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.

Effect of Earthworms on the Population Quantity of Meloidogyne incognita in Tomato Cultivation

[Objectives]The paper was to further investigate the correlation between the presence of earthworms and the occurrence of Meloidogyne incognita.[Methods]The effect of earthworms on the population quantity of M.incognita and the growth of tomato plants was assessed through a potting experiment utilizing Eisenia fetida and M.incognita as the primary subjects of investigation.[Results]E.fetida exhibited an inhibitory effect on both the reproductive capacity and the prevalence of M.incognita.Additionally,it mitigated the adverse effects of M.incognita on the growth and development of tomato plants.[Conclusions]The findings of this study will establish a theoretical framework for utilizing earthworms and their metabolites to modulate the rhizosphere microecological environment,thereby facilitating the management 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.

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.

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.

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.

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.

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.

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.

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.

Potential use of cucumber (Cucumis sativus L.) endophytic fungi as seed treatment agents against root-knot nematode Meloidogyne incognita

Seed treatment with endophytic fungi has been regarded as an effective method for plant parasitic nematode control.Endophytic fungi from cucumber seedlings were isolated and screened for their potential to be used as seed treatment agents against Meloidogyne incognita.Among the 294 isolates screened,23 significantly reduced galls formed by M.incognita in greenhouse test.The 10 most effective isolates were Fusarium(5),Trichoderma(1),Chaetomium(1),Acremonium(1),Paecilomyces(1),and Phyllosticta(1) .Their control efficacies were repeatedly tested and their colonizations as well as in vitro activity against M.incognita were studied.They reduced the number of galls by 24.0%-58.4%in the first screening and 15.6%-44.3%in the repeated test,respectively.Phyllosticta Ph511 and Chaetomium Ch1001 had high colonizations on both the roots and the aboveground parts of cucumber seedlings.Fusarium isolates had colonization preference on the roots,their root colonizations ranging from 20.1%to 47.3%of the total root area.Trichoderma Tr882,Paecilomyces Pa972,and Acremonium Ac985 had low colonizations on both the roots and the aboveground parts.Acremonium Ac985,Chaetomium Ch1001,Paecilomyces Pa972,and Phyllosticta Ph511 produced compounds affecting motility of the second stage juveniles of M.incognita.Based on these results,Chae-tomium Ch1001 was considered to have the highest potential as a seed treatment agent for M.incognita biocontrol.

八种杀线剂对南方根结线虫的毒杀活性测试

为筛选出高效低毒的烟草根结线虫病防治药剂,采用浸虫法测试了8种低毒杀线(虫)剂对南方根结线虫(Meloidogyne incognita)J_(2)幼虫的毒杀活性。结果表明,8种供试药剂以阿维菌素B_(2)、噻唑膦和氟吡菌酰胺的毒杀效果较好,以50μg/mL处理24 h时线虫的校正死亡率均为100.00%。毒力测试结果表明,阿维菌素B_(2)、噻唑膦和氟吡菌酰胺处理J_(2)幼虫24 h的LC_(50)分别为0.56、8.30、6.24μg/mL,以阿维菌素B_(2)的毒杀效果最佳。

Molecular cloning and functional analysis of the pepper resistance gene Me3 to root-knot nematode

Root-knot nematodes(RKNs)cause severe diseases in peppers annually around the world.In pepper,the Me3 gene provides a heat-stable and broad-spectrum resistance to RKNs.In this study,several simple sequence repeat(SSR)markers and insertion/deletion(In Del)markers were developed to fine map the Me3 gene.Analysis of 2272 individuals(F2progenies)revealed that Me3 was located in a 45-kb DNA region between markers SSR784 and SSR339,in which there were three candidate genes.Among them,as a novel nucleotide binding site and leucine rich repeat(NBS-LRR)family gene,the DNA sequence of Capana09g000163 of pepper line‘HDA149’was 6348 bp in length,with a 2802-bp open reading frame encoding 933 amino acids,including NB-ARC and LRR domains.Tobacco transient expression assays demonstrated that expression of Capana09g000163 triggered a hypersensitive response(HR)in Nicotiana benthamiana leaves.Subcellular localization results showed that the Capana09g000163 protein was localized in the cell nucleus.Ectopic expression of Capana09g000163 in Arabidopsis significantly increased resistance against Meloidogyne incognita compared with the wild-type(WT)Arabidopsis.Furthermore,M.incognita was almost unable to develop in transgenic Arabidopsis expressing Capana09g000163.Taken together,we cloned the Me3 gene and verified that it induced resistance against M.incognita with the methods of map-based cloning and transgenic technology,which may be of great significance to pepper breeding for resistance against RKNs.

Improvement of Bio-Efficacy to Reduce Bacterial Wilt Complex Disease in Tomatoes through Bacillus amyloliquefaciens and Pseudomonas fluorescens under Field Conditions

Bacterial wilt complex disease of tomato(Solanum lycopersicum L.)was incited jointly by bacterial wilt pathogen Ralstonia solanacearum and Meloidogyne incognita worldwide.Bio-efficacy of bacterial antagonists i.e.B.amyloliquefaciens DSBA-11 and P.fluorescens DTPF-3 was studied against the wilt disease complex in tomato at National Phytotran facility Indian Agricultural Research Institute(IARI),New Delhi,at 26±2°C.Minimum wilt disease incidence(26.00%)with the highest bio-control efficacy(64.15%),less juvenile population(19.33 J2/g of soil)of M.incognita was recorded in the combined application of DTPF-3+DSBA-11 after 30 d of inoculation under glasshouse conditions.In a field study,minimum bacterial wilt disease incidences 19.0%and 20.4%were recorded in the bleaching powder treatment followed by mixed application of DSBA-11+DTPF-3,19.6%and 21.2%wilt incidence in 2014 and 2015 respectively.However,a reduction of root-knot gall index was recorded a maximum of 59.76%and 69.62%in DSBA-11+DTPF-3 treated plants followed by 54.88%and 60.13%over control in DTPF-3 treatment in 2014 and 2015 respectively.The yield of tomato fruit was increased over control by 17.48%and 16.97%in 2014 and 2015 respectively under field conditions.A combination of P.fluorescens DTPF-3+B.amyloliquefaciens DSBA-11 suppressed bacterial wilt and root-knot diseases and also increased the yield of the tomato fruit significantly(p<0.05)under field conditions.

Chemical Composition of Different Extracts of Conyza bonariensis: Insecticidal and Nematicidal Activities

C. bonariensis (L.) Cronq. known as hairy fleabane was first described in Argentina but it is now widely spread through most warmer regions of Europe, Africa, Asia, the Caribbean and Central America. In this work, a chemical analysis by liquid and gas chromatography coupled with mass spectrometry of the whole plant, aerial part, flowers and roots extracts of C. bonariensis harvested in Togo (West Africa) was carried out. Two acetylenic compounds Lachnophyllum ester and limonene were identified as the main components of essential oils while Lachnophyllum and Matricaria lactones were dominant in chloroform extracts. Based on the plant chemical compositions, essential oils and chloroform extracts were tested on cowpea weevil Callosobruchus maculatus adults which are considered as one of the most cosmopolitan pests of stored beans, and on freshly hatched second-stage juveniles of root-knot nematode Meloidogyne incognita. Results showed that the whole plant essential oil demonstrated an LC50/24h value of 1.75 μL oil/L air on C. maculatus while at 3.91 μL oil/L air, it showed 100% mortality. Furthermore, the plant root chloroform extracts partitioned in diethyl ether-hexane mixture showed the strongest nematicidal activity with an LC50/72h value of 0.47 mg/mL. Our findings suggest that the widely diffused plant C. bonariensis and its acetylenic constituents could be considered as potent botanical insecticidal and nematicidal agents.

海南辣椒抗南方根结线虫种质资源的筛选

鉴于根结线虫的专化特性及其引发的植物病症防治的困难性与易复发性,选育并种植抗性品种仍然是目前最经济和最有效的防治策略之一,为加快辣椒抗南方根结线虫新品种的选育进程,有效应对近年来海南辣椒种植中大面积发生的南方根结线虫问题,通过PM6a和PM542个分子标记筛选,结合苗期接种抗性鉴定的方法,对本单位已有的53份商品性较好的辣椒种质资源进行了抗南方根结线虫筛选,4份通过分子标记筛选,并在接种鉴定试验中抗性达到抗(R),其中包括泡椒1份,尖椒2份,线椒1份,且各辣椒资源的商品性较好,加深了对本单位抗性辣椒资源的分布情况,并为进一步抗南方根结线虫辣椒新品种选育工作提供了切实基础。