Biology subjects

Abreo, E.

Publications and source records attributed to Abreo, E..

6 recordsLinked to original sources

bioRxiv2025

Biocontrol of Calonectria causing root rot in Eucalyptus

Calonectria spp. are among the most important pathogens affecting Eucalyptus production, causing severe root rot and significant losses in nurseries. In this study, we established a collection of locally isolated strains of Trichoderma spp. and Bacillus spp., complemented with commercial formulations, to evaluate their potential as biocontrol agents (BCAs) against Calonectria. Leaf bating in vitro assays were conducted using naturally colonized, non-sterilized substrates to closely simulate nursery conditions. Several locally isolated Trichoderma strains (T3, T5, T6, and T7), as well as two commercial products (PC1 and PC2), consistently reduced the incidence of Calonectria infection, indicating their capacity to decrease pathogen inoculum levels in the substrate. The reproducibility of these effects across independent trials underscores the robustness of Trichoderma as reliable BCAs. Altogether, these findings highlight the potential of locally isolated Trichoderma strains as promising alternatives for managing Calonectria root rot in Eucalyptus nurseries, while reinforcing the need for further trials under commercial greenhouse conditions to confirm their efficacy in real production systems.

microbiology↗

bioRxiv2025

From omics to enhanced fungal virulence: Overexpression of a putative secreted protein improves Beauveria bassiana biocontrol potential against the insect pests Piezodorus guildinii and Tenebrio molitor

The entomopathogenic fungus Beauveria bassiana is widely used as a biocontrol agent, but its efficacy varies depending on the target insect species. Piezodorus guildinii, a major soybean pest, exhibits low susceptibility to B. bassiana. Thus, biocontrol of this pest requires improving virulence of B. bassiana. Here, we used genomic and transcriptomic analyses to identify novel genes associated with the enhanced virulence of B. bassiana strain ILB308 when exposed to the insect epicuticular hydrocarbon n-pentadecane. Comparative analysis with the lower-virulence strain ILB205 revealed differentially expressed genes (DEGs) linked to genetic information process pathways and immune evasion. Among these DEGs, we identified BbCBM9_1, a secreted carbohydrate-binding protein, as a candidate virulence factor. Overexpression of BbCBM9_1 in ILB205 led to enhanced virulence against P. guildinii and Tenebrio molitor, as well as improved conidial germination, tolerance to oxidative and cell wall stress, and increased growth in nutrient-rich and glycerol-supplemented media. This demonstrates that the enhanced virulence observed in ILB308 grown on n-pentadecane can be replicated by overexpressing an associated gene in a low-virulence strain. Our study, highlights the potential of integrating transcriptomics and targeted genetic modifications to optimize fungal biocontrol agents for improved pest management.

microbiology↗

bioRxiv2024

Priestia megaterium ILBB592 based biofertilizer increases the efficiency of phosphorus fertilization, positively affects soybean nutrition and yield and modifies the rhizospheric bacterial community

Phosphorus (P) is needed by soybean plants to form vital molecules like ATP and nucleotides and perform plant functions like photosynthesis and Nitrogen biological fixation at nodules. Because P concentration in the soil solution is naturally low, P fertilization is applied to satisfy soybean requirements in high yielding crops. However, a small portion of added P is readily available to the plants, while most is retained by the soil matrix and eventually made available or lost through erosion and run-off to water bodies, where it promotes eutrophication. Therefore, technologies that enhance P uptake by crops could lead to lower P inputs and outputs from soybean cropping systems, improving sustainability. Priestia megaterium ILBB592 and Bacillus pumilus ILBB44 are two PGPR with P mobilization features that were single formulated as biofertilizers and co-inoculated with Bradyrhizobium elkanii on seeds of soybean Genesis 5602 in two consecutive years in the field, with and without P fertilization. Co-inoculation with ILBB592 improved plant P uptake, along with N and K, with and without P fertilization. Diversity was increased by co-inoculation with ILBB44 and ILBB592, and predicted genes related with P cycling in the rhizospheric soils were also augmented after co-inoculation with ILBB592, mostly with P fertilization. Shoot dry weight and yield were also improved although effect on yield was not statistically significant. P fertilization alone had no effect in the first year but showed some effect on nodules dry weight, P uptake and yield on the second year, suggesting a sufficient P level was obtained after repeated fertilizations. ILBB592 biofertilizer showed a positive effect on most plant parameters, including nodulation and P uptake in both years and both P fertilization regimes and is therefore considered as a useful technology to reduce P fertilization without jeopardizing plant performance.

microbiology↗

bioRxiv2024

Novel genomic features in entomopathogenic fungus Beauveria bassiana: supernumerary chromosomes and putative virulence genes involved in the infection process of soybean pest Piezodorus guildinii.

Biological control methods involving entomopathogenic fungi like Beauveria bassiana have shown to be a valuable approach in integrated pest management as an environmentally friendly alternative to control pests and pathogens. Identifying genetic determinants of pathogenicity in B. bassiana is instrumental for enhancing its virulence against insects like the resistant soybean pest Piezodorus guildinii. This study focused on comparative genomics of different B. bassiana strains and gene expression analyses to identify virulence genes in the hypervirulent strain ILB308, especially in response to infection of P. guildniii and growth on hydrocarbon HC15, a known virulence enhancer. Strain ILB308 showed the highest number of virulence-related features, such as candidate virulence proteins, effectors, small secreted proteins, and biosynthetic gene clusters. ILB308 also had a high percentage of unique DNA sequences, including six putative supernumerary scaffolds. Gene expression analysis at 4 days post-inoculation revealed upregulation of known virulence factors, including Tudor domain proteins, LysM motif-containing proteins, and subtilisin-like proteases, and novel genes like secreted effectors and heat-labile enterotoxins. Growth on HC15 led to the upregulation of genes associated with oxidoreductase activity related to cuticular alkane degradation and fermentation metabolism/antioxidant responses in the hemolymph. The presence of supernumerary chromosomes and unique virulence genes in ILB308 may contribute to its higher virulence and could be considered as potential targets for enhancing fungal virulence through genetic manipulation. Author SummaryUnderstanding mechanisms of virulence and virulence enhancement in Beauveria bassiana can lay the basis for the development of improved biocontrol agents. Here we used genomic and transcriptomic approaches to study the infection process of ILB308 -an hypervirulent strain- against insect pest Piezodorus guildinii. We found that this strain has putative supernumerary chromosomes and an enriched set of presumed virulence proteins like secreted effectors. We infer that the particular assortment of strain specific genes and supernumerary chromosome/s play a role in the degree of virulence exhibited by ILB308 and could be used for future strain improvement strategies.

genomics↗

bioRxiv2023

Phenotypic and genomic characterization of Bacillus sensu lato for their biofertilization effect and plant growth promotion features in soybean plants

Bacillus sensu lato were screened for their capacity to mineralize organic phosphorus (P) and promote plant growth, improving nitrogen (N) and phosphorus nutrition of soybean plants. Isolates were first identified based on their genomic sequences through TYGS and ANII. ILBB95, ILBB510 and ILBB592 were identified as Priestia megaterium, ILBB139 as Bacillus wiedmannii, ILBB44 as a member of a sister clade of B. pumilus (together with a human pathogenic strain), ILBB15 as Peribacillus butanolivorans and ILBB64 as Lysinibacillus sp. These strains were evaluated for their capacity to mineralize organic P as sodium phytate and solubilize inorganic P forms in liquid medium. These in vitro assays allowed the strains to be ranked according to their P mobilization potential, with ILBB15 and ILBB64 showing the highest orthophosphate production from phytate, ILBB592 the lowest and ILBB510 nil. In addition, features related to their rhizocompetence and plant growth promotion were evaluated in vitro and in silico. Finally, plant bioassays were deployed to assess the effect of the co-inoculation of Bacillus s.l. strains and rhizobial inoculant on nodulation, plant growth and nutrition. In planta bioassays showed that B. pumilus ILBB44 and P. megaterium ILBB95 increased P absorbed in plants grown on a poor substrate of sand and vermiculite and also on the richer mix of sand, vermiculite and peat. Priestia megaterium ILBB592 increased rhizobial nodulation and N content in plants grown on sand, vermiculite and peat mixture only. ILBB15 reduced plant growth and nutrition on both substrates. Genomes of ILBB95 and ILBB592 were characterized by genes related with plant growth and biofertilization whereas ILBB15 was differentiated by genes related to bioremediation. Priestia megaterium ILBB592 can be described as nodule-enhancing rhizobacteria (NER) and together with ILBB95, can be envisaged as prospective PGPR with the capacity to exert a positive effect on N and P nutrition of soybean plants.

microbiology↗

bioRxiv2021

Alkane-priming of Beauveria bassiana strains to improve biocontrol of the redbanded stink bug Piezodorus guildinii and the bronze bug Thaumastocoris peregrinus

Insect Epicuticle hydrocarbons (CHC) are known to be important determinants in the susceptibility degree of insects to fungal entomopathogens. Five Beauveria bassiana isolates were phenotypically analyzed regarding their response to CHC nutrition and their pathogenicity and virulence towards high fungal-susceptible Thaumastocoris peregrinus and low fungal-susceptible Piezodorus guildinii, which are important hemipteran pests in eucalyptus and soybean plantations, respectively. Two of these isolates, resulting the most (ILBB308) and the least (ILBB299) virulent to P. guildinii, were also evaluated at gene expression level after growth on n-pentadecane. B. bassiana most virulent isolate ILBB308 showed the lowest growth on most evaluated CHC media. However, this isolate distinctively induced most of the analyzed genes involved in CHC assimilation, cuticle degradation and stress tolerance. Virulence towards low susceptibility P. guildinii was enhanced in both hypervirulent ILB308 and hypovirulent ILBB299 isolates after growth on n-pentadecane as the sole carbon source, whereas virulence enhancement towards high susceptibility T. peregrinus was not observed in alkane-grown fungi. Virulence enhancement towards P. guildinii could be mostly explained by a priming effect produced by CHC on the induction of some genes related to hydrocarbon assimilation in ILB 205 and ILB 308, such as hydrophobin (Bbhyd2) and cytochrome P450 genes (BbCyp52g11 and BbCyp52x1), and partially by the induction of genes related to cuticle degradation (Bbchit and Bbcdep1) and stress tolerance (Bbsod1) observed only in ILB308.

microbiology↗