Plant diseases caused by phytopathogens are responsible for significant crop losses worldwide. Resistance induction and biological control have been exploited in agriculture due to their enormous potential. In this study, we investigated the antimicrobial potential of endophytic fungi of leaves and petioles of medicinal plants Vochysia divergens and Stryphnodendron adstringens located in two regions of high diversity in Brazil, Pantanal, and Cerrado, respectively. We recovered 1,304 fungal isolates and based on the characteristics of the culture, were assigned to 159 phenotypes. One isolate was selected as representative of each phenotype and studied for antimicrobial activity against phytopathogens. Isolates with better biological activities were identified based on DNA sequences and phylogenetic analyzes. Among the 159 representative isolates, extracts from 12 endophytes that inhibited the mycelial growth (IG) of Colletotrichum abscissum (≥40%) were selected to expand the antimicrobial analysis. The minimum inhibitory concentrations (MIC) of the extracts were determined against citrus pathogens, C. abscissum, Phyllosticta citricarpa and Xanthomonas citri subsp. citri and the maize pathogen Fusarium graminearum. The highest activity against C. abscissum were from extracts of Pseudofusicoccum stromaticum CMRP4328 (IG: 83% and MIC: 40 μg/mL) and Diaporthe vochysiae CMRP4322 (IG: 75% and MIC: 1 μg/mL), both extracts also inhibited the development of post-bloom fruit drop symptoms in citrus flowers. The extracts were promising in inhibiting the mycelial growth of P. citricarpa and reducing the production of pycnidia in citrus leaves. Among the isolates that showed activity, the genus Diaporthe was the most common, including the new species D. cerradensis described in this study. In addition, high performance liquid chromatography, UV detection, and mass spectrometry and thin layer chromatography analyzes of extracts produced by endophytes that showed high activity, indicated D. vochysiae CMRP4322 and P. stromaticum CMRP4328 as promising strains that produce new bioactive natural products. We report here the capacity of endophytic fungi of medicinal plants to produce secondary metabolites with biological activities against phytopathogenic fungi and bacteria. The description of the new species D. cerradensis, reinforces the ability of medicinal plants found in Brazil to host a diverse group of fungi with biotechnological potential.
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This work was supported by the INCT Citrus CNPq 465440/2014-2 Brazil and CNPq grant 309971/2016-0 and 424738/2016-3 to CG, CAPES-Brazil – grant to JI, and FAPESP 2015/50162-2 – grant to HF. This work was also supported by National Institutes of Health grants R01 CA243529, R01 GM115261, the Center of Biomedical Research Excellence (COBRE) in Pharmaceutical Research and Innovation (CPRI, NIH P20 GM130456), the University Professorship in Pharmacy (to JR), the University of Kentucky College of Pharmacy and the National Center for Advancing Translational Sciences (UL1TR000117 and UL1TR001998).
The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: [Diaporthe cerradensis MB#839350 – (https://www.mycobank.org/)].
Iantas, Jucélia; Savi, Daiani Cristina; da Silva Schibelbein, Renata; Noriler, Sandriele Aparecida; Assad, Beatriz Marques; Dilarri, Guilherme; Ferreira, Henrique; Rohr, Jürgen; Thorson, Jon S.; Shaaban, Khaled A.; and Glienke, Chirlei, "Endophytes of Brazilian Medicinal Plants with Activity against Phytopathogens" (2021). Pharmaceutical Sciences Faculty Publications. 173.