蓖麻提取物对南方根结线虫的防治作用

通过毒力测定及盆栽试验,研究了蓖麻提取物对南方根结线虫的杀线活性及防治效果.结果表明:蓖麻碱及蓖麻水提液均具有较强毒杀线虫活性,蓖麻碱浓度为2g·L-1、处理48 h杀线虫活性最强,线虫校正死亡率达91.5％,LC50为0.6 g·L-1;蓖麻水提液浓度为100g·L-1、处理48 h杀线虫活性最强,线虫校正死亡率达83.5％,LC50为18.3 g·L-1;蓖麻碱、蓖麻水提液和蓖麻叶植物粉处理接种南方根结线虫的番茄苗后,植株平均根结数分别为(17.6±1.7)、(20.6±1.5)和(22.8±3.7),均显著低于对照(37.4±2.3),根长分别比对照提高46.8％、34.5％和33.8％,株高分别比对照提高33.5％、22.6％和15.8％,植株鲜质量分别比对照增加41.4％、18.9％和10.1％.蓖麻提取物能减轻线虫危害,对盆栽番茄南方根结线虫病控制效果明显.     

蓖麻提取物和淡紫拟青霉对南方根结线虫的防治作用

通过杀线活性测定及盆栽试验,研究了蓖麻提取物和淡紫拟青霉(Paecilomyces lilacinus)对南方根结线虫(Meloidogyne incognita)的杀线活性及防治效果.结果表明:蓖麻碱不影响淡紫拟青霉孢子的萌发.蓖麻碱和淡紫拟青霉均具有较强杀线活性,蓖麻碱处理对南方根结线虫的卵孵化抑制率和二龄幼虫死亡率分别达61.7%和59.2%,显著高于对照处理;蓖麻碱和孢子液复合处理接种南方根结线虫的番茄苗后,植株平均根结数为15±3,显著低于对照的平均根结数37±2,株高、鲜重和根长增长率分别比对照提高38.5%、44.0%和57.0%.说明蓖麻提取物和淡紫拟青霉能减轻线虫危害,对番茄南方根结线虫病控制效果明显.     

山萘杀线虫活性成分的分离及鉴定

采用超声波提取法,用甲醇作溶剂对山萘进行粗提,分别测定了山萘提取物对松材线虫和南方根结线虫的毒性,结果显示,1 000 mg/L山萘甲醇粗提取物处理松材线虫和南方根结线虫,24 h校正死亡率均达到100%.采用活性追踪和柱层析法,以5种植物病原线虫为对象,提取、分离、纯化出山萘根中的活性成分,结果显示,在正己烷萃取组分中,得到活性较高的化合物A、B;用化合物A处理南方根结线虫、松材线虫、马铃薯腐烂茎线虫、海南根结线虫、象耳豆根结线虫72 h后,其LC50分别为17.79、29.70、43.21、57.64和36.94 mg/L;用化合物B处理72 h后LC50分别为1.49、2.81、10.09、26.67和14.47 mg/L.化合物A和B经1H-NMR、13C-NMR、GC-MS分析鉴定表明,A为肉桂酸乙酯,B为对甲氧基肉桂酸乙酯.     

窿缘桉树皮化学成分的分离鉴定及其生物活性研究

采用多种色谱技术从窿缘桉树皮中分离得到3个化合物,经1H NMR、13C NMR和质谱分析分别鉴定为3β-O-反式对羟基肉桂酰基-12-烯-28-齐墩果酸(1)、3β-O-反式对羟基肉桂酰基-2α-羟基-12-烯-28-乌苏酸(2)和3-O-methylellagic acid-4'-O-α-L-rhamnopyranoside(3)。其中,化合物1为首次从桃金娘科植物中分离得到,化合物1、2为首次从桉属植物的树皮中分离得到,化合物1~3均为首次从该植物中分离得到。分别测定分离得到的化合物对福寿螺、南方根结线虫的毒杀活性以及对斜纹夜蛾的卵巢细胞增殖抑制作用。结果表明以上3种化合物对福寿螺有较弱的毒杀活性,在50 mg/L的浓度下,72 h的死亡率分别为20.03%、22.14%和9.84%;在100 mg/L的浓度下,化合物1和2对南方根结线虫表现出较弱的毒杀活性,72 h的死亡率分别为28.12%和42.19%,化合物3没有杀线虫活性;化合物1和2对斜纹夜蛾卵巢细胞的增殖具有明显抑制作用,在20 mg/L浓度下,抑制率分别达到71.07%和84.03%,化合物3对斜纹夜蛾卵巢细胞的活性较弱,在相同测试浓度下,抑制率为44.30%。     

半夏和苦豆子生物碱的抗线虫活性

首次研究了半夏和苦豆子生物总碱,以及3种主要的苦豆子单体生物碱(槐定碱、氧化苦参碱和氧化槐果碱)的抗线虫活性。半夏生物总碱处理24 h,对松材线虫、南方根结线虫、全齿复合线虫和秀丽隐杆线虫的半抑制浓度(IC50)分别为16.18、20.25、33.24和20.77μg/m L。苦豆子生物总碱处理24 h,对上述4种线虫表现出更强的抑制活性,IC50值分别为0.622、0.383、1.476和1.224μg/m L,抗线虫活性强于或接近阳性对照阿维菌素。3种苦豆子单体生物碱均表现出明显的抗线虫活性,其中氧化槐果碱的抗线虫活性最强。研究结果为植物源杀线虫剂的研究和开发提供了依据。     

番木瓜和西番莲根结线虫病记述

本文对番木瓜根结线虫病和西番莲根结线虫病的症状作了描述。病原线虫经鉴定确认,侵染番木瓜的虫种为南方根结线虫(Meloidogneincognita),侵染西番莲的根结线虫是由南方根结线虫、高弓根结线虫(M. acrita)和花生根结线虫(M. arenaria)3个种组成的混合群体,南方根结线虫为优势种。     

朱砂莲果实化学成分杀南方根结线虫活性研究

为了解朱砂莲(Aristolochia tuberosa O.F.Liang et S.M.Huang)的化学成分,从其果实的甲醇提取物中分离得到4个化合物。通过波普数据分析,分别鉴定为马兜铃内酰胺W(1)、8-epidiosbulbin e acetate(2)、diosbulbin B(3)和β-sitosterol(4)。化合物1~3对南方根结线虫2龄幼虫具有不同程度的毒杀作用,尤其马兜铃内酰胺W(1)活性最好,其96 h后的LC50为119.94μg m L–1。马兜铃属植物具有开发为新型植物源杀根结线虫剂的潜在价值。     

苦豆碱及顺式氯氰菊酯对菜田蚜虫群落的毒力研究

研究了植物源杀虫剂苦豆碱及顺式氯氰菊酯对菜田蚜虫群落结构的影响,并测定了其对第一优势种菜缢管蚜的杀伤毒力.苦豆碱在1%浓度下,以药膜法和喷雾法,测定其击倒作用,KT50分别为29.74和25.38min;顺式氯氰菊酯在0.1%浓度下,KT50分别为1.73和0.78min.以点滴法测定此两种杀虫剂对菜缢管蚜的触杀作用,LD50分别为7.7×10-4及9.201μg/头,田间以0.1%喷雾,苦豆碱10d校正防效均可达到80%,而顺式氯氰菊酯仅能达到30%.结果显示,苦豆碱对菜缢管蚜有极强的毒杀作用,同时喷药前后菜田蚜虫群落结构也发生着明显的变化.     

放线菌Snea253代谢产物及寡糖对南方根结线虫活性的影响

本文针对前期筛选获得的高效放线菌Snea253菌株代谢产物中杀线虫活性成分进行试管法和薄层层析法预试,结果显示活性物质含糖和氨基酸。贝氏皿浸没法研究了Snea253代谢产物中杀线虫活性物质和已知寡糖对南方根结线虫卵孵化和二龄幼虫J2的影响,结果表明:Snea253活性物质对南方根结线虫卵孵化的相对抑制率为84.95%,供试寡糖中除麦芽糖和蔗糖有不显著的抑制作用外,半乳糖、果糖和木糖显著促进了南方根结线虫卵孵化;乳糖、葡萄糖和山梨糖均具有促进作用,但与对照相比不显著。Snea253活性物质对J2的校正死亡率为98.21%,与各寡糖处理和对照相比差异显著;葡萄糖、乳糖和蔗糖处理J2无死亡现象,反而利于南方根结线虫J2的存活。研究结果显示普通寡糖对南方根结线虫基本无毒性,而放线菌Snea253代谢产物中氨基糖类物质则对线虫有毒性。     

苦豆碱及顺式氯氰菊酯对莱田蚜虫群落的毒力研究

研究了植物源杀虫剂苦豆碱及顺式氯氰菊酯对菜田蚜虫群落结构的影响 ,并测定了其对第一优势种菜缢管蚜的杀伤毒力。苦豆碱在 1 %浓度下 ,以药膜法和喷雾法 ,测定其击倒作用 ,KT50 分别为2 9 74和 2 5 38min ;顺式氯氰菊酯在 0 1 %浓度下 ,KT50 分别为 1 73和 0 78min。以点滴法测定此两种杀虫剂对菜缢管蚜的触杀作用 ,LD50 分别为 7 7× 1 0 -4 及 9 2 0 1 μg 头 ,田间以 0 1 %喷雾 ,苦豆碱 1 0d校正防效均可达到 80 % ,而顺式氯氰菊酯仅能达到 30 %。结果显示 ,苦豆碱对菜缢管蚜有极强的毒杀作用 ,同时喷药前后菜田蚜虫群落结构也发生着明显的变化。     

Virtual screening and in vitro assay of potential drug like inhibitors from spices against Glutathione-S-Transferase of Meloidogyne incognita

Glutathione S-transferases (GSTs) enzymes are critical antioxidant and detoxification system responsible for long-term existence of nematodes in host species. Hence, 16 phytochemicals predicted and reported to have potential nematicidal activity have been docked to GST enzyme of Meloidogyne incognita to assess their binding affinity and inhibitory activity. In vitro effects of these phytochemicals from in silico results have been done for validation of docking studies and efficacy in GST inhibition of following compounds such as alpha- pinene, alpha- terpineol, beta- caryophyllene, capsaicin, cinnamic acid, citronellol, curcumin, eugenol, geraniol, isoeugenol, linalool, myristicin, neral, NVA (N-vanillylnonanamide), piperine, vanillin have been revealed. Nematode inhibition in vitro bioassay for selected compounds could conclude that maximum mortality was observed with highest concentrations of beta- caryophyllene (78%) followed by eugenol (61.6%), cinnamic acid (55%) and N-vanillylnonanamide (49%). These findings thus suggest that the above phytochemicals could be potentially developed as nematicidal molecules against M. incognita infections.     

Solubilization of insoluble zinc compounds by Gluconacetobacter diazotrophicus and the detrimental action of zinc ion (Zn2+) and zinc chelates on root knot nematode Meloidogyne incognita

AIM: To examine the zinc (Zn) solubilization potential and nematicidal properties of Gluconacetobacter diazotrophicus. METHODS AND RESults: Atomic Absorption Spectrophotometer, Differential Pulse Polarography and Gas Chromatography Coupled Mass Spectrometry were used to estimate the total Zn and Zn(2+) ions and identify the organic acids present in the culture supernatants. The effect of culture filtrate of Zn-amended G. diazotrophicus PAl5 on Meloidogyne incognita in tomato was examined under gnotobiotic conditions. Gluconacetobacter diazotrophicus PAl5 effectively solubilized the Zn compounds tested and 5-ketogluconic acid was identified as the major organic acid aiding the solubilization of zinc oxide. The presence of Zn compounds in the culture filtrates of G. diazotrophicus enhanced the mortality and reduced the root penetration of M. incognita under in vitro conditions. CONCLUSIONS: 5-ketogluconic acid produced by G. diazotrophicus mediated the solubilization process and the available Zn(2+) ions enhanced the nematicidal activity of G. diazotrophicus against M. incognita. SIGNIFICANCE AND IMPACT OF THE STUDY: Zn solubilization and enhanced nematicidal activity of Zn-amended G. diazotrophicus provides the possibility of exploiting it as a plant growth promoting bacteria.     

Process development of oxalic acid production in submerged culture of Aspergillus niger F22 and its biocontrol efficacy against the root-knot nematode Meloidogyne incognita

Bioprocess and Biosystems Engineering - Oxalic acid has potent nematicidal activity against the root-knot nematode Meloidogyne incognita. In this study, fermentation parameters for oxalic acid...     

3-hydroxypropionic acid as a nematicidal principle in endophytic fungi

3- Hydroxypropionic acid was isolated by bioactivity-guided fractionation of extracts obtained from submerged cultures of several endophytic fungi isolated from above-ground plant organs. This compound showed selective nematicidal activity against the plant-parasitic nematode Meloidogyne incognita with LD50 values of 12.5-15 microg/ml. Activity against the saprophytic Caenorhabditis elegans was fivefold lower. No antimicrobial, cytotoxic or phytotoxic effects were observed. Propionic acid and D- and L-lactic acids were not active against either nematode species. Based on morphological features and ITS, 18S and 28S rDNA analyses, the producing strains were identified as Phomopsis phaseoli isolated from the leaf of a tropical tree, and four strains of Melanconium betulinum isolated from twigs of Betula pendula and B. pubescens in Germany. This is the first report of 3-hydroxypropionic acid in fungi, and of the nematicidal activity of this metabolite.     

银胶菊叶和花提取物对南方根结线虫的毒杀活性比较

为进一步明确银胶菊(Parthenium hysterophorus L.)的杀线虫活性,对银胶菊叶和花的不同溶剂提取物、甲醇提取物的不同萃取物以及甲醇提取物碱水层的不同极性组分对南方根结线虫(Meloidogyne incognita Chitwood)的杀虫活性进行了检测,并对不同提取物、萃取物和萃取组分进行了生物碱的定性分析.结果表明:银胶菊叶和花的蒸馏水、甲醇、乙酸乙酯和石油醚提取物的得率分别为24.5％和20.3％、19.6％和10.9％、6.8％和7.7％、2.0％和2.7％,其中,叶和花的蒸馏水和甲醇提取物的杀线虫活性均较强,而石油醚提取物的杀线虫活性最弱.用质量体积分数1.0％和0.5％的叶和花蒸馏水提取物分别处理24和48 h后试虫的校正死亡率均达到100.00％;用质量体积分数1.0％和0.5％的叶和花甲醇提取物处理48 h,试虫的校正死亡率均大于90％.叶和花甲醇提取物的碱水层、三氯甲烷Ⅰ层和Ⅱ层萃取物均具有一定的杀线虫活性,其中,用质量体积分数1.0％的花和叶碱水层萃取物以及花的三氯甲烷Ⅰ层萃取物分别处理48 h,试虫的校正死亡率均为100.00％,而三氯甲烷Ⅱ层萃取物的杀线虫活性最弱.银胶菊叶和花甲醇提取物碱水层的11个不同极性组分(A1～A11)也表现出不同程度的杀线虫活性,其中,用质量体积分数0.2％和0.1％花的A2[溶剂为V(三氯甲烷)∶V(甲醇)=10∶1]和A7[溶剂为V(三氯甲烷)∶v甲醇)=1∶1]组分以及叶的A2和A6[溶剂为V(三氯甲烷)∶V(甲醇)=2∶1]组分处理48 h后,试虫的校正死亡率均达100.00％,显著高于其他组分.定性实验结果表明:银胶菊叶和花中具有杀线虫活性的提取物、萃取物和萃取组分中均含有生物碱.研究结果说明:银胶菊花的杀线虫活性高于叶片,其毒杀活性不仅与提取部位及溶剂的种类和极性有关,还与提取物浓度及作用时间等因素有关.     

Molecular detection of nematicidal crystalliferous Bacillus thuringiensis strains of Iran and evaluation of their toxicity on free-living and plant-parasitic nematodes

The characterization of nematode-effective strains and cry genes in the Iranian Bacillus thuringiensis (Bt) collection (70 isolates) is presented. Characterization was based on PCR analysis using 12 specific primers for cry5, cry6, cry12, cry13, cry14, and cry21 genes encoding proteins active against nematodes, crystal morphology, and protein band patterns as well as their nematicidal activity on root-knot nematode (Meloidogyne incognita) and two free-living nematodes (Chiloplacus tenuis and Acrobeloides enoplus). PCR results with primers for these genes showed that 22 isolates (31.5%) contain a minimum of one nematode-active cry gene. Strains containing the cry6 gene were the most abundant and represent 22.8% of the isolates. Bt strains harboring cry14 genes were also abundant (14.2%). cry21 and cry5 genes were less abundant, found in 4.2% and 2.8% of the strains, respectively. In total, six different nematode-active cry gene profiles were detected in this collection. Four isolates did not show the expected PCR product size for cry5, cry6, and cry21 genes; they might contain potentially novel insecticidal crystal protein genes. Twenty-two Bt isolates containing nematode-active cry genes were selected for preliminary bioassays on M. incognita. Based on these bioassays, four isolates were selected for detailed bioassays. Isolates YD5 and KON4 at 2 x 10(8) CFU/mL concentrations showed 77% and 81% toxicity on M. incognita, respectively. The free-living nematodes C. tenuis and A. enoplus were more susceptible and the highest mortality was observed within 48 h of incubation at all of the concentrations tested. Maximum mortality was recorded for isolates SN1 and KON4 at 2 x 10(8) CFU/mL concentrations and resulted in 68% and 77% adults deaths of C. tenuis and 68% and 72% for A. enoplus, respectively. Our results showed that PCR is a useful technique for toxicity prediction of nematicidal Bt isolates.     

Nematicidal prenylated flavanones from Phyllanthus niruri

Two prenylated flavanones have been isolated from the hexane extract of Phyllanthus niruri plant. The structure of these flavanones were established as 8-(3-Methyl-but-2-enyl)-2-phenyl chroman-4-one (1) and 2-(4-hydroxyphenyl)-8-(3-methyl-but-2-enyl)-chroman-4-one (2) on the basis of spectral analysis. These were evaluated for nematicidal activity against root-knot, Meloidogyne incognita, and reniform, Rotylenchulus reniformis, nematodes. Compound 2 exhibited nematicidal activity at par with the standard carbofuran (LC50 3.3 and 3.1ppm, respectively) when tested against reniform nematode. The LC50 value against root-knot nematode was found to be 14.5ppm. Compound 1 however, showed moderate activity against both the test nematodes.     

Essential Oils as Potent Source of Nematicidal Compounds

Bioassay tests were conducted to find out the nematicidal activity of eight essential oils against Meloidogyne incognita (Kofoid and White) Chitwood at four concentrations. Maximum activity was recorded in oils of Eucalyptus citriodora , Eucalyptus hybrida and Ocimum basilicum followed by Pelargonium graveolens , Cymbopogon martinii, Mentha arvensis, Mentha piperita and Mentha spicata oils, respectively. The eucalyptus ( E. citriodora and E. hybrida ) and Indian basil ( O. basilicum ) oils were highly toxic to M. incognita even at the lower concentrations, namely 500 and 250 ppm. The remaining oils were also toxic to the nematode but at different amounts.     

Chemical constituents of Cordia latifolia and their nematicidal activity

Following nematicidal activity‐guided isolation studies on the fruits, bark, and leaves of Cordia latifolia, two new constituents, cordinoic acid (=11‐oxours‐12‐ene‐23,28‐dioic acid; 1 ) and cordicilin (=2‐{[(E)‐3‐(3,4‐dihydroxyphenyl)prop‐2‐enoyl]oxy}‐3‐[4‐hydroxy‐3‐(stearoyloxy)phenyl]propanoic acid; 2 ) were isolated from the stem and leaves, respectively, together with nine known compounds, namely cordioic and cordifolic acid from the stem bark, latifolicin A–D and rosmarinic acid from the fruits, and cordinol and cordicinol from the leaves. Their structures were determined by means of spectroscopic analyses including 1D‐ and 2D‐NMR techniques. The nematicidal activities of these constituents were determined against the root‐knot nematode Meloidogyne incognita. Hundred percent mortality was caused by all of these after 72 h at a 0.125% concentration. Compound 1 and cordioic acid were most active and caused 100% mortality after 24 h at a 0.50% concentration. Furthermore, compound 2 , the ester of rosemarinic acid, was found to be more active than the free acid.     

Plant growth-promoting rhizobacteria, Paenibacillus polymyxa and Paenibacillus lentimorbus suppress disease complex caused by root-knot nematode and fusarium wilt fungus

Aim:  To screen and evaluate the biocontrol potential of Paenibacillus strains against disease complex caused by Meloidogyne incognita and Fusarium oxysporum f. sp. lycopersici interactions.
Methods and Results:  Paenibacillus strains were collected from rotten ginseng roots. The strains were tested under in vitro and pots for their inhibitory activities, and biocontrol potential against disease complex caused by M. incognita and F. oxysporum f. sp. lycopersici on tomato. In in vitro experiments, among 40 tested strains of Paenibacillus spp., 11 strains showed antifungal and nematicidal activities against F. oxysporum f. sp. lycopersici and M. incognita, respectively. Paenibacillus polymyxa GBR-462; GBR-508 and P. lentimorbus GBR-158 showed the strongest antifungal and nematicidal activities. These three strains used in pot experiment reduced the symptom development of the disease complex (wilting and plant death), and increased plant growth. The control effects were estimated to be 90–98%, and also reduced root gall formation by 64–88% compared to the untreated control.
Conclusion:  The protective properties of selected Paenibacillus strains make them as potential tool to reduce deleterious impact of disease complex plants.
Significance and Impact of the Study:  The study highlights biocontrol potential of Paenibacillus strains in management of disease complex caused by nematode-fungus interaction.