独岛枝芽胞杆菌MCCC 1A00493产生的4-乙烯基苯酚鉴定和作用南方根结线虫特性研究

[目的]根结线虫危害严重,难防难控,前期研究发现一株深海来源的独岛枝芽胞杆菌(Virgibacillus dokdonensis)MCCC 1A00493对南方根结线虫具有良好的体外拮抗效果,本研究分离鉴定菌株发酵液中杀线虫活性物质,对其作用线虫的多种模式进行研究,为菌株有效控制植物病原线虫的应用奠定理论基础.[方法]...     

A Review of the Potency of Plant Extracts and Compounds from Key Families as an Alternative to Synthetic Nematicides: History,Efficacy, and Current Developments

The global nematicides market is expected to continue growing. With an increasing demand for synthetic chemical-free organic foods, botanical nematicides are taking the lead as replacements. Consequently, in the recent years, there have been vigorous efforts towards identification of the active secondary metabolites from various plants. These include mostly glucosinolates and their hydrolysis products such as isothiocyanates; flavonoids, alkaloids, limonoids, quassinoids, saponins, and the more recently probed essential oils, among others. And despite their overwhelming potential, variabilities in quality, efficacy, potency and composition continue to persist, and commercialization of new botanical nematicides is still lagging. Herein, we have reviewed the history of botanical nematicides and regional progresses, the potency of the identified phytochemicals from the key important plant families, and deciphered some of the impediments involved in standardization of the active compounds in addition to the concerns over the safety of the purified compounds to non-target microbial communities.     

Isolation of Ceramides from Tagetes patula L. Yellow Flowers and Nematicidal Activity of the Fractions and Pure Compounds against Cyst Nematode,Heterodera zeae

Investigation of yellow flower extract of Tagetes patula L. led to the identification of an aggregate of five phytoceramides. Among them, (2R)‐2‐hydroxy‐N‐[(2S,3S,4R,8E)‐1,3,4‐trihydroxyicos‐8‐en‐2‐yl]icosanamide, (2R)‐2‐hydroxy‐N‐[(2S,3S,4R,8E)‐1,3,4‐trihydroxyicos‐8‐en‐2‐yl]heneicosanamide, (2R)‐2‐hydroxy‐N‐[(2S,3S,4R,8E)‐1,3,4‐trihydroxyicos‐8‐en‐2‐yl]docosanamide, and (2R)‐2‐hydroxy‐N‐[(2S,3S,4R,8E)‐1,3,4‐trihydroxyicos‐8‐en‐2‐yl]tricosanamide were identified as new compounds and termed as tagetceramides, whereas (2R)‐2‐hydroxy‐N‐[(2S,3S,4R,8E)‐1,3,4‐trihydroxyicos‐8‐en‐2‐yl]tetracosanamide was a known ceramide. A steroid (β‐sitosterol glucoside) was also isolated from the subsequent fraction. The structures of these compounds were determined on the basis of spectroscopic analyses, as well as chemical method. Several other compounds were also identified by GC/MS analysis. The fractions and some commercial products, a ceramide HFA, β‐sitosterol, and stigmasterol were evaluated against an economically important cyst nematode, Heterodera zeae. Ceramide HFA showed 100 % mortality, whereas, β‐sitosterol and stigmasterol were 40–50 % active, at 1 % concentration after 24 h of exposure time, while β‐sitosterol glucoside revealed no activity against the nematode.     

The Potential of Thiarubrine C as a Nematicidal Agent against Plant- parasitic Nematodes

Thiarubrine C, a polyacetylenic 1,2-dithiin isolated from the roots of Rudbeckia hirta (Asteraceae), exhibited strong nematicidal activity in in vitro and growth chamber assays. Thiarubrine C was toxic, in the absence of light, to the plant-parasitic nematodes Meloidogyne incognita and Pratylenchus penetrans at LC₅₀s of 12.4 ppm and 23.5 ppm, respectively. A minimum exposure time between 12 and 24 hours was the critical period for nematode mortality due to thiarubrine C. Although thiarubrine C was not totally dependent on light for toxicity, activity was enhanced in the presence of light, especially with the microbivorous nematode, Teratorhabditis dentifera. Upon exposure of M. incognita juveniles to 20 ppm thiarubrine C for 1 hour, infection of tomato plants was greatly reduced compared to untreated checks. Thiarubrine C was also effective in reducing plant infection when mixed with soil 24 hours prior to or at planting, unlike other related compounds such as δ-terthienyl.     

Nematicidal activity of <Emphasis Type="Italic">Paecilomyces</Emphasis> spp. and isolation of a novel active compound

Many species of Paecilomyces are entomogenous fungi and several are efficacious toward nematodes. To study the potential of Paecilomyces species in controlling nematodes, fungal extracts of 40 Paecilomyces spp. were evaluated for their nematicidal activity against Bursaphelenchus xylophilus and Panagrellus redivivus. The extracts of six Paecilomyces spp. exhibited the nematicidal activity against P. redivivus, and 11 species exhibited the nematicidal activity against B. xylophilus. The methanol extract of strain 1.01761 incubating on Czapek solid medium killed more than 95% P. redivivus in 24 h at 5 mg/ml, and the filtrate of strain 1.01788 cultured in Sabouraud’s broth medium resulted in 90% mortality of B. xylophilus in 24 h at 5 mg/ml. A novel nematicidal compound 4-(4′-carboxy-2′-ethyl-hydroxypentyl)-5,6-dihydro-6-methylcyclobuta[b]pyridine-3,6-dicarboxylic acid, was isolated from Paecilomyces sp. YMF1.01761. The LD₅₀ value of the compound within 24 h against P. redivivus was 50.86 mg/L, against Meloidogyne incognita was 47.1 mg/L, and against B. xylophilus was 167.7 mg/L.     

白花除虫菊化学成分及其生物活性的研究

该研究应用柱层析法、薄层层析法和波谱法对白花除虫菊(Pyrethrum cinerariifolium)全株甲醇提取物进行分离纯化、结构鉴定,并分别采用 MTT 法、生物活性测定法和抑菌圈法测定所得化合物抗肿瘤、杀线虫和抑菌活性。结果表明：经波谱法鉴定化合物结构分别为 tulirinol (1),sesamin (2),β-cyclopyrethrosin (3)和3,5-dihydroxy-2-(4-hydroxy-3-methoxyphenyl)-7,8-dimethoxy-4H-1-benzopyran-4-one (4)。抗肿瘤活性显示化合物3对白血病细胞株 HL-60、肝癌细胞株 SMMC-7721、肺癌细胞株 A-549、乳腺癌细胞株 MCF-7和结肠癌细胞株SW480均表现出显著的抑制活性,其 IC50分别为3.800、2.890、2.930、4.600和5.160μmol?L-1;化合物1活性比3稍弱,其 IC50分别为5.020、10.760、12.310、12.310和12.250μmol?L-1;其中化合物3对各肿瘤细胞株 IC50值均小于顺铂。抗菌活性表明化合物3对大肠杆菌、蜡样芽孢杆菌、枯草芽孢杆菌和金黄色葡萄球菌均表现出明显的抑菌活性,且随着浓度增加活性逐渐增强,而化合物1和化合物2仅对部分菌株表现出微弱抑菌活性;杀线虫活性显示化合物3对秀丽隐杆线虫和全齿复活线虫均表现出显著的毒杀活性,且随着时间、浓度增加活性逐渐增强;而在同一时间点对秀丽隐杆线虫的毒杀活性强于全齿复活线虫。从白花除虫菊中分离所得4个化合物均为首次从该植株中发现,且首次报道了化合物3杀线虫和抑菌活性,值得进一步开发应用。     

微杆菌Sneb159杀线虫活性物质的分离与鉴定

【目的】有关Microbacterium maritypicum在植物线虫生物防治方面的研究较少,探究菌株M. maritypicum Sneb159的杀线虫活性,明确菌株发酵液中具有杀线虫活性的物质,为生物农药的开发提供理论依据。【方法】本研究检测了菌株Sneb159发酵液对大豆胞囊线虫二龄幼虫的触杀活性;并以触杀活性为追踪,采用有机溶剂萃取、硅胶柱层析及半制备高效液相色谱等技术对菌株Sneb159发酵滤液中的活性物质进行分离纯化;采用核磁共振波谱对纯化物进行结构鉴定。【结果】菌株Sneb159具有杀线虫活性,在24 h和48 h处理组中线虫的死亡率均显著高于对照组。从菌株Sneb159发酵滤液中分离得到杀线虫活性物质A6,经结构鉴定确定该物质为苯乙酰胺。【结论】首次发现M. maritypicum对大豆胞囊线虫的触杀作用,并且明确活性物质为苯乙酰胺。结果表明菌株M. maritypicum Sneb159和苯乙酰胺在大豆胞囊线虫的生物防治方面具有较好的应用潜力。     

多粘类芽胞杆菌KM2501-1杀南方根结线虫活性产物研究

【目的】南方根结线虫(Meloidogyne incognita)是一种危害严重的土传性植物病原线虫,给农业生产造成了巨大的经济损失,前期研究发现多粘类芽胞杆菌(Panebacillus polymyxa) KM2501-1具有很好的温室防治南方根结线虫效果,且可产生多种挥发性杀线虫活性物质,但对其非挥发性产物是否有杀线虫活性没有研究。本研究拟进一步分离鉴定其产生的杀线虫活性代谢产物,发掘新的杀线虫药物。【方法】对菌株KM2501-1进行液体发酵并离心收集发酵上清液,通过硅胶柱层析、高效液相色谱分离等方法得到高纯度的杀线虫活性物质,并通过液相色谱质谱联用分析、核磁共振等技术鉴定杀线虫活性物质的结构。【结果】生物活性检测显示,多粘类芽胞杆菌KM2501-1发酵上清液具有较强的南方根结线虫触杀活性,并能有效抑制南方根结线虫卵孵化,体外杀线虫效率高达87.66%,抑制卵孵化效率达92.26%。结构鉴定结果显示多粘类芽胞杆菌产生的杀线虫活性物质为环二肽类物质cyclo (Pro-Phe),800 mg/L的cyclo(Pro-Phe)杀线虫效率达84.75%。进一步的显微观测结果表明,与对照组相比,活性物质cyclo(Pro-Phe)处理后的根结线虫肠道组织紊乱、结构发生破坏。【结论】多粘类芽胞杆菌KM2501-1产生的cyclo (Pro-Phe)是一个具有杀线虫新功能的活性物质,其可能通过破坏线虫肠道杀死线虫。     

Use of some emulsified plant seed oils as a safe alternative for the management of Meloidogyne incognita infecting tomato

Abstract

The aim of the present study was to formulate six different plant seed oils namely canola, cotton, flax, olive, sesame and soybean as emulsifiable concentrates. The composition of the formulation comprises at least one organic solvent, one surfactant and one plant oil. Physico-chemical properties of the formulated oils (emulsion stability test, cold stability and heat stability tests) were measured. The successfully emulsified oils were evaluated for nematicidal activity against Meloidogyne incognita infecting tomato plants under greenhouse conditions. Emulsified canola oil proved to be the most effective oil as a protectant against M. incognita infection to tomatoes followed by soybean, cotton, flax and sesame oil. In addition, employing a high rate of the tested emulsified oils gave higher activity in suppressing nematodes both in the soil and in tomato roots than using a low rate. Moreover, all tested formulated oils at both rates of application had no adverse effect on the growth of tomato plants except sesame oil which significantly decreased the shoot length when compared to the control. The prepared plant oils might be used as potential sources for sustainable eco-friendly botanical nematicides to protect plants from nematode attack.     

Aspyrone,a Nematicidal Compound Isolated from the Fungus,Aspergillus melleus

Aspyrone (1) was isolated from a culture filtrate of Aspergillus melleus, and the structure was determined by a comparison of spectroscopic data with those of an authentic sample. 1 showed nematicidal activity toward Pratylenchus penetrans by 80.8% at a concentration of 300 mg/liter.