Maria Fernanda Ratti

Root-knot nematodes of the genus Meloidogyne are among the most destructive endoparasitic nematodes due to their ability to infect a wide range of agriculturally important crops. In this context, nematode-trapping fungi have been widely recognized for their potential as biological control agents against plant-parasitic nematodes. In the present study, the nematode-trapping fungus Arthrobotrys thaumasius was isolated from roots soils of banana plants (Musa spp.) in the canton of Guayaquil, Guayas Province, Ecuador. Four strains were obtained and identified based on sequence analyses of molecular markers. In addition, the in vitro growth and sporulation of the isolates were evaluated, with cornmeal agar and oat agar proving to be the most suitable culture media. Three A. thaumasius isolates exhibited attraction and capture rates exceeding 65% against second-stage juveniles (J2) of Meloidogyne. This study represents the first report of the isolation and characterization of A. thaumasius in Ecuador and demonstrates that isolates HN-20, HN-21, and HN-24 have high potential as biological control agents, positioning them as promising candidates for the sustainable management of root-knot diseases caused by Meloidogyne spp.

Antarctica’s extreme cryospheric conditions impose severe thermodynamic constraints on the natural attenuation of hydrocarbon pollutants. Despite the Antarctic Treaty System’s protections, the footprint of human logistics has left persistent reservoirs of petroleum hydrocarbons that threaten endemic biodiversity. This review critically synthesizes the state-of-the-art in Antarctic bioremediation, moving beyond traditional culture-dependent studies to integrate recent multi-omics breakthroughs (2020–2025). We analyze the molecular mechanisms limiting bioavailability in frozen soils and highlight the adaptive strategies of psychrophilic consortia, including the modification of membrane fluidity and the expression of cold-active enzymes (e.g., RHDs, AlkB). Notably, we discuss emerging findings on novel long-chain alkane degradation genes (almA, ladA) identified in 2025, which challenge previous assumptions about recalcitrance. Furthermore, the review evaluates the engineering bottlenecks of in situ versus ex situ strategies, emphasizing the synergistic potential of bacterial–fungal co-cultures and the ecological necessity of “climate-smart” remediation to mitigate methane emissions from thawing permafrost. By bridging the gap between fundamental microbial genetics and applied field engineering, we propose a roadmap for the next generation of biotechnological solutions in the warming polar environment.

Parasitic nematodes in crops are a serious threat in worldwide agricultural production. The concerns regarding the environmental and toxicological risks associated with the usage of chemical substances encourage the pursuit of more environmentally friendly alternatives to control phytopathogenic nematodes. It's been considered viable to employ biological control agents, like bacteria, which besides having mechanisms that can control nematodes are also growth promoters for plants. This review's goal is to broaden the comprehension over bacterial agent mechanisms to suppress nematodes population and its phosphorus solubilization capability. Bacteria have antagonist interactions capable of producing metabolites, increasing the systemic resistance to plants and space competition. Chemical compounds produced by bacteria can mineralize organic phosphorus from the soil and supply it for plant adsorption. Rhizospheric bacteria have synergic action to improve growth and plant protection. This review's approach aims to contribute to the understanding of rhizobacterial potential, which dual action in vegetative growth and as nematophagus agents, makes them key tools for a sustainable management of phytopathogenic nematodes. This perspective opens the possibility to include these microorganisms and their metabolites in innovative plans for agricultural management, which can respond to productivity demand and climate change challenges.

La Antártida, continente que presenta uno de los ambientes más hostiles del planeta, alberga una alta biodiversidad de microorganismos que pueden ser una fuente potencial de recursos biotecnológicos, incluidos aquellos que pueden solubilizar fósforo y promover el crecimiento vegetal. El objetivo de esta investigación fue caracterizar molecularmente bacterias de la Antártida colectadas de suelo y organismos fotosintéticos durante el verano Antártico de 2023, y evaluar su efecto en la detección de sideróforos y solubilización de fosfato tricálcico en condiciones de laboratorio. Además, se indagó su efecto en la germinación de semillas de fréjol Phaseolus vulgaris L. Las bacterias aisladas pertenecieron a los géneros Pseudomonas, Sporosarcina, Sphingomonas, Arthrobacter y Moraxella. El 73% de las bacterias estudiadas poseen capacidad de producir sideróforos, y las cepas fueron capaces de solubilizar fosfato tricálcico en medio de agar Pikovskaya, siendo Arthrobacter la bacteria que presentó mejores resultados. estas bacterias promovieron el enraizamiento de P. vulgaris L. Estos resultados respaldan la posible producción y aplicación de biofertilizantes tolerantes al frío para contribuir al desarrollo de una agricultura sostenible en zonas altas.

Phytophthora cactorum is the most common causal agent of Phytophthora crown rot and leather rot of strawberry, but P. nicotianae is also responsible for the disease in Florida. Studies of P. nicotianae populations have suggested that different groups of genotypes are associated with different hosts; however, it is not yet clear how many lineages exist globally and how they are related to different production systems. The aim of this study was to determine the genetic relationships of P. nicotianae isolates from Florida strawberry with genotypes reported from other hosts, quantify the genetic variation on strawberry, and test for an association with nursery source. A total of 49 isolates of P. nicotianae were collected from strawberry plants originating from multiple nursery sources during six seasons of commercial fruit production in Florida. Microsatellite genotyping identified 28 multilocus genotypes on strawberry that were distinct among 208 isolates originating from various hosts and locations. Based on STRUCTURE analysis, two genetic groups were identified: one consisting of isolates from strawberry, and the other comprising samples from different hosts. Multilocus genotypes were shared among nursery sources, and populations defined by nursery were not differentiated. Both mating types were found among the isolates from North Carolina- and California-origin plants and in most strawberry seasons; however, a predominance of A1 was observed, and regular sexual reproduction was not supported by the data. This study reveals a unique genetic population of P. nicotianae associated with strawberry and emphasizes the vital role of nursery monitoring in mitigating disease spread.

Phytopathogenic nematodes are a threat for agriculture, they cause plant diseases and economic losses worldwide. Currently, the pursuit of compounds of biological origin for nematode biocontrol has become a priority as an environmentally friendly alternative. Microorganisms-derived compounds have several strategies to reduce the populations of infectious juvenile nematodes. Although microorganisms and their metabolites are the focus of literature reports reviews on nematicidal control, interactions between fungi, bacteria, and nematodes, as well as the compounds that are generated in such interactions, are not highlighted. The aim of this review was to discuss the latest advances on chemical compounds secreted by microorganisms and their interaction mechanisms for biological control of phytopathogenic nematodes. Results were organized based on: i) mode of action, ii) infection process, iii) nematicide compounds, iv) interactions and field applications, and v) current challenges. The scope of this review contributes to a better comprehension of the versatility of bacterial and fungal compounds for their use in the development of management plans for nematode control.

Root-knot nematodes are detrimental to agricultural crops and hard to control once established in the field. The objective of this research was to evaluate the growth, sporulation, and capture in vitro of asexual fungi against Meloidogyne sp. Molecular identification of the asexual fungi included in the study was performed by sequencing the ITS1 region of rDNA. The growth and sporulation of Arthrobotrys sp., Dactylellina sp. and Dactylaria sp. was evaluated in five culture media and two types of substrates (rice husks and ground corn). For the evaluation of attraction and capture of the nematodes, second stage juveniles of Meloidogyne sp. All the evaluated fungal isolates grew and sporulated in the culture media and substrates. The fungi Arthrobotrys sp. (C19-1-1) and Dactylellina sp. (C19-48) showed greater effectiveness in attracting and capturing Meloidogyne sp. The evaluated fungal isolates have the potential to colonize different culture media and substrates. In addition, they can form modified and specialized hyphae that control juvenile Meloidogyne sp. nematodes. Therefore, future studies should focus on evaluating fungal isolates against root-knot nematodes under field conditions.

Nematophagous fungi (NF) are a group of diverse fungal genera that benefit plants. The aim of this review is to increase comprehension about the importance of nematophagous fungi and their role in phosphorus solubilization to favor its uptake in agricultural ecosystems. They use different mechanisms, such as acidification in the medium, organic acids production, and the secretion of enzymes and metabolites that promote the bioavailability of phosphorus for plants. This study summarizes the processes of solubilization, in addition to the mechanisms of action and use of NF on crops, evidencing the need to include innovative alternatives for the implementation of microbial resources in management plans. In addition, it provides information to help understand the effect of NF to make phosphorus available for plants, showing how these biological means promote phosphorus uptake, thus improving productivity and yield.

Mecanismos de captura, colonización y alimentación empleados por parásitos y predadores de nematodos. Los organismos del suelo tienen un papel fundamental en la estructura y ciclo de nutrientes en los ecosistemas; especialmente los nematodos que son abundantes y funcionalmente diversos. Debido a que algunos taxones de nematodos causan enfermedades a las plantas, la mayoría de los estudios tienen un enfoque agrícola, por tanto, es de relevancia ecológica conocer los diferentes grupos de organismos de suelo que los consumen o parasitan. El propósito de esta revisión es discutir sobre los mecanismos de captura, colonización o alimentación que ejercen los enemigos naturales de los nematodos, especialmente los predadores y parásitos, tales como bacterias, hongos, nematodos, microartrópodos y tardígrados. Algunas bacterias que se encuentran en la rizosfera sintetizan moléculas tóxicas que matan a los nematodos mientras que los hongos nematófagos pueden ser predadores, endoparásitos, parásitos de huevos, productores de toxinas y presentar dispositivos especiales para la captura de sus presas. Además, los nematodos predadores presentan tres mecanismos de alimentación: las especies del orden Mononchida cortan a sus presas o las consumen enteras, las del orden Diplogasterida cortan y succionan los contenidos y finalmente las de los ordenes Dorylaimida y Aphelenchida emplean un estilete para perforar y succionar. En el caso de los microartrópodos, los colémbolos emplean sus maxilares y los ácaros sus quelíceros para agarrar, triturar y masticar, mientras que los tardígrados pueden devorar nematodos enteros. Conocer las estrategias de los parásitos y predadores de nematodos complementa la investigación en patógenos de importancia agrícola y contribuye a la comprensión de la complejidad de las redes tróficas del suelo.

In recent years, new data on the diversity of genera and species in the phylum Glomeromycota continue to be added and rearranged. Arbuscular mycorrhizal fungi are key to plant nutrition and agriculture. Studies report different short- and long-term cultivation practices that influence the abundance and diversity of Glomeromycota. To the best of our knowledge, there are no known studies of the fungal communities in the fine aroma cocoa cultivars. In this context, our work aims to discover the diversity of arbuscular mycorrhizae associated with two cocoa cultivation practices (conservative and semi-conservative) through the isolation of spores using microscopy and metabarcoding of the internal transcribed spacer region (ITS). Morphological analysis showed that the density of Glomeromycota spores exhibited significant differences between production systems. Although the metabarcoding analysis showed that diversity indices showed a higher increase in the roots than in the cocoa soil, independently of the cultivation practice. An abundance of 348 and 114 taxa were observed, corresponding to the conservative and semi-conservative practices, respectively. Seven genera were observed for the first time in cocoa crop agroforestry systems, including P. scintillans, R. diaphanus, R. fasciculatus, R. custos, D. disticha, M. perpusilla, and D. bernensis.