波发生的频率和持续时间,最终阻断钙波并降低[Ca^2＋];。结论：腺苷可通过抑制外钙内流和减少肌浆网内钙释放从而降低[Ca^2＋],其减少外钙内流可能是由于腺苷A1受体介导的电压依赖性Ca^2＋通道的抑制,NO可能参与这一过程。     

Trichiliadregeana胚轴的脱水敏感性与抗坏血酸的抗氧化作用

以顽拗性TrichiliadregeanaSond.种子为材料,研究其胚轴的脱水敏感性与抗坏血酸的抗氧化作用。T.dregeana胚轴的脱水耐性随着脱水进程逐渐下降,50%的胚轴被脱水致死的含水量(W50)大约为0.16gH2O/gDW。在脱水过程中,胚轴的电解质渗漏速率逐渐增加,超氧物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)、谷胱苷肽还原酶(GR)和脱氢抗坏血酸还原酶(DHAR)的活性下降,硫代巴比妥酸(TBA)-活性产物的含量增加。2.5~10.0mmol/L抗坏血酸处理能有效地增加胚轴的脱水耐性和SOD、APX、CAT和GR的活性,降低电解质渗漏速率和TBA活性产物的含量。结果表明,T.dregeana胚轴的脱水耐性与抗氧化酶的活性增加和脂质过氧化作用的降低密切相关。     

苦丁茶冬青的RAPD影响因素及实验条件的优化

以苦丁茶冬青为材料研究随机扩增多态DNA(RAPD)的影响因素及各种实验条件优化。研究结果表明：模板DNA的浓度适宜范围为20ng／反应-80ng／反应RAPD均可得到一致的结果;dNTVs的适宜浓度范围为200μmol／L-400μmol／L;Mg^2 适宜浓度范围为1．5mmol／L-2．0mmol／L;其合适的复性温度为35—37℃;2min的延伸时间,45次热循环。按照此优化的RAPD条件进行重复实验,实验结果重现性良好,因而确定了苦丁茶冬青RAPD反应体系之最佳的实验条件。     

酿酒酵母细胞增殖对Ca^2＋需求的新证据

本文研究了酿酒酵母细胞增殖对Ca^2 需求的证据。结果表明：SD—Ca培养基中外加1mmol/L。比的Ca^2 明显促进酿酒酵母细胞增殖,外源Ca^2 浓度在0—20mmol/L比范围内变动时,随Ca^2 浓度增加,细胞生长到达稳定期的终浓度也越大;5、10mmol/L。比的EGTA可明显延缓细胞生长的延滞期,但是最终不能抑制细胞增殖：酿酒酵母在SD—Ca培养基中继代培养4次,随增殖代数增加,细胞总钙含量没有明显变化,说明酵母能够在低钙介质中生长可能是因为具有捕捉和富集钙的功能;以Fluo-3作为胞质Ca^2 指示剂,通过激光扫描共聚焦显微镜观察,发现随胞外Ca^2 浓度增加,胞质中游离Ca^2 浓度也相应增加。这些证据都揭示了Ca^2 在酿酒酵母细胞增殖过程中是必需的。     

Ca2+对冷胁迫柑橘离体叶片的相关生理生化指标的影响

研究了不同浓度的外源Ca^2＋对柑橘离体叶片抗寒性的影响。结果表明：10-20mmol／L Ca^2＋处理能够增加柑橘可溶性糖和可溶性蛋白质的含量,提高SOD和POD的活性,同时减少膜质过氧化物丙二醛（MDA）的积累,从而提高柑橘的抗寒性。     

The inhibitory effect of NaCl on barley germination

Abstract The possibility that the nature of the inhibitory effect of NaCl is different during imbibition compared to germination was investigated. Germination in both NaCl and betaine (a non-toxic solute) improved with pre-imbibition in water. Seeds imbibed in inhibitory concentrations of either solute could be induced to germinate by brief exposure to water. Electron micrographs of tissue from seeds imbibed in 0.5 kmol m^?3 NaCl for 25 h showed cells identical to those in seeds imbibed in water for only 1 h, but seeds imbibed for 6 h in water exhibited many changes in ultrastructure. These results are consistent with the hypothesis that seed hydration must reach a critical value before germination can proceed, and that the inhibitory effect of NaCl is primarily osmotic in barley seeds that have not reached this hydration threshold. Although isotonic solutions of betaine and NaCl were equally inhibitory to germination, isotonic solutions of betaine and NaCl were not equally inhibitory to continued development in seeds which had been pre-imbibed in water. Calcium ions improved both germination and plumule emergence of pre-imbibed seeds in NaCl solutions, but calcium had little effect on pre-imbibed seeds placed in betaine. Very high concentrations of NaCl or betaine inhibited germination, but did not kill dry seeds. Both solutes, on the other hand, were lethal at high concentrations to germinating seeds. NaCl killed germinating seeds more rapidly than betaine, but calcium reduced the rate of killing to nearly that of betaine. We conclude that hydrated seeds are sensitive to both osmotic and toxic effects of NaCl and that calcium mitigates the toxic effect of NaCl, but not the osmotic effect.     

Ca~(2+)在粟酒裂殖酵母细胞周期时相中的作用

以粟酒裂殖酵母(Schizosaccharomyces pombe)为研究材料,研究了Ca~(2+)在细胞周期时相中的作用。当外源Ca~(2+)浓度在0.5-20 mmol/L范围内,随Ca~(2+)浓度增加,细胞增殖速度加快,延滞期逐渐缩短。但SD-Ca（CaCl2省略）并不能终止Sch. pombe的细胞周期。采用缺氮对群体细胞进行同步化,并以EGTA 螯合培养介质中低浓度的Ca~(2+),Sch. pombe 细胞增殖被完全抑制,细胞流式法测定结果表明：细胞周期被终止在G1期。分析认为Ca~(2+) 对Sch. pombe 细胞增殖是必不可少的,外源Ca~(2+)在G1期向S期转化过程中起着关键性的作用。     

红光对绿豆下胚轴线粒体Ca~(2+)积累、ATPase及NAD激酶活性的影响

绿豆下胚轴切段经红光处理后10min,其线粒体的Ca~(2+)积累下降15％,Ca~(2+)-ATPase 及 Mg~(2+)-ATPase活性也分别下降29％和10％,切段CaM含量增加近1倍。Ca~(2+)存在时,红光能促进线粒体NAD 激酶活性。说明Ca~(2+)-ATPase及一部分Mg~(2+)-ATPase可作为钙泵控制Ca~(2+)进入线粒体。     

Na+和Ca2+对拟南芥根原生质体质膜内向K+通道电流的影响

以拟南芥(Arabidopsis thaliana Columbia)根为材料,利用膜片钳技术测定其根细胞原生质体质膜内向K^ 电流,并对Na^ 对其K^ 电流的影响进行了初步研究,发现Na^2 可明显抑制拟南芥根细胞原生质体的内向K^ 电流,外施Ca^2 可缓解Na^ 对内向K^ 电流的抑制．说明Ca^2 参与了质膜上K^ 通道对K^ ／Na^ 的选择性吸收的调节,从而使植物适应盐胁迫．     

假槟榔种子催芽技术和脱水耐性的研究

为提高假槟榔的人工种植技术,对其种子做了不同的化学催芽处理,以寻求种子的有效催芽方法,并对种子脱水耐性进行了探讨。结果表明:20%过氧化氢和98%浓硫酸浸泡5min,0.3%亚硝酸钠和0.2%硝酸钾溶液浸种24h后,发芽率显著升高,速度显著加快,尤以浓硫酸和硝酸钾处理效果为好;200～1000mg/L赤霉素和20～100mg/L激动素溶液浸泡24h也显著促进种子萌发,但催芽效果与溶液浓度有关。成熟种子轻度脱水,发芽率有所上升,但含水量下降至17%以下,发芽率急剧下降,当含水量下降10%以下,发芽力完全丧失。由此可见,种子很可能是中间型种子。     

Changes in soluble sugars in relation to desiccation tolerance and effects of dehydration on freezing characteristics of Acer platanoides and Acer pseudoplatanus seeds

The role of soluble sugars in desiccation tolerance was investigated in seeds of two species from the genus Acer: Norway maple (Acer platanoides L.) — tolerant and sycamore (Acer pseudoplatanus L.) — intolerant to dehydration. During two years of observations it was found that seeds of Norway maple acquire desiccation tolerance at the end of August i.e. about 125 days after flowering (DAF). During seed development, the transition from intolerant to tolerant state in Norway maple seeds was accompanied by the accumulation in seed tissues of raffinose, stachyose and sucrose. The sucrose/raffinose ratio in Norway maple seeds was lower than in sycamore. In mature Norway maple seeds sucrose and raffinose contents were higher than in sycamore. It was concluded, that soluble sugars such as sucrose, raffinose and stachyose may play an important role in desiccation tolerance and/or intolerance of Norway maple and sycamore seeds. Differential thermal analysis (DTA) was used to study the relationship between desiccation sensitivity and the state of water in seed tissues. The level of non-freezable water was the same in both analysed seed species, but the temperature of water crystallization during desiccation was lower in sycamore seeds.     

Optimal hydration status for cryopreservation of intermediate oily seeds: Citrus as a case study

BACKGROUND AND AIMS: The purpose of this study was to investigate the basis of the optimal hydration status for cryopreservation of intermediate oily seeds using Citrus as a model. METHODS: The relationships between equilibrium relative humidity (RH), seed water content, presence of freezable water as determined by DSC analysis, and germination percentage after immersion in liquid nitrogen (LN) were investigated in Citrus aurantifolia, C. grandis, C. madurensis and C. reticulata. The relationship between the lipid content of seeds and their unfrozen water content was also investigated. KEY RESULTS: Independent of their level of seed desiccation tolerance, the optimal desiccation RH for seed tolerance to LN exposure was 75-80 % in the four species studied. This optimal hydration status always coincided with that at which presence of frozen water could not be detected in seed tissues during the cooling/thawing process. The unfrozen water content of seeds was variable between species and negatively correlated to seed lipid content. Using the present data, those obtained previously in seven coffee species and those reported by other authors for five other species, a significant linear relationship was found between the lipid content and the unfrozen water content of seeds. CONCLUSIONS: This study provides additional evidence that intermediate oily seeds do not withstand the presence of freezable water in their tissues during the cooling/warming process. Moreover, it offers two important applied perspectives: (1) independent of their level of desiccation tolerance, testing germination of seeds of a given oily seed species after equilibration in 75-80 % RH at 25 degrees C and LN exposure, gives a rapid and reliable evaluation of the possibility of cryopreserving whole seeds of this given species; (2) it is now possible to calculate the interval of water contents in which non-orthodox oily seeds of a given species are likely to withstand LN exposure as a function of their lipid content.     

Hydrogen Sulfide Alleviates Aluminum Toxicity in Germinating Wheat Seedlings

Protective role of hydrogen sulfide (H2S) on seed germination and seedling growth was studied in wheat (Triticum) seeds subjected to aluminum (Al3+) stress. We show that germination and seedling growth of wheat is inhibited by high concentrations of AICI3. At 30 mmol/L AICI3 germination is reduced by about 50% and seedling growth is more dramatically inhibited by this treatment. Pre-incubation of wheat seeds in the H2S donor NaHS alleviates AICI3-induced stress in a dose-dependant manner at an optimal concentration of 0.3 mmol/L. We verified that the role of NaHS in alleviating Al3+ stress could be attributed to H2S/HS- by showing that the level of endogenous H2S increased following NaHS treatment. Furthermore, other sodium salts containing sulfur were ineffective in alleviating Al3+ stress. NaHS pretreatment significantly increased the activities of amylases and esterases and sustained much lower levels of MDA and H2O2 in germinating seeds under Al3+ stress. Moreover, NaHS pretreatment increased the activities of guaiacol peroxidase, ascorbate peroxidase, superoxide dismutase and catalase and decreased that of lipoxygenase. NaHS pretreatment also decreased the uptake of Al3+ in AICI3-treated seed. Taken together these results suggest that H2S could increase antioxidant capability in wheat seeds leading to the alleviation of Al3+ stress.     

蛋白酶抑制剂对含水生菜种子耐冻性的影响

选取生菜(Lactuca sativa)种子作为试材,外源添加蛋白酶抑制剂2-硝基苯甲酸[5,5'-Dithiobis-(2-nitrobenzoic acid),DTNB]对种子吸胀处理,通过程序降温,分析2-硝基苯甲酸对低温下种子发芽率及生理活性的影响。结果表明,低温下含水生菜种子的致死温度为–20 ℃;外源添加2-硝基苯甲酸2 mmol·L–1时种子发芽率最高,即对种子活性的保护效果显著;在此浓度下种子内SOD活性比对照提高1.38倍,羟基自由基清除能力提高1.17倍;与对照组相比产生两种新的蛋白11 S种子贮藏球蛋白Jug r4和11 S种子贮藏球蛋白2,均属于球蛋白家族,可提高含水种子的耐冻性;低温下种子内积累更小分子量的球蛋白多肽,对种子具有低温保护效果。综上,低温条件下生菜种子产生一定的抗冷反应,外源添加2 mmol·L–1 2-硝基苯甲酸可提高含水种子发芽率及生理活性,产生抗冻蛋白,积累更小分子量的球蛋白多肽进而提高种子抗冻性。