Histology of the interactions of Paecilomyces lilacinus with Meloidogyne incognita on Eclipta alba (L.)

Abstract

Under greenhouse conditions, the experiment was conducted to test the efficacy of opportunistic and nematophagous hyphomycete, Paecilomyces lilacinus against root-knot nematode, Meloidogyne incognita on Eclipta alba. The treatment comprised inoculation of E. alba with M. incognita alone (N) and in combination with P. lilacinus (one week before (T₁), simultaneously (T₂), one week after (T₃), two weeks after (T₄) and three weeks after (T₅)). The results showed that the application of P. lilacinus before one week of nematode inoculation (T_l) was more effective than other treatments. A significant enhancement was noticed in the growth and yield of E. alba. Root-knot and egg mass indices were suppressed due to destruction of the mature females and the egg masses. Histopathological studies revealed the presence of P. lilacinus hyphae in and around the females and the eggs.     

Pathogenicity of root-knot nematode,Meloidogyne incognita on Lens culinaris (Medik.)

Effects of the root-knot nematode (Meloidogyne incognita) on lentil (Lens culinaris) were studied under greenhouse conditions. The plants were inoculated with 250, 500, 1000, 2000 and 4000 J₂ per plant. Plant growth, yield, nodulation, seed weight, chlorophyll, nitrogen, phosphorus and potassium, (NPK) contents, as compared to control, were found decreased in all the nematode infected plants. The extent of reduction increased with an increase in inoculum levels. The reductions were significant at 500 J₂ and at higher inoculum levels, i.e. 1000, 2000 and 4000 J₂ per pot over the control. An increase in inoculum level caused enhancement in galling, egg mass production and nematode population. At higher inoculum levels, the population of the nematode in the root as well as in the soil increased to a greater magnitude than at lower inoculum levels. On the contrary, reproduction factor (RF) and rate of population increase (RPI) decreased with increasing inoculum levels.     

In vitro studies of antagonistic fungi against the root-knot nematode,Meloidogyne incognita

The present study was carried out in vitro to determine the efficacy of indigenous fungi isolated from egg masses of root-knot nematode, Meloidogyne incognita on egg parasitism, egg hatching, mobility and mortality against root-knot nematode, M. incognita. The tested fungi were Acremonium strictum, Aspergillus terreus, A. nidulans, A. niger, Chetomium aubense, Chladosporium oxysporum, Fusarium chlamydosporium, F. dimarum, F. oxysporum, F. solani, Paecilomyces lilacinus, Pochonia chlamydosporia, Trichoderma viride and T. harzianum. All tested fungi showed varied effects against the nematodes. Culture filtrates of A. strictum was very effective against the nematode in regards to egg parasitism (53%), egg hatching inhibition (86%) and mortality (68%) compared to controls. A. strictum was found to have an advantage over P. lilacinus, P. chlamydosporia, T. viride and T. harzianum in that it caused greater mortality of the second stage juveniles (J₂). A. terreus did not show egg parasitism but was found to be highly toxic against second stage juveniles (J₂) causing high mortality (around 68%). Thus, A. strictum and A. terreus showed good biocontrol potential against root-knot nematode, M. incognita under in vitro conditions.     

Biological control of root-knot nematode,Meloidogyne incognita infesting tomato

Talc based formulations of two antagonistic fungi, Acremonium strictum W. Gams and Aspergillus terreus Thom were tested separately and together for their ability to suppress the development of root-knot disease of tomato caused by the root-knot nematode, Meloidogyne incognita Kofoid & White in two consecutive trials (2007–08). Tomato seedlings were each inoculated with M. incognita at 2 infective second stage juveniles /g of soil. M. incognita caused up to 48% reduction in plant growth parameters compared to un-inoculated control. Control efficacy achieved by combined soil application of both fungi, in terms of galls/root system and soil population/50 ml of soil, was 66 and 69% respectively at 60 days of inoculation compared to control. Soil application by individual fungus did not achieve as much effectiveness as the biocontrol agents applied together. The combined treatment was found to have antagonistic effect on M. incognita development and increased plant vigor. Incorporation of fine powder of chickpea pod waste with talc powder was beneficial in providing additional nutrients to both plant and biocontrol agents and increased the activity of the nematophagous fungi in soil. A. strictum and A. terreus were successfully established in the rhizosphere of tomato plants up to the termination of the experiment.     

Effect of certain organic materials in controlling Meloidogyne incognita root-knot nematode infesting banana

Efficacy of certain plant wastes as onion bulb envelope, dry leaves of sugar beet, fleabane and jojoba, filter cake or mud as sugar cane industrial residue and nile fertile mineral bio-fertilisers were studied under field conditions for managing Meloidogyne incognita on banana Cv. Williams. All the tested treatments significantly (P ≤ 0.05 and 0.01) proved to be effective in reducing the studied nematode criteria during the growing season of banana. The highest percentage reductions of 87.5 and 85.5% were recorded in the number of second-stage juveniles caused by fleabane at vegetative and harvest stages, respectively. As for galls, the highest percentage reductions of 80.4 and 79.6% were achieved at harvest stage by sugar beet waste and filter cake residue, respectively. Also, sugar beet waste was the best at increasing banana fruit yield per feddan (77.0%), followed by jojoba (53.1%) and fleabane (50.4%). The number of fingers and hands per bunch increased by the different materials at various degrees.     

Influence of cadmium on penetration of the root-knot nematode,Meloidogyne incognita and plant growth parameters of tomato

The results of experiment clearly reveal that cadmium inhibited root penetration by the second stage juveniles (J₂) of Meloidogyne incognita which subsequently affected the development of root galls in tomato. The heavy metal was highly injurious to tomato plants at all the concentrations tested for (7.5, 15.0, 30.0 and 60.0?ppm). The inhibitory effect on plant growth and other parameters (fresh and dry weight of plant, chlorophyll content of leaves, water absorption capability of roots) significantly increased with an increase in the concentration of the metal. It was further increased in the presence of the nematode.     

Interactions between the root-knot nematode Meloidogyne incognita and Glomus mosseae in banana

The effects of the interaction between the arbuscular mycorrhizal fungus Glomus mosseae and the root-knot nematode Meloidogyne incognita on growth and nutrition of micropropagated ;Grand Naine banana (Musa AAA) cultivar was studied under greenhouse conditions. Inoculation with two G. mosseae isolates significantly increased growth of plants in relation to non-mycorrhizal plants. Response to mycorrhizae was as effective as with an optimum P fertilization in promoting plant development for most growth parameters. Meloidogyne incognita had no apparent effect on the percentage of root colonization in mycorrhizal plants. In contrast, G. mosseae suppressed root galling and nematode buildup in the roots. The percentage of mycorrhizal colonization was high (over 80%) in low P fertilized plants, but optimum P rates for bananas (four times higher than low P) significantly reduced mycorrhizal colonization. Most elements were within sufficiency levels for banana with exception of N which was low for all treatments. Mycorrhizal plants fertilized with a low P rate showed higher N, P, K, Ca, and Mg contents as compared to non-mycorrhizal plants low in P with or without the nematode. Inoculation with G. mosseae favours growth of banana plants by enhancing plant nutrition and by suppressing nematode reproduction and galling during the early stages of plant development.     

Control of root-knot nematode,Meloidogyne incognita and reniform nematode,Rotylenchulus reniformis on pigeonpea and linseed

Abstract

Pigeonpea (Cajanus cajan) and linseed (Linum usitatissimum) are susceptible to Meloidogyne incognita and Rotylenchulus reniformis nematodes. Reduction in different growth parameters (length and weight of plant, number of pods), bulk density of pigeonpea stem, oil content of linseed, chlorophyll content of leaf and water absorption of roots caused by M. incognita and R. reniformis were statistically significant. Similar effects were also observed in plants raised from seeds soaked in different concentrations of water soluble fractions (WSF) of rice polish and pyridoxine solutions, however, the reductions were of a comparatively lesser extent. Higher concentrations of the solutions were more effective when compared to lower ones and pyridoxine was more beneficial than WSF for improving plant growth and reducing disease incidence.     

Interactive effect of root-knot nematode,Meloidogyne incognita and root-rot fungus,Rhizoctonia solani,on okra [Abelmoschus esculentus L.]

The individual, concomitant and sequential inoculation of second stage juveniles (at 2000 J₂/kg soil) of Meloidogyne incognita and Rhizoctonia solani (at 2 g mycelial mat/kg soil) showed significant reduction in plant growth parameters viz. plant length, fresh weight and dry weight as compared to control. The greatest reduction in plant growth parameters was recorded in the plants simultaneously inoculated with M. incognita and R. solani followed by sequential and individual inoculation. In sequential inoculation, plant inoculated with M. incognita 15 days prior to R. solani shows more reduction in comparison to plant inoculated with R. solani 15 days prior to M. incognita. Moreover, the multiplication of nematode and number of galls/root system were significantly reduced in concomitant and sequential inoculation as compared to individual inoculation, whereas the intensity of root-rot/root system caused by R. solani was increased in the presence of root-knot nematode M. incognita as compared to when R. solani was inoculated individually.     

Histological response of resistant tomato cultivars to infection of virulent Tunisian root-knot nematode (Meloidogyne incognita) populations

The response of a susceptible tomato cultivar (Solanum lycopersicum cv. Rio Grande) to infection by three populations of root-knot nematode (Meloidogyne incognita) was compared histologically with that of Lycopersicon esculentum cv. Monita, L. esculentum cv. VFN8 and Solanum lycopersicum cv. Nemador possessing the Mi-1 resistance gene and accession PI126443 of L. peruvianum possessing the Mi-3 gene. The resistant cultivars showed susceptibility to the Tunisian Meloidogyne populations. Feeding sites were characterised by the development of giant cells that contained granular cytoplasm and several hypertrophied nuclei. The cytoplasm of giant cells was aggregated along their thickened cell walls and consequently the vascular tissues within galls appeared disrupted and disorganised. Feeding site formed on resistant L. esculentum lines and susceptible cultivar Rio Grande are similar according to cell and nucleus number, and the nurse superficies. Resistant accession L. peruvianum PI126443, known to possess heat-stable nematode resistance, also showed susceptible reaction to Tunisian Meloidogyne incognita populations; however, nematode development was reduced in comparison with susceptible plants and less developed feeding cells were observed.     

The role of chitinase from Lecanicillium antillanum B-3 in parasitism to root-knot nematode Meloidogyne incognita eggs

B-3 fungal isolate was isolated from soil samples of Gwangju in Korea. Based on morphological and phylogenetic analysis, it was designated as Lecanicillium antillanum B-3 (syn. Verticillium antillanum B-3). The fungus was a chitinolytic-nematophagous microorganism. B-3 chitinase activity from 0.5% swollen chitin broth medium reached the highest level on the sixth day and then plateaued until 12 days. B-3 isolate showed the high rate of parasitism on Meloidogyne incognita eggs with more than 90% infection rate on the third day after treatment. B-3 crude chitinase damaged the eggshell structures more than 78% based on lactoglycerol staining data at a final protein concentration of 14.6 µg mL^?1 on the fourth day following treatment. Partially purified chitinase with molecular 37 kDa from DEAE-Sephadex chromatography also showed damaging effect on the eggs. These results suggested that chitinase from B-3 isolate was responsible for degradation of M. incognita eggshell structures.     

Pathogenic potential of root-knot nematode Meloidogyne incognita and root-rot fungus Fusarium solani on chilli (Capsicum annuum L.)

Damaging threshold levels of root-knot nematode Meloidogyne incognita and root-rot fungus Fusarium solani on plant growth parameters, viz., plant length, fresh and dry weight of chilli were determined by conducting their pathogenicity trials in pot experiments. The results revealed a significant reduction in the plant growth parameters at and above the inoculum level of about 1000?J₂ per plant of M. incognita and the highest reduction was recorded at 8000?J₂ per plant. Significant reduction in plant growth parameters was recorded at 1.00?g mycelial mat of F. solani per plant, while the highest reduction was observed at 8.00?g mycelial mat per plant. The damaging threshold level was 1000?J₂ per plant of M. incognita and 1.00?g mycelial mat of F. solani.     

Essential oils as soil biofumigants for the control of the root‐knot nematode Meloidogyne incognita on tomato

The effectiveness of soil fumigation with 50, 100 and 200 µL kg^?1 soil of essential oils (EOs) from the plant species Eucalyptus citriodora, Eucalyptus globulus, Mentha piperita, Pelargonium asperum and Ruta graveolens was assessed against the root‐knot nematode Meloidogyne incognita on potted tomato. Plant growth parameters and number of galls, nematode eggs and juveniles on tomato roots were evaluated after two months of maintenance of the treated plants at 25°C in greenhouse. EOs of E. globulus and P. asperum significantly reduced nematode multiplication and gall formation on tomato roots at all the tested rates, whereas the EOs of E. citriodora, M. piperita and R. graveolens were more suppressive at levels greater than 50 µL kg^?1 soil. Biofumigation with EOs of E. globulus and P. asperum resulted also in the largest increase of tomato plant top and root biomass. The five samples of EOs had a different chemical composition as determined by GC and GC‐MS. Structure–activity relationship based on the main constituents of the tested EOs and their nematicidal effect on M. incognita is discussed.     

Adventitious shoot formation induced by the root-knot nematode Meloidogyne hapla

 Observations were made on the infection process of the temperate sedentary root-knot nematode, Meloidogyne hapla, into roots of Arabidopsis thaliana (L.) Heynh cv. Landsberg erecta in monoxenic culture . After invasion, the infective second-stage juveniles follow a similar migratory path as has been observed in other Meloidogyne species, moving toward and turning within the root tip, to invade the vascular system and initiate the permanent feeding sites. About a week after invasion, there was extensive production of roots at the feeding site and, about 1 week later, the formation of adventitious shoots was observed at about 4.5% of all galls formed. In comparison, very little root production and no shoot formation was found on feeding sites of M. incognita. Received: 22 May 1998 / Revision received: 18 April 1999 / Accepted: 3 June 1999     

Bio-control activity of Purpureocillium lilacinum strains in managing root-knot disease of tomato caused by Meloidogyne incognita

The potential of 24 indigenous isolates of Purpureocillium lilacinum (Paecilomyces lilacinus) (Thom) Samson collected from different agro-climatic zones of India was investigated against the root-knot nematode, Meloidogyne incognita. The studies were conducted in vitro (larvicidal, ovicidal and egg-parasitising capacity) and under naturally infested field conditions with selected strains. Repeated field trials were conducted with talc-based preparations of fungal strains at 10 kg ha^?1, which were applied mixed in farm yard manure (FYM) at 1.5 t ha^?1. Results (in vitro) showed that all tested isolates were capable to parasitise eggs, inhibit egg hatching and cause juvenile mortality of M. incognita at various levels. Based on the performance under in vitro studies, eight isolates (NDPL-01, ANDPL-02, SHGPL-03, HYBPL-04, AHDPL-05, PTNPL-06, SNGPL-07 and VNSPL-08) were re-tested to confirm the results. HYBDPL-04 was found causing highest mortality (80%), inhibition of egg hatching (90%) as well as parasitisation of M. incognita eggs (75%). Under field trials also, the best protection of root-knot disease of tomato (Lycopersicon esculentum L.), in terms of reduction of galls (61%) and reproductive factor (P_f/P_i (RF) = 0.2) was achieved through application of HYBDPL-04 + FYM compared to control and other tested isolates. It also enhanced marketable yield of tomato up to 43%. It is concluded that the HYBDPL-04 strain of P. lilacinum is highly effective for management of root-knot disease of tomato under naturally infested field conditions. It is the isolate which produced the maximum number of metabolites which were extracted through high pressure liquid chromatography.     

Differential expression of root-knot nematode resistance genes in tomato and pepper: evidence with Meloidogyne incognita virulent and avirulent near-isogenic lineages

Reproduction of artificially selected near isogenic Meloidogyne incognita lineages virulent and avirulent against the Mi resistance gene of tomato was assessed on host and resistant lines and cultivars of pepper. Egg mass production following inoculation of individual potted seedlings with second-stage juveniles was studied in experiments conducted in controlled environment. Artificially selected Mi-virulent nematode populations were unable to develop on resistant pepper lines PM 217 and PM 687. This suggests that the genetic systems governing resistance to root-knot nematodes are differently expressed in tomato and pepper, in spite of the very close phylogenetic relationships and structural genomic homologies occurring between these two vegetable crops. Moreover, these artificially selected nematode populations were also found unable to develop on the susceptible pepper cultivars California Wonder and Doux Long des Landes, while their pathogenicity was not significantly affected on susceptible tomatoes. Due to the existence of naturally virulent Meloidogyne populations, these results enhance the need for a better understanding of the mechanisms involved, in order to develop new forms of management of plant resistance to root-knot nematodes.     

南方根结线虫初始接种密度对生姜生长的影响

在盆栽条件下,研究了南方根结线虫不同初始接种密度对生姜生长的影响.结果表明,南方根结线虫的侵染,降低生姜株高、茎粗、分枝数、茎叶鲜重和根系鲜重,最终降低生姜的产量,且随着接种密度的增加,生姜生长所受到的危害也随之增加.每100 g干土接种0、100和200个卵,可使生姜分别减产27.91%、37.73%和42.14%.初始接种密度对南方根结线虫繁殖速率也有很大影响.一般初始接种密度低时繁殖速率高,接种密度高时繁殖速率低,其在生姜上的平衡密度为每100 g干土746.20个.     

Comparison of concomitant and sequential inoculation of Steinernema sp. in the management of root-knot (Meloidogyne incognita) nematode infecting eggplant (Solanum melongena)

Culture of Steinernema sp. was maintained on Corcyra cephalonica larvae. Steinernema sp. (at 50, 500, 1000, 2500, 5000, 10,000 and 20,000 ij’s /500?g soil) was concomitantly inoculated with 500 J₂ of Meloidogyne incognita/500?g soil to the eggplant seedlings in the pots filled with 4?kg sterilised soil. The simultaneous inoculation of M. incognita with either of the inoculum levels (1000, 2500, 5000 and 10,000 J₃/500?g soil) of Steinernema sp. significantly reduced the damage caused by M. incognita in terms of plant growth parameters, viz. plant length, dry weight, number of flowers and weight of fruits. Moreover, the highest improvement in plant growth parameters, viz. plant length, dry weight, number of flowers and weight of fruits, was recorded in plants inoculated with 5000 J₃ of Steinernema sp./500?g soil followed by 2500, 1000 and 10,000 J₃/500?g soil. The highest reduction in the reproduction factor and number of galls/root system was recorded in the plants treated with 5000 J₃ Steinernema sp./500?g soil followed by 2500, 1000 and 10,000 J₃/500?g soil. Comparison of concomitant and sequential inoculations showed that the sequential inoculation (both prior and after) of Steinernema sp. at different inoculum levels (1000, 2500, 5000, 10,000 and 20,000 ij’s/500?g soil) was more effective in the management of root-knot nematode than the concomitant inoculation. Therefore, the application of Steinernema sp. might be useful for suppression of nematode pest on eggplant and may be used as an alternative for chemicals.     

Mode of action and efficacy of iprodione against the root‐knot nematode Meloidogyne incognita

The ban and restriction on the use of several synthetic chemicals for controlling plant parasitic nematodes, and concern about their side effects necessitate the availability of effective methods of control with low toxicity to humans and non‐target organisms. Therefore, efficacy and mode of action of iprodione, a dicarboximide fungicide, was evaluated against the root‐knot nematode Meloidogyne incognita, in vitro and in vivo conditions, in comparison with the nematicides fenamiphos, fosthiazate and oxamyl at 7.00, 1.66 and 1.66 mL/5 L water, respectively. In vitro, iprodione showed nematostatic rather than nematicidal activity against second‐stage juveniles of M. incognita in contrast to fenamiphos, fosthiazate and oxamyl which were nematicidal. In the in vivo experiment with tomato, iprodione controlled M. incognita less than fenamiphos, fosthiazate and oxamyl. No visual symptoms of phytotoxicity were observed. Therefore, iprodione can be a useful chemical for controlling nematode populations if included in an Integrated Pest Management program.