NaCl胁迫下胡杨(Populus euphratica)和群众杨(P.popularis)抗氧化能力及耐盐性

在盐浓度逐渐提高的胁迫条件下，对抗盐的胡杨（Populuseuphratica）和盐敏感的群众杨（Ppopularis35-44）1年实生苗木叶片中Na^＋、Cl^-水平、O2^-产生速率以及抗氧化酶：超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、过氧化氢酶（CAT）和谷胱甘肽还原酶（GR）的动态变化以及抗盐性进行了研究。结果表明，在盐浓度不断提高的胁迫条件下，群众杨叶片中Na^＋、Cl^-浓度持续增加，盐胁迫18d时，群众杨叶中Na^＋、Cl^-含量分别达到对照的17．8和14．6倍，此时O2^-产生速率也达到最高水平。而在盐胁迫期间，群众杨叶片SOD活性没有明显提高，CAT活性维持在对照水平以下，只有APX和GR活性在盐胁迫13—18d，即盐害症状出现前才有所上升，属于典型的盐害反应。胡杨与群众杨明显不同：在盐胁迫初期，胡杨叶片Na^＋、Cl^-含量虽然没有明显的变化，但胡杨叶片中O2^-产生速率在盐胁7d时明显提高，SOD、APX、CAT活性也都先后相应上升，表明胡杨能响应盐胁迫并上调SOD、APX和CAT等保护酶类，降低盐诱导的膜脂过氧化，从而减少了电解质外渗，最终提高了树木的抗盐性。

Two novel eukaryotic translation initiation factor 5A genes from Populus simonii×P.nigra confer tolerance to abiotic stresses in Saccharomyces cerevisiae

The role of plant eIF5A proteins in multiple biological processes, such as protein synthesis regulation, translation elongation, mRNA turnover, programmed cell death and stress tolerance is well known. Toward using these powerful proteins to increase stress tolerance in agricultural plants, in the present study, we cloned and characterized PsneIFSA2 and PsneIFSA4 from young poplar （P. simonii × P. nigra） leaves. The deduced amino acid sequences of PsneIF5A2 and PsneIF5A4 were 98 % similar to each other, and they are orthologs of eIF5A 1 in Arabidopsis. In a subcellular localization analysis, PsneIF5A2 and PsneIF5A4 proteins were localized in the nucleus and cytoplasm, qRT-PCR analysis showed that PsneIF5A2 and PsneIF5A4 were transcribed in poplar flowers, stem, leaves, and roots. In addition, they were also induced by abiotic stresses. Transgenic yeast expressing PsneIF5A2 and PsneIF5A4 had increased salt, heavy metal, osmotic, oxidative tolerance. Our results suggest that PsneIF5A2 and PsneIF5A4 are excellent candidates for genetic engineering to improve salt and heavy metal tolerance in agricultural plants.

Emissions of saturated C6-C10 aldehydes from poplar (Populus simonii×P. pyramidalis ‘Opera 8277’) cuttings at different levels of light intensity

Aldehydes play an important role in atmospheric chemistry and plant direct and indirect defense against environmental stresses.In this study,the emissions of saturated C6-C10 aldehydes from Populus simonii × P.pyramidalis ＇Opera 8277＇ cuttings were examined by using a gas chromatography/mass spectrometry（GC/MS） technique at three levels of light intensity（400,800 and 1 200 μmol·m-2·s-1）.A positive correlation between the emissions of these aldehydes and light intensity was found.Moreover,nordi-hydroguaiaretic acid（NDGA）,a special inhibitor of lipoxygenase（LOX）,significantly inhibited the emissions of C6-C9 aldehydes at three levels of light intensity,but did not influence the emission of decanal（C10）.The emissions of C6-C10 aldehydes in NDGA treated poplar cuttings,exhibited the same positive correlation with light intensity.The results indicated that LOX pathway contributes to the emissions of C6-C9 aldehydes,whereas some pathways regulated by light intensity might be a universal mechanism for emissions of C6-C10 aldehydes.

Responses of germination and radicle growth of two Populus species to water potential and salinity

Abstract The effects of water potential, NaCl and Na2SO4 on germination and radicle growth of two riparian tree species, Populus euphratica Oliv. and P. pruinosa Schrenk （Salicaceae）, were tested. Growth chamber studies revealed an optimum temperature range for seed germination of both species between 15-35℃. The final germination percentage of both species decreases with decreasing water potential in all types of solution applied in the experiments. P. pruinosa was less tolerant to low ψw stress than P. euphratica, especially in salt solutions. Germination percentages fell below 20% for P. pruinosa at -0.6 MPa （NaCl） or -0.4 MPa （Na2SO4） and for P. euphratica at -1.2 MPa （NaCl） or -0.6 MPa （Na2SO4）. Radicle growth of both species was inhibited by high concentrations of PEG1 NaCl and Na2SO4. However, growth was enhanced at -0.13 and -0.29 MPa in PEG or at -0.13 MPa in NaCl solutions compared to distilled water. Radicle growth of P. euphratica was higher than that of P pruinosa. Germination and radicle growth of both species exhibited ion toxicity. Na2SO4 was more toxic than iso-osmotic solutions of NaCl. Radicle growth proved to be more sensitive than seed germination. Thus, flooding does not only yield the necessary soil moisture for germination but also favors seedling establishment of both species through leaching of salts from the soil surface. The different sensitivity of the species during their early growth stages might, moreover, contribute to the observed differences in their distribution in the Talim Basin （northwest China）.

胡杨、灰叶胡杨P-V曲线水分参数的初步研究

运用P-V技术初步研究了人工林胡杨、灰叶胡杨两个树种的水分参数差异,探讨了树种的抗旱性。结果表明灰叶胡杨的主要水分参数(Ψ100、Ψ0、ROWC、AWC、RWD、ε)明显低于胡杨,渗透调节能力和束缚水含量高于胡杨,表现对干旱环境具有较强的耐旱能力。综合评判表明灰叶胡杨对干旱的适应性较强。

Activities of lipoxygenase and phenylalanine ammonia lyase in poplar leaves induced by insect herbivory and volatiles

A study was conducted to explore the defense response in woody plants after insect herbivory. The activities of two enzymes, lipoxygenase （LOX）, a key enzyme ofjasmonate （JA） pathway, and phenylalanine ammonia lyase （PAL）, a rate-limiting enzyme of phenyl- propanoid pathway, were measured in the leaves of one-year-old poplar （Populus simonii × P. pyramidalis ＇Opera 8277＇） cuttings after Clostera anachoreta larvae attack. The results show that the increased activities of LOX and PAL were found not only in the leaves wounded by C. anachoreta larvae but also in their tipper systemic leaves, indicating that JA and phenylpropanoid pathways were activated, and the defense response was stimulated systemically. The increase in LOX and PAL activities in neighboring intact poplar cuttings sug- gested that there exists the interplant communication between poplar plants mediated by the herbivore-induced volatiles. Methyl jasmonate （MeJA） was also proved to be an airborne signal to induce defense response in P simonii × P pyramidalis ＇Opera 8277＇ cuttings.

濒危物种胡杨和灰叶胡杨总DNA提取及RAPD体系优化

以濒危物种胡杨和灰叶胡杨硅胶干燥的叶片为材料,研究其总DNA提取方法及RAPD-PCR体系优化条件。结果表明,用改良CTAB法提取的DNA适用于胡杨和灰叶胡杨的RAPD分析。优化的胡杨和灰叶胡杨RAPD-PCR体系为:20μL的反应体系中含Mg2+2.5 mmol·L-1、dNTP 0.15 mmol·L-1、引物0.2μmol·L-1、模板DNA100 ng和1.5 U Taq DNA聚合酶。用6条多态性引物对优化体系的稳定性进行检测,结果显示扩增结果稳定,多态性丰富。该优化体系为在分子水平开展胡杨和灰叶胡杨的保护生物学研究提供了技术支持和参考。

小黑杨PnsGA20ox1基因的克隆及功能分析

根据与小黑杨(Populus simonii×P.nigra)亲缘关系较近的几个物种的赤霉素氧化酶基因(GA20ox)保守区设计兼并引物,克隆出小黑杨GA20ox基因片段;利用RACE技术得到其全长为1 678 bp的cDNA序列,进行蛋白质预测,发现其编码385个氨基酸,分子质量为44.04 ku,理论等电点为5.97,核酸序列与毛果杨GA20ox1同源性高达99%,将其命名为PnsGA20ox1。荧光定量PCR分析发现,GA20ox1基因在小黑杨各个组织中均表达,其中在成熟木质部中表达量最高,在节间组织中表达量最低。转PnsGA20ox1基因烟草分析表明,过表达PnsGA20ox1基因的烟草综纤维素含量和纤维长度比对照组均有不同程度的提高,而木质素含量与对照无明显差异。

小黑杨PnsICE1基因启动子克隆及瞬时表达分析

ICE1基因是能够编码类似MYC的b HLH转录因子,在低温条件下能够特定地结合CBF3启动子中的MYC作用元件,继而诱导CBF3调控的下游基因的表达,在植物逆境胁迫应答中具有重要的功能。本研究通过PCR扩增技术从小黑杨(Populus simonii×P.nigra)基因组DNA中克隆得到1 247 bp ICE1基因启动子序列,在线预测分析发现,该段序列中含有典型的真核生物核心启动子区域,除了包含多个TATA-box、CAAT-box等基本顺式作用元件外,还存在其它反应元件,如ABRE、DOFCOREZM、MYBCORE、W-box和MYCCONSENSUSATHSE等,这些元件有的与赤霉素、脱落酸等激素相关,有些与逆境胁迫诱导相关,这表明Pns ICE1基因启动子可能与逆境胁迫相关,在小黑杨抵御逆境胁迫的生理过程中具有重要功能。将克隆得到的Pns ICE1启动子取代p BI121中的Ca MV35S启动子,构建植物表达载体p BI121-ICEPro,由Pns ICE1启动子驱动报告基因gus表达,并用农杆菌介导的瞬时侵染法转化拟南芥。对瞬时侵染后的拟南芥进行GUS染色分析。结果表明,在Pns ICE1启动子的驱动下,报告基因gus在花及根部中特异表达,Pns ICE1启动子具有启动活性。

Analysis on the change of water potential of Populus euphratica Oliv.and P.Russkii Jabl under different irrigation volumes in temperate desert zone

The measurement of plant water potential is considered to be a direct approach to confirming the irrigation time in present irrigation systems.In this current study,two shelter forests species in the Junggar Basin (Central Asia),Populus euphratica and P.Russkii Jabl,were studied.We monitored leaf water potential (ψl),stem water potential (ψs) and soil water potential (ψsoil) under different irrigation conditions.The characteristics of the variation in leaf and stem water potential (ψl and ψs) of P.euphratica and P.Russkii Jabl,as well as the impact of soil water potential (ψsoil) on the leaf and stem water potential (ψl and ψs) under different irrigation conditions were discussed.Our results showed the following.(1) With increased irrigation,the intensity of drought stress on P.euphratica and P.Russkii Jabl decreased.(2) The intensity of drought stress experienced was less for P.Russkii Jabl than for P.euphratica under the same irrigation conditions.(3) The more intense the drought,the less sensitive was P.Russkii Jabl,but the more sensitive was P.euphratica,and vice versa.(4) For the P.euphratica community the soil water potential (Ψsoil) at 60 cm depth responded to variation in irrigation more strongly than at 30 and 90 cm depths.For the P.Russkii Jabl community the soil water potential (ψsoil) in the shallow surface layer responded to irrigation variation more strongly than that in deep layers.(5) In the event of relatively sufficient soil water,predawn stem water potential (ψpds) of plant was a reasonable indicator reflecting soil water potential (ψsoil).(6) The water demand of P.euphratica and P.Russkii Jabl shelter forests can be met with different irrigation policies:large volume and less frequency for P.euphratica but small volume and more frequency for P.Russkii Jabl.

Rhizosphere organic phosphorus fractions of Simon poplar and Mongolian pine plantations in a semiarid sandy land of northeastern China

The aim of this study was to investigate the role of rhizosphere organic phosphorus （P） in soil P supply in semiarid forests and the effects of tree species on rihizosphere organic P. We examined organic P fractions in rhizosphere and bulk soils of mono-specific Simon poplar （Populus simonii） and Mongolian pine （Pinus sylvestris var. mongolica） plantations in a semiarid sandy soil of Horqin Sandy Land in Northeast China. Total organic P （TPo） accounted for 76% of total P across the two stands. The concentration of organic P （Po） fractions decreased in the order of NaOH-Po〉Res-Po〉HCI-Po〉NaHCO3-Po in both plantations. The concentration of NaHCO3-Po was 38% and 43% lower in rhizosphere soil than in bulk soil in Simon poplar and Mongolian pine plantations, respectively. In contrast, total P, TPo and NaOH-Po significantly accumulated in rhizosphere soil in Simon poplar plantations, but no change in Mongolian pine plantations. Soil recalcitrant organic P fractions were positively correlated with soil organic carbon. The results suggest that rhizosphere labile organic P was an important source of plant-available P in this semiarid region, but the dynamic of rhizosphere recalcitrant organic P fractions varied with tree species and was correlated to organic carbon dynamics.

农杆菌抑菌剂的抑菌效果及其对小黑杨叶片不定芽产生率的影响

研究了几种抗生素及AgNO3对农杆菌的抑菌效果和对小黑杨花粉植株叶片不定芽产生率的影响。确定首选抑菌抗 生素是头孢噻肟钠,AgNO3的抑菌效果也很好,两者的有效抑菌浓度分别为200和3.0 mg·L-1,抑菌时间均为9 d,此浓 度下小黑杨叶片的不定芽产生率为88％和89％。

小黑杨转双价抗虫基因的研究

用根癌农杆菌介导的叶盘法,将蜘蛛杀虫肽与Bt基因C肽序列的融合基因导入小黑杨(Populus simonii×P.nigra),所获得的3株卡那霉素抗性再生植株进行PCR和PCR-Southern杂交检测的结果均为阳性,Southern杂交检测的结果2株为阳性。抗虫试验结果显示,3个转基因株系均具有明显的抗虫效果,能显著抑制舞毒蛾幼虫的生长发育,表现出强烈的抗虫作用。

胡杨、灰叶胡杨光合及叶绿素荧光特性的比较研究

比较研究了两年生胡杨和灰叶胡杨叶片的光合及叶绿素荧光特性.结果表明:胡杨和灰叶胡杨均表现出净光合速率(Pn)日变化呈单峰曲线,只是在12:00时胡杨的Pn略微降低;气孔导度日变化均呈单峰型曲线;胞间CO2浓度日变化呈近“V”字型曲线.相同的试验条件下,胡杨的净光合速率、气孔导度高于灰叶胡杨,净光合速率与气孔导度峰值出现在上午10:00时;胡杨胞间CO2浓度低于灰叶胡杨,胞间CO2浓度最低值均出现在中午14:00时.经充分暗适应后的叶片叶绿素荧光参数初始荧光、PSⅡ原初光能转换效率和PSⅡ潜在活性均为胡杨显著大于灰叶胡杨.以太阳光为光化学光,测定的叶绿素荧光参数日变化显示,胡杨PSⅡ实际的光化学反应量子效率、非循环电子传递速率、光化学猝灭系数均大于灰叶胡杨,而非光化学猝灭系数却较灰叶胡杨小.胡杨与灰叶胡杨在光合与叶绿素荧光特性上的差异,是胡杨更能适应干旱荒漠区高光、高温与低相对空气湿度环境,从而表现出高净光合速率的部分生理学原因之一.

转betA基因小黑杨的耐盐性分析及优良转基因株系的选择

在前期获得13个小黑杨转胆碱脱氢酶基因(betA)株系的基础上,选择9个生长正常的转基因株系与非转基因对照,用0、100、140、170、200mmol·L-15种浓度的NaCl处理盆栽苗木,分2、7、12、17、22d取处理材料叶片,测定转基因株系叶片中外源基因的最终合成产物———甜菜碱含量。盐处理60d后,测定苗木高度及转基因株系的盐害指数。结果表明,转基因株系与对照间的甜菜碱含量差异达到极显著水平,9个转基因株系的甜菜碱平均含量超过对照的27.1%;转基因株系的平均盐害指数较对照低15.8%;转基因株系的平均高度超过对照44.1%。综合转基因株系的生长速度,兼顾其耐盐性,初步选择转基因株系T4、T6、T5、T1作为生长速度快耐盐性高的优良株系。

杨树对潮霉素的敏感性研究

以山新杨、欧美杨、小黑杨无菌苗的幼叶、叶片分化的不定芽、茎段为外植体,研究了其对潮霉素的敏感性。结果表明:叶片分化时山新杨和欧美杨的潮霉素敏感性为2.0 mg/L,小黑杨为3.0 mg/L;不定芽生长和生根时山新杨和小黑杨的敏感性为2.0 mg/L,欧美杨为1.0 mg/L;茎段生长和生根时山新杨和小黑杨的敏感性为6.0 mg/L,欧美杨为2.0 mg/L。

虫咬及挥发物诱导后合作杨叶片中多酚氧化酶活性的变化

经杨扇舟蛾(Clostera anachoreta)幼虫取食,杨扇舟蛾幼虫诱导的挥发物熏蒸,及茉莉酸甲酯(MeJA)、水杨酸甲酯(MeSA)、顺式己烯醛(cis-hexenal)、反式己烯醛(trans-hexenal)及苯骈噻唑(benzothiazole)熏蒸后,分析了合作杨(Populus simonii×P.pyramidalis‘Opera 8277’)叶片中多酚氧化酶(PPO)活性的变化。虫咬叶及其上部叶片中PPO活性增加了2～4倍,表明合作杨产生了系统抗性。经虫咬诱导的挥发物熏蒸后,合作杨叶片中的PPO活性增加了1倍,推测是合作杨受伤后释放出了具有信号作用的挥发物,诱导邻近植株产生了防御反应。5种外源挥发物都引起了叶片PPO活性升高,因此均可能是合作杨间潜在的气体信号,并且混合挥发物的诱导效果显著高于单一挥发物。EGTA(钙离子螯合剂)和氯化镧(钙通道抑制剂)明显抑制了合作杨虫咬叶片、虫咬上部叶片及虫咬诱导挥发物熏蒸叶中PPO活性的升高,说明钙信号在虫咬及挥发物诱导的PPO活性升高中起着重要作用。

小胡杨小孢子发生及微管骨架变化

利用间接免疫荧光结合DAPI(4′,6-diamidino-2-phenylindole)染色方法,进行了小胡杨小孢子母细胞减数分裂过程中微管骨架变化和染色体行为的研究。结果表明:①小胡杨小孢子发生过程中细胞内微管骨架呈动态变化过程,中期Ⅱ形成平行纺锤体和垂直纺锤体;末期Ⅱ未观察到典型的成膜体结构,同时型胞质分裂由子核间微管系统的相对界面发生,胞质分裂后形成四边形和四面体型四分体。②小胡杨小孢子母细胞减数分裂过程中还存在各种异常细胞学现象,中期Ⅰ和中期Ⅱ存在落后染色体;中期Ⅱ相互平行纺锤体发生联合;中期Ⅱ和后期Ⅱ孢母细胞两个纺锤体间的胞质会出现裂沟;四分体时期存在三分体和二分体等,说明由于远缘杂交而造成小胡杨染色体的异质性,并在减数分裂过程中得到体现。

盐胁迫条件下杨树盐分与甜菜碱及糖类物质变化

以抗旱耐盐性强的胡杨 (Populuseuphratica)和非抗盐的群众杨 (P .popularis‘35 - 44’)为实验材料 ,研究了盐胁迫条件下盐分与甜菜碱、还原糖、蔗糖以及水溶性糖等细胞相容溶质的动态变化。两种杨树在盐处理期间表现出明显差异 :群众杨下部叶片首先表现出盐害症状 ,处理后两周苗木上部叶片也出现盐害并脱落。而胡杨在试验期间仅下部叶片发黄脱落 ,盐处理 1 5天后落叶量仅为 1 6%。群众杨盐害症状的出现主要是由叶片中盐离子的大量累积所致。与之比较 ,胡杨拒吸Na+的能力及控制Cl- 转运的能力均优于群众杨。另外 ,胡杨的耐盐性强于群众杨也与其有机溶质的变化有关。受到盐胁迫后胡杨根叶中甜菜碱浓度显著提高 ,在处理后 1 5天达到最高值 ,特别是叶片中甜菜碱的浓度提高了 2 4 3倍 ,达到 1 899.8μmol/L ,根中甜菜碱含量也增加了 9倍。此外 ,盐处理后胡杨叶和根中的还原糖、水溶性糖和蔗糖含量均呈明显上升趋势 ,分别在第 4天和第 1 5天达到峰值。与胡杨相反 ,耐盐性弱的群众杨在盐胁迫期间 ,叶中甜菜碱和糖含量并无显著提高 ,根中糖分水平还明显降低。由此可以得出结论 ,胡杨渗透调节能力高于群众杨 。

通辽杨花粉母细胞减数分裂及其染色体行为研究

在温室水培条件下对通辽杨（Populus simonii Carr．×P．nigra L,‘Tongliao’）花粉母细胞减数分裂进程及其染色体行为进行了研究。结果表明：（1）通辽杨花粉母细胞减数分裂与其雄花芽／花序外部特征和花药颜色有着密切关系，前期Ⅰ作为减数分裂过程中最关键而复杂的一个阶段，大约占整个减数分裂进程90％的时间；中期Ⅰ存在单价体，后期Ⅰ有落后染色体出现，表现出较强的遗传杂合性，而且中期Ⅱ平行纺锤体的出现与天然花粉中大花粉的存在之间可能有着一定的联系；（2）在通辽杨减数分裂过程中核仁数目存在1～8个的动态变化，这种现象可能与杨属植物古多倍性起源有关，并推测通辽杨染色体组内至少存在8对带有次缢痕的染色体；（3）在同一个花芽，同一个小花，乃至同一个花药中，往往能同时观察到5～9个不同的分裂相，这种减数分裂不同步性是通辽杨适应环境的一种进化表现，对其种群繁殖具有重要意义。