EFE-Mediated Ethylene Synthesis Is the Major Pathway in the Citrus Postharvest Pathogen Penicillium digitatum during Fruit Infection

Case report: Rare pulmonary fungal infection caused by Penicillium digitatum: the first clinical report in China

Penicillium digitatum is a common plant pathogen that causes citrus rot, which is extremely rare in humans. We report a case of a 66-year-old man with a history of consuming large amounts of citrus fruits, smoking for 30 years, and a history of emphysema. He had experienced intermittent coughing with sputum for more than 10 years and was admitted to the hospital due to worsening of symptoms over the past month. Despite antibiotic treatment, his condition did not improve. Subsequently, bronchoalveolar lavage fluid (BALF) was detected by metagenomic next-generation sequencing (mNGS), which showed the presence of P. digitatum. The fungal culture of BALF also indicated the presence of the Penicillium genus. The diagnosis was lung infection caused by P. digitatum, and the patient was treated with itraconazole. The lung infection was controlled. This is the third reported case of invasive pulmonary fungal infection caused by P. digitatum worldwide at the genus level, and the first reported case in China. Although human infections caused by P. digitatum are rare, as an emerging opportunistic pathogen, the detection of this fungus in immunocompromised patients should still be clinically important.

Metabolomics approach to understand molecular mechanisms involved in fungal pathogen-citrus pathosystems

Citrus is a crucial crop with a significant economic impact globally. However, postharvest decay caused by fungal pathogens poses a considerable threat, leading to substantial financial losses. Penicillium digitatum, Penicillium italicum, Geotrichum citri-aurantii and Phyllosticta citricarpa are the main fungal pathogens, causing green mold, blue mold, sour rot and citrus black spot diseases, respectively. The use of chemical fungicides as a control strategy in citrus raises concerns about food and environmental safety. Therefore, understanding the molecular basis of host-pathogen interactions is essential to find safer alternatives. This review highlights the potential of the metabolomics approach in the search for bioactive compounds involved in the pathogen-citrus interaction, and how the integration of metabolomics and genomics contributes to the understanding of secondary metabolites associated with fungal virulence and the fungal infection mechanisms. Our goal is to provide a pipeline combining metabolomics and genomics that can effectively guide researchers to perform studies aiming to contribute to the understanding of the fundamental chemical and biochemical aspects of pathogen-host interactions, in order to effectively develop new alternatives for fungal diseases in citrus cultivation. We intend to inspire the scientific community to question unexplored biological systems, and to employ diverse analytical approaches and metabolomics techniques to address outstanding questions about the non-studied pathosystems from a chemical biology perspective.

Penicillium digitatum, First Clinical Report in Chile: Fungal Co-Infection in COVID-19 Patient

Penicillium digitatum is one of the most important phytopathogens. It causes deterioration and rotting of citrus fruits, generating significant economic losses worldwide. As a human pathogen, it is extremely rare. We present a case of pulmonary co-infection in a patient diagnosed with pneumonia due to SARS-CoV-2. A 20-year-old female patient, primigravid, 36 weeks of gestation, without comorbidities, and diagnosed with severe pneumonia due to the SARS-CoV-2, showed rapid lung deterioration for which their pregnancy was interrupted by surgery. The patient was hospitalized in the Intensive Care Unit (ICU), connected to mechanical ventilation and receiving corticosteroids and antibiotics. The diagnosis of pulmonary fungal infection was made through bronchoalveolar lavage (BAL) culture, and the species identification was performed by sequencing of β-tubulin. Phylogenetic analysis with related species was performed for the confirmation of species identification. Antifungal susceptibility tests were performed for itraconazole (4 µg/mL), voriconazole (2 µg/mL), and amphotericin B (2 µg/mL). The patient was successfully treated with itraconazole. This is the second worldwide report of pulmonary infection by P. digitatum and the first in Chile. Although it is a fungus that rarely infects humans, it could represent an emerging opportunistic fungal pathogen, with associated risk factors that should be considered in the differential diagnosis of Penicillium species isolated from infections in humans.

Action mechanisms of small microbial volatile compounds in plants

Microorganisms communicate with plants by exchanging chemical signals throughout the phytosphere. Before direct contact with plants occurs, beneficial microorganisms emit a plethora of volatile compounds that promote plant growth and photosynthesis as well as developmental, metabolic, transcriptional, and proteomic changes in plants. These compounds can also induce systemic drought tolerance and improve water and nutrient acquisition. Recent studies have shown that this capacity is not restricted to beneficial microbes; it also extends to phytopathogens. Plant responses to microbial volatile compounds have frequently been associated with volatile organic compounds with molecular masses ranging between ~ 45Da and 300Da. However, microorganisms also release a limited number of volatile compounds with molecular masses of less than ~45Da that react with proteins and/or act as signaling molecules. Some of these compounds promote photosynthesis and growth when exogenously applied in low concentrations. Recently, evidence has shown that small volatile compounds are important determinants of plant responses to microbial volatile emissions. However, the regulatory mechanisms involved in these responses remain poorly understood. This review summarizes current knowledge of biochemical and molecular mechanisms involved in plant growth, development, and metabolic responses to small microbial volatile compounds.