Here, we analyzed the effects on Capsicum annuum plants of Trichoderma atroviride P. Karst strains altered in the expression of SWOLLENIN (SWO1), a protein with amorphogenic activity on plant cell wall components. Strains of T. atroviride that overexpressed the Taswo1 gene were constructed as well as deletion mutants. A novel, cheap and accurate method for assessing root colonization was developed. Colonization assays showed that the Taswo1 overexpressing strains invaded the host root better than the WT, resulting in a stronger plant growth-promoting effect. The expression of plant defense marker genes for both the systemic acquired resistance and induced systemic resistance pathways was enhanced in plants inoculated with Taswo1 overexpressing strains, while inoculation with deletion mutant strains resulted in a similar level of expression to that observed upon inoculation with the wild-type strain. Response to pathogen infection was also enhanced in the plants inoculated with the Taswo1 overexpressing strains, and surprisingly, an intermediate level of protection was achieved with the mutant strains. Tolerance to abiotic stresses was also higher in plants inoculated with the Taswo1 overexpressing strains but was similar in plants inoculated with the wild-type or the mutant strains. Compatible osmolyte production in drought conditions was studied. This study may contribute to improving Trichoderma biocontrol and biofertilization abilities.

White-rot fungi are efficient lignin degraders due to the secretion of lignin peroxidase, manganese peroxidase, laccase, and versatile peroxidase (VP) on decayed wood. The VP is a high-redox-potential enzyme and could be used to detoxify reactive oxygen species (ROS), which accumulate in plants during biotic and abiotic stresses. We cloned the VP gene and expressed it via the Agrobacterium transformation procedure in transgenic tobacco plants to assay their tolerance to different abiotic stress conditions. Thirty independent T₂ transgenic VP lines overexpressing the fungal Bjerkandera adustaVP gene were selected on kanamycin. The VP22, VP24, and VP27 lines showed significant manganese peroxidase (MnP) activity. The highest was VP22, which showed 10.87-fold more manganese peroxidase activity than the wild-type plants and led to a 34% increase in plant height and 28% more biomass. The VP22, VP24, and VP27 lines showed enhanced tolerance to drought, 200 mM NaCl, and 400 mM sorbitol. Also, these transgenics displayed significant tolerance to methyl viologen, an active oxygen-generating compound. The present data indicate that overproducing the VP gene in plants increases significantly their biomass and the abiotic stress tolerance. The VP enzyme is an effective biotechnological tool to protect organisms against ROS. In transgenic tobacco plants, it improves drought, salt, and oxidative stress tolerance. Thus, the VP gene represents a great potential for obtaining stress-tolerant crops.

Large-scale mining activities generate significant amounts of waste that accumulates in the environment. These wastes, known as mine tailings, contain high levels of heavy metals, posing risks to human health and causing severe damage to ecosystems. In this study, we determined the heavy metal content of mine tailings in the Sierra de Huautla Biosphere Reserve (REBIOSH), Mexico, and investigated their effect on microbial composition. One of the sites historically contaminated with metals was sampled in three different locations, labeled S1, S2, and S3. A fourth site free of heavy metals (S4) was also used as a control. Our results showed high levels of As, Pb, Cd, and Ag, potentially dangerous metals that exceed thresholds set by international regulatory agencies. Metal contamination indices indicated moderate to extreme enrichment for As, Cd, and Pb, posing potential ecological risks. A metagenomic study of mine tailings showed a core specie-specific microbiome covered by Sinimarinibacterium flocculans, Jiangella anatolica, Thiobacillus denitrificans, Fontimonas thermophile, Sphingomonas koreensis. These may be associated with the processing of heavy metals. A comparative study using the ALDEx2 revealed that less represented species like Variovorax paradoxus, Usitatibacter rugosus, Usitatibacter palustris, Sphingosinicella microcystinivorans, Sphingobium yanoikuyae, and Stella humosa may serve as microbial markers in metal-contaminated environments. In addition, we detected rare or low-abundance species belonging to the phylum Armatimonadota, Candidatus Melainobacteriota, Candidatus Saccharimonadota, Chlamydiota, Deinococcota, Elusimicrobiota, Bacillota, Rhodothermota and Verrucomicrobiota, which could play an important role in ecosystems contaminated with heavy metals. Also, we found site-specific taxonomic representatives such as Nitrososphaera gargensis and Nitrospira nitrificans dominating the S3 ecosystem; Ensifer aridi (S2 and S1), N. nitrificans (S2), while Reyranella soli dominate the S1 soil. These organisms could be crucial for nitrogen access in oligotrophic environments and underscore the adaptability of microbial life to extreme conditions. This is the first comprehensive study of the microbial composition in this important ecological site of the Mexican geography and can provide future guidance for the management and biological treatment of mining wastes.

The Capsicum genus has significant economic importance since it is cultivated and consumed worldwide for its flavor and pungent properties. In 2021, Mexico produced 3.3 billion tons on 45,000 hectares which yielded USD 2 billion in exports to the USA, Canada, Japan, etc. Soil type has a dramatic effect on phosphorus (P) availability for plants due to its ion retention. In a previous study, novel fungal isolates were shown to solubilize and mineralize P in different kinds of soils with different P retention capacities. The aim of this work was to study the effects of the mineralogy of different kinds of “milpa” soils on the germination, biomass production, and P absorption of chili plants (Capsicum annuum). The germination percentage, the germination speed index, and the mean germination time were significantly increased in the plants treated with dual inoculation. Foliar phosphorus, growth variables, and plant biomass of chili plants grown in a greenhouse were enhanced in different soil types and with different inocula. Correlation studies suggested that the most significant performance in the foliar P concentration and in the growth response of plants was achieved in Vertisol with dual inoculation of 7 × 10⁶ mL⁻¹ spores per chili plant, suggesting this would be an appropriate approach to enhance chili cultivation depending on the soil type. This study stresses the importance of careful analysis of the effect of the soil type in the plant–microbe interactions.

The human milk microbiota (HMM) of healthy women can vary substantially, as demonstrated by recent advances in DNA sequencing technology. However, the method used to extract genomic DNA (gDNA) from these samples may impact the observed variations and potentially bias the microbiological reconstruction. Therefore, it is important to use a DNA extraction method that is able to effectively isolate gDNA from a diverse range of microorganisms. In this study, we improved and compared a DNA extraction method for gDNA isolation from human milk (HM) samples to commercial and standard protocols. We evaluated the extracted gDNA using spectrophotometric measurements, gel electrophoresis, and PCR amplifications to assess its quantity, quality, and amplifiability. Additionally, we tested the improved method’s ability to isolate amplifiable gDNA from fungi, Gram-positive and Gram-negative bacteria to validate its potential for reconstructing microbiological profiles. The improved DNA extraction method resulted in a higher quality and quantity of the extracted gDNA compared to the commercial and standard protocols and allowed for polymerase chain reaction (PCR) amplification of the V3–V4 regions of the 16S ribosomal gene in all the samples and the ITS-1 region of the fungal 18S ribosomal gene in 95% of the samples. These results suggest that the improved DNA extraction method demonstrates better performance for gDNA extraction from complex samples such as HM.

Fungi use oxylipins (oxidized lipids) as signaling molecules to induce asexual development. These molecules play an essential role in the response to wounding, exerting a protective effect against plant pathogens, and are part of the inflammatory process in animals. However, the physiological and molecular mechanisms triggered by oxylipins that lead to asexual development in fungi are not well understood. Using a genetic approach, mass spectrometry, and phenotypic analysis, we describe the functional role of a patatin-like phospholipase ( plp1 ) and a unique lipoxygenase ( lox1 ) in the response to injury in the model fungus Trichoderma atroviride. lox1 and plp1 are co-expressed and regulated by damage signaling and sensing components. Phenotypic analysis revealed an essential defect in the emergence of aerial hyphae in the lox1 and plp1 null mutant strains, blocking injury-induced conidiation. In addition, functional loss analysis demonstrated that both genes are essential for wound-associated linoleic acid-derived oxylipin 13-hydroxy-9Z,11E-octadecadienoic acid (13-HODE) production and the transcriptional reprogramming required for conidiation. T. atroviride requires LOX1 and PLP1 to induce transcription factors involved in asexual development such as brlA , hox2 , and azf1 homologs at the early stages of the response and at a later stage to activate lipid metabolism and the structural proteins involved in aerial mycelium emergence. Our study shows how the cooperative function of lox1 and plp1 , during the response to wounding, regulates the molecular and physiological processes of damaged-sensitized cells that lead to reproductive aerial mycelium development and consequently, ensure survival through asexual reproduction. IMPORTANCE: In addition to being considered a biocontrol agent, the fungus Trichoderma atroviride is a relevant model for studying mechanisms of response to injury conserved in plants and animals that opens a new landscape in relation to regeneration and cell differentiation mechanisms. Here, we reveal the co-functionality of a lipoxygenase and a patatin-like phospholipase co-expressed in response to wounding in fungi. This pair of enzymes produces oxidized lipids that can function as signaling molecules or oxidative stress signals that, in ascomycetes, induce asexual development. Furthermore, we determined that both genes participate in the regulation of the synthesis of 13-HODE and the establishment of the physiological responses necessary for the formation of reproductive aerial mycelium ultimately leading to asexual development. Our results suggest an injury-induced pathway to produce oxylipins and uncovered physiological mechanisms regulated by LOX1 and PLP1 to induce conidiation, opening new hypotheses for the novo regeneration mechanisms of filamentous fungi.