贵州魔芋软腐病菌多基因分子鉴定及其致病力分析

为明确贵州魔芋软腐病菌种类?致病力及分布特点, 采用组织分离法对贵州主要魔芋种植区软腐病样进行病原菌分离, 对icdA, mdh, mtlD, proA, rpoS 等5个管家基因进行了扩增?序列测定, 分别用单基因和多基因联合系统发育树对病菌进行鉴定, 同时采用组织块接种方法测定了不同菌株的致病力?通过组织分离法共分离魔芋软腐病菌株47株; 采用5个管家基因进行分子鉴定, 将病菌分别鉴定为海芋果胶杆菌Pectobacterium aroidearum?胡萝卜果胶杆菌Pectobacterium carotovorum和方中达迪基氏菌Dickeya fangzhongdai 3个种, 其中海芋果胶杆菌P.aroidearum为贵州魔芋软腐病主要致病菌, 占分离菌株的70%, 广泛分布在多个地区; 其次为方中达迪基氏菌D. fangzhongdai, 占分离菌株的28%, 也普遍存在于贵州各魔芋种植区; 胡萝卜果胶杆菌P. carotovorum最少, 占分离菌株的2%?致病力测定结果表明, 菌株间致病力存在一定的差异, 其中海芋果胶杆菌不同菌株之间致病力差异较大, 低?中?高致病力菌株都有, 方中达迪基氏菌差异较小, 仅有中?高致病力菌株?本研究确定了贵州魔芋软腐病菌种类?致病力及在贵州的分布特点, 首次报道了海芋果胶杆菌?方中达迪基氏菌是贵州魔芋软腐病的主要病原菌, 进一步加深了对魔芋软腐病及其发生流行的认识, 为软腐病的科学防控提供了科学依据?     

抑制植物病原细菌的植物筛选

以3种重要的植物病原细菌—辣椒青枯病菌(Ralstonia solanacearum)、柑橘溃疡病菌(Xanthomonas citri)和大白菜软腐病菌(Erwinia carotovorapv.carotovora)为供试菌,对43种植物甲醇提取物进行离体抑菌活性测定。研究结果表明,漆树对辣椒青枯病菌抑菌活性最强,其次是金秀清明茶;抑制柑橘溃疡病菌活性最高的植物有漆树和十大功劳;对大白菜软腐病菌没有筛选到抑菌活性较好的植物;垫状卷柏、七叶一枝花、少花龙葵、水半夏和豆瓣菜粗提物对3种植物病原细菌均无抑制作用。     

两种植物粗提液对烟草青枯病菌致病力的影响

洋葱和大蒜对多种病原微生物具有较好地抑制作用,能有效降低病原菌的致病力。用洋葱和大蒜植物粗提液5种浓度对烟草青枯病菌做室内抑制测定,采用TTC培养基检测其抑制效果。结果表明,洋葱和大蒜粗提液均可以减弱烟草青枯病菌的致病力。在5种浓度下,随着植物粗提液浓度的升高,菌落在TTC培养基上表现的红斑范围越大,颜色越深。烟草青枯菌的致病力强弱与红斑大小、颜色深浅呈反比。因此,洋葱和大蒜粗提液可抑制烟草青枯病菌的致病力,是良好的植物源生物药剂。     

扁茎黄芪植株中化学成分的分离鉴定及其抑菌活性

为综合开发利用药用植物扁茎黄芪Astragalus complanatus，对其非药用部位的化学成分及抑菌活性进行了初步研究。采用硅胶柱层析和LH-20凝胶层析技术从扁茎黄芪植株中分离鉴定了7个化合物，并测定了各化合物对8种细菌的抑菌活性。根据波谱分析结果，7个化合物分别被鉴定为β-谷甾醇 (1) 、β-sitostenone (2) 、lawsaritol A (3) 、3β-羟基-5α,8α-桥二氧麦角甾-6,22-二烯 (4) 、3′,7-二羟基-2′,4′-二甲氧基异黄烷 (5) 、D-1-O-甲基肌醇 (6) 和沙苑子苷 (7) ，所有化合物均为首次从扁茎黄芪植株中分离得到。抑菌活性测定结果表明:化合物 5 对蜡状芽孢杆菌Bacillus cereus、大肠杆菌Escherichia coli、金黄色葡萄球菌Staphylococcus aureus、枯草芽孢杆菌Bacillus subtilis、白菜软腐病菌Erwinia carotovora、猕猴桃溃疡病菌Pseudomonas syringaepv.actinidiae和烟草青枯病菌Ralstonia solanacearum均有不同程度的抑制作用，其中对猕猴桃溃疡病菌、烟草青枯病菌和白菜软腐病菌的最低抑制浓度(MIC)分别为37.5、18.8和75.0 μg/mL。3′,7-二羟基-2′,4′-二甲氧基异黄烷 (5) 的农用抑菌活性为首次报道。     

不同药剂对蔬菜软腐病菌的抑制效果

用 1 5种杀菌剂分别在PDA平板上和辣椒果实上对蔬菜软腐病菌进行抑制效果测定。结果表明 :1 0 %农用硫酸链霉素可溶性粉剂 (4 0 0× 1 0× 1 0 -6)的抑菌效果最好。其次为 80 %芋腐灵可性粉剂 (6 0 0倍 )、88%水合霉毒可湿性粉剂 (2 0 0 0倍 )、冠菌清 5 7 6 %干粒剂 (1 5 0 0倍 )和 5 3 8%可杀得 2 0 0 0干悬浮剂 (90 0倍 )。     

几种化学物质诱导彩色马蹄莲对软腐病抗性的研究

本试验测定了纳米硅、草酸、硅酸钠和硫酸亚铁4种化学物质在不同浓度下对彩色马蹄莲软腐病菌的室内抑菌活性和诱导抗病效果。结果表明,硫酸亚铁3种浓度对彩色马蹄莲软腐病菌均表现较强的抑制作用;1 g/L纳米硅、0.15 g/L草酸和0.2 g/L硅酸钠3种化学物质对软腐病菌无明显抑制作用且诱导抗病效果较好,分别达到62.28%、77.56%、88.46%;经3种化学物质诱导处理后再进行接种,诱导处理和接种期间彩色马蹄莲叶片组织内过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)酶活性均高于对照,其中硅酸钠处理后彩色马蹄莲叶片组织内POD、PAL活性高于纳米硅和草酸处理,草酸处理后叶片组织内PPO活性高于纳米硅和硅酸钠处理。     

桧木醇对西瓜枯萎病菌的抑制作用

由尖孢镰刀菌西瓜专化型(Fusarium oxysporum f. sp. niveum,FON)引起的西瓜枯萎病是一种毁灭性的土传病害。本研究通过离体及活体试验，测定了植物源天然抑菌活性物质桧木醇对西瓜枯萎病菌的抑制活性、对西瓜枯萎病的盆栽防效以及对病原菌生理生化指标的影响。结果表明：桧木醇对西瓜枯萎病菌具有明显的抑制效果，其对病原菌菌丝生长和孢子萌发的抑制作用EC₅₀值分别为31.1和45.2μg/mL；在250、500和1000μg/mL 3个质量浓度下，桧木醇对西瓜枯萎病均有显著的防治效果，其中1000μg/mL时防效可达75.2%，与对照药剂多菌灵500μg/mL的效果相当。生理生化指标测定及外观形态观察发现，经桧木醇处理后，西瓜枯萎病菌菌丝相对电导率上升，菌丝体内镰刀菌酸含量显著降低，菌丝呈现扭曲、畸形、缠绕等不规则外观形态。研究表明，桧木醇不仅能显著抑制西瓜枯萎病菌的生长，同时能抑制其相关毒素的生物合成或促进其代谢，从而降低病原菌的致病力，具有开发为西瓜枯萎病防治替代药剂的潜力。桧木醇处理能破坏病原菌细胞膜的完整性、干扰病原菌次生代谢物的合成或代谢过...     

广西杧果炭疽病病菌致病力差异测定

采用组织分离法从广西不同地区不同生境分离获得19株杧果炭疽病病菌,通过离体针刺接种测定了菌株的致病力差异。结果表明,以接种病菌后7 d的病情指数进行聚类分析,将可19株菌株划分为3个致病类型:强致病型、中等致病型、弱致病型。各类型菌株所占比例大小为:弱致病型中等致病型强致病型。表明广西杧果炭疽病病菌不同菌株的致病力存在明显差异。其中,弱致病型菌株占优势。     

苹果斑点落叶病菌对戊唑醇敏感基线建立及抗性突变体适合度

本研究测定了苹果斑点落叶病菌对戊唑醇的敏感性,并建立了敏感基线;在此基础上,室内筛选获得了9株抗戊唑醇突变体,对其适合度进行了测定,为指导戊唑醇防治苹果斑点落叶病提供理论依据。在山西省5个地市未使用过戊唑醇及同类药剂的果园中采集分离得到64株苹果斑点落叶病菌,敏感性测定结果表明,其EC50值在0.768 7~2.673 8μg·mL~(-1)之间,平均值为1.622 4±0.558 2μg·mL~(-1),呈连续性单峰曲线,可作为苹果斑点落叶病菌对戊唑醇的相对敏感基线。通过紫外线(UV)诱导获得低抗突变体6株,药剂驯化获得中抗突变体3株。2株中抗突变体抗药性可稳定遗传;低抗突变体在无药剂胁迫时,药剂敏感性上升。抗性突变体适合度测定结果显示,突变体菌丝生长速率、产孢量、孢子萌发率及分生孢子竞争力均低于敏感菌株。突变体在无药情况下致病力比敏感菌株弱。     

新疆加工型辣椒细菌性斑点病的发生和病原鉴定

 新疆加工型辣椒主要产区巴音郭楞蒙古自治州发生了一种严重危害辣椒的细菌性病害。从发病辣椒叶片中分离细菌,通过烟草过敏性反应、马铃薯软腐试验和接种辣椒等致病性测定,确定了13个致病菌株,各菌株之间致病力无明显差异。通过菌体形态、培养性状观察、生理生化反应、寄主范围测定,结合16S rDNA和rpoD基因扩增、序列测定和系统发育分析,将病原菌鉴定为丁香假单胞菌丁香致病变种(Pseudomonas syringae pv. syringae)。病原菌人工接种还能侵染番茄、茄子、马铃薯及黄瓜、四季豆、白菜、萝卜、芹菜等植物。P. syringae pv. syringae引起加工型辣椒细菌性斑点病在国内属首次报道。     

Hymenopteran Parasitoids on Fruit-infesting Tephritidae (Diptera) in Latin America and the Southern United States: Diversity, Distribution, Taxonomic Status and their use in Fruit Fly Biological Control

We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.     

Brief Guide for Authors

正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad     

The parasitoid complex ofLiriomyza cicerina on chickpea (Cicer arietinum)

Liriomyza cicerina (Diptera: Agromyzidae) is an important pest on chickpea in Turkey. The objective of this study was to determine the parasitoids and rates of parasitism ofL. cicerina on chickpea (Cicer arietinum L.) during the 2005 and 2006 seasons in ?anl?urfa province, Turkey. Leaves with mines were sampled weekly and kept in the laboratory to observe and count emerging leafminer and parasitoid adults. Eight parasitoid species were collected: the braconidsOpius monilicornis Fischer andOpius tersus Foerster and the eulophidsDiaulinopsis arenaria (Erdös) andNeochrysocharis formosa (Westwood), which occurred in both the winter and summer seasons;Diglyphus crassinervis Erdös,Neochrysocharis ambitiosa Hansson,Neochrysocharis sericea (Erdös) andPediobius metallicus (Nees), which occurred only in the summer growing areas.Diaulinopsis arenaria was the predominant parasitoid with 4–7.7% parasitism rate whileN. ambitiosa andO. monilicornis were the second and third most predominant species. The results of these trials show that sinceDia. arenaria occurred throughout every season, it could potentially be used for control of the leafminerL. cicerina.     

Plant–herbivore asynchrony necessitates augmentative releases of the exotic beetle,Zygogramma bicolorata,to enhance the biological control of P arthenium hysterophorus

Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F ₃, F ₄ and F ₅, but not in F ₁ and F ₂ that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F ₁ and F ₂ in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Relationship Between Production of the Phytotoxin Prehelminthosporol and Virulence in Isolates of the Plant Pathogenic Fungus Bipolaris sorokiniana

A gas chromatographic method was developed to quantify the phytotoxin prehelminthosporol, which is a sesquiterpene metabolite of the plant pathogen Bipolaris sorokiniana. The toxin was extracted from mycelium or culture filtrates, pre-cleaned using solid phase extraction, and analyzed by gas chromatography as a trimethylsilyl-derivative. The detection limit of the method was 5ngl^–1 (signal to noise ratio 4:1) which corresponds to ca. 15ng prehelminthosporol per mg dry weight of mycelium or 15ng prehelminthosporol per ml culture filtrate. The total amount of prehelminthosporol (mycelium plus culture filtrate) increased with cultivation time when examined in six isolates of B. sorokiniana after 6, 9, 12 and 15 days of incubation. The screening experiment of 17 isolates for prehelminthosporol production after 8 days of incubation revealed significant differences in the toxin production between the isolates. The isolates with low toxin production had lower virulence towards barley roots compared to those with higher production of the toxin. However, the virulence did not increase with prehelminthosporol level among the high producing isolates. Prehelminthosporol was also analyzed in a number of related Bipolaris and Drechslera species. In addition to B. sorokiniana, three out of six Bipolaris species (B. setariae, B. zeicola, B. victoriae) produced prehelminthosporol, which indicates that ability to produce prehelminthosporol is conserved among closely-related Bipolaris species.     

Effect of botanical insecticides and bacterial toxins on the gut enzyme of the rice leaffolderCnaphalocrocis medinalis

The effect of botanical insecticides and bacterial toxins on gut enzyme activity of larvae of the rice leaffolderCnaphalocrocis medinalis (Guenée) (Insecta: Lepidoptera: Pyralidae) was investigated. Gut enzyme activities were affected by botanical insecticides and bacterial toxin individually and in combination. When fed a diet of rice leaves treated with botanical insecticides and bacterial toxins, in bioassays the activities of gut tissue enzymes — acid phosphatases (ACP), alkaline phosphatases (ALP) and adenosine triphosphatases (ATPase) — of rice leaffolder larvae were affected. When combined, the effect was more severe at a low concentration. Larvae that were chronically exposed to botanical insecticides and bacterial toxins showed a reduction in weight (59–89%) and exhibited a significant reduction in ACP, ALP and ATPase activities. The combination ofBacillus thuringiensis kurstaki and botanical insecticides caused a decrease of twofold in enzyme activity even at reduced concentration. A synergistic effect was found when botanical insecticides and bacterial toxins were combined at low doses. These effects were most pronounced in early instars. Clear dose-response relationships were established with respect to enzyme activity. In conclusion: (i) biopesticides are relatively safe and biodegradable; (ii) a synergistic effect of botanical insecticides and bacterial toxins was found; (iii) less expensive, readily available and naturally occurring biopesticides could be an alternative for organic and inorganic pesticides in controlling RLF. http://www.phytoparasitica.org posting Sept. 28, 2004.