藓类提取物对植物病原真菌的抑菌性研究

以立枯丝核菌(Rhizoctonia)、尖孢镰孢菌(Fusarium oxysporum)、苹果轮纹病菌(Macrophoma kawatsukai)、梨黑星病菌(Fusicladium pirina)、草莓灰霉菌(Botrytis cinerea)等七种植物病原真菌为供试菌,通过生长速率法测定了24种藓类的乙醇提取物对病原真菌的抑制作用.结果表明,在提取物浓度为1.2mg干样/mL,大镰刀藓提取物对立枯丝核菌的抑制作用最强,抑菌率为67.8%.藓类提取物不仅对植物病原真菌有抑菌活性,而且还有多种藓类提取物对病原真菌菌丝有促进生长活性,如锐尖匍灯藓对立枯丝核菌菌丝生长的促进率为95.1%.选出大镰刀藓、扁灰藓、紫萼藓、山地水灰藓、疣小金发藓、橙色净口藓、锐尖匍灯藓和羊角藓对立枯丝核菌和灰霉菌的抑菌性或菌丝生长促进性进行了进一步研究,藓类提取物对病原菌的抑菌性或菌丝生长促进性在一定范围内随浓度的增加而增强,并且抑菌性随时间的延长呈下降趋势.     

20种植物提取物抑制植物病原菌活性研究

以小麦纹枯病菌(Rhizoctonia cerealis)、番茄灰霉病菌(Alternaria solani)这两种植物病原真菌为供试菌,对采自江西省吉安市的20种植物提取物的抑制菌丝生长活性及孢子萌发进行测定.结果表明,在供试质量浓度为1 mg/mL时,黄花草木樨乙醇提取物的乙酸乙酯萃取部分抑菌效果最好,对小麦纹枯病菌和番茄灰霉病菌两种菌的抑制率均达100%;窃衣、小白酒草、羊蹄和车前草的抑制作用次之,对两种菌的抑制率均大于80%;单从对一种病原菌的抑制作用看,还有黄荆对小麦纹枯病菌率为100%,空心莲子草、窃衣、小白酒草和鬼针草对番茄灰霉病菌的抑制率为100%,但是,这20种供试植物的石油醚相和水相萃取物对两种病原真菌的抑制效果均不强.抑制病原菌孢子萌发亦得到类似结果.以上结果提示植物抑菌活性成分主要存在于乙酸乙酯萃取部分,黄花草木樨、窃衣、小白酒草等的提取物作为植物源杀菌剂值得进一步研究.     

独蒜兰提取物对植物病原真菌的抑菌活性

【目的】研究独蒜兰假鳞茎乙醇提取物对植物病原真菌的抑菌作用,为植物源杀菌剂的开发提供依据。【方法】采用菌丝生长速率法,研究独蒜兰假鳞茎乙醇提取物对15种植物病原菌的抑制活性;以西瓜尖孢镰刀菌作为供试菌,进一步研究该提取物对病原真菌的菌丝干重、细胞膜、过氧化氢酶（CAT）、过氧化物酶（POD）和超氧化物歧化酶（SOD）等的影响。【结果】独蒜兰假鳞茎提取物对辣椒疫霉病菌、西瓜尖孢镰刀菌、番茄灰霉病菌和非洲隐地疫霉菌的抑菌效果明显,其EC₅₀值分别为0.849、0.782、0.813和1.161 mg·mL^-1;经独蒜兰提取物处理后的西瓜尖孢镰刀菌菌丝干重随着药剂浓度的增加而减少;细胞膜丙二醛含量和相对电导率增加;菌丝体细胞内CAT、POD和SOD 3种保护酶活性增加。【结论】独蒜兰假鳞茎提取物对植物病原真菌具有较好的抑菌活性,其抑菌作用可能与其干扰菌丝生长、使菌丝细胞膜正常功能受损等有关。     

卷叶黄精对植物病原菌的抗菌活性研究

采用菌丝生长速率法研究了卷叶黄精根提取物对植物病原菌的抗菌活性。结果表明:卷叶黄精对所选10种植物病原菌中的7种呈现不同程度的抗菌活性,而且各萃取物的抑菌菌种各不相同,其中正丁醇萃取物对4种病原菌、乙酸乙酯萃取物对3种病原菌有明显的抑菌活性,水浓缩物仅对1种病原菌有抗菌活性,而石油醚萃取物对供试植物病原菌没有抗菌活性;正丁醇萃取物对苹果褐腐病、玉米大斑病、棉黄萎病病原菌抑制作用较强,EC50分别为261.26、376.03和430.05μg.mL-1;乙酸乙酯萃取物对苹果腐烂病、番茄黑霉病病原菌抑制作用较强,EC50分别为386.00和865.75μg.mL-1,各样品对植物病原菌的毒力随着浓度的增高而增强;卷叶黄精对植物病原菌的抑菌活性随着作用时间的延长,均呈现不同的下降趋势。     

天然植物提取物对茄子黄萎病菌的抑制活性

以茄子黄萎菌为供试菌种,研究了54种天然植物的乙醇提取液对茄黄萎菌的抑菌活性. 结果表明, 有15种植物提取物对茄子黄萎菌菌丝生长抑制率大于50%,其中细辛、黄连、厚朴、儿茶、苦参、甘草、蛇床子、桔梗、洋葱的提取物对供试菌菌丝生长抑制作用较强,抑制效果均在65%以上,蛇床子的抑菌率达86.84%.有16种植物提取物对病菌孢子萌发的抑制作用大于70%,其中7种植物提取物对孢子萌发的抑制率大于95%以上,细辛、黄连、厚朴基本上抑制了孢子的萌发.儿茶提取物对菌丝生长的抑制效果较差,但却显著抑制了孢子萌发,抑制率达100%.蛇床子提取物虽然抑菌效果较高,但其处理的孢子萌发率为11.3%.研究发现天然植物提取物中存在着抑制黄萎菌的活性物质,这为生物防治黄萎病和进一步研究蔬菜抗病增产理论提供了新的思路与途径.     

丁布对小麦赤霉病菌和玉米小斑病菌的抑制作用

采用菌丝生长速率法和孢子萌发试验法检测了抗菌化合物丁布对小麦赤霉病菌和玉米小斑病菌的抑菌作用。结果表明,丁布在PDA培养基中浓度为0.2-1.0 mg/ml时对两种供试病菌的菌丝生长无抑制作用;丁布浓度为0.4-1.0 mg/ml时对两种供试病菌孢子悬浮液中孢子的萌发具有显著抑制作用;1.0 mg/ml丁布药液中培育15h的小麦赤霉病菌和培育5h的玉米小斑病菌的孢子萌发抑制率分别达到100%和83.6%。     

孜然种子提取物枯茗醛和枯茗酸抑菌作用研究

以番茄早疫病菌、棉花黄萎病菌、小麦纹枯病菌、烟草赤星病菌、小麦全蚀病菌、油菜菌核病菌、辣椒疫霉病菌、水稻纹枯病菌、小麦白粉病菌和番茄灰霉病菌等为供试菌种,采用离体与活体相结合的方法系统地测定了枯茗醛和枯茗酸的抑菌活性。离体抑菌活性测定结果表明,枯茗醛和枯茗酸对多种病原菌具有一定的抑制效果,其中对油菜菌核病菌菌丝生长的抑制效果高于其它供试病原菌,有效中浓(EC50)分别为2.1和7.3 mg/L;枯茗醛和枯茗酸对小麦白粉病的防治实验结果表明,供试浓度为1000 mg/L时,两种药剂的保护防效均高于50%;相同处理浓度下,枯茗酸对油菜菌核病的保护防效与速克灵处理相当,达到57.52%。     

陕北野生甘草内生菌的分离及抑菌活性筛选

采用组织块分离法从陕北野生甘草根中分离出21株内生菌,其中细菌12株,真菌6株,放线菌3株.为明确内生菌代谢产物的抑菌活性,采用抑制菌丝生长速率法和组织测定法系统测定了其发酵液对植物病原真菌的抑制作用.结果表明,在离体条件下,甘草内生菌发酵液对供试的7种植物病原菌菌丝生长均有一定的抑制作用,其中Z4和F1菌株的发酵液对供试病原菌菌丝生长的抑制作用较强,特别是对苹果干腐病菌和烟草赤星病菌的抑制作用最强,抑制率分别可达92.36%、90.16%和91.20%、90.43%,EC50分别仅为54.38、90.31和57.50、89.58 mg·L-1;组织法测定中,发酵液稀释10倍后,Z4和F1菌株对苹果干腐病的保护作用分别为75.39%和73.13%,治疗效果分别为67.61%和60.75%.     

一株新的拮抗细菌SL19及其抑菌活性物质

生防菌SL19对多种植物病原菌有抑菌活性。通过形态观察、生理生化实验和基于16S rDNA同源性序列分析构建系统发育树,鉴定该菌为Bacillus velezensis。利用对峙实验测定了该菌的抑菌谱,发现该菌对大丽轮枝菌、尖孢镰刀菌、灰葡萄孢菌、立枯丝核菌、疮痂链霉菌等多种植物病原微生物有明显的抑菌作用。利用硫酸铵盐析法分离纯化活性物质,并对其理化性质进行初步探索显示:抑菌活性物质经60°C、80°C处理20 min后的抑菌活性不变;经100°C处理20 min,活性降低为原来的75.3%;经120°C处理20 min后抑菌活性完全丧失。对胰蛋白酶、胃蛋白酶、蛋白酶K、氯仿、紫外光均不敏感,SDS-PAGE检测发现该抑菌活性物质中含有分子量约为50 kD的蛋白质,初步推测该菌分泌的抑菌活性物质主要是蛋白质类物质。实验表明,该抗菌蛋白能够抑制大丽轮枝菌菌丝的生长及孢子的萌发,为该菌用于生物防治提供了理论基础。     

山鸡椒植物源抑菌成分的筛选研究

以山鸡椒为植物材料,以活性追踪的方法测定了不同组分对几种植物病原菌的抑制活性,并从中分离纯化出一种有效抗菌物质L1。实验结果表明:粗提物不同萃取相中,乙酸乙酯相的抑制作用最好,其对杨树溃疡病菌和苹果霉心病菌抑制率达到75%以上;乙酸乙酯相各个组分对几种植物病原真菌均有一定的抑制活性,其中组分6和组分7抑菌效果强,组分6对苹果霉心病菌抑制率达到100%,组分7对番茄灰霉病菌抑制率达到100%;而对抑菌活性物质L1的抑菌活性研究中,随着L1浓度逐渐升高,对几种病原菌的抑制作用也依次增强,尤其是对苹果霉心病菌的抑制效果更加明显,在供试浓度为0.1 mg/mL时,抑制率达到100%;活性成分L1最终通过波谱学方法和文献对比确定为5,8-二羟基-67,-二甲氧基黄酮。     

Isolation, identification and antifungal susceptibility of lemon pathogenic and non pathogenic fungi

Numerous species of filamentous fungi were isolated from lemon on different plantations in the province of Tucuman, Argentina. The techniques suggested by the Subcommittee of Antifungal Susceptibility of the National Committee for Clinical Laboratory Standards, (USA) were adapted. The effect of three different concentrations of the fungicides imazalil, guazatine, SOPP and thiabendazole on the fungi Fusarium oxysporum, Fusarium moniliforme, Aspergillus niger, Aspergillus flavus, Aspergillus clavatus, Geotrichum candidum, Rhizopus sp, Penicillium sp, Penicillium digitatum and Mucor sp were studied. All the tested strains were resistant to thiabendazole. We assayed a mixture of SOPP (5%), guazatine (350 ppm) and imazalil (100 ppm), which showed a synergic effect on Rhizopus sp. Mucor sp was the only fungus resistant to the four fungicides tested as well as to the above mentioned mixture.     

Fungicidal management of wilt complex of scented geranium

Systemic fungicides, carbendazim + mancozeb and carbendazim alone completely inhibited the mycelia growth even at 100 and 200 ppm, whereas among non-systemic fungicides, thiram was found to be the most effective and gave 52.77, 62.77 and 85.00% inhibition at 500, 1000 and 1500 ppm concentrations, respectively. Thiram was found to be most effective fungicides in inhibiting the both fungi (68.84 and 58.69%) followed by the indofil M 45 (47.59 and 51.38%). In pot house condition, carbendazim + mancozeb (0.2%) and carbendazim (0.1%) were most effective fungicides in reducing cent percent disease incidence and severity, but it was at par with thiram (82.35; 87.50). In field condition, mulching with transparent polyethylene mulch (25 μm) resulted in highest survival rate (95.83%) and least mortality rate (4.16%) of rooted geranium cuttings after 30 days of germination. The application of carbendazim (Bavistin) at 0.1% when applied individually was also found almost complete control as is evident from low disease incidence (1.04%) and severity (0.52%), considered to be second best treatment. Apparent infection rate (0.0) was observed in carbendazim + mancozeb and carbendazim followed by copper oxychloride (0.006) and carboxin (0.009). Area under disease progress curve was less than 100 in cabendazim + mancozeb and carbendazim.     

Influence of selenium on the efficiency of fungicide action against certain fungi

Aspergillus funiculosus was isolated from rotted banana fruits, whereas Alternaria tenuis and Fusarium sp. were isolated from rotted tomato fruits. The isolated fungi tolerated relatively high levels of the fungicide, Dithane, up to 2560 ppm on solid medium, but grew well at 40 ppm when supplemented with liquid medium. They are able to tolerate selenite up to 2% (w/v) sodium selenite. A. funiculosus showed no growth in the presence of mixture of 2.5 ppm selenium and 20 ppm Dithane, whereas Fusarium sp. failed to grow at 2.5 ppm selenium and 10 ppm Dithane, or at 10 ppm of each. Nevertheless, Alternaria tenuis is more tolerant; it showed growth in the presence of relatively high levels of selenium and Dithane; up to 10 ppm selenium and 40 ppm Dithane, however, its growth was inhibited by the presence of a mixture of both. The results suggested new form of highly active fungicides. Selenium as an essential nutrient at such very low concentrations, as well as the application of very low concentrations of the fungicide, would certainly reduce the hazardous effect of such pollutant in the environment.     

根际真菌对黄瓜土传病害的抑制作用

为了了解根际真菌对黄瓜土传病害的影响,通过平板对峙试验和温室人工接种盆栽试验,对分离自根际土的16株真菌开展了对土传病原真菌的拮抗作用和黄瓜土传病害的抑制作用研究.结果表明: 有4株真菌对一种或多种供试病原真菌表现有拮抗作用,其中经鉴定为土曲霉的菌株JCL143对黄瓜枯萎病菌、立枯病菌和菌核病菌3种供试病原真菌均有较强的拮抗作用.在温室盆栽试验中,接种菌株JCL143对黄瓜3种病害的相对防效均在74%以上;而在不灭菌育苗基质的盆栽试验中,接种菌株JCL143对立枯病和菌核病的防效均在85%以上.在用自然土进行的温室盆栽试验中,接种菌株JCL143对伸蔓期黄瓜枯萎病的相对防效平均达84.1%.菌株JCL143的发酵液对3种供试病原真菌菌落生长都有不同程度的抑制作用,对菌核病菌的菌落生长抑菌率达63.3%.发酵液的抑菌活性随处理温度的升高而下降,对碱性pH值比酸性pH值敏感,而对蛋白酶处理不敏感.说明土曲霉是土壤中抑制植物土传病害的重要因素,菌株JCL143的抑病效果稳定,具有潜在的生防应用价值.     

Selective effects of three herbicides on the fungus flora of egyptian soil

2,4-D (2,4-dichlorophenoxyacetio acid) when applied to the soil at three doses (1.9, 7.6 and 15.2 mg per kg dry soil) had a stimulating effect on the total count of soil fungi and on several fungal species especially between 5 and 20 d after treatment. When the herbicide was incorporated in the agar medium it had a stimulating effect on the counts of total fungi, Aspergillus sp., A. niger, A.fumigatus and Fusarium app. at the low dose (6.3 ppm), but wag toxic at this dose toward Humicola grisea and Myrothecium verrucaria at the medium and high doses (25.2 and 50.4 ppm), it was toxic to the total count of fungi and to the majority of fungal species. VCS-438 [2-(3,4-dichlorophenyl)-4-methyl-l,2,4-oxadiazolidine-3,5-dione] was beneficial to the total count of fungi 2 and 5 d after soil treatment with the medium dose (8.0 mg per kg dry soil). Some fungal species could benefit from the low and the high doses (2.0 and 16.0 mg per kg dry soil) after these experimental periods. In the agar medium the counts of total fungi, Aspergillus sp., A. niger and A.fumigatus were almost significantly reduced by the three doses (6.8, 27.2 and 54.8 ppm). Planavin (4-methylsulphonyl-2,6-dinitro-N,N-dipropylaniline) was stimulating for the total count of fungi, Aspergillus, A.niger and A.ochraceus 2 and 5 d after treatment with the medium dose (8.0 mg per kg dry soil), and was also stimulating to Fusarium population at the medium dose after 2 d and at the high dose (16 mg per kg dry soil) after 20 d. In the agar medium Planavin at the low dose (6.8 ppm) was stimulating to A.terreus and inhibitory to A.nidulans and A.fumigatus. The medium and high doses (27.2 and 54.8 ppm) were generally toxic to the total count of fungi.     

玫烟色拟青霉适温性及抗多菌灵特性的种内变异

在15 ℃～35 ℃的温度范围内比较测定了玫烟色拟青霉(Paecilomyces fumosoroseus) 6株野生菌的菌落生长、产孢量及孢子活力.结果显示,3个指标均以25 ℃左右最好,但同一温度下菌株间或同一菌株在不同温度下的差异显著, 菌株Pfr116和Pfr6206具有相对稳定优良的生长、产孢及活孢率性状.对不同浓度多菌灵对6株野生菌的菌落生长和单孢菌落形成的影响测定表明,菌株间存在较大差异.不同多菌灵浓度对单孢菌落形成的抑制率观察值可用逻辑斯蒂模型较好地拟合(r²≥0.90).用所获参数估计的最低禁菌浓度MIC值显示,Pfr4205和Pfr116对多菌灵表现为低抗性（MIC≤20.0 μg·ml^-1）;Pfr153、Pfr612和Pfr2175属于低水平中抗,MIC值仅略大于20 μg·ml^-1;而Pfr6206的MIC值高达93.5 μg·ml^-1,接近MIC>100 μg·ml^-1的高抗标准.因此,Pfr6206为适温性和抗多菌灵特性俱佳的菌株,可作为抗多菌灵和适应不同季节或地区的害虫生防菌剂的候选菌株.     

芦竹内生真菌F0238对植物病原菌的拮抗作用

从黄海海岸低盐药用植物芦竹(Arundo donax L．)中分离得到木霉属的内生真菌F0238,对其进行拮抗植物病原菌活性及作用机制的试验研究。结果表明F0238发酵液对Botrytis cinerea,Sclerotium rolfsii等8种植物病原菌有强的抑菌活性及抑制孢子萌发作用,且这种作用在发酵原液被稀释了160倍后仍然存在;对峙培养试验表明F0238菌对植物病原菌有很强的拮抗作用,拮抗机制主要为重寄生作用、营养竞争作用及抗生作用等。     

Effect of two systemic fungicides on cellulose decomposing fungi of tomato plants and on some enzymatic activities

Kocide 101 (77% cupric hydroxide) and Ridomil plus (15% metalaxyl and 35% copper oxychloride) were used in the treatment of tomato plants. The two fungicides exerted a depressive effect on the total counts and on the individual cellulose decomposing fungal species associated with the roots and shoots of tomato. When these fungicides were incorporated in the liquid culture medium specified for growth and extracellular enzyme production by some selected fungal species, there was a significant reduction in mycelial growth as well as in amylase, cellulase, lipase and protease production by the fungi tested, particularly at the higher doses (200-400 ppm). Exceptions were observed with lower doses (50 and 100 ppm) especially in case of Aspergillus flavus, Cunninghamella echinulata, Penicillium chrysogenum and Fusarium oxysporum grown for amylase or cellulase production.     

Jatrorrhizine and columbamine alkaloids isolated from Argemone mexicana are inhibitory to spore germination of some plant pathogenic fungi

The isomeric alkaloids jatrorrhizine and columbamine isolated from the whole plant of Argemone mexicana were assessed against spore germination of some fungi, e.g. Alternaria cajani, Bipolaris sp., Helminthosporium sp., Fusarium udum and Curvularia sp. Both the alkaloids were effective against most of the fungi tested. Jatrorrhizine was highly effective against spore germination of Bipolaris sp., Fusarium udum and Curvularia sp. at 5000 ppm concentration, whereas columbamine was highly effective against Alternaria cajani, Helminthosporium sp. and Fusarium udum at 5000 ppm.     

Strains of Colletotrichum coffeanum, the causal agent of coffee berry disease, tolerant to benzimidazole compounds in Kenya

The detection of Colletotrichum coffeanum tolerant to methyl ester of benzimidazole 2-carbamic acid (carbendazim) and a related benzimidazole compound, cypendazole, followed increases in levels of coffee berry disease observed on Coffea arabica in experimental plots sprayed for 2 yr with these compounds. Sporulation by the pathogen on naturally infected berries removed from carbendazim-, cypendazole- or benomyl-sprayed plots was not checked by a further application of 0–05 % (a.i.) of any of the compounds. Nearly all the isolates from these berries were capable of some growth on agar media containing 1000 ppm (a.i.) of either carbendazim or cypendazole. However, only a few could tolerate 1000 ppm of benomyl and the inability of this compound to reduce sporulation on berries infected with tolerant strains was presumably due to its rapid conversion to carbendazim within the host tissue. Less than 1 ppm of carbendazim, cypendazole or benomyl was needed to give 50% inhibition of conidia of the normal strain. Against the most tolerant strains, however, the LD 50 was > 100 ppm of carbendazim and about 30 ppm of benomyl. Whether isolated from unsprayed or benzimidazole-sprayed plots, all isolates of Colletotrichum acutatum, a saprophytic cohabitant of lesions initiated on berries by C. coffeanum, showed the highest degree of tolerance to benzimidazole compounds. No tolerance of either fungus to the ‘conventional’ fungicide captafol was detected.