赤潮藻米氏凯伦藻(Karenia mikimotoi)藻际细菌群落及其原位抑藻效应

采用16S rRNA高通量测序技术分析了赤潮藻米氏凯伦藻藻际细菌群落组成,探究了原位营养刺激下藻际细菌对米氏凯伦藻生长的抑制作用。结果表明:米氏凯伦藻藻际环境以Proteobacteria为主(α-Proteobacteria 48.1%,γ-Proteobacteria 8.6%),其次Sphingobacteria 22.4%,Cyanobacteria 10.8%。通过加混合抗生素获得了米氏凯伦藻无菌培养体系,验证了所加营养液对藻的生长无明显影响。向米氏凯伦藻培养体系中添加体积比5%的2216E培养基、甘油和柠檬酸钠时,米氏凯伦藻的生长受到显著抑制,抑制率分别为99.6%、96.0%和91.5%。对2216E刺激下藻际细菌群落变化进行分析表明,α-Proteobacteria丰度增至58.7%,其中Rhodobacteraceae由8.7%增至22.3%,Thalassobaculum由2.7%增至13.3%,γ-Proteobacteria增至13.3%,其中Pseudomonas由2.4%增至4.9%。米氏凯伦藻藻际环境存在着丰富的微生物类群,适量外部营养刺激可以实现藻际细菌原位抑藻效应。     

藻际环境中微生物胞间通讯行为及作用

藻际环境中,微生物通过营养物质交换和活性物质释放相互作用,进而引发共生、竞争或合作等行为.结合环境条件的影响,藻际环境一般具有稳定而多样的微生态结构.以上行为发生的基础是以信号分子为媒介的微生物胞间通讯作用.本文系统综述了藻际环境的特征、藻际胞间通讯行为以及藻际胞间信号分子的类别与作用机制.特别针对痕量信号分子特性,结...     

应用PCR-DGGE技术研究石莼、网地藻藻际微生物多样性

应用变性凝胶梯度电泳(PCR-DGGE)技术对石莼、网地藻藻际微生物多样性进行研究,并对其进行相似性、未加权聚类分析(UPGMA)及微生物多样性(Shannon)指数分析。结果表明,PCR-DGGE图谱显示,石莼、网地藻藻际微生物DGGE图谱有着明显的差异性,具体表现在条带数及密度值的不同。Quantity one图谱分析表明:石莼藻际微生物16S r RNA基因的V3区共分离得到25条DNA片段,网地藻为16条DNA片段。DGGE相似性及未加权聚类分析表明:网地藻藻际微生物间的相似性为77.78%,石莼藻际微生物细菌群落间的相似性为49.25%。Shannon指数分析表明,石莼藻际微生物多样性指数显著高于网地藻(P0.05)。石莼藻际微生物细菌群落较网地藻丰富。     

凤眼莲与其根际细菌相互作用的研究

凤眼莲及其根际细菌的相互关系明显地受营养条件的影响,生长在含糖培养基中的凤眼莲根分泌物不改变其根际细菌的生长动态,但在含酚和无机营养条件下生长的凤眼莲根分泌物分别使其根际细菌出现２次和３次增长;而且在含酚环境中,根际细菌对凤眼莲表现出更为强烈的根际效应．细菌的代谢产物能提高凤眼莲体内的多酚氧化酶的活性,却抑制过氧化物酶的活性和减少其体内酚的富集量;然而接菌后的凤眼莲,其体内多酚氧化酶和过氧化物酶同时得到激活,且酚富集量增加．     

凤眼莲浸出液对东海原甲藻生长的抑制作用

研究了凤眼莲浸出液对赤潮藻东海原甲藻生长的影响。浸出液浓度以单位体积溶液中所含凤眼莲鲜重表示。结果显示,在浸出液浓度大于2g·L^-1时,活体凤眼莲浸出液和干凤眼莲浸出液对东海原甲藻的生长都有明显的抑制作用。在浸出液浓度达到8g·L^-1时,活体凤眼莲浸出液和干凤眼莲浸出液对东海原甲藻都具有杀灭作用,东海原甲藻全部死亡出现的时间分别为培养后的第4t和第5t。经121℃高温处理20min后的活体凤眼莲浸出液对东海原甲藻的抑制作用仍然存在,抑制作用并没有显著减弱。研究结果表明凤眼莲的抑藻物质具有用来控制赤潮生物东海原甲藻的潜在价值。     

坛紫菜养殖周期中的藻际微生物多样性

摘要:【目的】坛紫菜是我国江浙海区栽培地主要经济藻类。观察紫菜养殖过程中藻际微生物的群落特点及变化,研究藻际环境中的微生物因素在紫菜栽培中的作用,为保证紫菜健康生长及病害防治提供理论与实验基础。【方法】采用传统纯培方法和PCR-DGGE 技术分离归类坛紫菜养殖周期中的藻际微生物,并利用16SrDNA (细菌)和18S rDNA(真菌)序列测定及在线BLAST比对鉴定到属,比较分析不同生长阶段、不同养殖海区及养殖过程的坛紫菜藻际微生物的多样性特点。【结果】在坛紫菜养殖过程中总共分离到467株细 菌,共41个属。分类结果显示藻际细菌归属于变形菌门(Alphaproteobacteria和Gammaproteobacteria)、放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes),优势菌群为α-变形菌纲和γ-变形菌纲。分离到55株真菌,共15个属。分类结果显示绝大多数真菌归属于子囊菌门(Ascomycota),仅1株归属于担子菌门(Basidiomycota)伞菌纲(Agaricomycetes)。细菌多样性大于真菌。坛紫菜藻际细菌有19个特异菌属,对照海水细菌有13个特异菌属;从丝状体中分离到大部分真菌和放线菌,坛紫菜养殖丝状体和不同叶状体养殖阶段的藻际微生物类别差异明显。在分离的坛紫菜藻际微生物中发现了与引起细菌性红烂病的海科贝特菌(Cobetia marina)、引起白斑病的紫菜茎点菌(Phoma porphyrae)高度相似的菌株,以及与典型的腐霉如镰孢霉菌(Fusarium sp.)和曲霉(Aspergillus sp.)高度相似的菌株。【结论】坛紫菜养殖过程中藻际微生物的多样性受到紫菜生长形态、养殖时间及养殖环境等因素的影响。在藻际微生物中发现与紫菜致病菌高度相似的微生物,作为潜在致病微生物应得到重视。     

凤眼莲根系分泌物对塔玛亚历山大藻的化感作用(英文)

以塔玛亚历山大藻香港株(Alexandriumtamarense,HKstrain)为材料,研究了凤眼莲(Eichhorniacrassipes)根系分泌物及其丙酮、乙酸乙酯提取物对塔玛亚历山大藻的化感作用(Allelopathic effect)。凤眼莲根粉末的用量为0.1g/L、0.5g/L、1.0g/L、1.5g/L和2.0g/L;丙酮、乙酸乙酯提取物的用量为0.01g/L、0.03g/L、0.05g/L和0.07g/L。由于凤眼莲根系丙酮、乙酸乙酯提取物水溶性比较低,实验中,溶剂提取物置于盖玻片上。培养体系中溶剂提取物的实际浓度通过实验前后盖玻片的差值获得。实验结果表明,凤眼莲根粉末用量大于1.5g/L,对塔玛亚历山大藻抑制率100%,0.5g/L和1.0g/L4d后开始有促进生长的作用。凤眼莲根系丙酮、乙酸乙酯提取物的实际浓度达到0.038g/L、0.022g/L时,对塔玛亚历山大藻抑制超过50%。凤眼莲作为杀藻剂的材料有一定的应用前景。       

5株北极微藻藻际环境的细菌多样性

对5株北极微藻,如脆杆藻(Fragilariopsis sp.)、微单胞藻(Micromonas sp.)、四棘藻(Attheya septentrionalis)、海链藻(Thalassiosira sp.)和小球藻(Chlorella sp.)的不同生长时期的粘附细菌和游离细菌的16S rRNA基因进行PCR-DGGE分析,研究藻际环境的细菌多样性。结果表明,5株微藻具有不同的藻际微生物群落结构组成,其中微单胞藻、脆杆藻、四棘藻和海链藻的藻际细菌主要由Cyanobacteria(藻蓝细菌)、α-Proteobacteria(α-变形菌纲)和γ-Proteobacteria(γ-变形菌纲)组成,仅微单胞藻和脆杆藻检测出CFB(Cytophaga-Flexibacter-Bacteroides,噬纤维菌-屈挠杆菌-拟杆菌)。小球藻由Cyanobacteria、CFB、α-Proteobacteria和β-Proteobacteria(β-变形菌纲)组成。微单胞藻的藻际菌群结构稳定,不同生长时期的游离细菌和粘附细菌组成差异不明显。3株硅藻-脆杆藻、四棘藻和海链藻的游离细菌主要由γ-Proteobacteria组成,小球藻的游离细菌主要为β-Proteobacteria,而5株微藻的粘附细菌主要由Cyanobacteria组成。从DGGE图谱来看,在脆杆藻生长的延滞期、指数期和稳定期,其藻际游离细菌和粘附细菌的16S rRNA基因扩增条带数量和位置均有明显差异,但优势扩增条带较稳定;其他4株藻粘附细菌和游离细菌的扩增条带比较稳定,说明藻际关联菌群结构较稳定。藻菌种间特异性关系为不同微藻藻株提供了重要的线索,同时也带来更多的隐藏在藻际环境中的信息。     

盐爪爪根部微生物分布特征及盐浓度对碳源代谢分析的影响

【背景】耐盐植物盐爪爪广泛分布于盐碱荒漠区域,其根际存在明显的盐离子富集,形成"盐岛效应",研究此过程中微生物如何演替和适应,对揭示盐爪爪根际微生物的分布及其耐盐特性、"盐岛"的形成具有重要科学意义。【目的】揭示盐爪爪根际、根区及其周围环境土壤中微生物分布特征,确定不同盐浓度处理对根际微生物Biolog Eco微平板碳源代谢多样性的影响。【方法】采用Biolog Eco微平板技术,对采自新疆和硕地区的盐爪爪根际、根区和环境土壤微生物碳源利用情况进行分析,并采用不同浓度NaCl溶液对盐爪爪根际土壤样品进行稀释加样,评估盐浓度对根际微生物活性及多样性分析的影响。【结果】样品微生物代谢活性总体呈现根际根区环境的趋势;随着与根部距离的增加,样品中利用氨基酸、胺类碳源微生物所占比例明显降低,而利用吐温和肝糖等多聚化合物类碳源微生物所占比例明显增加;多样性分析表明,随着与根部距离的增加,Shannon指数(H)随之降低且存在明显差异。不同浓度NaCl溶液对采用BiologEco微平板技术分析盐爪爪根际微生物的代谢活性和代谢多样性有着明显的影响,其中采用5%NaCl溶液作为稀释加样液的根际微生物活性最高。【结论】盐爪爪根部微生物组成和分布有着明显的演变规律,且采用Biolog Eco微平板技术分析微生物代谢多样性时需进行培养条件的优化。     

藻际环境微生态结构与功能的研究进展

藻际环境是以藻类分泌物为骨架构成的微型生态结构,包含多样的生物和非生物,主要是微生物、胞外多糖、蛋白质和核酸等物质。藻际环境为复杂的藻菌互动提供平台,也为藻际系统的物质代谢、能量流动和信息交流提供基础。藻际环境不仅可以形成特殊的生态位,而且藻菌作用对多种生源要素循环起到了关键的作用;同时,藻际多糖的沉降为碳封存做出了重要贡献;再者,藻类在应激的时候,可以通过藻际环境形成对种群的保护。基于藻际环境结构和功能多样化的特点,解析其中的生态过程,对未来阐释生态现象的发生(如藻华)和生态修复都具有重要意义。该文综述了藻际环境的特性、影响因素和功能,旨在更好地认识藻际生态位,为藻类系统生态学发展提供理论依据。     

Response of transgenic potato seedlings to allelopathic pressure and the effect of nutrients in the culture medium

Chinese farmers frequently use a wheat–potato cropping system. The land area planted to transgenic potatoes is increasing because transgenic potatoes have greater resistance to pests and diseases. However, little is known about the bio-compatibility of transgenic potatoes with wheat straw. The objective of this tissue culture study was to determine the allelopathic effects of wheat straw on transgenic potato seedlings. Seedlings were cultured on normal MS medium (normal treatment) and nutrient-deficient MS medium (acclimated treatment) and then transferred to MS medium, which contained wheat straw powder. Wheat straw powder inhibited potato seedling growth in both treatments. Among the parameters analyzed in this study, inhibition was greatest for plant fresh weight and least for plant height. The inhibitive effects of wheat straw were greater for seedling roots compared to shoots. Resistance to allelopathic pressure from wheat straw was greater in acclimated seedlings compared to normal seedlings. This suggested that previous pressure may have induced tolerance in the transgenic potato seedlings. Furthermore, growth inhibition of potato seedlings from the normal treatment increased as the amount of wheat straw powder in the culture medium increased. Calculations indicated that the presence of wheat straw would lead to a 55% reduction in the total biomass of normal potato seedlings compared to a 39% reduction for acclimated seedlings. Parameters such as net photosynthesis rate (Pn) and quantum yield (Y(II)) changed as the nutrient content of the culture medium increased or decreased, but the changes in the parameters were smaller for acclimated seedlings compared to normal seedlings. This suggests that nutrient status during the culture period could help transgenic potato seedlings adapt and compensate for energy loss from seedlings in defending against allelopathic pressure. In summary, the results show that previous exposure to pressures such as nutrient deficiency may increase the allelopathic pressure resistance of transgenic potato seedlings.     

Allelopathic effects of interrupted fern on northern red oak seedlings: Amelioration bySuillus luteus L.: Fr.

Summary The allelopathic effects of interrupted fern frond leachates on ectomycorrhizal (inoculated) and nonmycorrhizal (noninoculated) northern red oak (Quercus rubra L.) seedlings were investigated. Container-grown northern red oak was inoculated with vegetative mycelium ofSuillus luteus L. Fr. following acorn germination. Noninoculated control seedlings were also maintained. Seedlings were grown in a glasshouse under full sunlight or shaded (25% of full sunlight) conditions. Leachate or deionized water solutions were applied to seedlings eleven times over a 91-day period to simulate a rainfall induced transfer of allelopathic chemicals from fern fronds to the soil. Fern frond leachates significantly reduced seedling survival, however, inoculated seedlings showed less mortality. Chromium concentrations of pooled lateral root or leaf tissue were comparatively higher in tissues exhibiting greater mortality. Root biomass was reduced by fern fern frond leachate applications. Seedling biomass was not significantly affected by fungal inoculation. Our results confirm previous documentation of the allelopathic potential of ferns, and suggest that ectomycorrhizal fungi may ameliorate allelopathic effects of ferns on northern red oak seedling survival and growth.     

Barnyard grass-induced rice allelopathy and momilactone B

Here, we investigated chemical-mediated interaction between crop and weeds. Allelopathic activity of rice seedlings exhibited 5.3-6.3-fold increases when rice and barnyard grass seedlings were grown together, where there may be the competitive interference between rice and barnyard grass for nutrients. Barnyard grass is one of the most noxious weeds in rice cultivation. The momilactone B concentration in rice seedlings incubated with barnyard grass seedlings was 6.9-fold greater than that in rice seedlings incubated independently. Low nutrient growth conditions also increased allelopathic activity and momilactone B concentrations in rice seedlings. However, the increases in the low nutrient-induced allelopathic activity and momilactone B concentration were much lower than those in barnyard grass-induced allelopathic activity and momilactone B concentration. Root exudates of barnyard grass seedlings increased allelopathic activity and momilactone B concentration in rice seedlings at concentrations greater than 30 mg/L of the root exudates, and increasing the exudate concentration increased the activity and momilactone B concentration. Therefore, barnyard grass-induced allelopathic activity of rice seedlings may be caused not only by nutrient competition between two species, but also by components in barnyard grass root exudates. As momilactone B shows strong allelopathic activities, barnyard grass-induced allelopathic activity of rice may be due to the increased concentration of momilactone B in rice seedlings. The present research suggests that rice may respond to the presence of neighboring barnyard grass by sensing the components in barnyard grass root exudates and increasing allelopathic activity by production of elevated concentration of momilactone B. Thus, rice allelopathy may be one of the inducible defense mechanisms by chemical-mediated plant interaction between rice and barnyard grass, and the induced-allelopathy may provide a competitive advantage for rice through suppression of the growth of barnyard grass.     

番茄（Lycopersicon）的化感作用研究

采用室内生测、室外盆栽和水培相结合的研究方法,以多种受体品种来探讨番茄 的化感作用．结果表明,番茄植物不仅具有自毒作用,番茄植株的水提液对黄瓜、萝卜、生 菜、白菜、包心菜的幼苗生长均有显著的抑制作用;番茄植株的挥发物对黄瓜的生长具有 明显的抑制作用,但对绿豆、白菜、生菜及番茄自身的幼苗生长则无明显的影响;番茄移苗 后４０ ｄ之内,其根分泌物对黄瓜生长有明显抑制作用,但对生菜作用不明显认为自毒作 用是造成番茄连作障碍的原因之一,指出番茄种植应采用轮作方式,水培或大棚种植番茄 时,应避免与黄瓜间种．     

Effect of steam sterilization of soil on two desert plant species

Summary Franseria dumosa Gray and Hilaria rigida (Thurb.) Benth. ex Scribn. seedlings were grown in a glasshouse in potted soil which was collected from the Mojave Desert near Mercury, Nevada. The soil represented areas under living shrubs and also areas between shrubs. Soil was either steam sterilized or not steam sterilized. The sterilization resulted in greatly decreased yields of plants possibly because of induced P deficiency. It was suggested that symbiotic mycorrhizae necessary for P absorption for the species involved might have been eliminated by the sterilization. The effect did not hold for a noncalcareous soil well supplied with available P. Soil sterilization increased both Mn and Zn in plants. There was an interaction in that plants did not grow well in soil from under shrubs regardless of steaming indicating possible allelopathic effects. re]19720711     

Inhibition of seedling survival under Rhododendron maximum (Ericaceae): could allelopathy be a cause?

In the southern Appalachian mountains a subcanopy species, Rhododendron maximum, inhibits the establishment and survival of canopy tree seedlings. One of the mechanisms by which seedlings could be inhibited is an allelopathic effect of decomposing litter or leachate from the canopy of R. maximum (R.m.) on seed germination, root elongation, or mycorrhizal colonization. The potential for allelopathy by R.m. was tested with two bioassay species (lettuce and cress), with seeds from four native tree species, and with three ectomycorrhizal fungi. Inhibitory influences of throughfall, fresh litter, and decomposed litter (organic layer) from forest with R.m. (+R.m. sites) were compared to similar extractions made from forest without R.m. (-R.m. sites). Throughfall and leachates of the organic layer from both +R.m. and -R.m. sites stimulated germination of the bioassay species above that of the distilled water control, to a similar extent. There was an inhibitory effect of leachates of litter from +R.m. sites on seed germination and root elongation rate of both bioassay species compared with that of litter from -R.m. sites. Native tree seed stratified in forest floor material from both forest types had a slightly higher seed germination rate compared with the control. A 2-yr study of seed germination and seedling mortality of two tree species, Quercus rubra and Prunus serotina, in field plots showed no significant influence of litter or organic layer from either forest type. Incorporating R.m. leaf material into the growth medium in vitro depressed growth of one ectomycorrhizal species but did not affect two other species. Leaf material from other deciduous tree species depressed ectomycorrhizal growth to a similar or greater extent as leaf material from R.m. In conclusion, R.m. litter can have an allelopathic effect on seed germination and root elongation of bioassay species as well as some ectomycorrhizal species. However, this allelopathic affect is not manifest in field sites and is not likely to be an important cause for the inhibition of seedling survival within thickets of R.m.     

Low allelopathic potential of an invasive forage grass on native grassland plants: a cause for encouragement?

Tall fescue (Festuca arundinacea Schreb.), a highly competitive European grass that invades US grasslands, is reportedly allelopathic to many agronomic plants, but its ability to inhibit the germination or growth of native grassland plants is unknown. In three factorial glasshouse experiments, we tested the potential allelopathic effects of endophyte-infected (E+) and uninfected (E−) tall fescue on native grasses and forbs from Midwestern tallgrass prairies. Relative to a water control, at least one extract made from ground seed, or ground whole plant tissue of E+ or E− tall fescue reduced the germination of 10 of 11 species in petri dishes. In addition, the emergence of two native grasses in potting soil was lower when sown with E+ and E− tall fescue seedlings than when sown with seeds of conspecifics or tall fescue. However, when seeds of 13 prairie species were sown in sterilized, field-collected soil and given water or one of the four tall fescue extracts daily, seedling emergence was lower in one extract relative to water for only one species, and subsequent height growth did not differ among treatments for any species. We conclude that if tall fescue is allelopathic, its inhibitory effects on the germination and seedling growth of native prairie plants are limited, irrespective of endophyte infection. On the other hand, the apparent inability of these plants to detect tall fescue in field soil could hinder prairie restoration efforts if germination near this strong competitor confers fitness consequences. We propose that lack of chemical recognition may be common among resident and recently introduced non-indigenous plants because of temporally limited ecological interactions, and offer a view that challenges the existing allelopathy paradigm. Lastly, we suggest that tall fescue removal will have immediate benefits to the establishment of native grassland plants.     

连作大豆植株化感作用的模拟研究

使用组培技术在无菌条件下研究了大豆根系分泌物和大豆组织水浸液对大豆苗的化感作用。结果表明,大豆根系分泌物和大豆组织水浸液对“下茬”大豆苗的生长和某些生理活性均有显着影响。这种影响与大豆苗生长激素代谢紊乱有关。从根系分泌物和植株水浸液中均分离出了已知酚酸类化感物质香草酸、香草醛和对羟基苯甲酸。这类物质的影响对大豆连作障碍有直接关系.     

中国南部基塘区农业模式的变迁与凤眼蓝的入侵

为了探究凤眼蓝(别名凤眼莲, Eichhornia crassipes)入侵中国南部基塘区的主要原因, 对历史文献与档案资料进行了综合分析, 结果表明: 凤眼蓝在中国大陆的出现早于1930年。1911年后, 凤眼蓝曾入侵浙江省杭嘉湖平原水网河道。凤眼蓝也是1911年以来珠江三角洲地区十分常见的水生植物。1911-1980年, 基塘农业是浙江省的杭嘉湖地区和广东省珠江三角洲地区的典型农业经营模式, 凤眼蓝在这两个地区都曾被用作有机肥。20世纪50年代末至70年代, 长江流域曾推广凤眼蓝栽培技术, 对凤眼蓝进行了大规模的养植, 但1950-1980年的广积肥运动控制了凤眼蓝的繁殖速度和规模。1980年以来, 基塘地区成为长江三角洲和珠江三角洲城镇化与工业化快速发展的区域, 传统的循环农业经营模式普遍被废弃, 同时, 基塘区河网湿地水文生态环境的改变是凤眼蓝入侵中国南部基塘区的主要原因。     

The application of growth kinetics to the control of Eichhornia crassipes (Mart) solms. Through nutrient removal by mechanical harvesting

The growth of Eichhornia crassipes (water hyacinth) under nitrate-nitrogen limiting conditions can be explained by the Monod rectangular model. The kinetic constants maximum specific growth rate, half saturation constant and yield coefficient were determined under nitrate-nitrogen limiting conditions in nutrient culture at an air temperature of 25°C. The practical application of these constants for the possible control of water hyacinth through nutrient limitation is illustrated.