硝基苯酚胁迫下外源褪黑素对水稻幼苗生长及生理特性的影响

采用液体培养实验方法,研究硝基苯酚胁迫对水稻(Oryza sativa L.)幼苗生长、抗氧化特性、光系统Ⅱ(PSⅡ)光合特性的影响,以及添加外源褪黑素对缓解硝基苯酚胁迫的作用。结果显示,随着硝基苯酚胁迫浓度的升高,水稻幼苗株高、根长、地下部干重、地上部干重、全株干重和叶片PSⅡ实际光化学效率[Y(Ⅱ)]、光化学淬灭系数(q P)、PSⅡ电子传递速率(ETR)、叶绿素含量均有所下降,而叶片非光化学淬灭系数(qN、NPQ)上升;同时,根系活性氧[过氧化氢(H_2O_2)和超氧阴离子(O·-2)]积累量、抗氧化酶[超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)]活性,以及渗透调节物质(可溶性蛋白和可溶性糖)含量呈先升高后降低的趋势。在非硝基苯酚胁迫下,与对照组相比,添加外源褪黑素显著提高了幼苗地下部干重、根系可溶性糖含量和SOD活性、叶片PSⅡ光化学效率和叶绿素含量。与单独添加硝基苯酚处理相比,硝基苯酚+褪黑素复合处理显著缓解了硝基苯酚胁迫对幼苗生长、叶片PSⅡ光化学效率和叶绿素合成的抑制作用;降低了根系活性氧水平、抗氧化酶活性和渗透调节物质含量。研究结果表明添加外源褪黑素能够显著缓解硝基苯酚胁迫对水稻幼苗生长、根系活性氧水平、抗氧化酶活性、叶片PSⅡ光化学效率及叶绿素合成的不良影响,提高水稻幼苗对硝基苯酚胁迫的适应性。     

外源多胺对盐胁迫下玉米叶绿体结合态多胺水平和光合作用的影响

在100 mm o l/L N aC l胁迫下,研究了外源多胺-腐胺(Pu t)、尸胺(C ad)、亚精胺(Spd)和精胺(Spm)对玉米幼苗生长、光合速率和PSⅡ光化学效率(Fv/Fm)、叶绿体结合多胺和叶片丙二醛(M DA)含量以及抗氧化酶活性的影响.结果表明,叶面喷施1 mm o l/L的Pu t、Spd和Spm可显著增加盐胁迫下玉米幼苗干物质重、叶绿体内结合态多胺的含量、叶片净光合速率和PSⅡ光化学效率(Fv/Fm),并降低了叶片中M DA含量.外源Spd和Spm明显增加盐胁迫下玉米幼苗的抗坏血酸过氧化物酶(APX)、过氧化物酶(POD)和过氧化氢酶(CAT)活性;外源Pu t可增强APX和POD活性,对CAT活性的影响不明显.这些结果表明多胺对玉米盐害的缓解作用可能是由于提高了叶绿体中结合态多胺的含量和叶片抗氧化酶的活性,从而增强了盐胁迫下的玉米光合能力.     

氯化胆碱对盐胁迫黄瓜幼苗渗透调节物质及活性氧代谢系统的影响

以盐敏感型黄瓜品种津春4号为材料,采用水培方法研究了叶面喷施不同浓度(0.5、1.0和1.5 mmol·L-1)氯化胆碱(CC)对NaCl胁迫(75 mmol·L-1)下黄瓜幼苗鲜重、叶片叶绿素、渗透调节物质含量及活性氧代谢系统的影响.结果表明:(1)单独CC处理可提高黄瓜叶片的叶绿素、可溶性糖和可溶性蛋白含量以及过氧化氢酶(CAT)与过氧化物酶(POD)活性,降低O2·-产生速率,但对植株鲜重及超氧化物岐化酶(SOD)活性影响不大;(2)NaCl胁迫处理增加了黄瓜幼苗叶片中可溶性糖和可溶性蛋白含量,增强了SOD、POD和CAT活性,提高了O2·-产生速率及丙二醛(MDA)的含量,但同时降低了叶绿素含量与植株鲜重;(3)盐胁迫前CC预处理可缓解黄瓜幼苗叶绿素含量和植株鲜重的下降、以及MDA含量和O2·-产生速率的上升趋势,且进一步提高了盐胁迫下黄瓜叶片中SOD、POD和CAT活性.因此,适宜浓度的氯化胆碱可显著提高盐胁迫下黄瓜叶片的抗氧化酶活性,提高清除活性氧的能力,缓解盐胁迫对黄瓜幼苗细胞膜的伤害,增强黄瓜幼苗的耐盐性.     

臭氧胁迫对梓树光合生理特性的影响

采用开顶箱气室(OTC)模拟熏蒸法,研究高浓度臭氧(O3)对沈阳市常用绿化树种梓树(Catalpa ovata)生长和光合作用的影响。结果表明:高浓度臭氧显著抑制了梓树的生长;与对照组(OA)相比,160 nmol·mol-1O3处理20 d后,梓树叶片的相对含水量、干重、鲜重、比叶重、干重增量、鲜重增量均显著下降(P0.05);梓树叶片净光合速率(Pn)随O3处理时间延长逐渐降低,胞间CO_2浓度(Ci)和蒸腾速率(Tr)与气孔导度(Gs)的变化趋势一致,表现为先降低后升高的趋势,高浓度O3对梓树叶片Pn的降低主要是由非气孔因素限制引起;高浓度O3处理后,梓树叶片光合系统受损,发生光抑制现象,PSⅡ最大光化学效率(Fv/Fm)和PSⅡ电子传递量子产率(ΦPSⅡ)随着处理时间的延长而显著下降(P0.05);梓树叶片超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性在高浓度O3处理下呈下降趋势,表明梓树抗氧化系统无法承受高浓度的臭氧胁迫,2种抗氧化酶在短期O3胁迫下都未能做出积极的生理响应。     

胞外ATP通过H_2O_2对菜豆叶片光系统Ⅱ光化学特性的系统性影响

研究了细胞外ATP对菜豆叶片光系统Ⅱ(PSⅡ)光化学特性的系统性影响及可能的内在机制。研究发现,用外源ATP处理菜豆叶片的一侧,处理侧和同叶未处理侧潜在最大光化学效率(F_v/F_m)、非调节性能量耗散量子产量(Y(NO))与对照相比无显著变化;而实际光化学效率(Y(Ⅱ))、电子传递速率(ETR)和光化学猝灭系数(q P)与对照相比显著上升,但非光化学猝灭系数(q N)和调节性能量耗散量子产量(Y(NPQ))则显著下降。表明了细胞外ATP能够系统性地提高菜豆叶片PSⅡ光化学效率。用外源ATP处理菜豆叶片的一侧,检测叶片处理侧与同叶未处理侧过氧化氢的含量,发现与对照相比,叶片处理侧与未处理侧过氧化氢含量均显著上升。用外源过氧化氢(H2O2)处理菜豆叶片一侧也导致了处理侧与同叶未处理侧Y(Ⅱ)、ETR和q P的显著上升,以及q N和Y(NPQ)的显著下降。因此,过氧化氢和ATP能够对处理侧与同叶未处理侧叶片的光化学特性产生相似的影响。进一步研究表明,用过氧化氢的淬灭剂N,N'-二甲基硫脲(DMTU,dimethylthiourea)可以减弱ATP对菜豆叶片处理侧与未处理侧Y(Ⅱ)、ETR、q P、q N和Y(NPQ)产生的影响。这些结果表明:菜豆叶片局部细胞外ATP的增加可加强邻近组织PSⅡ的光化学效率,并且胞外ATP对叶片PSⅡ光化学特性的这种系统性影响依赖于H_2O_2调节的下游信号途径。     

外源一氧化氮供体SNP对黑麦草种子萌发和幼苗生长的影响

采用水培试验,研究了不同浓度NO供体硝普钠(SNP)对黑麦草种子萌发和幼苗生长的影响。结果表明:50和100μmol.L-1SNP促进了黑麦草种子的发芽率、幼苗干物质积累速率、萌发种子α-淀粉酶活性、幼苗叶片可溶性蛋白质及叶绿素含量的提高。根和叶片中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性及还原型谷胱甘肽(GSH)、抗坏血酸(ASC)含量增加,超氧阴离子(O.2-)积累速率和过氧化氢(H2O2)含量下降,丙二醛(MDA)积累降低。高浓度SNP(500~2000μmol.L-1)抑制种子的萌发和幼苗生长,幼苗叶绿素、可溶性蛋白质及GSH、ASC含量下降,MDA含量和H2O2、O.2-产生速率提高,SOD、POD和APX活性降低,但叶片CAT活性升高。推测NO可能通过提高种子淀粉酶活性和幼苗活性氧清除能力,促进黑麦草种子的萌发和幼苗生长。     

油菜黄单胞杆菌AhpC突变对被侵染菜豆叶片光化学反应特性的影响

该文研究了两种不同基因型的黄单胞杆菌[野生型( Xcp-W)和烷基过氧化物还原酶亚基C( AhpC)的缺失突变体( Xcp-ahpC)]侵染菜豆叶片( Phaseolus vulgaris)3 d后,叶片侵染位点以及同一叶片上距侵染位点不同距离处叶绿素荧光参数的变化。结果表明：与对照相比,两种病原菌侵染后叶片被侵染位点以及同叶距侵染位点一定距离处潜在最大光化学效率( Fv/Fm )的变化不显著,而光系统Ⅱ( PSⅡ)实际光化学效率[ Y(Ⅱ)]、电子传递速率( ETR)以及光化学猝灭系数( qP和qL )均显著降低。与野生型病原菌Xcp-W的侵染相比,Xcp-ahpC突变型菌株侵染后叶片的以上参数的降低更为明显。野生型病菌Xcp-W侵染对非调节性能量耗散产量[ Y(NO)]和调节性能量耗散产量[ Y(NPQ)]无显著影响;但Xcp-ahpC型病原菌侵染则导致了( Y(NO)和Y(NPQ)的显著上升。综上可知,白叶枯病菌侵染使得叶片光系统Ⅱ的光能使用效率受到了系统性的抑制,而病原菌烷基过氧化物还原酶亚基C的缺失对叶片光系统Ⅱ的光能使用效率的抑制作用更为强烈,并影响了植物的光能耗散机制。     

外源水杨酸对光抑制条件下小麦叶片光合作用的影响

以浓度为50、100、200 mg·kg-1的水杨酸(SA)预先处理灌浆期的小麦叶片,可有效防护强光所致的氧化损伤,维持较高的超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性,减轻丙二醛(MDA)积累.叶片在光抑制条件下,可维持较高的通过PSⅡ电子传递速率(Fm/Fo)、PSⅡ原初光化学效率(Fv/Fm)、PSⅡ量子效率(ΦPSⅡ)、光化学猝灭系数(qP)、净光合速率(Pn)和较低的非光化学猝灭系数(qNP).其中,以较低浓度SA(50 mg·kg-1)的效果较好.     

水杨酸、脱落酸和过氧化氢对镉胁迫小麦幼苗光合及抗氧化酶活性的影响

采用溶液培养方法,用水杨酸(SA)、脱落酸(ABA)或过氧化氢(H2O2)对2叶期小麦进行处理,研究了Cd胁迫下小麦的光合速率及抗氧化酶活性。结果表明:3种处理能不同程度增强叶片和根系中超氧化物歧化酶(SOD)和过氧化物酶(POD)的活性,提高叶片过氧化氢酶(CAT)活性,降低丙二醛(MDA)含量;增加叶片叶绿素含量及其光合速率。说明3种处理能增强小麦对Cd的抗性,其中H2O2预处理的效果最明显。     

低温胁迫对巨尾桉幼苗膜脂过氧化及保护酶的影响

以木本植物巨尾桉幼苗为材料 ,研究低温胁迫对巨尾桉膜脂过氧化及保护酶的影响 ,测定了幼苗叶片的O 2(超氧阴离子 )产生速率、H2 O2 、(过氧化氢 )、MDA(丙二醛 )含量、相对电导率和SOD(超氧化物歧化酶 )、POD(过氧化物酶 )、CAT(过氧化氢酶 )、APX(抗坏血酸过氧化物酶 )活性。结果表明 :低温胁迫使叶片O 2 产生速率、H2 O2 、MDA含量和相对电导率增加 ,但抗寒锻炼植株的增幅远小于对照 ;抗寒锻炼植株的SOD、POD、CAT和APX活性均低于对照。     

Interconversion of trans, trans and cis, trans farnesol by enzymes from Andrographis

When trans, trans-farnesol [4,8,12-¹⁴C₃,1-³H₂] is isomerized to cis, trans-farnesol by soluble enzymes from Andrographis paniculata tissue cultures, 50% of the tritium label is lost. The same loss is observed when isomerization occurs in the opposite direction. This is in accordance with the proposed mechanism for isomerization via aldehydes.     

Dinuclear ruthenium sawhorse-type complexes containing bridging ligands with ferrocenyl substituents in endo/endo, endo/exo and exo/exo orientations

The dinuclear ruthenium complexes Ru₂(CO)₄(OOCC₅H₄FeC₅H₅)₂L₂ (L = NC₅H₅: 1, L = PPh₃: 2) have been synthesized from Ru₃(CO)₁₂, ferrocene carboxylic acid and pyridine or triphenylphosphine, respectively. The single-crystal X-ray structure analysis reveals for 1 and 2 a Ru₂(CO)₄ sawhorse backbone with the two ferrocenyl substituents of the two carboxylato bridges being endo/exo with respect to each other in the solid state. With the new pyridine derivative NC₅H₄OOCC₅H₄FeC₅H₅ (4-ferrocenoyl pyridine) (3) as axial ligand, the complex Ru₂(CO)₄(OOCC₅H₄FeC₅H₅)₂(NC₅H₄OOCC₅H₄FeC₅H₅)₂ (4) was obtained, the single crystal X-ray structure analysis showing an exo/exo orientation of the two carboxylato bridges in the solid state. The endo/endo orientation is found in the solid-state structure of Ru₂(CO)₄(HNOCC₅H₄FeC₅H₅)₂(PPh₃)₂ (5), the two OCNH bridges being transoïd with respect to each other; this complex is accessible from Ru₃(CO)₁₂, ferrocenamide and triphenylphosphine.     

Nitrogen-containing non-steroidal secondary metabolites of Solanum, Cyphomandra, Lycianthes and Margaranthus

Of the 49 species of Solanum studied, cuscohygrine has been detected in 25, solamine and related amines in 17 and solamine-derived amides in 16. Five species of Cyphomandra examined all contained both amines and amides. From roots of Margaranthus solanaceus cuscohygrine has been isolated which probably occurs, too, in roots of Lycianthes rantonnettii. The distribution of these compounds throughout the taxa could be of chemotaxonomic value.     

Cortinarius sect. Brunnei (Basidiomycota, Agaricales) in North Europe

The section Brunnei was extensively studied based on material from North Europe. To stabilise the nomenclature we studied the relevant types of taxa included in this section. Phylogenetic relationships and species limits were investigated using rDNA ITS sequences and the results were compared with the morphological data. We recognised 11 species: Cortinarius brunneus, C. clarobrunneus comb. nov., C. coleoptera, C. ectypus, C. gentilis, C. glandicolor (neotypified), C. pseudorubricosus, and four species described as new C. caesiobrunneus, C. albogaudis, C. carabus, and C. cicindela. They are described here and their taxonomy, ecology, distribution, and relationships are discussed. In addition, a key to species of the section Brunnei is provided. A total of 77 new sequences of 11 species are published including nine type sequences. Also the taxonomic assignments of sequences in the public databases belonging to the section Brunnei are revised.     

Iridoid glucosides in Griselinia, Aralidium and Toricellia

From three of five investigated species of Griselinia a new iridoid glucoside, griselinoside, was isolated. It was found to be present also in foliage of Aralidium pinnatifidum and Toricellia angulata, accompanied in the former by aralidioside another novel iridoid glucoside. The structures and absolute configurations of the two iridoids were elucidated by NMR spectroscopy and chemical conversions. From G. littoralis and T. angulata the glucosides magnolioside and syringoside respectively were isolated. ¹³C NMR spectra are given for thirteen iridoid derivatives.     

Recent advances in the cryopreservation of shoot-derived germplasm of economically important fruit trees of Actinidia, Diospyros, Malus, Olea, Prunus, Pyrus and Vitis

This paper presents the advances made over the last decade in cryopreservation of economically important vegetatively propagated fruit trees. Cryopreservation protocols have been established using both dormant buds sampled on field-grown plants and shoot tips sampled on in vitro plantlets. In the case of dormant buds, scions are partially dehydrated by storage at − 5 °C, and then cooled slowly to − 30 °C using low cooling rates (c.a. 1 °C/h) before immersion in liquid nitrogen. After slow rewarming and rehydration of samples, regrowth takes place either through grafting of buds on rootstocks or excision of apices and inoculation in vitro. In the case of shoot tips of in vitro plantlets, the cryopreservation techniques employed are the following: controlled rate cooling procedures involving slow prefreezing followed by immersion in liquid nitrogen or vitrification-based procedures including encapsulation–dehydration, vitrification, encapsulation–vitrification and droplet-vitrification. The current status of cryopreservation for a series of fruit tree species including Actinidia, Diospyros, Malus, Olea, Prunus, Pyrus and Vitis is presented. Routine application of cryopreservation for long-term germplasm storage in genebanks is currently limited to apple and pear, for which large cryopreserved collections have been established at NCGRP, Fort Collins (USA), using dormant buds and in vitro shoot tips, respectively. However, there are a growing number of examples of pilot scale testing experiments under way for different species in various countries. Progress in the further development and application of cryopreservation techniques will be made through a better understanding of the mechanisms involved in the induction of tolerance to dehydration and cryopreservation in frozen explants.     

Rhizobium pisi sv. trifolii K3.22 harboring nod genes of the Rhizobium leguminosarum sv. trifolii cluster

The taxonomic status of the Rhizobium sp. K3.22 clover nodule isolate was studied by multilocus sequence analysis (MLSA) of 16S rRNA and six housekeeping chromosomal genes, as well as by a subsequent phylogenic analysis. The results revealed full congruence with the Rhizobium pisi DSM 30132^T core genes, thus supporting the same taxonomic position for both strains. However, the K3.22 plasmid symbiosis nod genes demonstrated high sequence similarity to Rhizobium leguminosarum sv. trifolii, whereas the R. pisi DSM 30132^Tnod genes were most similar to R. leguminosarum sv. viciae. The strains differed in the host range nodulation specificity, since strain K3.22 effectively nodulated red and white clover but not vetch, in contrast to R. pisi DSM 30132^T, which effectively nodulated vetch but was not able to nodulate clover. Both strains had the ability to form nodules on pea and bean but they differed in bean cultivar specificity. The R. pisi K3.22 and DSM 30132^T strains might provide evidence for the transfer of R. leguminosarum sv. trifolii and sv. viciae symbiotic plasmids occurring in natural soil populations.     

Performance of Anisantha (Bromus) tectorum and Rumex acetosella in sandy calcareous soil

Many plants are adapted to an eroded landscape with a large proportion of virgin soil. Open and disturbed soils are today almost only restricted to agricultural fields with high loads of fertilizers. We conducted a pot experiment in order to investigate growth and nutritional constraints of one calcicole species, Anisantha (syn. Bromus) tectorum, and one calcifuge species, Rumex acetosella, in decalcified topsoil and recently exposed calcareous subsoil from a field experiment in sandy grassland. In the pot experiment we implemented one treatment where we limed topsoil with CaCO₃ to the same amount as in subsoil.The subsoil had approximately 10% CaCO₃ and both species grew less in this soil compared to the topsoil, which had less than 1% CaCO₃. Germination rate of A. tectorum was higher in subsoil than in topsoil or limed topsoil. P fertilization of the limed topsoil counteracted the negative liming effect for A. tectorum, but only partly so for R. acetosella. P fertilization of subsoil increased the shoot biomass of A. tectorum, but not of R. acetosella. P concentration in plants was not reduced when growing on subsoil or limed topsoil compared to topsoil. The results show that lime addition may reduce the P availability also to calcicole species such as A. tectorum and we found indications for that Ca toxicity may be a causing factor for the calcifuge behavior of R. acetosella. The significance of the results for conservation management practices in sandy grasslands is discussed.