Effect of Six Bacterial Strains on the Activity of Second Instar Larvae and Egg Hatching of Meloidogyne incognita

[Objectives]The paper was to screen effective biocontrol strains against Meloidogyne incognita.[Methods]The effect of six bacterial strains sourced from the research group s strain library on the activity of second instar larvae of M.incognita,as well as on egg hatching,was evaluated.[Results]The treatment of fermentation supernatant derived from the X-2 strain exhibited a pronounced lethal effect on M.incognita,with a corrected mortality rate reaching 97%within 72 h.Additionally,this treatment significantly inhibited egg hatching,achieving an inhibition rate of 94.69%at a 20-fold dilution.The strain was identified as Bacillus velezensis,belonging to the genus Bacillus,and was designated as RKN1111.[Conclusions]This study presents alternative strains and a theoretical framework for the biological control of M.incognita.

Resistance Evaluation of Capsicum spp. Germplasm to Meloidogyne incognita

[Objective] This study aimed to screen out hot pepper germplasms highly resistant to Meloidogyne incognita, thereby providing resistant resources for hot pep- per breeding. [Method] Comprehensive analysis combining cluster analysis and sub- ordinate function was conducted through determining related resistance indexes of 67 hot pepper germplasms 50 days after inoculated with M. incognita. [Result] The effects of M. incognita on related resistance indexes were significantly different am- ong the hot pepper germplasms. Egg index and gall index had abundant genetic variation with variation coefficients of 143.16% and 118.95%, respectively. Based on the gall indexes, cluster analysis of hot pepper germplasms was performed. The 67 hot pepper germplasms were divided into 4 groups （resistant, moderately resistant, susceptible and high susceptible）. The resistance intensity of the hot pepper germplasms were ranked according to the sum of subordinate function values of various resistance indexes. The total function values of Rela 2 and L506M were the largest （2.00）, indicating that these two germplasms were immune to M. incognita. The total function values of L287-2, L522-1M, L504M, L515-2, 13SM100-1, L512M, L292-1, L319, L316, L317, 13SM87-1 and Rela 5 were larger than 1.95, indicating that these germplasms were highly resistant to M. incognita. [Conclusion] This study could provide certain resistant resources for resistance breeding of hot pepper to M. incognita.

土壤修复剂协同昆虫病原线虫对南方根结线虫Meloidogyne incognita以及黄瓜幼苗生长的影响

为了探究土壤修复剂SA协同昆虫病原线虫(Heterorhabditis beicherriana)对南方根结线虫(Meloidogyne incognita)的室内抑制效果,以及二者结合施用对黄瓜生长的促进效果,本文以千秋1号为供试黄瓜品种,采用室内试验方法,人工接种南方根结线虫,并施入土壤修复剂SA和昆虫病原线虫,从实验第7、14、21天时根结线虫二龄幼虫J2与H.beicherriana三龄幼虫J3的存活率,实验30 d时黄瓜幼苗的叶面积、株高、鲜重以及根结数几个方面做了研究。结果表明:实验第7、14、21天后,土壤修复剂SA和昆虫病原线虫处理组的根结线虫(J2)存活数却明显低于根结线虫清水对照组(M组),且第21天时SA处理组的死亡根结线虫数量约是M组的2倍,加入昆虫病原线虫的处理组中死亡根结线虫数量约是M组的3倍,然而昆虫病原线虫在SA处理组中的存活率却明显高于其他组。此外,土壤修复剂SA协同昆虫病原线虫加入到添加根结线虫的黄瓜土壤中,可以增加黄瓜幼苗叶面积、鲜重、株高,并能减少单位长度内根结数量,说明土壤修复剂SA协同昆虫病原线虫的施用,提高了植株抵抗根结线虫能力,减少了根结线虫对根系危害,该结果为有效修复被根结线虫污染土壤的研究提供理论基础。

Field evaluation of Streptomyces rubrogriseus HDZ-9-47 for biocontrol of Meloidogyne incognita on tomato

Streptomyces rubrogriseus HDZ-9-47,isolated from eggs of Meloidogyne spp.,was evaluated as a potential biocontrol agent of Meloidogyne incognita under in vitro and protective field.Microscopic observations showed that HDZ-9-47 parasitized eggs of M.incognita within 7 days.In vitro,the culture filtrate of HDZ-9-47 caused 97.0%mortality of second-stage juveniles（J2s）of M.incognita and inhibited more than 50%egg hatching.In the field,compared with the control,the rootknot index and J2s density in the treatment of drench the broth contained 1012 HDZ-9-47 spores were respectively reduced by 51.1 and 80.7%at 90 days post transplantation,which were better than that in other application doses and methods.In addition,reduction rates of root-knot index and J2s density of the treatment of combined application of HDZ-9-47 with biofumigation was 87.1 and 91.0%,respectively,better than either of HDZ-9-47 or biofumigation used alone or fosthiazate treatment.And tomato yield also increased by 16.1%.Together,our results suggest that HDZ-9-47 could be an effective biocontrol agent of M.incognita,and that application of HDZ-9-47 combined with cabbage residue biofumigation was a promising and sustainable option for M.incognita control.

Studies on the management of root-knot nematode, Meloidogyne incognita-wilt fungus, Fusarium oxysporum disease complex of green gram, Vigna radiata cv ML-1108

Studies were conducted under pot conditions to determine the comparative efficacy ofcarbofuran at 1 mg a.i./kg soil, bavistin at 1 mg a.i./kg soil, neem （Azadirachta indica） seed powder at 50 mg/kg soil, green mould （Trichoderma harzianum） at 50.0 ml/kg soil, rhizobacteria （Pseudomonas fluorescens） at 50.0 ml/kg soil against root-knot nematode, Meloidogyne incognita-wilt fungus, Fusarium oxysporum disease complex on green gram, Vigna radiata cv ML-1108. All the treatments significantly improved the growth of the plants as compared carbofuran and A. indica seed powder increased plant growth to untreated inoculated plants. Analysis of data showed that and yield significantly more in comparison to bavistin and P. fluorescens. Carbofuran was highly effective against nematode, bavistin against fungus, A. indica seed powder against both the pathogens and both the bioagents were moderately effective against both the pathogens.

Sources for Heat-Stable Resistance to Southern Root-Knot Nematode (Meloidogyne incognita) in Solanum lycopersicum

Southern root-knot nematode （Meloidogyne incognita） is a major problem in vegetable production in China due to the expansion of plastic tunnel and solar greenhouse. Using resistant cultivars is an effective approach to control the disease. Nine genes, Mi-1 to Mi-9, have been reported and only Mi-1 has been successfully used in tomato breeding. However, Mi-1 is inactive at a temperature above 28~C. In order to identify sources for heat-stable resistance to southern root-knot nematode, 53 genotypes of tomato （Solarium spp.） were inoculated with an isolate of M. incognita in the growth chamber at 28 or 32℃ for initial screening. 28 lines had less than 25 galls and were considered as resistant candidates. The top 60% （16 in total） of resistant candidates obtained from each temperature were subject to re-evaluation at 32~C using the same nematode isolate. Three lines ZN17, ZN 48, and LA0385 showed heat-stable resistance with an average of 10 galls or less per plant. LA0385 is a wild species, while ZNI7 and ZN48 are elite breeding lines. These lines were grown in a greenhouse for two seasons, and also showed high resistance with less than 10 galls per plant. Thus they were considered as good sources for breeding resistance to southern root-knot nematode in tomato.

A Meloidogyne incognita effector Minc03329 suppresses plant immunity and promotes parasitism

Meloidogyne incognita is a devastating plant-parasitic nematode.Effectors play important roles during the stages of nematodes infection and parasitism,but their molecular functions remain largely unknown.In this study,we characterized a new effector,Minc03329,which contains signal peptide for secretion and a C-type lectin domain.The yeast signal sequence trap experiments indicated that the signal peptide of Minc03329 is functional.In situ hybridization showed that Minc03329 was specifically expressed in the subventral esophageal gland.Real-time qPCR confirmed that the expression level of Minc03329 transcript was significantly increased in pre-parasitic and parasitic second-stage juveniles(pre-J2s and par-J2s).Tobacco rattle virus(TRV)-mediated gene silencing of Minc03329 in host plants largely reduced the pathogenicity of nematodes.On the contrary,ectopic expression of Minc03329 in Arabidopsis thaliana significantly increased plant susceptibility to nematodes.Transient expression of Minc03329 in Nicotiana benthamiana leaves suppressed the programmed cell death triggered by the pro-apoptotic protein BAX.Moreover,the transcriptome analysis of Minc03329-transgenic Arabidopsis and wild type revealed that many defense-related genes were significantly down-regulated.Interestingly,some different expressed genes were involved in the formation of nematode feeding sites.These results revealed that Minc03329 is an important effector for M.incognita,suppressing host defense response and promoting pathogenicity.

Determination of Nematicidal Effects of Some Biopesticides against Root-Knot Nematode （Meloidogyne incognita） on Kiwifruit

The aim of this study was to determine the nematicidal effects of some biopesticides againist root-knot nematodes （RKNs） （Meloidogyne incognita） on Bruno type kiwifruit seedlings. Research was conducted in the Atattirk Central Horticultural Research Institute （ACHRI, Yalova, Turkey） greenhouse during 2013-2014. Biopesticides observed in this study were： sesame oil （Devalone EC）, castor oil （Ricinus communis）, Myrothecium verrucaria （M. verrucaria strain AARC-0255, Inferno DF）, Glomus spp. （Endomycorrhizal fungi, Endo Roots Soluble SP） and Paecilomyces lilacinus （Entomopathogenic fungi, P. lilacinus strain PL1, Bionematon SL）. Nematicide Nemacur EC 400 （fenamiphos） was used as treated control （TC） and trials were set up as randomized parcel design （RPD） with seven characters and 10 replicates. Reproduction ratio was determined according to scale values in trial applications and second stage juvenile （J2） populations of M. incognita in soil. The results showed that the best nematicidal effects against RKNs were determined in castor oil （77.92% in 2013 and 73.61% in 2014） and P. lilacinus （61.03% in 2013 and 55.55% in 2014）.

Efficiency of Some Plant Essential Oils on Root-Knot Nematode Meloidogyne incognita

During the last few decades, researchers have been in the search for environmental friendly ways to cope with agricultural pests, instead of using chemical pesticides. The use of essential oils has a high potential to become an alternative control strategy against plant parasitic nematodes. This study was conducted to determine the toxicity of 10 essential oils （Artemisia absinthium, Citrus bergamia, Eucalyptus citriodora, Hypericum perforatum, Lavandula officinalis, Mentha arvensis, Ocimum basilicum, Piper nigrum, Thymus serpyllum and Zingiber officinale） against the second stage juveniles of the root-knot nematode Meloidogyne incognita. The aqueous solutions of these essential oils have been applied to the second stage juveniles in three different concentrations （1%, 3% and 5%） at four different application time intervals （12, 24, 48 and 72 h）. The interactions between the variables have been examined with repeated measure analysis of variance （ANOVA）. This showed that the interactions of essential oil-time and essential oil-concentration were statistically significant, and it is concluded that L. officinalis, A. absinthium, P. nigrum, C. bergamia and M. arvensis have the most toxic effect in all concentrations and times, respectively.

温度对南昌市郊区南方根瘿线虫(Meloidogyne incognita)发育的影响

一、前言寄生于植物并导致严重病害的根瘿线虫(Meoloidogyne)是变温动物。了解这类动物二期幼虫侵入寄主植物之后的发育起点温度及达到性成熟而产卵所需的有效积温,不但在理论上而且在生产上都有重要意义。然而有关这方面的文献不多,提出过报告的作者有Tyler(1933)乌斯基诺夫,Milne和Plessis(1964),Starr和mai(1976),Bird和Milln(1979)。南昌市郊侵害多种蔬菜作物的根瘿线虫是M.incognita,值得注意的是,上述作者中只有Bird和Milln在澳大利亚对这个种进行过观察。该作者的观察结果是否适合于南昌市郊这个居群?我们在防治实践中应该认定的数据是什么?问题必须予以回答。

Screening of field pea (Pisum sativum) selections for their reactions to root-knot nematode (Meloidogyne incognita)

Pot studies were carried out to evaluate the reactions of 23 selections of field pea （Pisum sativum） against Meloidogyne incognita （2000 freshly hatched juveniles （J2）/pot）. Experiment was conducted under greenhouse conditions （（24.7±3） ℃ and （62±7）% RH） and terminated 45 d after inoculation. The roots of all the selections were assessed to determine root-knot indices （RKI） on a 0-4 scale. Out of 23 selections HFP-990713, Pant P-25, and HFP-0129 were resistant; Pant P-2005, NDP-2 and Pant P-42 were tolerant; LFP-305, HFP-8909, HFP-4, HUP-31, HFP-0128, Pant P-31, Pant P-40, LFP-363, and HFP-0118 were moderately resistant; HFP-0110, HUDP-28, HUDP-15, HUDP-27, HUP-30, HUP-2 and HUDP-26 were moderately susceptible; and only Ambika was susceptible to M. incognita. It was observed that reproduction of nematode was favored on tolerant and susceptible cultivars but inhibited on resistant ones. Strong negative correlation was observed between the total fresh and dry plant weights and the root-knot index. The selection Pant P-42 showed highest tolerance among all the selections tested and can be recommended for field trials, whereas, selection Ambika showed highest susceptibility and should be avoided.

Identification and Evaluation of Resistance to Meloidogyne incognita in Bitter Gourd Germplasms

[ Objective] This study aimed to identify and evaluate the resistance of bitter gourd germplasms to Meloidogyne incognita. [ Method] A total of 71 bit-ter gourd germplasms were artificially inoculated with M. incognita at seedling stage to investigate the effects of M. incognita on resistance indexes of bitter gourd seedlings. Cluster analysis and subordinate function analysis were performed to identify and evaluate the resistance of experimental materials. [ Result] The infec-tion of M. incognita increased the variation coefficients of resistance indexes. The resistance to M. incognita varied significantly among different bitter gourd germ- plasms. Based on gall index, 71 bitter gourd germplasms were divided into five types by cluster analysis, including resistant materials, moderately resistant materi-als ,moderately susceptible materials, susceptible materials and highly susceptible materials. The subordinate function analysis showed that total subordinate func-tion values of Y107, Y109, Y108, Y51, Y105, Y81, Y89, Y140 and Y94 exceeded 1.95 , indicating high resistance to M. incognita. [ Conclusion] This study could provide resistant materials for breeding root-knot nematode resistant varieties of bitter gourd.

Comparative study of <i>Fusarium oxysporum</i>f sp. <i>lycopersici</i>and <i>Meloidogyne incognita</i>race-2 on plant growth parameters of tomato

Many species of soil-inhabiting fungus Fusarium, cause severe yield loss in many crops. Experiments were conducted in net house condition with complete randomized block design to determine the individual effect of different in-oculum levels of root-knot nematode, Meloidogyne incognita, Race-2 and Fusarium oxysporum f sp. lycopersici on plant growth parameters viz., Plant length, fresh and dry weight and number of fruits of tomato var. P21. The experimental results showed that both the pathogens cause significant reduction in plant growth parameters. However, the fungus was not much effective on plant growth parameters in comparison to root-knot nematode. Greatest reduction in plant growth parameters was recorded in plants inoculated with 8000 J2/Kg soil of Meloidogyne in-cognita race 2. The threshold level of root-knot nematode was 1000 J2/kg soil while threshold level of Fusarium was @ 1 g/Kg soil. Inoculum level of Fusarium oxysporum f sp. lycopersici and Meloidogyne in-cognita race-2 was pathogenic and caused significant reduction at and above 1 g/kg soil and 1000 J2/Kg soil respectively.

Chemotaxis of <i>Meloidogyne incognita</i>in Response to Different Salts

The chemotactic responses of Meloidogyne incognita were studied in salt gradients in an agarose gel. Forty-eight combinations of sodium, copper, cesium, manganese , barium, potassium, ferric or ammonium cations and chloride, nitrate, sulphate, hydrogen-phosphate, bicarbonate, acetic acid, thiocyanic acid and hydroxyl anions were tested at six concentrations from 0.0625 × 10-2 to 2 × 10-2 mol·L-1. M. incognita was repellented to salts that included Cl- and SCN-. Other salts that comprised the same anions had different chemotactic responses, among which M. incognita was repellented to ammonium salts that included Ba(NO3)2, NH4NO3, Mn(NO3)2, and hydrogen-phosphate salts that included KH2PO4, K2HPO4, and bicarbonate salts that included Na2CO3, K2CO3, (NH4)2CO3, KHCO3, and hydroxyl salts that included KOH, NaOH, and organic acid that included C2H4O2, C3H6O3 and C4H6O6. The repellent or attraction properties of different salts having the same cations were not consistent. The order of repellence was SCN- > NO3- > Cl- > OH- > CO32- >H2PO-4 > organic acid >SO42- . The chemotaxis of nematodes to KCl, Ba(NO3)2, NH4NO3, Mn(NO3)2, (NH4)2CO3, CH3COOH and C4H6O6 increased with the increasing concentration, while the concentration of other salts tested did not influence nematode chemotaxis significantly.

Comparative transcriptome analysis provides insights into the molecular mechanism of the anti-nematode role of Arachis hypogaea(Fabales:Fabaceae)against Meloidogyne incognita(Tylenchida:Heteroderidae)

Background:Plant root-knot nematode(RKN)disease is a serious threat to agricultural production across the world.Meloidogyne incognita is the most prominent pathogen to the vegetables and cash crops cultivated.Arachis hypogaea can effectively inhibit M.incognita,but the underlying defense mechanism is still unclear.Methods:In our study,the chemotaxis and infestation of the second-stage juveniles(J2s)of M.incognita to A.hypogaea root tips were observed by the Pluronic F-127 system and stained with sodium hypochlorite acid fuchsin,respectively.The transcriptome data of A.hypogaea roots with non-infected or infected by J2s were analyzed.Results:The J2s could approach and infect inside of A.hypogaea root tips,and the chemotactic migration rate and infestation rate were 20.72%and 22.50%,respectively.Differential gene expression and pathway enrichment analyses revealed ubiquinone and other terpenoid-quinone biosynthesis pathway,plant hormone signal transduction pathway,and phenylpropanoid biosynthesis pathway in A.hypogaea roots responded to the infestation of M.incognita.Furthermore,the AhHPT gene,encoding homogentisate phytyltransferase,was considered to be an ideal candidate gene due to its higher expression based on the transcriptome data and quantitative real-time PCR analysis.Conclusion:Therefore,the key gene AhHPT might be involved in the A.hypogaea against M.incognita.These findings lay a foundation for revealing the molecular mechanism of A.hypogaea resistance to M.incognita and also provide a prerequisite for further gene function verification,aiming at RKN-resistant molecular breeding.

Integrated Control of Meloidogyne Incognita Infesting Tomato Plants Using Callus Powders Derived from Certain Plants Either Alone or in Combination with Oxamyl under Out-Door Conditions

The effect of four dried callus powders derived from certain plants, i.e. tomato, Lycopersicon esculentum; periwinkle, Catharanthus roseus; thorne apple, Datura stramonium and oleander, Nerium oleander applied separately or concomitantly with oxamyl at a half of the recommended dose each on tomato seedlings grown in soil naturally heavy infested with M. incognita under field conditions, indicated that dried callus powder derived from N. oleander either alone or mixed with oxamyl significantly surpassed the other tested treatments in improving percentages of increase in whole plant fresh and shoot dry weights as well as increasing numbers and weights of fruits. Concerning other treatments including oxamyl at a half of recommended dose with each tested callus powder, similar results were evident regarding tomato plant growth parameters. C. roseus plus oxamyl achieved the highest percentage of increase in whole plant fresh weight （141.4%） and shoot dry weight （189.7%） and ranked second to N. oleander ＋ oxamyl in this respect over the untreated plants, respectively. One the other hand, among all tested materials single application of either L. esculentum or oxamyl gave the least values of such criteria which averaged 34.4% and 61.7% or 39.5% and 11.2%, respectively. All tested treatments significantly reduced the total number of galls, egg-masses and eggs in egg-masses especially, dried callus powder of N. oleander which applied singly or combined with oxamyl. The least values of reduction percentages of galls and eggs in egg-masses among all treatments were recorded from tomato plant received dried callus powders of L. esculentum applied alone or concomitant with oxamyl.

Screening of genotypes for their resistance againstMeloidogyne incognita and Fusarium chlamydosporum causing wilt complex on Coleusforskohlii Briq.

A pot culture experiment was carried out for the Screening of 11 popular genotypes against to Meloidogyne incognita and Fusarium chlamydosporum wilt complex on Coleus forskohlii. Genotype viz., yellow tubers and Rabakavi local showed resistant reaction, Orange tuber and Nimbanur local showed moderately resistant reaction. Rest of the seven genotvDes showed suscentible reactions.

番茄响应南方根结线虫侵染相关转录因子的初步分析

为明确番茄接种根结线虫后基因种类和表达量在转录水平的变化规律,利用RNA-seq对未接种及接种南方根结线虫2龄幼虫6、12、24和48 h的番茄进行转录组测序,探究番茄响应南方根结线虫侵染相关的关键转录因子,并采用qRT-PCR方法对测序结果进行验证。结果显示,接种南方根结线虫后6、12、24和48 h分别有350、390、580、1154个基因差异表达,其中差异表达转录因子分别为11、11、19、50个。这些转录因子属于15个家族,其中数量最多的为MYB家族和bHLH家族(均为20个),其次是ERF家族19个、WRKY家族15个、bZIP家族9个。南方根结线虫侵染过程差异表达最明显的主要为ERF、WRKY、MYB和bHLH家族转录因子,其中Solyc03g005520、Solyc02g094270和Solyc09g066350显著上调,接种后48 h log2FC分别为9.16、6.49和6.33;Solyc02g079280、Solyc12g100140和Solyc04g072460显著下调,接种后48 h log2FC分别为-2.60、-1.72和-1.70。qRT-PCR验证结果显示,6个随机选取基因的表达趋势与测序结果基本一致。以上结果表明,ERF、WRKY、MYB和bHLH家族转录因子可能参与番茄与南方根结线虫互作,在番茄响应南方根结线虫侵染反应中发挥着重要的调控作用。

减施化肥增施蚯蚓粪有机肥对连作甜瓜的影响

【目的】研究减施化肥增施蚯蚓粪有机肥对连作甜瓜产量及品质的影响,为甜瓜生产中减施化肥增效提供基础数据。【方法】以甜瓜品种黄梦脆为材料,在优化施肥基础上配施4个蚯蚓粪有机肥梯度处理,研究减施化肥增施蚯蚓粪有机肥对连作甜瓜生理、光合特性、产量、品质和线虫根结数量的影响。【结果】相较于常规施肥,T_(2)处理的蔓长、蔓鲜重、蔓干重、根鲜重、根干重较对照分别增加了26.3%、39.9%、23.5%、80.6%和53.3%;光合指标T_(2)处理的净光合速率、气孔导度和蒸腾速率较对照分别提升了38.6%、45.4%和66.1%,与对照差异显著;甜瓜品质关键指标在T_(2)处理下达到最大,与对照差异显著。【结论】T_(2)处理(蚯蚓粪有机肥300 kg/667m^(2)+复合肥50 kg/667m^(2))综合表现最佳,可作为连作甜瓜施肥。

烟草抗感南方根结线虫品种根部差异表达mRNA的PPI网络分析

基于品种间的差异表达基因,选取烟草抗病品种K326与感病品种长脖黄为试验材料,利用生物信息学分析方法筛选出与抗感染相关的关键基因,通过蛋白互作网络分析(Protein-Protein Interaction,PPI)以及Gene Ontology(GO)功能分类分析(包括Biological Process分析与KEGG通路分析)对差异表达基因进行生物学功能注释,并找出PPI网络中的重要基因以及作用通路一致的基因,并对这些基因加以解析,以明确抗南方根结线虫烟草品种抗性机制,为研究烟草抗南方根结线虫的分子机制提供理论依据。结果表明,差异表达基因主要在细胞代谢、胞内体转运、RNA介导的基因沉默等9条与抗感染相关的通路中显著富集,并且筛选出Fab1b、Fab1c、Fab1d、Glu1、Dcl1、Dcl2、Dcl4共7个同时构成PPI网络的关键基因。