In silico analysis of the biodiversity of endophytic fungi isolated from the Brazilian Cerrado / Análise in silico da biodiversidade de fungos endofíticos isolados do Cerrado brasileiro

Abstract Endophytic microorganisms are those that inhabit the interior of plant tissues and organs without causing damage to the plant, triggering a mutualistic interaction. These endophytes are known to produce compounds with various applications in the areas of biotechnology, pharmaceutical industry and agriculture; therefore, molecular methods are used to investigate the phylogeny of these organisms. The Brazilian Cerrado is the second largest biome in Brazil and is considered a hotspot, with a high diversity of endemic fauna and flora. The objective of this work was to analyze, through in silico analysis, the phylogeny of cultivable endophytic fungi isolated from plants found in the Brazilian Cerrado biome. A search was carried out for articles that worked with endophytes in the period between 2012 and 2022. The dendrogram was generated using the Neighbor-joining method based on the ITS1-5.8S-ITS2 conserved region obtained by GenBank codes of isolated endophytes. The genera Xylaria, Diaporthe, and Colletotrichum were isolated in more than three plants in the seven articles found. Most of the articles found related to the biodiversity of endophytic fungi from the Brazilian Cerrado aim at the bioprospecting of bioactive compounds, through culture-dependent methods; as such, a part of endophytic diversity may be lost due to the inability of certain endophytes to grow in artificial media. In silico analysis can assist in the investigation of phylogenetic relationships between endophytic fungi and has the potential to guide future work aimed at prospecting for bioactive compounds, phylogenetic identification, or biodiversity of this group of endophytes.

Resumo Microrganismos endofíticos são aqueles que vivem no interior de tecidos e órgãos vegetais sem causar dano à planta, desencadeando uma interação mutualística. Esses endófitos são conhecidos por produzir compostos com diversas aplicações nas áreas de biotecnologia, indústria farmacêutica e agricultura; logo, métodos moleculares são utilizados para investigar a filogenia destes organismos. O Cerrado brasileiro é o segundo maior bioma do Brasil e é considerado um hotspot, com uma alta diversidade de fauna e flora endêmica. O objetivo deste trabalho foi analisar, por meio da análise in silico, a filogenia de fungos endofíticos cultiváveis isolados de plantas encontradas no bioma Cerrado brasileiro. Foi realizada uma busca por artigos que trabalharam com endófitos no período entre 2012 e 2022. O dendrograma foi gerado usando o método Neighbor-joining baseado na região conservada ITS1-5.8S-ITS2 obtida pelos códigos GenBank de endófitos isolados. Os gêneros Xylaria, Diaporthe e Colletotrichum foram isolados em mais de três plantas nos sete artigos encontrados. A maior parte dos artigos encontrados relacionados à biodiversidade de fungos endofíticos do Cerrado brasileiro visam à bioprospecção de compostos bioativos, através de métodos dependentes de cultura; como tal, uma parte da diversidade endofítica pode ser perdida devido à incapacidade de certos endófitos crescerem em meios artificiais. A análise in silico pode auxiliar na investigação das relações filogenéticas entre fungos endofíticos e tem potencial para orientar trabalhos futuros voltados à prospecção de compostos bioativos, identificação filogenética ou biodiversidade deste grupo de endófitos.

Toxicity of ß-(1→3, 1→6)-á´ -glucans produced by Diaporthe sp. endophytes on Metarhizium anisopliae (Metschnikoff) Sorokin assessed by conidia germination speed parameter / Toxicidade de ß- (1 → 3, 1 → 6) -á´ -glucanas produzidas por endófitos Diaporthe sp. sobre Metarhizium anisopliae (Metschnikoff) Sorokin avaliada pelo parâmetro de velocidade de germinação dos conídios

We have previously reported that ß-(1→3,1→6)-ᴅ-glucans produced by endophytes Diaporthe sp. G27-60 and G65-65 (GenBank accession codes JF766998 and JF767007, respectively) are promising anti-proliferation agents against human breast carcinoma (MCF-7) and hepatocellular carcinoma (HepG2-C3A) cells. However, the literature fails to describe the effects of Diaporthe exopolysaccharides (EPS) on eukaryotic healthy cells. The fungus Metarhiziumanisopliae has been employed as model-system to evaluate the toxicity of pharmaceutical and agricultural-interest substances, taking into account, among other parameters, the speed of conidia germination. Current study verified the effect of different concentrations of Diaporthe ß-glucans on the germination speed of M. anisopliae. Conidia were incubated with ß-glucans treatments (50, 200 and 400 µg/mL) at 28ºC, sampled during 24 h and analyzed by light microscopy. At the end of a 24-h incubation, the amount of germinated conidia reached ≈99% for controls and ranged between 97.7 and 98.6% for treatments. Bayesian analysis indicated that Diaporthe glucans had no toxicity on M. anisopliaeand the curve of germination occurred as expected for this fungal strain. Considering the validity of filamentous fungi as model-systems, results are important data on the toxicity of endophytic EPS on healthy cells and may be associated with our previous results obtained for these polymers against tumor cells.

Anteriormente, um estudo mostrou que ß-(1→3,1→6)-ᴅ-glucanas produzidas pelos endófitos Diaporthe sp. G27-60 e G65-65 (códigos de acesso no GenBank JF766998 e JF767007, respectivamente) são agentes promissores com ação antiproliferativa contra células HepG2-C3A (hepatoma humano) e MCF-7 (adenocarcinoma mamário humano). No entanto, os efeitos de exopolissacarídeos (EPS) produzidos por fungos do gênero Diaporthe em células eucarióticas sadias não estão descritos na literatura atual. O fungo Metarhiziumanisopliae tem sido utilizado como sistema-modelo para avaliar a toxicidade de substâncias de interesse farmacêutico e agronômico, considerando, entre outros parâmetros, a velocidade de germinação de conídios. O presente estudo teve como objetivo verificar os efeitos de diferentes concentrações de ß-glucanas produzidas por Diaporthe sp. sobre a velocidade de germinação de M. anisopliae. Os conídios foram incubados com os tratamentos de ß-glucanas (50, 200 e 400 µg/mL) a 28 ºC, com amostras coletadas ao longo de 24 h, e analisados por microscopia de luz. Ao final das 24 h de incubação, o total de conídios germinados nos controles foi de ≈99%, e variou entre 97,7 e 98,6% para os tratamentos. A análise bayesiana indicou que as glucanas de Diaporthe sp. não apresentaram toxicidade sobre M. anisopliae, e a curva de germinação atendeu ao esperado para essa linhagem fúngica. Considerando a validade dos fungos filamentosos como sistemas-modelo, esses resultados representam dados importantes sobre a toxicidade dos EPS de endófitos sobre células sadias e podem ser associados aos resultados anteriormente obtidos para esses polímeros em testes contra células tumorais.

Antifungal and proteolytic activities of endophytic fungi isolated from Piper hispidum Sw

Endophytes are being considered for use in biological control, and the enzymes they secrete might facilitate their initial colonization of internal plant tissues and direct interactions with microbial pathogens. Microbial proteases are also biotechnologically important products employed in bioremediation processes, cosmetics, and the pharmaceutical, photographic and food industries. In the present study, we evaluated antagonism and competitive interactions between 98 fungal endophytes and Alternaria alternata, Colletotrichum sp., Phyllosticta citricarpa and Moniliophthora perniciosa. We also examined the proteolytic activities of endophytes grown in liquid medium and conducted cup plate assays. The results showed that certain strains in the assemblage of P. hispidum endophytes are important sources of antifungal properties, primarily Lasiodiplodia theobromae JF766989, which reduced phytopathogen growth by approximately 54 to 65%. We detected 28 endophytes producing enzymatic halos of up to 16.40 mm in diameter. The results obtained in the present study highlight the proteolytic activity of the endophytes Phoma herbarum JF766995 and Schizophyllum commune JF766994, which presented the highest enzymatic halo diameters under at least one culture condition tested. The increased activities of certain isolates in the presence of rice or soy flour as a substrate (with halos up to 17.67 mm in diameter) suggests that these endophytes have the potential to produce enzymes using agricultural wastes.