Characterization of Penicillium Species by Ribosomal DNA Sequencing and BOX, ERIC and REP-PCR Analysis

Exploring the Diversity and Ecological Dynamics of Palm Leaf Spotting Fungi-A Case Study on Ornamental Palms in Portugal

Palm trees (Arecaceae) are among the most popular ornamental plants worldwide. Despite extensive research on the fungi associated with Arecaceae, the diversity and ecological dynamics of fungi affecting ornamental palms remain poorly studied, although they have significant impact on palm health and economic value. Furthermore, while research on palm fungal diversity has traditionally focused on tropical assemblages, ornamental palms in temperate climates offer a unique opportunity to explore the diversity of palm fungi in non-native habitats. The present study conducted a preliminary assessment of the diversity and ecology of potential phytopathogenic fungi associated with foliar lesions on various ornamental palm host species in Portugal, combining morphological examination, PCR-based genomic fingerprinting, and biodiversity data analysis. The examination of 134 foliar lesions sampled from 100 palm trees resulted in a collection of 2064 palm leaf spotting fungi (PLSF), representing a diverse fungal assemblage of 320 molecular operational taxonomic units (MOTUs) across 97 genera. The overall fungal community composition revealed a distinct assemblage dominated by Neosetophoma, Alternaria, Phoma, and Cladosporium, with a profusion of infrequent and rare taxa consistent with a logseries distribution. Significantly positive co-occurrence (CO) patterns among prevalent and uncommon taxa suggest potential synergistic interactions enhancing fungal colonisation, persistence, and pathogenicity. The taxonomic structures of the PLSF contrasted markedly from tropical palm fungi, especially in the prevalence of pleosporalean coelomycetes of the Didymellaceae and Phaeosphaeriaceae, including recently introduced or not previously documented genera on Arecaceae. This novel assemblage suggests that climatic constraints shape the structure of palm fungal communities, resulting in distinctive temperate and tropical assemblages. In addition, the fungal assemblages varied significantly across palm host species, with temperate-native palms hosting more diverse, coelomycete-enriched communities. The present findings highlight foliar lesions as hyperdiverse microhabitats harbouring fungal communities with intricate interactions and a complex interplay of climatic, host, and ecological factors. With climate change altering environmental conditions, the identification of fungi thriving in or inhabiting these microhabitats becomes crucial for predicting shifts in pathogen dynamics and mitigating future fungal disease outbreaks. Understanding these complex ecological dynamics is essential for identifying potential phytopathogenic threats and developing effective management strategies for the health and sustainability of ornamental plants.

Analysis of Whole-Genome for Identification of Seven Penicillium Species with Significant Economic Value

The Penicillium genus exhibits a broad global distribution and holds substantial economic value in sectors including agriculture, industry, and medicine. Particularly in agriculture, Penicillium species significantly impact plants, causing diseases and contamination that adversely affect crop yields and quality. Timely detection of Penicillium species is crucial for controlling disease and preventing mycotoxins from entering the food chain. To tackle this issue, we implement a novel species identification approach called Analysis of whole GEnome (AGE). Here, we initially applied bioinformatics analysis to construct specific target sequence libraries from the whole genomes of seven Penicillium species with significant economic impact: P. canescens, P. citrinum, P. oxalicum, P. polonicum, P. paneum, P. rubens, and P. roqueforti. We successfully identified seven Penicillium species using the target we screened combined with Sanger sequencing and CRISPR-Cas12a technologies. Notably, based on CRISPR-Cas12a technology, AGE can achieve rapid and accurate identification of genomic DNA samples at a concentration as low as 0.01 ng/µL within 30 min. This method features high sensitivity and portability, making it suitable for on-site detection. This robust molecular approach provides precise fungal species identification with broad implications for agricultural control, industrial production, clinical diagnostics, and food safety.

Evaluation of MALDI-TOF MS, sequencing of D2 LSU rRNA and internal transcribed spacer regions (ITS) for the identification of filamentous fungi isolated from a pharmaceutical facility

The identification of filamentous fungi through culture characterization may be hampered by phenotypic variability. Information obtained from the identification of microorganisms are important for investigation of sources of contamination of a product or process. The aim of this study was to identify filamentous fungal strains (n = 50) isolated from a pharmaceutical facility by using Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), as well as D2 domain of the large-subunit (LSU) ribosomal RNA gene and internal transcribed spacer regions (ITS) sequencing. MALDI-TOF MS system only identified five strains at the species level, while 45 were not identified. The analysis through GenBank allowed the identification of up to 19 strains at the species level, while MycoBank allowed the identification of up to nine strains at the species level. The databases identified up to 11 genera: Penicillium, Aspergillus, Cladosporium, Chaetomium, Coniochaeta, Curvularia, Diaporthe, Fusarium, Trichoderma, Rhizopus and Microdochium. MALDI-TOF MS showed an insufficient database to identify the species of fungi. DNA sequencing was the best methodology to identify to the genus level but was unable to differentiate between closely related species. Therefore further methods for the identification of filamentous fungi from pharmaceutical areas at species level need to be developed.

Dispersion, persistence, and stability of the biocontrol agent Penicillium frequentans strain 909 after stone fruit tree applications

The capacity of dispersion, persistence, and stability from biocontrol agents is essential before these organisms can be developed into a commercial product. Interactions that microorganisms establish with stone fruit trees may be beneficial in the exploitation of trees in agriculture as crop production. The natural background levels of Penicillium frequentans strain 909 dispersion, persistence, and stability were assessed after tree applications and postharvest conditions. A fingerprinting-based approach to trace genetic stability of P. frequentans along stored time and its release in the field was developed. P. frequentans was successfully traced and discriminated. This strain was dispersed well in treated trees, persisting in the ecosystem up to 2 weeks and staying genetically stable after 36 months of storage. However, the dispersal of P. frequentans was very limited on around untreated trees and soil. P. frequentans dispersed randomly into the air, and its presence reduced from the first day to disappear completely at 15-21 days after application. Great losses of P. frequentans and its increased dispersal in open field conditions probably resulted from rainfall. Biological control strategies with Pf909 were discussed.

The development of genetic and molecular markers to register and commercialize Penicillium rubens (formerly Penicillium oxalicum) strain 212 as a biocontrol agent

Penicillium oxalicum strain 212 (PO212) is an effective biocontrol agent (BCA) against a large number of economically important fungal plant pathogens. For successful registration as a BCA in Europe, PO212 must be accurately identified. In this report, we describe the use of classical genetic and molecular markers to characterize and identify PO212 in order to understand its ecological role in the environment or host. We successfully generated pyrimidine (pyr-) auxotrophic mutants. In addition we also designed specific oligonucleotides for the pyrF gene at their untranslated regions for rapid and reliable identification and classification of strains of P. oxalicum and P. rubens, formerly P. chrysogenum. Using these DNA-based technologies, we found that PO212 is a strain of P. rubens, and is not a strain of P. oxalicum. This work presents PO212 as the unique P. rubens strain to be described as a BCA and the information contained here serves for its registration and commercialization in Europe.

Mating type genes and genetic markers to decipher intraspecific variability among Fusarium udum isolates from pigeonpea

To ascertain the variability in Fusarium udum (Fu) isolates associated with pigeonpea wilt is a difficult task, if based solely on morphological and cultural characters. In this respect, the robustness of five different genetic marker viz., random amplified polymorphic DNA (RAPD), enterobacterial repetitive intergenic consensus (ERIC), BOX elements, mating type locus, and microsatellite markers were employed to decipher intra-specific variability in Fu isolates. All techniques yielded intra-specific polymorphism, but different levels of discrimination were obtained. RAPD-PCR was more discriminatory, enabling the detection of thirteen variants among twenty Fu isolates. By microsatellite, ERIC- and BOX-PCR fingerprinting, the isolates were categorized in seven, five, and two clusters, respectively. Cluster analysis of the combined data also showed that the Fu isolates were grouped into ten clusters, sharing 50-100% similarity. The occurrence of both mating types in Fu isolates is reported for the first time in this study. All examined isolates harbored one of the two mating-type idiomorphs, but never both, which suggests a heterothallic mating system of sexual reproduction among them. Information obtained from comparing results of different molecular marker systems should be useful to organize the genetic variability and ideally, will improve disease management practices by identifying sources of inoculum and isolate characteristics.

Efficiency of rep-PCR fingerprinting as a useful technique for molecular typing of plant pathogenic fungal species: Botryosphaeriaceae species as a case study

Progress in molecular biology and the advent of rapid and accurate molecular techniques have contributed to precise and rapid detection and differentiation of microbial pathogens. Identification of the Botryosphaeriaceae species based on morphology has been problematic over time. In this study, we used rep-PCR technique as a molecular tool for typing and differentiation of the Botryosphaeriaceae species, well-known and cosmopolitan fungal pathogens on woody plants. Three primer sets BOX, ERIC and REP were used to differentiate 27 species belong to eight genera. The majority of them were examined in terms of typing and differentiation using molecular methods for the first time. All the primer sets were able to generate species-specific DNA fingerprints from all the tested strains, with two exceptions in the genera Diplodia and Spencermartinsia. Despite the deficiency of each primer sets to separate a few species, cluster analysis of combined data sets indicated the ability of rep-PCR technique to separate 26 out of 27 examined species in highly supported clusters corresponded to the species recognized based on DNA sequence data. Our findings revealed the efficiency of rep-PCR for detection and differentiation of the Botryosphaeriaceae species, especially cryptic species with the same ITS sequences and similar morphology.

WITHDRAWN: Molecular characterization of mango anthracnose pathogen Colletotrichum gloeosporioides sensu lato

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Genetic diversity of Cercospora kikuchii isolates from soybean cultured in Argentina as revealed by molecular markers and cercosporin production

Leaf blight and purple seed, caused by the fungal pathogen Cercospora kikuchii (Matsumoto & Tomoyasu) M. W. Gardner are very important diseases of soybean (Glycine max L. Merr.) in Argentina. The aims of this work were: (a) to confirm and to assess the genetic variability among C. kikuchii isolates collected from different soybean growing areas in Santa Fe province using inter simple sequence repeats (ISSR) markers and sequence information from the internal transcribed spacer (ITS) region of rDNA and (b) to analyze the cercosporin production of the regional C. kikuchi isolates in order to assess whether there was any relationship between the molecular profiles and the toxin production. Isolates from different regions in Santa Fe province were studied. The sequence of the ITS regions showed high similarity (99-100%) to the GenBank sequences of C. kikuchii BRCK179 (accession number AY633838). The ISSR markers clustered all the isolates into many groups and cercosporin content was highly variable among isolates. No relationship was observed between ITS region, ISSR groups and origin or cercosporin content. The high degree of genetic variability and cercosporin production among isolates compared in this study characterizes a diverse population of C. kikuchii in the region.