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

Karl-Magnus Andersson,Dharmendra Kumar,Dag Ahrén,Eva Friman,Johan Bentzer,Anders Tunlid

doi:10.1186/1471-2164-15-968

Karl-Magnus Andersson, Dharmendra Kumar + Show 4 more

Open Access

https://doi.org/10.1186/1471-2164-15-968

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Abstract

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.

Highlights

Nematode-trapping fungi are soil-living fungi that capture and kill nematodes using special hyphal structures called traps
Infection experiments The nematodes M. hapla or H. schachtii were added to plates containing the nematode-trapping fungi A. oligospora, M. cionopagum or A. dactyloides and the infection was followed under a light microscope (Figure 1)
The PHI-base genes that differ in Conclusions This is the first study examining the variation in gene expression patterns among nematode-trapping fungi during infection of different host species

Summary

Introduction

Nematode-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. The traps of the nematode-trapping fungi develop from hyphae and can be formed spontaneously or be induced in response to signals from the environment [3] There is a these studies have shown that the nematode-trapping fungi have evolved along two major lineages: one basal lineage leading to species with constricting rings and one lineage containing species that form adhesive traps, including three-dimensional networks, knobs and branches [5,6,7,8]. Following the trapping of nematodes, the infection mechanisms appear to be rather similar in the species with constricting rings and adhesive traps: the fungus forms a penetration tube that pierces the nematode cuticle. The internal tissues are rapidly colonized and digested by fungal hyphae [13]

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