Understanding the Transcriptional Changes During Infection of Meloidogyne incognita Eggs by the Egg-Parasitic Fungus Purpureocillium lilacinum

The egg-pathogenic fungus Purpureocillium lilacinum parasitizes on nematode eggs, and thus, it is used as a good biocontrol agent against plant root-knot nematodes. However, little is known about the transcriptional response of P. lilacinum while infecting nematode eggs. This study presents the whole transcriptome sequencing of P. lilacinum and transcriptome-wide gene expression analysis of P. lilacinum upon infecting the eggs of Meloidogyne incognita compared to non-infecting controls. A transcriptomic library of P. lilacinum was used as reference gene set and six transcriptomic libraries of the non-infecting control and P. lilacinum infecting M. incognita eggs were constructed, respectively, comprising three biological replicates of each. A total of 1,011 differently expressed genes (DEGs) were identified in the infecting samples, including 553 up-regulated and 458 down-regulated genes compared to the non-infecting control samples. Furthermore, functional enrichment analysis exhibited that these DEGs were primarily involved in oxidative phosphorylation, oxidoreductase activity, and metabolic processes. Fifteen DEGs were randomly selected to verify the RNA sequencing results through quantitative real-time polymerase chain reaction (qPCR). The study focused on P. lilacinum genes that were strongly expressed upon infecting M. incognita eggs. These DEGs were primarily involved in detoxification, parasitic behavior, and nutritional utilization. This study contributes significantly to the understanding of the molecular mechanisms underlying the parasitic action of P. lilacinum on nematode eggs and provides a valuable genetic resource for further research on parasitic behavior of P. lilacinum. Notably, this study examined the transcriptomics of P. lilacinum infecting M. incognita eggs at only one time point. Since there were fungi at different stages of the infection process at that time point, the transcriptional profiles are not precisely examining one specific stage in this process.

Characterization of the complete mitochondrial genome of the nematophagous fungus Purpureocillium lavendulum

The complete mitochondrial genome of Purpureocillium lavendulum was characterized in this study. This mitogenome is a closed circular molecule of 23,567 bp in length with a GC content of 28.46%, including 15 protein-coding genes, 25 transfer RNA genes, 2 ribosomal RNA genes. Phylogenetic analyses based on sequences at the 14 concatenated mitochondrial protein-coding genes showed that P. lavendulum was closely related to Hirsutella minnesotensis.

Effect of silver nanoparticles (AgNP's) from Duddingtonia flagrans on cyathostomins larvae (subfamily: cyathostominae)

The in vitro effect of silver nanoparticles of the Duddingtonia flagrans filtrate enriched with chitin was evaluated on infective larvae of cyathostomins (L₃). After biosynthesis, an assay was carried out with two experimental groups in microtubes, for a period of 24 h: G1 (AgNP's-D. flagrans (43.4 μg/mL) + 120 L₃) and G2 (distilled water + 120 L₃). At the end of this period, AgNP's-D. flagrans (G1) demonstrated an effect on L₃ with a 43% reduction (p < 0.01) in relation to G2. Thus, the authors suggest new designs with AgNP's-D. flagrans for the control of cyathostomins.

First report of the nematicidal activity of Flammulina velutipes, its spent mushroom compost and metabolites

The aim of the present work was to evaluate the nematicidal potential of Flammulina velutipes and its spent mushroom compost. Additionally, the nematicidal activity of enzymes and metabolites was analyzed. Isolated F. velutipes and its SMC had significant nematicidal effect on Panagrellus sp. larvae. The percentages of reduction in relation to the control group were: 69, 57.5 and 70% for SMC and 56, 24.5 and 26.6% for the isolated fungus, for 24, 48 and 72 h, respectively. The active SMC crude extract showed nematicidal action with reduction percentages of 43 and 57% for 24 and 48 h of incubation, respectively. The boiled crude extract also showed nematicidal action, however, the reduction percentages were lower than those of the active extract. This demonstrated that the nematicidal action was due to enzyme activities and other metabolites. The results demonstrated that SMC, the isolated fungus, the crude extract and the boiled crude extract showed a significant percentage of reduction on Panagrellus sp. larvae. SMC evidenced a higher nematicidal activity than the isolated fungus. In addition, nematophagous activity of F. velutipes was observed for the first time.

Colonization and destruction of ants of the genus Camponotus sp. (Hymenoptera: Formicidae) in vitro by the fungus Pochonia chlamydosporia in the southeast region of Brazil

The objective of this study was to evaluate, in vitro, the colonization and destruction of ants of the genus Camponotus sp. by the ovicidal fungus Pochonia chlamydosporia (VC4 isolate), in the southeast region of Brazil. The insects used in the experiment were worker ants of the genus Camponotus sp., collected periodically in the environment and immediately transported to the laboratory in test tubes. Then, VC4 growth was promoted in 2% chitin agar medium (2% WQ) to obtain a fungal solution containing conidia and/or chlamydospores. Two experimental groups were formed. Treated group consisted of Petri dishes containing 2% agar-water culture medium (2% WA) with nine live insects and 20 µL of fungal solution at the concentration of 15,000 conidia/chlamydospores. Control group consisted of Petri dishes containing 2% WA culture medium and nine live insects. The dishes in the treated and control groups were incubated in BOD at 25 ± 1 °C and 80 ± 10% relative humidity for 4 days. After 4 days, it was observed that the VC4 had grown, colonized, and caused the destruction of the ants. The fungus P. chlamydosporia was efficient at colonizing and destroying the urban ants collected on an experimental basis. Thus, it could open up new ways to reduce the use of chemical compounds in the future, decreasing health and environmental problems.

Sequencing and functional analysis of the genome of a nematode egg-parasitic fungus, Pochonia chlamydosporia

Pochonia chlamydosporia is a worldwide-distributed soil fungus with a great capacity to infect and destroy the eggs and kill females of plant-parasitic nematodes. Additionally, it has the ability to colonize endophytically roots of economically-important crop plants, thereby promoting their growth and eliciting plant defenses. This multitrophic behavior makes P. chlamydosporia a potentially useful tool for sustainable agriculture approaches. We sequenced and assembled ∼41 Mb of P. chlamydosporia genomic DNA and predicted 12,122 gene models, of which many were homologous to genes of fungal pathogens of invertebrates and fungal plant pathogens. Predicted genes (65%) were functionally annotated according to Gene Ontology, and 16% of them found to share homology with genes in the Pathogen Host Interactions (PHI) database. The genome of this fungus is highly enriched in genes encoding hydrolytic enzymes, such as proteases, glycoside hydrolases and carbohydrate esterases. We used RNA-Seq technology in order to identify the genes expressed during endophytic behavior of P. chlamydosporia when colonizing barley roots. Functional annotation of these genes showed that hydrolytic enzymes and transporters are expressed during endophytism. This structural and functional analysis of the P. chlamydosporia genome provides a starting point for understanding the molecular mechanisms involved in the multitrophic lifestyle of this fungus. The genomic information provided here should also prove useful for enhancing the capabilities of this fungus as a biocontrol agent of plant-parasitic nematodes and as a plant growth-promoting organism.