Species Of Nematode-trapping Fungi Research Articles

Surrounding the swollen roots of sweetpotato with a decomposing band of an organic amendment enhances nematode-suppressive services and reduces damage caused by root-knot nematode

A previous field trial showed that marketable yield increased and root-knot nematode populations declined when the swollen roots of sweetpotato were surrounded by a sawdust-based amendment. Further evidence that such amendments provide worthwhile levels of nematode control was obtained in this study. Customised pots filled with an organic amendment or amended soil were kept in a greenhouse or buried in the field for various times and then the nematode-control potential of various treatments was assessed by surrounding the pots with soil infested with Meloidogyne incognita. Swollen root production generally increased, and root-knot nematode populations consistently declined, when sawdust was used as an amendment. The addition of an organic nitrogen source generally improved the level of control. Laboratory and greenhouse assays confirmed that amended soils were biologically suppressive, as root-knot nematode numbers were lower and fewer galls were produced in soil containing decomposing amendments than in soil or sand that had been heated to kill the soil biota. A predatory nematode morphologically similar to Clarkus papillatus was one of the suppressive agents as numbers were very high in some experiments. Mesostigmatid mites in the family Laelapidae and genera Sejus, Protogamasellus, Holaspulus and Gamasiphis were also contributing, while an acarid mite (Rhizoglyphus robini) occurred in high numbers and was observed devouring root-knot nematode juveniles on agar plates. Nematophagous fungi were also involved as three species of nematode-trapping fungi (Arthrobotrys musiformis, A. thaumasia and A. oligospora) and an unidentified fungus that captures nematodes on bulbous hyphal extensions were consistently isolated from amended soils. These results suggest that sawdust-based amendments enhance the nematode-suppressive services provided by a wide range of predators.

Classification of dendrocola nematode-trapping fungi

Pine wilt disease, caused by Bursaphelenchus xylophilus and Bursaphelenchus mucnatus, is a serious quarantined disease. Arboreal nematode-trapping fungi of Pinus spp. are effective predators on nematodes and have strong host adaptability. The development of these fungal resources may be an effective way to control pine wood nematodes. We collected 515 samples of pine wilt disease from the areas of Ninghai City (Zhejiang province), Shuangbai County (Yunnan province), and Daxing’anling (Heilongjiang province), China. Through isolation, culture and identification, 6 species of nematode-trapping fungi (Arthrobotrys cladodesr, A. oligospora, A. musiformis, A. dendroides, Dactylellina ellipsospora, Monacrosporium thaumasium) were identified for predation against B. xylophilus, and 9 species (Arthrobotrys dactyloides, A. cladodesr A. oligospora A. dendroides, Dactylellina ellipsospora, Dactylella asthenopaga, D. leptospora, Arthrobotrys superba, Monacrosporium drechseri) were identified for predation against B. mucnatus. This study provides information in the classification of arboreal predator nematodes and provides an important basis for future biological control of pine wood nematodes.

Efficacy of a Simple Formulation Composed of Nematode-Trapping Fungi and Bidens pilosa var. radiata Scherff Aqueous Extracts (BPE) for Controlling the Southern Root-Knot Nematode.

We tested a formulation composed of a mixture of Bidens pilosa var. radiata extract (BPE) and nematode-trapping fungi for its effects on Meloidogyne incognita. In earlier evaluations of the effects of plant extracts on the hyphal growth of 5 species of nematode-trapping fungi with different capture organs (traps), the growth of all species was slightly inhibited. However, an investigation on the number of capture organs and nematode-trapping rates revealed that Arthrobotrys dactyloides formed significantly more rings and nematode traps than those of the control. An evaluation of simple mixed formulations prepared using sodium alginate showed that nematodes were captured with all formulations tested. The simple mixed formulation showed a particularly high capture rate. Furthermore, in a pot test, although the effects of a single formulation made from the fungus or plant extract were acceptable, the efficacy of the simple mixed formulation against M. incognita root-knot formation was particularly high.

Interspecific and host-related gene expression patterns in nematode-trapping fungi.

BackgroundNematode-trapping fungi are soil-living fungi that capture and kill nematodes using special hyphal structures called traps. They display a large diversity of trapping mechanisms and differ in their host preferences. To provide insights into the genetic basis for this variation, we compared the transcriptome expressed by three species of nematode-trapping fungi (Arthrobotrys oligospora, Monacrosporium cionopagum and Arthrobotrys dactyloides, which use adhesive nets, adhesive branches or constricting rings, respectively, to trap nematodes) during infection of two different plant-pathogenic nematode hosts (the root knot nematode Meloidogyne hapla and the sugar beet cyst nematode Heterodera schachtii).ResultsThe divergence in gene expression between the fungi was significantly larger than that related to the nematode species being infected. Transcripts predicted to encode secreted proteins and proteins with unknown function (orphans) were overrepresented among the highly expressed transcripts in all fungi. Genes that were highly expressed in all fungi encoded endopeptidases, such as subtilisins and aspartic proteases; cell-surface proteins containing the carbohydrate-binding domain WSC; stress response proteins; membrane transporters; transcription factors; and transcripts containing the Ricin-B lectin domain. Differentially expressed transcripts among the fungal species encoded various lectins, such as the fungal fruit-body lectin and the D-mannose binding lectin; transcription factors; cell-signaling components; proteins containing a WSC domain; and proteins containing a DUF3129 domain. A small set of transcripts were differentially expressed in infections of different host nematodes, including peptidases, WSC domain proteins, tyrosinases, and small secreted proteins with unknown function.ConclusionsThis is the first study on the variation of infection-related gene expression patterns in nematode-trapping fungi infecting different host species. A better understanding of these patterns will facilitate the improvements of these fungi in biological control programs, by providing molecular markers for screening programs and candidates for genetic manipulations of virulence and host preferences.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-968) contains supplementary material, which is available to authorized users.

Taxonomic revision of the nematode-trapping fungus Arthrobotrys multisecundaria

The gene encoding an extracellular serine protease was cloned from Arthrobotrys multisecundaria using degenerate primers. The gene was highly similar (99.26%) to protease Mix from Monacrosporium microscaphoides. To clarify the taxonomic relationship between these species, genes encoding the internal transcribed spacer (ITS) and beta-tubulin were also cloned and sequenced from A. multisecundaria and M. microscaphoides, respectively. Homologous analysis of the nuclear (ITS) and protein (beta-tubulin) encoding genes showed that the two species of nematode-trapping fungi also shared extensive identity (99.82 and 99.63%, respectively), although they exhibited obvious differences in secondary conidia morphology. Accordingly, a taxonomic revision is recommended, with A. multisecundaria being revised as A. microscaphoides var. multisecundaria. In addition, the identified mutation may better facilitate the study of the sporulation of nematode-trapping fungi.

Diversity and trapping efficiency of nematophagous fungi from Oman.

Summary. A survey of the nematophagous mycobiota biodiversity of 82 soil and leaf-litter samples in the Sultanate of Oman yielded ten species of nematode trapping fungi belonging to three genera. The species are: Arthrobotrys eudermata, A. thaumasia, A. musiformis, A. oligospora, A. oligospora var. oligospora, A. oudemansii, A. multiformis, A. javanica, Drechslerella brochopaga and Gamsylella geophyropaga. This is the first record of these species in Oman. Arthobotrys multiformis represents the second record of this species worldwide. A systematic study showed that A. oudemansii, A. multiformis and A. javanica were morphologically more variable than was so far known. In four days, A. oligospora, A. thaumasia, D. brochopaga and A. eudermata trapped all nematodes added to the Petri dishes (Panagrellus redivivus, 100 specimens per dish). No significant differences were found in the trapping efficiency among the species tested.

Two new species of nematode-trapping fungi: relationships inferred from morphology, rDNA and protein gene sequence analyses

Two new nematode-trapping fungi, Dactylellina sichuanensis and D. varietas from China, which capture nematodes by both adhesive knobs and non-constricting rings, are described and illustrated. D. sichuanensis is characterized by both adhesive knobs and non-constricting rings, solitary conidiophores and 3-(4)-6 septate conidia, as compared with species such as D. appendiculata, D. candida, D. leptospora and D. lysipaga. Although D. sichuanensis shares similar types of trapping devices, the presence of simple conidiophores and spindle-shaped conidia with these species, it can be distinguished by its larger conidia and presence of more than four septa. In D. sichuanensis, a single conidium is born at the tip of conidiophore, while in D. candida, 3–10 conidia are born near the apex of conidiophore in a capitate arrangement. It produces spindle-shaped conidia with 3–6 septa, whereas D. leptospora produces cylindrical-shaped conidia with 5–15 septa. D. appendiculata captures nematodes by adhesive knobs whereas D. sichuanensis captures nematodes by both adhesive knobs and non-constricting rings. They also differ in conidial size (35–82.5 μm in D. sichuanensis as compared with 57–108 μm in D. appendiculata). D. varietas is characterized by conidiophores that are branched at right-angles, and elongate to fusoid conidia, with 7–8 septa (more than 25% of which are curved). D. varietas resembles D. asthenopaga, Dactylella oxyspora and Monacrosporium multiseptatum, but has elongate-fusoid conidia, whereas D. asthenopaga possesses obconical or clavate conidia. D. varietas forms both adhesive knobs and non-constricting rings whereas Dactylella oxyspora does not produce any trapping device. M. multiseptatum differs from D. varietas in having larger conidia with an inflated middle cell. Phylogenetic analyses based on nuclear and protein coding DNA sequences (18 S, and a combined 28 S + 5.8 S + β-tubulin dataset) indicate that these two taxa should be assigned to the family Orbiliaceae.

Suppression of an Entomopathogenic Nematode by the Nematode-Trapping Fungi Geniculifera paucispora and Monacrosporium eudermatum as Affected by the Fungus Arthrobotrys oligospora

In soils of a coastal shrubland, nematode- trapping fungi may influence the distribution of the entomopathogenic nematode, Heterorhabditis hepi- alus. In previous studies with shrubland soil, Arthro- botrys oligospora was the most common fungus, fol- lowed by Monacrosporium eudermatum and Geniculi- fera paucispora, and all three fungi suppressed H. he- pialus when tested individually in soil microcosms. Because shrubland soil usually contained multiple species of nematode-trapping fungi, and especially A. oligospora, we quantified nematode suppression by combinations of A. oligospora and G. paucispora or M. eudermatum. Fungi were added in the form of fungal-colonized nematodes to pasteurized soil, and nematode suppression was measured by comparing nematode invasion of wax moth larvae. Suppression of H. hepialus tended to be less in mixed treatments with A. oligospora than in treatments with G. paucis- pora or M. eudermatum alone. Population densities of M. eudermatum and G. paucispora were less in the presence than in the absence of A. oligospora. In con- trast, A. oligospora population density was unaffected or possibly enhanced by the other fungi.

Suppression of an entomopathogenic nematode by the nematode-trapping fungi Geniculifera paucispora and Monacrosporium eudermatum as affected by the fungus Arthrobotrys oligospora

In soils of a coastal shrubland, nematode-trapping fungi may influence the distribution of the entomopathogenic nematode, Heterorhabditis hepialus. In previous studies with shrubland soil, Arthrobotrys oligospora was the most common fungus, followed by Monacrosporium eudermatum and Geniculifera paucispora, and all three fungi suppressed H. hepialus when tested individually in soil microcosms. Because shrubland soil usually contained multiple species of nematode-trapping fungi, and especially A. oligospora, we quantified nematode suppression by combinations of A. oligospora and G. paucispora or M. eudermatum. Fungi were added in the form of fungal-colonized nematodes to pasteurized soil, and nematode suppression was measured by comparing nematode invasion of wax moth larvae. Suppression of H. hepialus tended to be less in mixed treatments with A. oligospora than in treatments with G. paucispora or M. eudermatum alone. Population densities of M. eudermatum and G. paucispora were less in the presence than in the absence of A. oligospora. In contrast, A. oligospora population density was unaffected or possibly enhanced by the other fungi.

Role of amino acids, peptides, and medium composition in trap formation by nematode-trapping fungi

The influence of 22 amino acids and 12 peptides on trap formation by four species of nematode-trapping fungi was determined on a low-nutrient medium (LNM) and cornmeal agar (CMA). Only Arthrobotrys conoides could be induced to form traps in the presence of the amino acids or peptides, while A. flagrans, Monacrosporium eudermatum, and M. rutgeriensis were not induced by the amino acids and peptides studied. Trap formation was greater in the presence of the more nutrient rich CMA than on the LNM. On the LNM, asparagine and aspartic acid were the most active amino acids in inducing traps, while aspartic acid, valine, and phenylalanine were most active on CMA. With respect to the peptides, those containing valine, phenylalanine, and aspartic acid induced the most traps, with valine-containing peptides being especially active on both the LNM and CMA.

Binding Characteristics of Lectins Involved in the Trapping of Nematodes by Fungi

Seventeen saccharides were tested for their ability to bind to the trap lectins of three species of nematode-trapping fungi and prevent nematode capture. The lectin of Arthrobotrys conoides was found to be inhibited by alpha-d-glucose/d-mannose and similar saccharides. The lectins of Monacrosporium eudermatum and Monacrosporium rutgeriensis were inhibited by alpha-l-fucose and 2-deoxy-d-glucose, respectively. Human group O(H) erythrocytes agglutinated to traps of M. eudermatum but not A. conoides or M. rutgeriensis. There was no agglutination of group A or B to traps formed by all three fungi. Exposure of the traps to trypsin eliminated the ability to capture nematodes. The presence of d-glucose/d-mannose and l-fucose residues on the nematode cuticle was suggested through the use of commercially prepared lectin-peroxidase conjugates.

Influence of Cadmium, Zinc, and Lead on Growth, Trap Formation, and Collagenase Activity of Nematode-Trapping Fungi

Growth and morphogenesis of seven species of nematode-trapping fungi and the activity of a collagenase produced by Arthrobotrys amerospora were measured in the presence of various concentrations of divalent cadmium, zinc, or lead. In general, growth varied with species and was dependent on the metal present and the concentration at which it was tested. Cadmium was found to exhibit the greatest toxicity followed by zinc and lead, respectively. In most cases, inhibition of growth was directly correlated with a decreased capacity to form traps. However, in a few cases, trap formation was inhibited either more or less than was growth. The activity of the collagenase was less sensitive than was growth or trap formation to heavy-metal inhibition.

Nematode–Trapping Fungi from a Tussock Grassland Soil in New Zealand

Abstract Six species of nematode-trapping fungi are reported from 14 isolations made from 30 soil samples of a tussock grassland soil in New Zealand. Two species, Harposporium lilliputanum Dixon and Monacrosporium parvicollis Drechsler, arc recorded for the first time in New Zealand. The morphology and disease cycle of H. lilliputanum are described and illustrated

Effect of Nematode-Trapping Fungi, Media, and Temperature On the Morphometrics of Aphelenchus Avenae

The parthenogenic nematode, Aphelenchus avenae, was maintained with four species of nematode-trapping fungi on three different media at four temperatures for 7 days. De Man's procedures were utilized for the measurement of nematodes and the data were analyzed statistically. The data suggested that the culture variables in the study accounted for more of the variability in 'V' than did the other measures. The 'V' values were considered the best taxonomic parameter for identification of A, avenae in the present study.