醉马草内生真菌共生体研究进展

有关醉马草(Achnatherum inebrians)内生真菌(Epichloë gansuensis, E. inebrians)共生体的研究, 代表了我国禾草内生真菌研究领域的重要方向, 使中国的醉马草-内生真菌与美国的苇状羊茅(Festuca arundinacea)-内生真菌(E. coenophiana)和新西兰的多年生黑麦草(Lolium perenne)-内生真菌(E. festucae var. lolii)成为禾草内生真菌国际三大研究分支。该文综述了近30年来对醉马草内生真菌共生体的系统研究, 包括: 内生真菌的分布、带菌率、检测方法、多样性, 内生真菌提高宿主的抗旱、耐寒、耐盐碱、耐重金属、抗虫、抗病等抗逆性及其机理, 共生体产生的生物碱等次生代谢物, 对草食动物的毒性, 及其在草地生态系统中的作用等。研究者实验证实了醉马草本身无毒, 只有当内生真菌与醉马草共生并产生麦角新碱和麦角酰胺等麦角类生物碱后才能导致采食醉马草家畜中毒。文章展望了醉马草内生真菌基因组学和功能分析, 利用杀菌剂杀死内生真菌进行醉马草脱毒, 利用无毒内生真菌菌株进行饲用醉马草新品种选育, 利用有毒醉马草内生真菌共生体进行抗虫防鸟的机场绿化新品种选育及生物源农药与医药开发等。     

Advances in research of Achnatherum inebrians-Epichloë endophyte symbionts北大核心CSCD

Research on drunken horse grass (Achnatherum inebrians)-endophytic fungi (Epichloë gansuensis, E. inebrians) represented an important area of endophyte research in China. Compared with tall fescue (Festuca arundinacea)-endophyte (E. coenophiala) in the United States and perennial ryegrass (Lolium perenne)-endophyte (E. festucae var. lolii) in New Zealand, A. inebrians-endophyte research in China is becoming a leading branch of endophyte research. The studies of A. inebrians-endophyte symbionts over the past three decades were reviewed, mainly including endophyte distribution, detection methods, infection rate, fungal diversity, stress tolerances of drought, cold, salt, heavy metal, pest, disease and their mechanisms, secondary metabolite of alkaloids, feeding experiments and its ecological functions etc. Research reveals that drunken horse grass itself has no toxicity, the grazed animals will be intoxicated if the grass bears infection by Epichloë endophytes and produces ergot alkaloids. Future research will focus on E. gansuensis and E. inebrians genomics and endophyte functions. In other research we will create new grass cultivars that are 1) sanitized of the endophyte and non-toxic, 2) utilizing novel endophytes that deter birds feeding and 3) utilizing endophytes that are modified to produce novel fungicides, pesticides or medicines. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All rights reserved.     

Epichloë endophyte effects on leaf blotch pathogen (Rhynchosporium sp.) of tall fescue (Schedonorus phoenix) vary among grass origin and environmental conditions

ABSTRACT

Background

Systemic Epichloë endophytes are common fungal symbionts of many cool-season grasses. They are known for their capability of increasing host plant tolerance against biotic and abiotic stressors, including grass pathogens. However, results on endophyte-mediated disease resistance have been ambiguous, and the underlying mechanisms of disease resistance remain unknown.     

Identification and characterization of bacterial endophytes of rice

We isolated seven different bacteria from rice seedlings grown from surface sterilized seeds. Three were associated with the rice seed husk and the other four were growing endophytically within the seed. Microscopic studies revealed that the endophytes were concentrated in the root stele region. Some of the bacteria exhibited strong anti-fungal activity against Rhizoctonia solani, Pythium myriotylum, Guamannomyces graminis and Heterobasidium annosum.     

宁夏盐池不同坡位旱地紫苜蓿水分来源

紫苜蓿(Medicago sativa)是一种经济和生态价值较高的优良牧草, 但其耗水量大, 在西北半干旱地区仅靠天然降水难以满足紫苜蓿的正常生长发育。宁夏盐池北部地处毛乌素沙地南缘, 地下水埋深较浅, 地下水有可能成为紫苜蓿的潜在水源, 弥补天然降水的不足。本试验在地势平坦的缓坡丘陵梁地和丘间低地, 选择8年生旱地紫苜蓿试验地作为研究对象, 采用稳定同位素技术, 研究了不同海拔的4个坡位(海拔自低到高分别为: 坡1、坡2、坡3和坡4)紫苜蓿的水分来源及其生长生理表现。结果表明: 坡位对0-300 cm土壤剖面含水量有显著影响, 海拔最低的坡1土壤含水量最高。土壤水和植物茎秆水δ ¹⁸O-δD坐标点大部分位于中国西北地区地方大气降水线(LMWL)的右侧, 说明植物利用的水源氢氧同位素组成受到蒸发的影响而发生了富集作用。0-450 cm土壤剖面水δ ¹⁸O值随着海拔高度的增加而增大。同一坡位土壤水δ ¹⁸O值随着土壤深度的增加逐渐下降。深层土壤水δ ¹⁸O值与地下水δ ¹⁸O相近, 说明地下水通过土壤毛细管上升而补充其上层土壤水分。0-40 cm土壤水δ ¹⁸O值随季节波动较大, 270 cm以下土壤水δ ¹⁸O值较为稳定。4、7、8月份坡1紫苜蓿茎秆水δ ¹⁸O值显著低于其他3个坡位(p < 0.001)。在4、6、7三个月, 坡位1紫苜蓿对深层土壤水(270 cm以下)的利用率最高。而在8月份, 坡1、坡3、坡4紫苜蓿主要利用150-270 cm、270-450 cm土层土壤水以及地下水, 坡2对表层(0-20 cm)土壤水利用率最高。坡1紫苜蓿的产量、整株Δ ¹³C值及气孔导度显著高于其他3个坡位。本研究表明: 在平均年降水量只有280 mm的西北半干旱地区种植旱地紫苜蓿要尽量选择地势较低的滩地, 使其能够利用到埋深较浅地下水, 以满足植物生长发育的需要并取得较好的生态和经济效益。     

Fisheries management in the twenty-first century: will new paradigms apply?

The last decade has seen growing concern at the uncertain effectiveness of most fisheries assessment and management approaches as reflected by trends in global landing statistics published by FAO. These imply full exploitation of the majority of fishery resources and a serious overcapitalization of fleets at the global level. Projected increases in demand, future prices for fisheries products, and impacts of growing world populations on the ecosystem all require an urgent search for improved management frameworks.Improved management of fisheries requires, first, an understanding of the axioms and working assumptions underlying the current approaches and how these evolved in response to regional or local conditions and target species. This should promote integration of methodologies which better reflect local situations and can be expressed in the form of one or more working paradigms. These paradigms should incorporate ecosystem considerations, including environmental fluctuations and socio-economic factors. They should not assume that current production levels are independent of natural fluctuations and human impacts and should recognize the dangers of maintaining open access to marine resources throughout their seasonal cycle, life history and distribution range.Wide-use management paradigms incorporating explicit user rights, participatory management and inputs from a variety of disciplines and stakeholders are becoming popular, but must operate within a hierarchy of pre-negotiated responses to pre-specified limit reference points so that social and economic options are not lost because conservation issues have not been given precedence.Academic and research institutions could aid the management process by more participation, by promoting interdisciplinary teamwork with stakeholders and by breaking down excessive specialization and regionalization within fisheries studies. On the management side, the key elements for improving the situation seem to be consultative management frameworks that explicitly incorporate watchdog functions and implement precautionary approaches to management. Risk-averse strategies are appropriate but, given the high level of uncertainty that managers face with natural systems, fail-safe management with redundancy, both in the data sources they rely on for fishery performance and in the management measures applied, seem appropriate.For near-shore resources, governments could consider partly devolving management responsibility to appropriate levels in society, involving coastal communities, individual use rights and other vehicles for allocating access. Changing emphasis of modern technology from fisheries exploitation to improved management will be one aspect of successful future management systems, perhaps incorporating geotemporally defined access rights to near-shore and shelf resources.Recent international agreements, including the formal ratification of the Law of the Sea, show that governments are prepared for more ecologically appropriate approaches. The key stake of the fisheries industry in sustainable fisheries development needs supporting, particularly for developing countries, now the major source of aquatic marine products. High priorities for management of marine resources are rebuilding depleted resources and restoring habitats, with concern for maintaining genetic and ecological diversity. There will be a need to consider impacts of global trade on conservation of resources for future generations, if proper management is to be maintained in the face of growing demand.International agreements of relevance to future management paradigms which are compatible with the Law of the Sea Convention (and each other), include Agenda 21 of UNCED, the Biodiversity Convention, the UN Agreement on Straddling Fish Stocks and Highly Migratory Fish Stocks, the Compliance Agreement and the FAO Code of Conduct for Responsible Fisheries. Such agreements, ratified or now open for signature, provide a comprehensive basis for future customary law that can assist authorities in constructing appropriate management frameworks. Current concern remains with application of these agreements in international waters, where limited access as required for proper management still has not been established.     

高寒山区草本植物的保护酶系统及其在低温生长中的作用

研究了高寒山区几种草本植物在低温生长过程中植物叶中抗氧化酶、抗氧化物和膜脂过氧化产物的变化及其作用。结果表明,耐寒性差、生长期短的一年生植物微孔草MDA含量较低,保护酶活力也较低。耐寒性强、生长期长的苜蓿、垂穗披碱草、草地早熟禾、无芒雀4种多年生植物MDA含量较高,保护酶活力和抗氧化物含量也较高。其生长季平均MDA含量分别比微孔草高2．27倍、1．64倍、2．07倍和1．55倍,超氧化物歧化酶（SOD）活力分别比微孔草高16．7％、27．1％、46．2％和11．5％;地氧化氢酶（CAT）分别高51．5％、123．0％、25．3％和9．4％,类胡萝卜麦含量分别高126．5％、142．7％、138．4％和394．4％。当气温低于0℃后,微孔草死亡,完成生活史,以种子越冬,在生理上无明显抗冻特征。而此时多年生植物SOD活力趋于增强,仍能一定生长,至－5℃～10℃低温时地上部才枯死,其细胞具有较强的耐膜脂过氧化能力和抗氧化酶系统,对环境的快速反应可能是其在高寒山区低温生长的重要生理机理。     

Competition for nitrogen between Australian native grasses and the introduced weed Nassella trichotoma

BACKGROUND: and Aims Nassella trichotoma is an unpalatable perennial grass weed that invades disturbed native grasslands in temperate regions of south-eastern Australia. This experiment investigated whether elevated N levels, often associated with disturbance, increases the competitiveness of N. trichotoma relative to C3 and C4 native Australian grasses. METHODS: A pot experiment investigated competitive interactions between four native grasses, two C3 species (Microlaena stipoides and Austrodanthonia racemosa) and two C4 species (Themeda australis and Bothriochloa macra), and N. trichotoma at three different N levels (equivalent to 0, 60 and 120 kg ha-1) and three competing densities (zero, one and eight neighbouring plants), using an additive design. KEY RESULTS: All native grasses were competitive with N. trichotoma at low N levels, but only M. stipoides was competitive at high N. High densities of native grasses (8:1) had a major competitive effect on N. trichotoma at all N levels. The competitive ranking of native grasses, across all N levels, on N. trichotoma was: M. stipoides>A. racemosa>B. macra>T. australis. The C3 species were generally more competitive than the C4 species and C4 grasses were not inherently more productive at low N levels, in contrast to the results of other studies. CONCLUSION: To resist invasion from N. trichotoma, these native grasses need to be maintained at a high density and/or biomass. The results do not support the theory that species such as N. trichotoma, with high tissues density, are always less competitive than those of low tissue density; in this case competitiveness depended on N levels. The ability of N. trichotoma to accumulate biomass at a higher rate than these native grasses, helps to explain why it is a major weed in disturbed Australian native grasslands.     

植物内生菌定殖检测技术及其应用

自然环境中内生菌定殖于植物体内,对宿主植物产生多种有益效应,但是内生菌定殖情况难以检测,相关研究不够深入系统。目前在该领域使用较为广泛的检测技术包括：荧光标记、抗生素标记、荧光定量PCR和高通量测序等。内生菌通过孔隙伤口和降解细胞壁等方式侵染植物,通过种子垂直传递核心内生菌。对植物内生菌定殖的侵染方式、定殖方法和检测技术进行了归纳和整理,介绍了内生菌多种侵染和迁移途径,总结了目前内生菌定殖在生物防治、促进植物生长和污染修复等方面的功能,综述了多种检测方式在应用中的特点,以期为内生菌定殖植物的相关研究及其应用提供参考依据。     

Production,formulation and application of the entomopathogenic fungus Beauveria bassiana for insect control: current status

This review summarizes the progress and achievements made in the last decade in mass production formulation and application technology of the entomopathogenic fungus Beauveria bassiana. Reports published on relevant research from Belgium, Canada, China, Cuba, Czechoslovakia (former), France, Germany, Great Britain, Philippines, Poland, Switzerland, USA and USSR (former) regarding this topic have been covered. Much of the non‐English language literature, particularly that from Eastern European and Chinese sources, has not been translated and is inaccessible to most English or other western language readers. We have done this translation and through this review provide technological details about mass production of B. bassiana in China. Various aspects of B. bassiana growth, substrate use, production of mycelia, conidiospore and blastospores, process technologies associated with separation, drying and milling, formulation, storage and ‘shelf‐life’, and field efficacy are reviewed. Data are presented on: a modified diphasic production technology developed in China during the 1980s; comparisons between submerged fermentation, which usually produces blastospores, and those producing conidia; the use of mycelial preparations pelletized with alginate or gelatinized with cornstarch or cornstarch‐oil; and data on low or ultra‐low volume sprays of emulsifiable or oil conidial suspensions and dust formulations. B. bassiana has proved to be competitive with chemical insecticides for the annual protection of 0.8–1.3 million hectares against forest and farm insect pests in China. It is hoped that this review will help to bridge the language gap between eastern and western scientists in microbial control using B. bassiana.     

Summer season and long-term drought increase the richness of bacteria and fungi in the foliar phyllosphere of Quercus ilex in a mixed Mediterranean forest

We explored the changes in richness, diversity and evenness of epiphytic (on the leaf surface) and endophytic (within leaf tissues) bacteria and fungi in the foliar phyllosphere of Quercus ilex, the dominant tree species of Mediterranean forests. Bacteria and fungi were assessed during ontogenic development of the leaves, from the wet spring to the dry summer season in control plots and in plots subjected to drought conditions mimicking those projected for future decades. Our aim was to monitor succession in microbiota during the colonisation of plant leaves and its response to climate change. Ontogeny and seasonality exerted a strong influence on richness and diversity of the microbial phyllosphere community, which decreased in summer in the whole leaf and increased in summer in the epiphytic phyllosphere. Drought precluded the decrease in whole leaf phyllosphere diversity and increased the rise in the epiphytic phyllosphere. Both whole leaf bacterial and fungal richness decreased with the decrease in physiological activity and productivity of the summer season in control trees. As expected, the richness of epiphytic bacteria and fungi increased in summer after increasing time of colonisation. Under summer dry conditions, there was a positive relationship between TRF (terminal restriction fragments) richness and drought, both for whole leaf and epiphytic phyllosphere, and especially for fungal communities. These results demonstrate that changes in climate are likely to significantly alter microbial abundance and composition of the phyllosphere. Given the diverse functions and large number of phyllospheric microbes, the potential functional implications of such community shifts warrant exploration.     

中国互花米草防治措施研究进展及展望

互花米草原产于美国大西洋沿岸,20世纪80年代被引入我国,由于抗逆性和繁殖能力强,在我国沿海地区大肆蔓延,对湿地生态系统生物多样性和社会经济发展产生严重威胁,如何有效防治互花米草已成为学者研究的热点和社会关注的焦点之一。本文在文献分析的基础上,阐明了互花米草在国内的分布现状和入侵态势;总结了物理、化学、生物和综合防治法在互花米草防治中的适用范围及优劣势,指出现有防治技术仍存在防治难度大、成本高、治理后易复发和预警体系不完善等问题,为防控互花米草入侵提供理论支持;并进一步提出了基于遥感的“信息收集+早期预警+分级防控”的防控对策和以防治为主、利用为辅的互花米草“防治+利用”技术体系,为今后互花米草的防治和利用提供了新的研究思路。     

草坪害虫淡剑袭夜蛾生物学及防治技术的研究

淡剑袭夜蛾（Sidemia depravata Butler)在山东草坪草上1年发生4－5代,危害盛期在7－8月。田间发生量以冷季型草托亚黑麦草上最多,猎狗高羊茅和午夜早熟禾次之,暖季型草牙根上最少。4种草坪草品种对其幼虫发育历期、雌雄蛹重、单雌产卵量和存活率均有影响,但对蛹期影响不大。管理措施对幼虫的发生量有显影响,以长势好、田间湿度大、刈草不及时的地块发生重。拟除虫菊酯类的夜蛾必杀和高效氯氰菊酯。有机磷类的敌百虫、辛硫磷和奎硫磷对该虫都很敏感,在常用浓度下防效均达95％以上。Bt乳剂和灭幼脲3号对低龄期幼虫防治效果高,但速效性差。     

Genetic and functional characterization of a Bacillus sp. strain excreting surfactin and antifungal metabolites partially identified as iturin-like compounds

AIMS: A bacterial strain producing antifungal compounds active against the plant pathogenic fungi Fusarium, Rhizoctonia and Sclerotinia has been characterized and shown to control Rhizoctonia root rot of soya bean. METHODS AND RESULTS: The metabolites excreted by Bacillus BNM 122 remained active after autoclaving, were resistant over a wide pH range and to hydrolytic enzymes. By (1)H-NMR and thin-layer chromatography analyses surfactin and iturin-like compounds were partially identified. Moreover, soya bean seeds bacterization with BNM 122 in a compost-based formulation was as effective controlling Rhizoctonia solani as pentachloronitrobenzene. According to its 16S rDNA sequence BNM 122 was closely related to Bacillus amyloliquefaciens and Bacillus subtilis. PCR analysis of the 16S-23S rRNA intergenic spacer region and repetitive sequence-based PCR (rep-PCR) genomic fingerprinting revealed a close genetic relationship to B. amyloliquefaciens. However, by physiological characterization using API tests, this strain resembled more B. subtilis. CONCLUSIONS: This is the first report describing the co-production of surfactin and iturin-like compounds by a putative strain of B. amyloliquefaciens. The synergistic effect of both lipopetides is a remarkable trait for a candidate biocontrol agent. SIGNIFICANCE AND IMPACT OF THE STUDY: This kind of research has relevance in order to minimize the use of synthetic fungicides and surfactants, contributing to the preservation of the environment.     

我国蓝藻水华的发生机理、危害及防控利用研究进展

近些年蓝藻水华的大规模爆发不仅危害了水产养殖业,而且严重影响了人类日常生活、供水、旅游业等。主要介绍了蓝藻水华爆发的内在因素（假空泡、类胡萝卜素、厚壁孢子、细胞壁等）及外在因素（营养物质、温度、微量元素、滤食性鱼类等）。阐述了蓝藻水华对生产、生态和生活造成的危害,归纳总结了蓝藻水华防控的化学、物理、生物等方法。最后描述了蓝藻水华的有效利用并提出其研究中存在的问题。