乡土植物芦苇对外来入侵植物加拿大一枝黄花的抑制作用

在城市建筑荒地中设立实验样地,通过对样方植物进行实地观测,并结合实验室比叶重和生物量测算,了解和分析野外建筑荒地中自然混生条件下芦苇(Phragmites communis)和加拿大一枝黄花(Solidago canadensis)的竞争过程和结果。结果表明芦苇和加拿大一枝黄花混生群落中芦苇发展近似于单优群落,芦苇以较高的平均株高和密度抑制加拿大一枝黄花生长,混生群落逐渐趋向于芦苇单优群落。混生群落芦苇比叶重和平均每株生物量近似于单优群落,加拿大一枝黄花比叶重和平均每株生物量显著低于其单优群落,光合作用受到显著抑制。de Wit模型分析显示,混生群落中芦苇和加拿大一枝黄花相互竞争、拮抗,前者竞争攻击力高于后者,模型预测混生群落中芦苇最终将把加拿大一枝黄花从样地中排除出去。浸提液种子培养显示加拿大一枝黄花具有化感作用,在低浓度条件(12.5mg/mL)下,对自生种子发芽有促进作用,高浓度条件下出现强烈抑制,但各浓度下芦苇种子不受加拿大一枝黄花化感作用影响;芦苇种子繁殖能力相对较弱,混生样地中加拿大一枝黄花在芦苇竞争胁迫下,种子千粒重和发芽率显著上升,扩散能力增强。芦苇具有在一定区域生态控制加拿大一枝黄花的潜力。     

芦苇水提液对加拿大一枝黄花生长及光合作用的化感效应

以芦苇叶为化感供体材料,采用砂培法研究其不同浓度[0(CK)、0.025 g·mL-1(2.5%)、0.05 g·mL-1(5%)和0.1 g·mL-1(10%)]水提液对入侵植物加拿大一枝黄花生长及光合生理特征的化感效应。结果表明:芦苇叶水提液对加拿大一枝黄花株高和生物量的影响表现为低浓度无明显作用,高浓度抑制;低浓度处理对光合速率和气孔导度无显著影响,但高浓度处理则使二者明显降低,并缩短了叶片有效光合功能期;水提液对叶绿素含量、最大净光合速率、光饱和点和表观量子效率有明显的"低促高抑"的效应,类胡萝卜素含量则随水提液浓度的升高而上升,各处理暗呼吸速率均显著高于对照,但随浓度升高有下降的趋势。可见,芦苇化感作用可以通过影响加拿大一枝黄花的光合作用,包括叶绿素含量、叶片气孔开放程度以及植物对光照的响应能力等方面,进而对其生长产生影响。     

氮沉降对不同入侵程度加拿大一枝黄花化感作用的影响

为探究全球氮沉降影响外来植物入侵扩张的作用机制,该文通过受控模拟试验,以入侵植物加拿大一枝黄花(Solidago canadensis)为对象,研究了三种氮水平(N0、N5和N12)下五种不同入侵程度(种内及种间竞争)的加拿大一枝黄花凋落叶浸提液对本地植物莴苣(Lactuca sativa)种子萌发和幼苗生长化感作用的影响。结果表明:(1)N0、N5和N12处理下的不同入侵程度加拿大一枝黄花凋落叶浸提液均显著抑制莴苣的萌发和生长,其中N5土壤入侵初期(S1A3)处理浸提液的化感作用最显著,其发芽速度指数、发芽活力指数、根长、株高和叶长比对照分别降低了61%、79%、84%、68%和13%,此时凋落叶中的总酚和总黄酮含量最高,分别为0.48 mg·g^-1和1.50 mg·g^-1。(2)相同氮添加下,入侵程度对加拿大一枝黄花化感作用有显著影响,随着入侵程度的增加,加拿大一枝黄花化感作用显著减弱,入侵初期(S1A3)凋落叶化感作用显著高于入侵后期(S3A1)。(3)相同入侵程度下,氮添加对加拿大一枝黄花化感作用有显著影响,N5处理的加拿大一枝黄花化感作用比N0或N12处理显著增加。(4)氮添加与入侵程度有交互作用,两者共同作用显著影响了莴苣种子的综合化感作用。综上结果表明,氮沉降可能会增强入侵初期加拿大一枝黄花凋落叶对本地植物的化感抑制作用,进一步促进外来植物的成功入侵,为进一步研究加拿大一枝黄花的化感作用及生态防治提供了一定的理论参考。     

菊芋块茎浸提液对生菜种子萌发生长的化感作用

以新鲜菊芋块茎、烘干菊芋块茎全粉和菊粉的水浸液作为化感物质,以发芽率、芽长、根长、超氧化物歧化酶(SOD)、丙二醛(MDA)、可溶性蛋白作为种子萌发和幼苗生长的指标,探讨不同菊芋块茎浸提液对生菜种子萌发生长的化感作用。结果表明:当菊粉溶液浓度为40 mg·mL~(-1)(T4)时,发芽率最高,比对照高20.1%;当干样浸提液浓度为5 mg·mL~(-1)(T1)时,发芽率比对照高9.6%;当干样浸提液浓度为40 mg·mL~(-1)(T4)时,对生菜种苗芽长促进作用最明显,比对照高9.2%,在干样浸提液浓度为5 mg·mL~(-1)(T1)时,根长最长,比对照高28.3%;当菊芋块茎鲜样浸提液浓度为20 mg·mL~(-1)(T3)时,SOD的活性达到最高,而MDA含量低于对照,说明菊芋鲜样浸提液可以有效提高生菜的抗逆性;当菊粉溶液浓度为5 mg·mL~(-1)(T1)和10 mg·mL~(-1)(T2)时,MDA含量和蛋白含量极低,显著低于对照。采用化感综合效应指数分析菊芋块茎浸提液对生菜种子萌发的影响,结果表明,块茎鲜样和干样浸提液对生菜的种子萌发具有明显促进作用,而菊粉溶液具有较强的抑制作用。在实际生产中,应根据不同的生长要求,使用不同浓度的浸提液,以达到最佳的促进效果。研究表明,菊芋全粉可以更有效地作为化感物质,促进生菜种子萌发和幼苗生长。     

芦苇(Phragmites australis)抑制四种植物扩散的化感潜力研究

为评估湿地芦苇植物通过化感抑制非芦苇湿地植物扩散的能力, 运用实验室生物活性测试的方法, 比较了杭州湾湿地围垦区芦苇(Phragmites australis)与其他6 种主要禾本科植物的化感潜力。以加拿大一枝黄花(Solidago canadensis)、田菁(Sesbania cannabina)、小飞蓬(Conyza canadensis)和苣荬菜(Sonchus brachyotus)等研究区域扩散植物种为受体, 研究了芦苇水提取液对上述物种种子萌发影响。结果表明: (1)除白茅(Imperata cylindrical)外, 7 种本地禾本科植物水提液浓度(0-2.50 g·100mL–1)均和萝卜幼苗胚根长呈极显著的负相关(p<0.001); 芦苇具有较强的化感潜力;(2)芦苇根、茎和叶水提液 (0、2.5、5.0、10.0 g·100mL–1)作用下, 不同物种和不同浓度处理下种子萌发指数差异显著(p<0.001), 其中加拿大一枝黄花、苣荬菜和小飞蓬3 种植物对芦苇水提液较为敏感, 而田菁敏感程度较弱。种子萌发指数表现出低浓度(2.5 g·100mL–1)促进和高浓度(5.0 g·100mL–1 和10.0g·100mL–1)抑制的“低促高抑”效应特征。除田菁外, 种子胚根长一般随浓度增加而降低。芦苇不同组织部位水提液对4 种植物抑制程度按大小依次为叶>茎>根, 叶片可能是芦苇化感物质主要来源。芦苇具有较强的化感潜力, 其化感作用可能是抑制其他植物扩散的重要机制之一。     

外来杂草加拿大一枝黄花对入侵地植物的化感效应

采用人工气候箱培养试验,初步研究了入侵杂草加拿大一枝黄花对本地植物的化感作用.测定了根系和根状茎的不同浓度浸提液对白三叶发芽率和幼苗生长的影响;不同播种密度下根系1:60提取浓度对白三叶种子萌发和幼苗生长的影响;根状茎1:60提取浓度对白三叶、红三叶、天蓝苜蓿、黑麦草、北美车前、鸡眼草、苇状羊茅、胜红蓟、马齿苋、碱蓬和刺苋的种子萌发和幼苗生长的影响.结果表明,加拿大一枝黄花根系和根状茎的化感抑制作用均随浓度的升高而增强,且根状茎提取物的抑制效应高于根系提取物的效应;在1:60低浓度根系浸提液作用下,不同密度的白三叶幼苗萌发率和幼根、幼芽长度差异不显著;1:60低浓度根状茎提取物对11个物种的种子萌发均有显著抑制作用,但对不同物种的抑制程度有差异,对禾本科植物的抑制作用大于非禾本科和豆科;1:60低浓度根状茎提取物对10个物种的幼根影响与对萌发率的影响相似,但在对幼芽的影响上,仅对鸡眼草、刺苋和苇状羊茅起抑制作用,而对其他植物无显著抑制(黑麦草、北美车前、胜红蓟、马齿苋和刺苋)或起促进作用(白三叶、红三叶、天蓝苜蓿).     

西芹种子浸提液处理后黄瓜枯萎病菌弱毒菌株的筛选

研究了西芹种子浸提液对黄瓜枯萎病菌菌落生长的抑制作用及浸提液处理后病菌致病力的变化.结果表明:在连续5代浸提液作用下,50 mg·mL-1的西芹种子乙醇、丙酮浸提液处理与其对照相比,显著抑制了黄瓜枯萎病菌菌落的生长;50 mg·mL-1的西芹种子蒸馏水浸提液处理在1～3代培养过程中,显著抑制了黄瓜枯萎病菌菌落的生长,而在4～5代培养过程中,与其对照相比,抑制菌落生长的差异不显著;用各代经西芹不同浸提液处理的黄瓜枯萎病菌接种到黄瓜上进行致病力测定,并于1周开始发病后调查病情,西芹种子丙酮、乙醇和蒸馏水浸提液处理的病情指数分别由第1代的26.7％、20.8％和22.5％降为第5代的17.5％、3.3％和18.3％;3种浸提液与其对照相比,其病情指数也表现降低,其中,乙醇浸提液处理与其对照差异达显著水平;接种至第5代时,乙醇浸提液处理的病情指数为3.3％,病菌毒力的致弱作用最强.综上所述,西芹种子浸提液不但抑制黄瓜枯萎病菌菌落的生长,而且还能弱化病菌的毒力.实验通过浸提液的连续处理获得了黄瓜枯萎病菌的弱毒菌株.     

白桦、落叶松不同器官水浸液对种子萌发和播种苗生长的种间化感作用

研究了白桦的根、枝、叶,落叶松的根、枝、叶和皮不同浓度水浸液(5.0、12.5、25.0、50.0和100.0 mg·mL-1)对另一树种种子萌发和当年生播种苗生长的化感作用.结果表明:落叶松不同器官水浸液(根5.0 mg·mL-1除外)处理均抑制白桦种子的萌发,其平均发芽率为:对照(75％)＞根(66％)＞皮(59％)＞枝(58％)＞叶(54％),随浓度增加,根、枝水浸液的抑制作用增强,而叶、皮水浸液的抑制作用减弱.落叶松各器官水浸液对白桦胚根和胚轴生长具有较强的抑制作用,且以100.0 mg·mL-1浓度的叶水浸液抑制作用最强,胚根和胚轴长分别降低38％和55％(P＜0.05).落叶松枝、叶水浸液处理对白桦播种苗的苗高、地径及生物量有一定的促进作用,根、皮水浸液则具有抑制作用.白桦各器官水浸液能促进落叶松种子的萌发,根和枝的水浸液促进胚轴生长,叶的水浸液抑制胚轴生长,50.0和100.0 mg·mL-1浓度的叶水浸液处理的种子胚轴分别较对照降低27％和28％(P＜0.05).其对落叶松播种苗生长的影响以促进作用为主,5.0 mg·mL-1浓度的白桦叶水浸液处理的落叶松苗高、地径、生物量分别较对照高54％、60％和100％ (P＜0.05).白桦与落叶松之间存在明显的化感作用,混交可能对林木生长产生一定的促进作用.     

外来入侵植物牛膝菊和野茼蒿水浸提液化感作用的生物测定

采用培养皿滤纸法,以小麦(Triticum aestivum L. )和玉米(Zea mays L. )为实验材料,以种子的发芽率、发芽指数、活力指数以及幼苗的株高和根长为测定指标,结合化感效应指数的综合效应值,对外来入侵植物野茼蒿[Crassocephalum crepidioides (Benth. ) S. Moore]和牛膝菊(Galinsoga parviflora Cav. )茎叶水浸提液的化感活性分别进行了测定.结果表明,随野茼蒿和牛膝菊水浸提液质量浓度(0.01～0.10 g·mL-1)的提高,小麦和玉米种子的发芽率、发芽指数、活力指数以及幼苗的株高和根长总体上逐渐减小;与对照组相比,0.01 g·mL-1牛膝菊水浸提液对小麦的幼苗株高以及玉米的种子发芽率和幼苗株高具有一定的促进作用,但对小麦和玉米的幼苗根长有显著抑制作用;而0.01 g·mL-1野茼蒿水浸提液仅对小麦种子的发芽率略有促进作用.0.04～0.10 g·mL-1野茼蒿和牛膝菊水浸提液对小麦和玉米种子萌发及幼苗生长的各项指标基本上均有显著的抑制作用;野茼蒿和牛膝菊水浸提液对玉米种子萌发和幼苗生长的抑制作用大于小麦.0.01～0.10 g·mL-1野茼蒿和牛膝菊水浸提液对小麦和玉米种子萌发和幼苗生长的化感效应指数的综合效应值均小于0,表现为抑制作用,并随2种植物水浸提液质量浓度的提高综合效应值逐渐降低,且前者的化感效应指数的综合效应值大于后者.研究结果显示,野茼蒿和牛膝菊水浸提液对小麦和玉米的化感活性均表现为抑制作用,且化感作用的强度与水浸提液的质量浓度相关;野茼蒿水浸提液的化感作用效应大于牛膝菊.     

开花期加拿大一枝黄花水浸提液对3种作物种子萌发和幼苗生长的影响

测定了入侵杂草加拿大一枝黄花（Solidago canadensis）开花期的茎、叶和花序水浸提液对辣椒(Capsicum annuum)、番茄(Lycoperiscum esculetum)、长梗白菜(Brassica chinensis var. communis)种子萌发和幼苗生长的影响。结果表明：（1）处于开花期的加拿大一枝黄花存在明显的化感作用,在25 mg·mL^-1时,对3种作物种子苗生长有促进作用,浸提液高于50 mg·mL^-1时,作物种子的萌发率和生长受到抑制,这种抑制作用随处理液浓度的提高而增强,在100 mg·mL^-1浓度处理下,甚至使作物种子失去活力;（2）加拿大一枝黄花叶和花序的水浸提液对种子萌发和生长的影响要大于其茎的浸提液;（3）在3种作物中,长梗白菜种子对加拿大一枝黄花水浸提液的敏感性最高。     

Uptake of isolated plant chromosomes by plant protoplasts

For mass isolation of plant metaphase chromosomes, cultured cells of wheat (Triticum monococcum) and parsley (Petroselinum hortense) were synchronized by hydroxyurea and colchicine treatment. This synchronization procedure resulted in high mitotic synchrony, especially in suspension cultures of parsley in which 80% of the cells were found to be at the metaphase stage. Mitotic protoplasts isolated from these synchronized cell cultures served as a source for isolation of chromosomes. The described isolation and purification method yielded relatively pure chromosome suspension. The uptake of the isolated plant chromosomes into recipient wheat, parsley, and maize protoplasts was induced by polyethylene-glycol treatment. Cytological studies provided evidences for uptake of plant chromosomes into plant protoplasts.Abbreviations PEG polyethylene glycol - HU hydroxyruea - C colchicine - HUC hydroxyurea and colchicine - CIM chromosome isolation medium - TCM Tris chromosome medium     

Role of plant hormones in plant defence responses

Plant hormones play important roles in regulating developmental processes and signaling networks involved in plant responses to a wide range of biotic and abiotic stresses. Significant progress has been made in identifying the key components and understanding the role of salicylic acid (SA), jasmonates (JA) and ethylene (ET) in plant responses to biotic stresses. Recent studies indicate that other hormones such as abscisic acid (ABA), auxin, gibberellic acid (GA), cytokinin (CK), brassinosteroids (BR) and peptide hormones are also implicated in plant defence signaling pathways but their role in plant defence is less well studied. Here, we review recent advances made in understanding the role of these hormones in modulating plant defence responses against various diseases and pests.     

Patenting of plant varieties and plant breeding methods

This article considers the relationship between patenting and plant variety rights protection, through a detailed analysis of the recent determination by the Extended Board of Appeal of the European Patent Office that methods for breeding broccoli and tomatoes were not patentable. It concludes that the right to patent agricultural innovations is increasingly located within a political context.     

Top 10 plant viruses in molecular plant pathology

Many scientists, if not all, feel that their particular plant virus should appear in any list of the most important plant viruses. However, to our knowledge, no such list exists. The aim of this review was to survey all plant virologists with an association with Molecular Plant Pathology and ask them to nominate which plant viruses they would place in a 'Top 10' based on scientific/economic importance. The survey generated more than 250 votes from the international community, and allowed the generation of a Top 10 plant virus list for Molecular Plant Pathology. The Top 10 list includes, in rank order, (1) Tobacco mosaic virus, (2) Tomato spotted wilt virus, (3) Tomato yellow leaf curl virus, (4) Cucumber mosaic virus, (5) Potato virus Y, (6) Cauliflower mosaic virus, (7) African cassava mosaic virus, (8) Plum pox virus, (9) Brome mosaic virus and (10) Potato virus X, with honourable mentions for viruses just missing out on the Top 10, including Citrus tristeza virus, Barley yellow dwarf virus, Potato leafroll virus and Tomato bushy stunt virus. This review article presents a short review on each virus of the Top 10 list and its importance, with the intent of initiating discussion and debate amongst the plant virology community, as well as laying down a benchmark, as it will be interesting to see in future years how perceptions change and which viruses enter and leave the Top 10.     

Ask the plant: investigating and teaching plant structure

The discipline of comparative plant morphology can play an important role in both teaching and research at a comprehensive university. Natural variation can be used as the basis for studies that begin with the simple premise of 'ask the plant'. Research questions from a variety of disciplines can be examined using the unique methods and perspectives of comparative morphology. In addition to its common application in clarifying developmental relationships and processes, comparative morphology is naturally and has been historically suited to examining the adaptations of plants to their environments. Two examples (one from grasses and another from native Utah shrubs) of studies relating plant form to patterns of growth and competition will be used to illustrate this interface between morphology and ecology. The potential role of comparative morphology in teaching will be described for three different levels in the university curriculum: Biology I (an introductory course for first-year students); Plant Structure (an elective for third- or fourth-year students); and Ecological Plant Morphology and Anatomy (post-baccalaureate or postgraduate level). Describing and explaining plant diversity and variation in the context of common structural adaptations, rather than from a strictly taxonomic perspective, has been an effective 'hook' to interest students in plants in the introductory course. In the more advanced courses it has provided a useful framework for understanding how plant diversity reflects adaptive value as well as common descent and has provided a broader perspective for student research projects in the basic and applied plant sciences.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 73–78.     

Defining plant functional groups to guide rare plant management

To effectively manage plant populations for conservation, there is a need to provide reliable information on the conditions required for maintaining viable populations. This is particularly true for the management of populations of rare plant taxa. Western Australia contains over 45% of Australia’s gazetted rare or threatened flora, 80% of which are found within the highly fragmented southwest region. Resources do not exist to undertake comprehensive studies on the population dynamics and demographics for every rare plant of this diverse region. Here, we describe a method of classifying rare plant taxa into functional groups as a basis for guiding rare flora conservation and management. Data on four floral and two life-history traits were collected for each of the 351 declared rare flora taxa of Western Australia. A hierarchical, agglomerative clustering method was applied to the resulting taxa by traits matrix to extract emergent groupings of plant taxa. The resulting polythetic groups were analysed to determine the variation in traits, including response to disturbance and recorded flower visitors, and how these may affect population persistence in a fragmented landscape. Multivariate methods were used to define emergent groups based on a combination of floral structure and life-history traits of the declared rare flora of Western Australia. Seven emergent functional groups were identified and were largely differentiated by flower shape and life form. These seven functional groupings varied significantly in their response to disturbance. By deriving these functional groups, we plan to develop models for each group on how rates of pollination, seed production and seed fitness are affected by population size and landscape context. The rationale would be to use these profiles to determine whether there are thresholds in population size or position in the landscape at which reproductive rates severely decline. General management guidelines could then be developed for each functional group. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Nomenclature Paczkowska and Chapman (2000).     

Top 10 plant pathogenic bacteria in molecular plant pathology

Many plant bacteriologists, if not all, feel that their particular microbe should appear in any list of the most important bacterial plant pathogens. However, to our knowledge, no such list exists. The aim of this review was to survey all bacterial pathologists with an association with the journal Molecular Plant Pathology and ask them to nominate the bacterial pathogens they would place in a 'Top 10' based on scientific/economic importance. The survey generated 458 votes from the international community, and allowed the construction of a Top 10 bacterial plant pathogen list. The list includes, in rank order: (1) Pseudomonas syringae pathovars; (2) Ralstonia solanacearum; (3) Agrobacterium tumefaciens; (4) Xanthomonas oryzae pv. oryzae; (5) Xanthomonas campestris pathovars; (6) Xanthomonas axonopodis pathovars; (7) Erwinia amylovora; (8) Xylella fastidiosa; (9) Dickeya (dadantii and solani); (10) Pectobacterium carotovorum (and Pectobacterium atrosepticum). Bacteria garnering honourable mentions for just missing out on the Top 10 include Clavibacter michiganensis (michiganensis and sepedonicus), Pseudomonas savastanoi and Candidatus Liberibacter asiaticus. This review article presents a short section on each bacterium in the Top 10 list and its importance, with the intention of initiating discussion and debate amongst the plant bacteriology community, as well as laying down a benchmark. It will be interesting to see, in future years, how perceptions change and which bacterial pathogens enter and leave the Top 10.