Pochonia Chlamydosporia Var Research Articles

Modeling Root-Knot Nematode Regulation by the Biocontrol Fungus Pochonia chlamydosporia.

Two models of increasing complexity were constructed to simulate the interactions between the root-knot nematode (RKN) Meloidogyne incognita and the biocontrol fungus Pochonia chlamydosporia var. catenulata in a rhizosphere microcosm. The models described discrete population dynamics at hourly rates over a 6-month period and were validated using real parasitism and nematode or fungus data. A first, general Pochonia-nematode-root model (GPNR) used five functions and 16 biological constants. The variables and constants describing the RKN life cycle included the rates of egg production, hatching, juvenile (J2), and mature female development, including root or nematode self-density-dependent factors. Other constants accounted for egg parasitism, nematode-induced root losses, growth, and mortalities. The relationship between nematodes and fungal propagules showed density dependence and cyclic variations in time, including an attractor on the propagules and J2 phases space. The simulations confirmed a P. chlamydosporia optimal initial density of 5 · 103 propagules · cc soil-1, as usually applied in assays. The constants used in GPNR showed adherence to the nematode biology, with 103 eggs per egg mass, a 10-day average lifespan of J2, with 2 days required to enter roots, and adult lifespan lasting 24 days. The fungus propagule lifespan was 25 days, with an average feeder root lifespan lasting around 52 days. A second, more complex Pochonia-nematode-root detailed model (GPNRd) was then constructed using eight functions and 23 constants. It was built as GPNR did not allow the evaluation of host prevalence. GPNRd allowed simulations of all RKN life stages and included non-parasitic and parasitic fungus population fractions. Both GPNR and GPNRd matched real J2 and fungus density data observed in a RKN biocontrol assay. Depending on the starting conditions, simulations showed stability in time, interpreted as effective host regulation. GPNRd showed a fungus cyclic relationship with the J2 numbers, with prevalence data close to those observed (38.3 vs. 39.4%, respectively). This model also showed a further density-independent nematode regulation mechanism based on the P. chlamydosporia switch from a non-parasitic to a parasitic trophic behavior. This mechanism supported the biocontrol of M. incognita, also sustained by a concomitant increase of the root density.

Phosphate–solubilizing fungi co–inoculated with Bradyrhizobium promote cowpea growth under varying N and P fertilization conditions

We evaluated the compatibility between two nitrogen–fixing Bradyrhizobium inoculant strains and phosphate–solubilizing fungal strains and the effect of co–inoculation of these bacterial and fungal strains on cowpea growth under different N and P conditions. First, the compatibility between Bradyrhizobium strains UFLA03–84 and INPA03–11B and fungi Haematonectria ipomoeae FSA381, Eleutherascus lectardii FSA257a, Pochonia chlamydosporia var. catenulata FSA109, and Acremonium polychromum FSA115 was tested in both solid and liquid media. Cowpea growth and nodulation promotion under two mineral N doses and two P conditions (a low dose of soluble P plus a high dose of Ca3(PO4)2 and another condition with a high dose of soluble P) were tested with two N2 fixing Bradyrhizobium strains co–inoculated with each of the P–solubilizing fungal strains FSA109, FSA115, and FSA381. There was compatibility between each fungal strain and the two Bradyrhizobium strains, except for FSA257a with either of the bacterial strains in liquid medium. When both mineral N and P were limiting, plants were able to grow and accumulate N and P based on biological N2 fixation and solubilization of calcium phosphate in the same amount as the mineral N and soluble phosphate. Even when both nutrients were fully available, the type of co–inoculation promoted plant growth and nutrient accumulation. The responses varied in accordance with the co–inoculated strains, the N source, and the P source, reflecting the enormous complexity of the biological interactions between plants and microorganisms, and the nutrient conditions provided by the environment.

On the enzymes\u2019 actions of entomopathogenic fungi against certain indigenous and invasive insect pests

BackgroundPathogenicity of entomopathogenic fungi (EPF) depends mainly on their ability to produce efficient enzymes, which degrade insect’s integument and other cellular components. Lipases are the first enzymes secreted by these fungi, then proteases, phospholipases, and chitinases.ResultsTwenty-six fungal strains, isolated from the aphids, Aphis sp., Linnaeus (Homoptera, Aphididae), the tomato leaf minor, Liriomyza trifolii, Burgess (Diptera, Agromyzidae) (indigenous insects), the red palm weevil, Rhynchophorus ferrugineus, Olivier (Coleoptera, Curculionidae), and the peach fruit fly, Bactrocera zonata, Saunders (Diptera, Tephritidae) (invasive insects) were tested for their enzymatic activities. Results showed that the majority of these strains were able to produce lipolytic enzymes with the most active being Aspergillus niger, Botryotrichum atrogriseum, Cochliobolus spicifer, Fusarium chlamydosporum, and F. proliferatum. Phospholipase was successfully produced by 73.1% of the tested strains among which Aspergillus flavus, A. niger, Mucor racemosus, Pochonia chlamydosporia var. catenulata, and Scopulariopsis brevicaulis were the highest producers. Proteolytic enzymes were detected in cultures of all the fungal strains except Aspergillus chevalieri and M. racemosus. The best proteolytic strain was S. brevicaulis followed by A. flavus, A. sydowii, and F. semitectum. The chitinolytic ability of the fungal strains was generally weak and the relatively active species belonged to A. flavus, A. niger, B. atrogriseum, F. chlamydosporum, F. solani, S. brevicaulis, and Nigrospora oryzae. Quantitative determination of chitinase revealed that the enzyme concentration ranged from 3.478 to 6.44 IU/ml.ConclusionMost of the isolated fungi had enzymatic activities, but A. niger, F. semitectum, F. solani, F. chlamydosporum, P. chlamydosporia var. catenulata, and S. brevicaulis, were the most active ones.

Effect of arbuscular mycorrhizal fungi, glomus mosseae and G. intraradices and antagonistic fungi pochonia chlamydosporia var. chlamydosporia and purpureocillium lilacinum on disease indices and reproduction rate of Meloidogyne javanica in three peach rootstocks under greenhouse conditions.

Biocontrol is one of the methods widely studied to reduce nematode damage. The biological control efficacy of two arbuscular mycorrhizal fungi, Glomus mosseae and G. intraradices and two antagonistic fungi, Pochonia chlamydosporia var. chlamydosporia and Purpureocillium lilacinum on disease indices and reproduction rate of root-knot nematode, Meloidogyne javanica were studied on three local cultivars of peach rootstocks namely Helendri, Shorabi3 and Gf677. The experiment was conducted as a factorial experiment in a completely randomized design with 30 treatments and five replications under greenhouse conditions. Evaluations were performed 90 days after nematode inoculation by measuring the plant growth parameters and growth and reproduction rate of M. javanica. Results of nematode reproduction indices showed more effect of P. chlamydosporia var. chlamydosporia on reduction of nematode biological activity than other biocontrol fungi. The number of galls, egg masses, second stage juveniles and reproduction factor in GF677 treated with this fungus decreased comparing to control, as 42.2, 41.8, 39 and 6.36 percent, respectively. Although the fungus was effective on all stages of nematode development, but the number of egg masses and number of eggs per egg mass were more affected.

Biocontrol of Bean and Wheat Aphids by Fungi Isolated from Indigenous and Invasive Insects Collected from Different Locations in Minia Governorate, Egypt

A total of 26 fungal strains were isolated from aphids and tomato leaf miner as indigenous species and from red palm weevil and peach fruit fly as an invasive insect. Fungal strains tested for their abilities to attack both bean and wheat aphids. The mortality of aphids due to thesefungi was estimated. Results showed that eight entomopathogenic fungi Scopulariopsis brevicaulis, Verticillium sp., Fusarium chlamydosporum, Fusarium proliferatum, Fusarium semitectum, Pochonia chlamydosporia var. catenulata, Fusarium solaniand Fusarium verticillioides exhibited high virulence 60-100%. However, Scopulariopsis brevicaulis, Verticillium sp., Fusarium chlamydosporum and Fusarium solani proved to be the most virulent species against the target aphids inducing 90%-100% mortality.

Assessment of three strategies for the management of Meloidogyne arenaria on carrot in Mexico using Pochonia chlamydosporia var. mexicana under greenhouse conditions

ABSTRACTThree control strategies for management of Meloidogyne arenaria were evaluated on carrot under greenhouse conditions. The control strategies tested were: i) incorporation of fresh broccoli; ii) carbofuran (Furadan®); and iii) Pochonia chlamydosporia var. mexicana, isolate Pcp21. Each strategy was evaluated separately and in combination (16 treatment combinations), each with three replicates. The experiment was done between February and April 2014 and repeated over the same time period in 2015. Each replicate experimental unit consisted of a 1 kg pot filled with tyndallised soil, to which broccoli, fungus and carbofuran were added according to treatment. Carrot seeds were sown into each pot and inoculated with M. arenaria eggs according to treatment. Pots were then maintained in the glasshouse for 12 weeks at 25 ± 5°C. After this time the fresh root weight, root length, percent reduction in root galling, P. chlamydosporia var. mexicana colony forming units (CFU)/g of soil, and CFU/g root were all measured. Results showed that isolate Pcp21 of P. chlamydosporia var. mexicana significantly reduced root galling percentage by 50 and 78% in 2014 and 2015, respectively. Application of the fungus in combination with broccoli or carbofuran also reduced root galling. The number of CFU/ g of soil or root remained the same over the 12 weeks of the experiment. This isolate of P. chlamydosporia significantly reduced damage caused by M. arenaria on carrot and is a promising agent for management of this nematode.

Pochoniolides A and B, new antioxidants from the fungal strain Pochonia chlamydosporia var. spinulospora FKI-7537

New natural products, designated pochoniolides A and B, were isolated from the cultured broth of fungal strain FKI-7537 using a physicochemical screening methodology. Strain FKI-7537 was isolated from a soil sample collected at Niijima, Tokyo, Japan and identified as Pochonia chlamydosporia var. spinulospora by morphological characteristics and DNA sequence analysis. The chemical structures of pochoniolides A and B were elucidated by NMR and mass spectra and found to be new compounds consisting of a muconolactone moiety connected with a chromone unit. Pochoniolides A and B were identified as racemate mixtures using data on optical rotation and circular dichroism spectra. Furthermore, enantiomers of pochoniolide B, pochoniolides B1 and B2, were separated using a chiral HPLC column. Pochoniolides A and B showed hydroxyl radical-scavenging and singlet oxygen-quenching activities.

Biocontrol potential of Pochonia chlamydosporia var. chlamydosporia isolates against Meloidogyne javanica on pistachio

The biocontrol potential of four Pochonia chlamydosporia var. chlamydosporia isolates on the root-knot nematode, Meloidogyne javanica was investigated on pistachio plants in a greenhouse experiment. Isolates were applied at 10,000, 5000 and 1000 chlamydospores per gram of soil; the latter two densities were being used for strain Pcc60 only and designated as PccB and PccA, respectively. Plants were inoculated with a suspension containing 3000 eggs of M. javanica. Nematode reproduction was reduced to 57% by Pcc20 and 36% by Pcc10 and Pcc60C after 4 months. Pcc20 was the most promising isolate as the final egg population of nematodes was reduced by nearly 61 and 36% by Pcc10 and Pcc60C, respectively. All strains infected eggs on the roots to varying degrees. Pcc20 was the most effective colonizer of all the isolates, infecting 37% of the eggs, while Pcc10 and Pcc60C as the second best colonizers caused an average infection rate of 17.5%. The potential of the fungus was reduced at lower densities of spore inoculum. Semi-selective medium was used to re-isolate the fungi from soil and rhizosphere but was not able to detect Pcc60A at 1000 cfu/g soil, despite the fact that 3% of the eggs were parasitized. The efficiency of the different isolates in controlling nematode reproduction parameters and their relationships in terms of survival and abundance is discussed further.

Long-term biological effectiveness of Pochonia chlamydosporia var. catenulata against Meloidogyne incognita infection in a crop rotation systemi

ABSTRACTThe aim of this study was to determine the effectiveness of Pochonia chlamydosporia var. catenulata and the bacteria Tsukamurella paurometabola strain C-924 (HeberNem™), to control Meloidogyne incognita infection in a crop rotation system (cucumber, tomato and pepper) under greenhouse production during six crop cycles. We determined gall index, prevalence, intensity of disease, and number of juvenile nematodes in soil. At the end of the sixth cycle, plants protected with P. chlamydosporia showed a reduction in gall index (≤2), prevalence, and median (42%) intensity of disease similar or more pronounced than those observed in plants protected with T. paurometabola (80%). Both treatments were more efficient at reducing galling than at reducing prevalence and therefore reduction of intensity of disease was mainly due to the reduction in galling. The hydrolytic activity of P. chlamydosporia and its resistant spores make this fungus one of the best options for the long-term control of RKNs by decreasing egg masses or galls. Pochonia chlamydosporia var. catenulata is an important part of a potential biological control strategy in rotation systems of vegetable crop and can be used for long-time IPM strategies in Cuba and the Caribbean.

Susceptibility of the biocontrol fungi Metarhizium anisopliae and Trichoderma asperellum (Ascomycota: Hypocreales) to imbibitional damage is driven by conidial vigor

Imbibition damage (ID) is a phenomenon characterized by the death of dehydrated conidia when immersed in water at temperatures⩽ca. 25°C, as a result of the transition in the conformation of the plasma membrane in the presence of free water. In the present study we evaluated the susceptibility to ID of eight major species or varieties of fungi used in biological control programs in several countries (Isaria farinosa, I. fumosorosea, I. javanica, Nomuraea rileyi, Pochonia chlamydosporia var. catenulata, P. chlamydosporia var. chlamydosporia, Purpureocillium lilacinum, and Trichoderma asperellum). A commercial isolate of Metarhizium anisopliae sensu stricto, known to be sensitive to ID, was also included. Within all tested taxa, significant reductions in germination of dehydrated conidia after immersion in cold water (15°C) compared to immersion in warm water (33–37°C) were reported, due to delayed germination and/or ID. Additional tests with dehydrated M. anisopliae and T. asperellum conidia produced on different substrates revealed that susceptibility to ID was greatly impacted by vigor (% dehydrated conidia with rapid germination). Low mortality (1–7%) of dehydrated conidia immersed in cold water was observed when vigor was ⩾95%. Conversely, mortality was ⩾20% when vigor ranged from 50 to 90%. We hypothesize that, in vigorous dehydrated conidia, the cell wall is capable of slowing down water influx, allowing rehydration of the cell membrane by water vapors before contact with free water, thus mitigating ID. The marked effect of conidial quality on susceptibility of M. anisopliae and T. asperellum to ID highlights the need for production and post-production procedures (drying, harvesting, formulation and packaging) that ensure high vigor of conidia used as active ingredients in mycopesticides with low water contents.

Pochonia chlamydosporia var. chlamydosporia (Goddard) Zare & W. Gams for the management of lettuce infected with Meloidogyne javanica (Treub, 1885)

The application of the nematophagous fungus Pochonia chlamydosporia var. chlamydosporia (Goddard) Zare & W. Gams during seedling production of vegetable crops can be an efficient approach to control root-knot nematode. The aim of this study was to evaluate the effect of treating seedlings and/or soil with bionematicide (wettable powder formulation) based on chlamydospores from isolate Pc-10 on the Meloidogyne javanica (Treub, 1885) control in lettuce (Lactuca sativa L.). Isolate Pc-10 was diluted in water and applied when watering the seedlings (0, 4.5, 9.0, 13.5, and 18.0 g L-1) and/or to the potted soil (5000 chlamydospores g-1) used for growing lettuce. The soil in each pot was infested with 3000 M. javanica eggs. The number of M. javanica eggs was reduced in lettuce roots when isolate Pc-10 was applied either to seedlings or soil; there was no interaction between application methods. The decrease in the number of eggs was proportional to the increase of isolate Pc-10 applied to seedlings with maximum reduction of 43.5% at the 18 g L-1 dose. When the fungus was applied to the soil, the number of eggs was reduced by 12.3%. Increasing doses of isolate Pc-10 reduced the number of galls up to 21% with the 18 g L-1 dose. Applying bionematicide based on P. chlamydosporia isolate Pc-10 at 18 g L-1 on seedlings controls M. javanica in lettuce.

Phosphate Solubilization by Several Genera of Saprophytic Fungi and Its Influence on Corn and Cowpea Growth

The aim of this study was to test the ability of several strains of fungi, which were isolated from the Brazilian Amazon, to solubilize calcium phosphate in vitro and to promote corn and cowpea growth under axenic conditions. Each plant species received six treatments: inoculation with strains with high solubilization index (SI) (Haematonectria ipomoeae CML 3249 and Pochonia chlamydosporia var. catenulate CML 3250) and control treatments: inoculation with strain that does not solubilize phosphate on Pikovskaya agar (PVK) (Acremonium polychromum FSA115), and non-inoculated treatments with high concentration of insoluble phosphate (HPins), high concentration of soluble phosphate (HPs) or low concentration of soluble phosphate (LPs). The fungi strains had SI between 1.07 cm and 2.03 cm including species without previous report in the literature of their capacity to solubilize calcium phosphate. The two phosphate-solubilizing strains promoted greater corn and cowpea root growth than the controls FSA115, HPins and LPs, to a level similar to the HPs control.

Pochonia chlamydosporia controls Meloidogyne incognita on carrot

The fungus Pochonia chlamydosporia var. chlamydosporia isolate Pc-10 (Pc-10) presents great potential for the management of root-knot nematodes on vegetable crops. However, there is no information about the use of Pc-10 on carrot. Thus, we evaluated in this study the effect of Pc-10 incorporated into the soil (PCI) or applied to the surface of the beds (PCS) on control of Meloidogyne incognita on carrot under field conditions, in comparison to an untreated control and the bionematicides Paecilomyces lilacinus + Bacillus subtilis (PLBS), mix of nematophagous fungi and Bacillus sp. (NFB) and P. lilacinus (PL). PCI increased the total and marketable production of carrot roots by 25.35 and 55.03 %, respectively. The production of unmarketable roots was reduced by about 50 % in plots treated with PCI, PCS and PLBS. All bionematicides reduced the number of unmarketable roots with galls, but only PCI reduced the reproduction factor of the nematode. The incorporation of Pc-10 in the soil of the beds controls M. incognita and improves carrot quality and yield.

Use of Pochonia chlamydosporia to control Meloidogyne javanica in cucumber

This study was done to evaluate the effect of the bionematicide Pc-10, based on Pochonia chlamydosporia var. chlamydosporia, on the control of Meloidogyne javanica. The fungus was applied by two methods: (1) drenching the substrate of seedlings with an aqueous suspension of Pc-10 (0, 4.5, 9.0, 13.5 and 18.0g/L), or (2) incorporating Pc-10 into the soil of potted plants at a rate of 5000 chlamydospores/g of soil. The soil of each pot was infested with 3000 eggs of M. javanica, and one cucumber seedling was transplanted to each pot after 1week. Increasing the doses of Pc-10 in the seedlings reduced the numbers of galls/g and eggs/g in the roots of cucumber plants in both experiments, regardless of the application method of the fungus in the soil. The application of 18g/L of Pc-10 in the seedlings reduced the number of galls/g of roots by 46.04% and 49.44%, and the number of eggs/g of roots by 48.32% and 40.58% in the first and second experiments, respectively. Soil application of Pc-10 reduced the number of eggs/g of roots by 19.42% in the first experiment only. Drenching the substrate of seedlings with Pc-10 at 18g/L controls M. javanica in cucumber and does not require additional fungus application in the soil.

In vitro evaluation of nematophagous activity of fungal isolates

Four filamentous fungi associated with nematodes were isolated and identified from litter samples collected in the Integral Natural Reserve "Bosco Siro Negri" (PV, Italy): Arthrobotrys dactyloides, Arthrobotrys oligospora var. oligospora, Pochonia bulbillosa, and Pochonia chlamydosporia var. catenulata. Their capacity to break down the nematode population was evaluated in vitro by means of simple and reproducible multiwell plates method. All fungal strains were able to cause a death-rate significantly different from the controls (p < 0.05). Precisely, A. dactyloides caused, on average, a 26% death rate increase in the nematode population compared to the control, A. oligospora var. oligospora 25%, P. bulbillosa 12%, and P. chlamidosporia var. catenulata 17%. The method has also allowed to determine the more active fungi as regards the prey's life cycle stage. The most active strains against nematodes (adults) were A. dactyloides and A. oligospora var. oligospora, known to attack adults or larval stages by means of tridimensional traps. On the contrary P. bulbillosa and P. chlamydosporia, known to attack mainly the nematode life stage of cysts, showed lower activity against adult nematodes.

The effect of different salts (heavy metals) on the mycelium growth of Nematophagus fungi

Environmental pollution in addition to direct damage on plant growth, with the destruction of biological control agents, causes indirect damage to plants. The aim of this research was to study the effects of different concentrations (0, 500, 1000, 1500 and 2000 ppm) of heavy metals including Ag, Co, Cu, Fe, Hg, Mn, Pb and Zn on the mycelial growth and to assess the fungicidal or fungistatic effects of these salts on five Nematophagus fungi including Trichoderma harzianum (T8), Trichoderma virens (T21), Trichoderma hamatum (T9), Pochonia chlamydosporia var. chlamydosporia and Arthrobotrys oligospora. The results show that Ag, Co, Cu, Fe and Hg could stop the mycelium growth of all fungi, but Mn, Pb and Zn cannot inhibit the growth of these fungi completely. Among the first group, Hg and Cu stopped the growth of fungi even in 500 ppm. Among these metals that inhibit the growth of fungi, Cu has fungistatic effect and others have fungicide effect. The experiment was conducted in vitro condition, using potato dextrose agar (PDA) under complete randomised design with four replications. The data of mycelium growth were recorded at seven days after inoculation at 25 ± 2°C.

Effect of cultural condition on biomass production of some Nematophagous fungi as biological control agent

Nematophagous fungi include a group of fungal antagonists to nematodes. The nematophagous fungi have been suggested as promising candidates for biological control of plant parasitic nematodes. Impacts of different pH levels, temperature, light intensity, carbon and nitrogen source were tested on the growth of five nematophagus fungi under in vitro conditions. Three isolates of Trichoderma harzianum T7, T8, and T14, one isolate of Pochonia chlamydosporia var. chlamydosporia and one isolate of Arthrobotrys oligospora were tested. The results of experiment indicated that the growth of isolates of Trichoderma harzianum was maximum in pH range of 7.008.00. The best growth of Pochonia chlamydosporia var. chlamydosporia and Arthrobotrys oligospora was in 4.00-7.00. Effect of temperature differs between range of 15-30°C, for isolates of Trichoderma harzianum was 20-25°C, Pochonia chlamydosporia var. chlamydosporia was 15-20°C, and Arthrobotrys oligospora was 20-25°C. Maximum growth of two isolates of Trichoderma harzianum T7, T8 and Pochonia chlamydosporia var. chlamydosporia was in darkness. Best growth of one isolates of T. harzianum (T7) was in light and maximum growth of Arthrobotrys oligospora and Trichoderma harzianum T14 occurred in 12 h light and 12h dark. The best source of nitrogen for Trichoderma harzianum (T8,T14) was Nitrate potassium, while Nitrate ammonium was the best nitrogen source for (T7).The maximum growth of A. oligospora and P. chlamydosporia occuerd in Nitrate sodium. Between carbon sources Arabinose are suitable for A.oligospora and Trichoderma harzianum (T7).The maximum growth of P. chlamydosporia and T. harzianim (T14) occuerd in the use of fructose. Best growth of T. harzianum (T8) was in Mnitole.

Effects of crop plants on abundance of Pochonia chlamydosporia and other fungal parasites of root-knot and potato cyst nematodes

The effects of a host plant on reproduction/abundance of fungal populations in relation to soil nutrients released by plants in the rhizosphere were studied. Abundance in the soil and potato rhizosphere of the fungi Paecilomyces lilacinus, Monographella cucumerina (CABI 380408) and Pochonia chlamydosporia var. chlamydosporia (Pc280, potato cyst nematode biotype) and P. chlamydosporia var. catenulata (Pc392, root-knot nematode biotype) were assessed. The different ability of break crops (oilseed rape, sugarbeet and wheat) in the potato rotation to support Pa. lilacinus, Pochonia isolates Pc280 and Pc392 and abundance of the latter two isolates in soil and rhizosphere of potato plants infected with Meloidogyne incognita were also studied. Potato chits and crop seedlings were planted into boiling tubes containing 5000 chlamydospores or conidia g−1 in acid washed sand (pH 6) and kept in a growth chamber at 20°C, and 16 h of light for up to 9 weeks. The abundance of the fungi in sand (fallow) differed significantly between fungal species, being in general less abundant in the absence than in the presence of the plant, although there was no interaction between plant species and fungal isolate. There was evidence of a different response to Me. incognita for Pc392 than for Pc280 but there was no significant effect of the presence of the nematode on the rate of increase of the fungus.

Cultural and morphological characterization of Pochonia chlamydosporia and Lecanicillium psalliotae isolated from Meloidogyne mayaguensis eggs in Brazil

The root-knot nematode, Meloidogyne mayaguensis, causes serious economic loss to guava plantation in Brazil. Fungi associated with eggs of M. mayaguensis in Brazilian soil have not been studied yet, but this knowledge could form the basis for future field studies on biological control of this nematode. The egg parasitic fungi, Pochonia chlamydosporia var. chlamydosporia, P.chlamydosporia var. catenulata and Lecanicillium psalliotae, were isolated from M. mayaguensis eggs and analyzed based on their cultural and morphological characteristics. The optimum temperature for growth and spore production ranged between 24 and 28oC for P. chlamydosporia isolates. For the isolate of L. psalliotae, the best growth was at 30oC. In solid state fermentation, P. chlamydosporia isolates produced between 3.5 and 5.2 x 106 chlamydospores per g of colonized substrate, whereas L. psalliotae isolate produced 8.5 x 108 conidia per g of colonized substrate. Future studies are required to clarify the potential of these fungi as biological control agents of M. mayaguensis.

Detection of Meloidogyne incognita and Pochonia chlamydosporia by fluorogenic molecular probes*

Fluorescent molecular probes were applied for detection of the plant parasitic nematode Meloidogyne incognita and the nematode‐egg parasitic fungus Pochonia chlamydosporia var. chlamydosporia. A region in the M. incognita rDNA including ITS2 was selected for amplification and recognition with a real‐time PCR assay, based on a combination of three specific motifs, each recognized by a specific fluorescent probe. Similarly, a Scorpion probe was designed for the RT‐PCR quantification of P. c. chlamydosporia. For this purpose, the ITS‐2 rDNA gene of the fungus was sequenced from a number of Italian isolates. A conserved region unique for P. c. chlamydosporia found in the ITS‐2 rDNA gene was used. The probes allowed recognition of single juveniles of M. incognita and of the mycelium‐ or soil‐extracted fungal DNA. The potentialities of the detection procedures are discussed.