Pestalotiopsis Microspora Research Articles

Complete genome sequence analysis of Pestalotiopsis microspora, a fungal pathogen causing kiwifruit postharvest rots

BackgroundThe postharvest rot of kiwifruit is one of the most devastating diseases affecting kiwifruit quality worldwide. However, the genomic basis and pathogenicity mechanisms of kiwifruit rot pathogens are lacking. Here we report the first whole genome sequence of Pestalotiopsis microspora, one of the main pathogens causing postharvest kiwifruit rot in China. The genome of strain KFRD-2 was sequenced, de novo assembled, and analyzed.ResultsThe genome of KFRD-2 was estimated to be approximately 50.31 Mb in size, with an overall GC content of 50.25%. Among 14,711 predicted genes, 14,423 (98.04%) exhibited significant matches to genes in the NCBI nr database. A phylogenetic analysis of 26 known pathogenic fungi, including P. microspora KFRD-2, based on conserved orthologous genes, revealed that KFRD-2’s closest evolutionary relationships were to Neopestalotiopsis spp. Among KFRD-2’s coding genes, 870 putative CAZy genes spanned six classes of CAZys, which play roles in degrading plant cell walls. Out of the 25 other plant pathogenic fungi, P. microspora possessed a greater number of CAZy genes than 22 and was especially enriched in GH and AA genes. A total of 845 transcription factors and 86 secondary metabolism gene clusters were predicted, representing various types. Furthermore, 28 effectors and 109 virulence-enhanced factors were identified using the PHI (pathogen host-interacting) database.ConclusionThis complete genome sequence analysis of the kiwifruit postharvest rot pathogen P. microspora enriches our understanding its disease pathogenesis and virulence. This study establishes a theoretical foundation for future investigations into the pathogenic mechanisms of P. microspora and the development of enhanced strategies for the efficient management of kiwifruit postharvest rots.

Exploring Brominated Aromatic Butenolides from Aspergillus terreus EGF7-0-1 with Their Antifungal Activities.

Fungal diseases could severely harm agricultural productions. To develop new antifungal agents, based on the Global Natural Products Social Molecular Networking, typical bromine isotope peak ratios, and ultraviolet absorptions, cultivation of the soft coral-derived endophytic fungi Aspergillus terreus EGF7-0-1 with NaBr led to the targeted isolation of 14 new brominated aromatic butenolides (1-14) and six known analogues (15-20). Their structures were elucidated by extensive spectroscopic analysis and quantum chemical calculations. Compounds 1-14 exhibited wildly antifungal activities (against Colletotrichum gloeosporioides, Pestalotiopsis microspora, Fusarium oxysporum f. sp. cubense, Botrytis cinerea, and Diaporthe phoenicicola). The bioassay results showed that compounds 1-14 exhibited excellent antifungal activities against C. gloeosporioides, with concentration for 50% of maximal effect (EC50) values from 2.72 to 130.41 nM. The mechanistic study suggests that compound 1 may disrupt nutrient signaling pathways by reducing the levels of metabolites, such as carbohydrates, lipids, and amino acids, leading to an increase in low-density granules and a decrease in high-density granules in the cytoplasm, accompanied by numerous vacuoles, thereby inhibiting the growth of C. gloeosporioides. Monobrominated γ-butenolide 1 may be expected to exploit a novel agriculturally antifungal leading drug. Meanwhile, compound M1 has conformed antifugual activities against C. gloeosporioides by papayas in vivo.

Unveiling the anticancer potential of Pestalotioprolide E, an unexplored macrolide: Targeting TRXR1-TRX1-ASK1-P38 signaling cascade in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is highly aggressive and metastatic in nature. Existing treatment modalities for TNBC are associated with severe side effects. Thioredoxin reductase (TRXR), the pivotal component of the thioredoxin system, remains overexpressed in various cancer cells including TNBC; promotes cell growth, proliferation, and metastasis, and inhibits apoptosis. Pestalotioprolide E is one of the potent macrolides, a class of secondary metabolites derived from an endophytic fungus Pestalotiopsis microspora with relatively unexplored biological activities. Our study revealed increased expression and activity of TRXR1 in MDA-MB-231 cells compared to the non-cancerous cells. In silico docking analysis and in vitro activity assay demonstrated that Pestalotioprolide E directly interacts with TRXR1 and inhibits its enzymatic activity. This inhibition induces apoptosis via TRX1/ASK1/P38MAPK death signaling cascade and retards metastasis through modulating VEGF, MMP-2, MMP-9, E-cadherin, N-cadherin in MDA-MB-231 cells. Taken together present study establishes TRXR1 as a molecular target for Pestalotioprolide E and its anticancer effect can be attributed to the inhibition of TRXR1 activity in MDA-MB-231.

Morphotype Analysis of Endophytic Fungus Isolated from Taxus sumatrana of Mount Singgalang, West Sumatra Region

Taxus sp. plants in temperate climates like Europe and America have been extensively studied and identified as promising sources of endophytic microbes that produce anticancer compounds such as Taxol. These endophytic microbes exhibit high adaptability to the specific growing conditions of their host plants. Research has highlighted metabolic differences between tropical and temperate endophytes. The presence of Taxus sumatrana plants in tropical areas like Mount Singgalang in West Sumatra, Indonesia was subjected to explore potential new sources of bioactive compounds from tropical microbes. This research aims to identify the morphotypes of endophytic fungi isolated from the barks of Taxus sumatrana plants originating from Mount Singgalang. The method used is small pieces of the inner bark of Taxus sumatrana were placed on the surface of growth medium (PDA). The small hyphae emerging from the piece of plant samples were regularly monitored for the morphological characteristics of the colony and conidia structure. Each fungal culture was checked for purity and transferred to another PDA plate by the hyphal tip method. The investigation isolated two endophytic fungi from the bark of Taxus sumatrana: Pestalotiopsis microspora and Neopestalotiopsis sp.

Pathogenicity and enzyme screening of some selected non-dermatophytic moulds.

Ten non-dermatophytic moulds isolated from both symptomatic and asymptomatic cattle skin, including Penicillum citrinum, Aspergillus welwitschiae, Aspergillus aculeatus, Curvularia kusanol, Cladosporium teniussmum, Pestalotiopsis microspora, Fusarium oxysporum, Fusarium linchenicola, Absidia sp. and Aspergillus fumigatus, were subjected to a pathogenicity test using albino mice. These isolates were also screened for five enzymes using a standard plate method. Results from pathogenicity tests showed that Absidia sp., Cladosporium tenuissimum and Aspergillus welwitschiae were able to elicit discoloration, lesion production and alopecia on the albino mice skin, respectively, providing evidence of clinical symptoms associated with cutaneous mycoses. The enzyme screening results revealed the highest zone of activity for keratinase (65 mm), amylase (86 mm), protease (60 mm), lipase (60 mm) and cellulase (86 mm) which were observed on Pestalotiopsis microspora, Aspergillus welwitschiae, Cladosporium tenuissimum, Aspergillus welwitschiae and Aspergillus welwitschiae respectively. Pathogenicity tests showed that some of these moulds may be virulent and this can be attributed to their possession of some virulence factors, including secretion of hydrolytic enzymes.

Evaluation and chemical characterization of bioactive secondary metabolites from endophytic fungi associated with the ethnomedicinal plant Bergenia ciliata

Abstract The objective of this work was to assess the bioactive potential of endophytic fungi, Colletotrichum brevisporum (JPSK3), Pestalotiopsis microspora (JPSK19), and Guignardia mangiferae (JPSK25), from Bergenia ciliata. The antibacterial effects were determined by the well diffusion technique against human pathogens (Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Salmonella typhi) and they showed good activities. In the antioxidant assay, the fungal extract P. microspora shows higher free radical scavenging effects in 2,2-diphenyl-1-picrylhydrazyl (82.48%), hydrogen peroxide (84.91%), superoxide (78.85%), and reducing power absorbance of 0.125 at a dosage of 125 g/mL than other two fungi. The fungal extract was also subjected to phenol and flavonoid quantifications. The fungus P. microspora shows the highest phenol (89.56 0.03 mg of GAE/g of extract) and flavonoid (51.52 0.69 mg of quercetin equivalents/g of extract), respectively. The chemical composition of abundant biologically active compounds was determined by gas chromatography-mass spectrophotometry (GC-MS). Furthermore, it was confirmed through spectral and analytical analysis (thin layer chromatography, ultraviolet, Fourier transform infrared spectroscopy, high-performance liquid chromatography, GC-MS, and nuclear magnetic spectroscopy). In P. microspora, the compound phenol, p-tert-butyl (C10H14O), was confirmed for the first time. This fungal compound could be a potential alternative medicine in the future. This is the first work on endophytic fungal studies of ethnomedicinal plant Bergenia ciliata.

Respiratory and energy metabolisms participate in the disease occurrence of fresh Chinese olive caused by Pestalotiopsis microspora

Pestalotiopsis microspora (P. microspore) is the primary pathogen causing postharvest rot and spoilage in Chinese olive (Canarium album L.). This study investigated P. microspore-induced disease development in postharvest Chinese olives in relation to respiratory and energy metabolism. Results suggested that P. microspore-inoculated Chinese olives had higher fruit disease index, fruit disease diameter, and fruit respiration rate, but a lower energy charge. Furthermore, P. microspore-inoculated Chinese olives displayed higher respiratory metabolism-related enzymes (RMREs) activities, higher levels of NAD(H), and lower levels of NADP(H). Additionally, P. microspore-inoculated Chinese olives had lower ATPase activities, as well as lower ATP and ADP contents but higher AMP content. These findings suggest that P. microspore infection exacerbates disease development in postharvest Chinese olives by increasing respiration metabolism and causing energy deficiency.

Soil cadmium stress affects the phyllosphere microbiome and associated pathogen resistance differently in male and female poplars.

Microorganisms associated with the phyllosphere play a crucial role in protecting plants from diseases, and their composition and diversity are strongly influenced by heavy metal contaminants. Dioecious plants are known to exhibit sexual dimorphism in metal accumulation and tolerance between male and female individuals. Hence, in this study we used male and female full-siblings of Populus deltoides to investigate whether the two sexes present differences in their phyllosphere microbiome structures and in their associated resistance to the leaf pathogenic fungus Pestalotiopsis microspora after exposure to excess soil cadmium (Cd). We found that Cd-treated male plants grew better and accumulated more leaf Cd than females. Cd stress reduced the lesion areas on leaves of both sexes after pathogen infection, but male plants exhibited better resistance than females. More importantly, Cd exposure differentially altered the structure and function of the phyllosphere microbiomes between the male and female plants, with more abundant ecologically beneficial microbes and decreased pathogenic fungal taxa harbored by male plants. In vitro toxicity tests suggested that the sexual difference in pathogen resistance could be attribute to both direct Cd toxicity and indirect shifts in the phyllosphere microbiome. This study provides new information relevant for understanding the underlying mechanisms of the effects of heavy metals involved in plant-pathogen interactions.

Identification and characterization of Pestalotiopsis spp. causing leaf spot and leaf blight on jabon (Neolamarckia spp.) in Indonesia

Abstract. Herliyana EN, Oktavianto P, Siregar UJ. 2022. Identification and characterization of Pestalotiopsis spp. causing leaf spot and leaf blight on jabon (Neolamarckia spp.) in Indonesia. Biodiversitas 23: 6547-6556. Jabon (Neolamarckia spp.) is one of the fast-growing trees with high economic value for industrial plantations. Its monoculture planting system is faced with certain problems, such as the leaf spot and leaf blight diseases caused by Pestalotiopsis sp. Therefore, the aim of this research was to describe the morphology of Pestalotiopsis species through macroscopic and microscopic observations, followed by the identification of fungus using DNA barcoding causing leaf spot and leaf blight on the tree. A total of 11 Pestalotiopsis isolates were used for this research. The morphology was identified by observing mycelium colonies and fungal conidia, while DNA barcoding was initiated after DNA isolation using cetyltrimethylammonium bromide (CTAB) method, amplification with ITS 1 and 4 primers, followed by sequencing process. The results of DNA barcoding showed that 5 species of Pestalotiopsis, namely Pseudopestalotiopsis theae, Pestalotiopsis microspora, Pestalotiopsis palmarum, Neopestalotiopsis clavispora, and Pestalotiopsis virgatula were found associated with leaf spot and blight disease. All the five species were further classified into 3 clades using phylogeny according to their median cells and apical appendage shape. The clade X consisted of P. palmarum, N. clavispora, and P. virgatula with versicolorous median cells, whereas clade Y included P. microspora with concolorous median cell, and clade Z consisted Ps. theae with concolorous median cell and knobbed apical appendage.

Chemical Constituents of the Endophytic Fungus Pestalotiopsis microspora Derived from Artemisia argyi and their P-Glycoprotein Inhibitory Activity

Chemical Constituents of the Endophytic Fungus Pestalotiopsis microspora Derived from Artemisia argyi and their P-Glycoprotein Inhibitory Activity

Transcriptomic Analysis to Unravel Potential Pathways and Genes Involved in Pecan (Carya illinoinensis) Resistance to Pestalotiopsis microspora.

Fruit black spot (FBS), a fungal disease of pecan (Carya illinoinensis (Wangenh) K. Koch) caused by the pathogen Pestalotiopsis microspora, is a serious disease and poses a critical threat to pecan yield and quality. However, the details of pecan responses to FBS infection at the transcriptional level remain to be elucidated. In present study, we used RNA-Seq to analyze differential gene expression in three pecan cultivars with varied resistance to FBS infection: Xinxuan-4 (X4), Mahan (M), and Wichita (W), which were categorized as having low, mild, and high susceptibility to FBS, respectively. Nine RNA-Seq libraries were constructed, comprising a total of 58.56 Gb of high-quality bases, and 2420, 4380, and 8754 differentially expressed genes (DEGs) with |log2Fold change| ≥ 1 and p-value < 0.05 were identified between M vs. X4, W vs. M, and W vs. X4, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway analyses were performed to further annotate DEGs that were part of specific pathways, which revealed that out of 134 total pathways, MAPK signaling pathway, plant–pathogen interaction, and plant hormone signal transduction were highly enriched. Transcriptomic profiling analysis revealed that 1681 pathogen-related genes (PRGs), including 24 genes encoding WRKY transcription factors, potentially participate in the process of defense against Pestalotiopsis microspora infection in pecan. The correlation of WRKY TFs and PRGs was also performed to reveal the potential interaction networks among disease-resistance/pathogenesis-related genes and WRKY TFs. Expression profiling of nine genes annotated as TIFY, WRKY TF, and disease-resistance protein-related genes was performed using qRT-PCR, and the results were correlated with RNA-Seq data. This study provides valuable information on the molecular basis of pecan–Pestalotiopsis microspora interaction mechanisms and offers a repertoire of candidate genes related to pecan fruit response to FBS infection.

Bioactive secondary metabolites from two sponge-derived actinomycetes

Actinomycetes residing in marine habitat are an excellent treasure house of structurally novel and bioactive natural products with potent medicinal values. To exploit chemically diverse and bioactive natural products from actinomycetes living in underexplored ecological niche, we isolate a large number of marine actinomycetes from marine sponges, corals, algae, mollusks, sea grasses, and sediments collected from the South China Sea. In order to assess the values of these special marine actinomycetes in the green development of tropical agriculture, we screen the activity of marine actinomycetes against phytopathogenic fungi and bacteria. As a result, we identify two strains of sponge-derived actinobacteria <italic>Streptomyces</italic> sp. HMH1 and HML1 possessing antagonism effect against tested phytopathogenic microbes. The secondary metabolites produced by these two actinomycete strains and their anti-phytopathogenic fungi activity are investigated. The secondary metabolites from the fermentation extract of <italic>Streptomyces</italic> sp. HMH1 and HML1 are isolated and purified using various chromatography methods including silica gel column, reverse gel column and Sephadex LH-20 column chromatography. The structures of the isolated compounds are characterized by NMR, HR-ESI-MS spectroscopic data analyses and comparison with previously reported data. Three major compounds belonging to the family of actinomycin are purified from the solid fermentation extract of the sponge-derived actinobacterium <italic>Streptomyces</italic> sp. HMH1. They actinomycin D, actinomycin X₂, and actinomycin X_oβ. A compound identified as K-252d belonging to the family of indolocarbazole alkaloid is isolated from the solid fermentation extract of another sponge-derived actinobacterium <italic>Streptomyces</italic> sp. HML1. The anti-phytopathogenic fungi and bacteria activities of these compounds are evaluated against ten species of plant pathogenic fungi including <italic>Fusarium oxysporum</italic> FOC4, <italic>Lasiodiplodia theobromae, Phomopsis caricae-papayae</italic> Fetrak&amp;Cif., <italic>Corynespora cassiicola, Phytophthora capsica, Pythium aphanidermatum</italic> (Edson) Fitzp, <italic>Corynespora</italic> sp., <italic>Fusarium graminearum, Verticillium dahlia, Pestalotiopsis microspora</italic>, and two species of plant pathogenic bacteria including <italic>Xanthomonas oryzae</italic> pv. <italic>oryzae</italic> and <italic>Ralstonia solanacearum</italic>. The bioactivity test results of the compound against agricultural pathogens show that actinomycin D possesses inhibitory activity against the growth of these tested phytopathogenic fungi and bacteria. among which, actinomycin D has the most potent inhibitory activity against the plant pathogenic fungi <italic>Lasiodiplodia theobromae, Phomopsis caricae-papayae</italic> Fetrak&amp;Cif., <italic>Fusarium graminearum</italic> and <italic>Phytophthora capsica</italic>, with inhibitory rate of (60.09 ± 0.66)%, (48.82 ± 0.66)%, (46.47 ± 1.14)% and (44.13 ± 0.66)%, respectively. In addition, actinomycin D displays strong antibacterial activity on the plant pathogenic bacteria <italic>Xanthomonas oryzae</italic> pv. <italic>oryzae</italic> and <italic>Ralstonia solanacearum</italic> with bacteriostatic diameter at (36.00 ± 0.82) mm and (15.00 ± 0.47) mm, respectively. These results provide new compounds and bacteria resources for the development of high-efficiency biocontrol agents for agricultural disease control.

The antifungal activity and mechanism of silver nanoparticles against four pathogens causing kiwifruit post-harvest rot.

Post-harvest rot causes enormous economic loss to the global kiwifruit industry. Currently, there are no effective fungicides to combat the disease. It is unclear whether silver nanoparticles (AgNPs) are effective in controlling post-harvest rot and, if so, what the underlying antifungal mechanism is. Our results indicated that 75 ppm AgNPs effectively inhibited the mycelial growth and spore germination of four kiwifruit rot pathogens: Alternaria alternata, Pestalotiopsis microspora, Diaporthe actinidiae, and Botryosphaeria dothidea. Additionally, AgNPs increased the permeability of mycelium’s cell membrane, indicating the leakage of intracellular substance. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that AgNPs induced pathogen hypha shrinkage and distortion, as well as vacuolation in hypha cells, implying that AgNPs caused cellular and organelle structural degradation. The transcriptome sequencing of mycelium treated with AgNPs (24 h / 48 h) was performed on the Illumina Hiseq 4000 sequencing (RNA-Seq) platform. For the time points of 24 h and 48 h, AgNPs treatment resulted in 1,178 and 1,461 differentially expressed genes (DEGs) of A. alternata, 517 and 91 DEGs of P. microspora, 1,287 and 65 DEGs of D. actinidiae, 239 and 55 DEGs of B. dothidea, respectively. The DEGs were found to be involved in “catalytic activity,” “small molecule binding,” “metal ion binding,” “transporter activity,” “cellular component organization,” “protein metabolic process,” “carbohydrate metabolic process,” and “establishment of localization.” Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis also revealed that “carbohydrate metabolism,” “amino acid metabolism,” “energy metabolism,” and “xenobiotics biodegradation and metabolism” of “metabolism processes” were the most highly enriched pathways for these DEGs in four pathogens, with “cellular processes” being particularly enriched for B. dothidea. Furthermore, quantitative polymerase chain reactions (qPCRs) were used to validate the RNA-seq results. It was also confirmed that AgNPs could significantly reduce the symptoms of kiwifruit rot without leaving any Ag+ residue on the peel and flesh of kiwifruit. Our findings contributed to a better understanding of the antifungal effect and molecular mechanisms of AgNPs against pathogens causing kiwifruit post-harvest rot, as well as a new perspective on the application of this novel antifungal alternative to fruit disease control.

Anti-MRSA and clot lysis activities of Pestalotiopsis microspora isolated from Dillenia pentagyna Roxb.

There is an urgent call to search for novel natural compounds against developing multidrug-resistant microorganisms. The present work focuses on the characterization of a plant-associated fungus having bioactivity against methicillin-resistant Staphylococcus aureus (MRSA) strains. A fungal strain P31 was isolated from bark of Dillenia pentagyna and identified as Pestalotiopsis microspora. The maximum anti-MRSA activity was observed from extract of P31 grown in sabouraud dextrose broth. The minimum inhibitory concentrations(MIC) values of P31 extract were 14 μg/ml for methicillin-sensitive S. aureus (MSSA) and 32 μg/ml for MRSA strain, respectively. A crude P31 extract showed strong bactericidal activity by killing all treated MRSA cells within 24 h of treatment at their respective MIC value. A scanning electron microscopic study visualized morphological damage of MRSA cells. The membrane permeability of P31 extract-treated MRSA cells gradually increased which caused release of internal cytoplasmic nucleic acids, proteins and potassium ions (K+ ) from cells suggesting cell lysis or leakage from cells. A very low concentration of P31 extract was able to inhibit biofilm formed by MRSA cells. Thin layer chromatographic separation followed by gas chromatography-mass spectrometry analysis of the P31 extract revealed a number of antimicrobial compounds along with an anti-MRSA compound 2,4-di-tert-butylphenol. In addition, the P31 extract also showed in-vitro human blood clot lysis activity at various concentrations. The clot lysis activity of P31 extract was found maximum at 500 µg/ml. These findings suggest that fungal isolate P31 has potential as a source of anti-MRSA compounds useful in staph infections.

First Report of Pestalotiopsis microspora Causing Leaf Spot on Moyeam in China.

Ampelopsis grossedentata, commonly known as moyeam, has been widely used as health care herbal tea since it contains natural plant protein cream, 17 amino acids, 14 micronutrients and lots of functional flavonoid and provides a wide range of pharmaceutical functions such as antioxidant, anti-inflammatory, antitumor (Carneiro et al. 2021; Zhang et al. 2020). Moyeam is primarily produced in Zhangjiajie, stretching over the area from between 109'40 to 110'20E to between 28'52 to 29'48N, at 1300 to1890 meter above the sea level, with subtropical humid monsoon climate. Its economic value surpasses $1.25 billion in China (Liang et al. 2020). In July 2020, leaf spots were observed on some moyeam plants in Zhangjiajie. Initial spots were pinhead-sized with a yellow halo margin. The spots developed into light brown necrotic spots 6 to 8 mm in diameter, often with a dark brown margin. After 4 days of development, the spots enlarged and coalesced into irregular shape, frequently falling out and giving the leaves a tattered appearance. The infected plants eventually died with disease incidence ranging from 18 to 23%. This disease resulted in production losses of up to $1.7 million in 2020. One fungal isolate was isolated from the symptomatic leaves based on our previously published methods (Yi et al. 2019). Colonies on potato dextrose agar (PDA) were thick and villous with white at the front of the plate and yellowish at the back. After 1 week, the fungus produced conidia, which were spindle-shaped, straight or slightly curved, with 5 cells, 4-euseptates and 2-3 apical accessory filaments. Morphologically, the fungus was similar to Pestalotiopsis spp. Aerial hyphae with vigorous growth were collected for molecular identification. ITS nucleotide sequence of the rDNA and β-tubulin gene were amplified and sequenced with universal primers ITS1/ITS4 and self-designed primers based on β-tubulin gene conserved motif. BLAST searches against GenBank indicated that the ITS nucleotide sequence shared 99% similarity with that of P. microspora (MG808374.1) and the β-tubulin gene sequence shared 99% similarity with that of P. microspora (AF115396.1). Based on morphological and molecular characteristics, the fungus was identified as P. microspora. ITS and the β-tubulin nucleotide sequences were deposited in GenBank (accession no. MW350011 and MW816914). Pathogenicity tests were carried out with the following procedure. Three healthy moyeam seedlings were sprayed with a conidial suspension of 1 x106 conidia/ml while the other three seedlings were sprayed with distilled water as the controls. Plants were maintained in a greenhouse at 28±1°C. After one day of inoculation, symptoms identical to those in the field developed in the plants inoculated with the fungus. In contrast, no symptoms developed on the control plants. P. microspora has been reported to cause diseases in many crops in China. However, this is the first report of P. microspora causing leaf spot in moyeam in China. Identifying the pathogen causing the disease is important to the development of effective disease management strategies for control of this disease.

Acquiring novel chemicals by overexpression of a transcription factor DibT in the dibenzodioxocinone biosynthetic cluster in Pestalotiopsis microspora.

The endophytic fungus Pestalotiopsis microspora has drawn attention due to its production of dibenzodioxocinones which are a new class of inhibitors of cholesterol ester transfer protein (CETP). Previous studies showed that the pks8 gene cluster is responsible for the biosynthesis of dibenzodioxocinones in P. microspora. Disrupting the gene encoding a transcription factor DibT, which contains a zinc-finger functional domain, led to a significant decrease in the production of dibenzodioxocinones. To further investigate the function of DibT in the expression of pks8 cluster, we constructed dibT-overexpressing strains and found that all genes in the pks8 cluster were upregulated and the yields of dibenzodioxocinones were significantly increased. Moreover, function of DibT was required for the expression of most PKS genes outside of pks8 clusters, i.e., 43 out of 48 defined PKS genes, and boosted pigmentation of the mycelium and conidia. Still, we identified a new dibenzodioxocinone, 1',2'-dimethyl-3'-formyl- 1',2'-dehydropenicillide (6) and a previously known, but conditionally synthesized dibenzodioxocinone, 3'-methoxy-1',2'-dehydropenicillide (4) from the overexpression strains. Our results show that DibT was the key transcription factor in the expression of pks8 cluster and still has a wide effect on the expression of PKS genes in the genome. This work provides information for the regulation of dibenzodioxocinone biosynthesis and may be helpful for the development of new CETP inhibitors.

Impact Of Pestalotiopsis Leaf Fall Disease On Leaf Area Index and Rubber Plant Production

Currently, Pestalotiopsis leaf fall disease caused by the fungus Pestalotiopsis microspora is commonly found in Indonesian rubber plantations. The rubber defoliation period usually occurs for 1 month as a response to drought during the dry season. However, due to this disease, the rubber defoliation period occurs gradually with an earlier fall. Leaf fall can cause a decrease in the number of plant canopy which affects the leaf area index and latex production. Therefore, this study was carried out to examine the effect of Pestalotiopsis leaf fall disease on the decrease in leaf area index and latex production. The study was carried out at the Experimental Garden of the Indonesian Rubber Research Institute, Sembawa, South Sumatra by observing disease severity in RRIC 100 and GT 1 clones, measuring leaf area index, and observing latex production for 1 year. The results showed that there was a strong correlation between an increase in the Pestalotiopsis leaf fall disease severity and a decrease in leaf area index. In addition, the decrease in leaf area index affects the decrease in latex production.

Pestalotiopsis microspora causes leaf spot on Adenium obesum

AbstractAmong the main ornamental plants grown in Brazil, Adenium obesum stands out for its appearance, drought resistance and beautiful flowers. However, diseases can be a limiting factor because they affect crop quality and yield. The aim of this study was to report the first occurrence of Pestalotiopsis microspora as the causal agent of leaf spots on desert rose. A. obesum leaves with necrotic spots on the edges and/or tips were collected for indirect isolation of the pathogen. Three morphologically similar fungal isolates were obtained. In pathogenicity testing, healthy leaves were inoculated with mycelial disks and controls with disks containing potato dextrose agar (PDA) medium. Symptom development was assessed on a daily basis, followed by reisolation. The DNA of pure cultures was extracted and submitted to PCR using the primers ITS1 and ITS4. The PCR product was sequenced. The inoculated leaves initially developed symptoms of chlorosis that progressed to necrosis. The fungal colonies exhibited white mycelia with radial, cottony growth and the formation of dark masses of conidia and hyaline, branched septate hyphae. The euseptate conidia had two hyaline cells (apical and basal) and three dark‐coloured fusiform median cells. The morphological characteristics of the isolates were similar to those described for the genus Pestalotiopsis. When compared to sequences deposited in GenBank, the sequences of the ITS gene showed 100% identity with the Pestalotiopsis microspora species. These results extend the range of known hosts of this pathogen, since this is the first report of P. microspora attack in Adenium obesum.

Transcription Factors Pmr1 and Pmr2 Cooperatively Regulate Melanin Biosynthesis, Conidia Development and Secondary Metabolism in Pestalotiopsis microspora.

Melanins are the common fungal pigment, which contribute to stress resistance and pathogenesis. However, few studies have explored the regulation mechanism of its synthesis in filamentous fungi. In this study, we identified two transcription factors, Pmr1 and Pmr2, in the filamentous fungus Pestalotiopsis microspora. Computational and phylogenetic analyses revealed that Pmr1 and Pmr2 were located in the gene cluster for melanin biosynthesis. The targeted deletion mutant strain Δpmr1 displayed defects in biosynthesis of conidia pigment and morphological integrity. The deletion of pmr2 resulted in reduced conidia pigment, but the mycelial morphology had little change. Moreover, Δpmr2 produced decreased conidia. RT-qPCR data revealed that expression levels of genes in the melanin biosynthesis gene cluster were downregulated from the loss of Pmr1 and Pmr2. Interestingly, the yield of secondary metabolites in the mutant strains Δpmr1 and Δpmr2 increased, comparing with the wild type, and additionally, Pmr1 played a larger regulatory role in secondary metabolism. Taken together, our results revealed the crucial roles of the transcription factors Pmr1 and Pmr2 in melanin synthesis, asexual development and secondary metabolism in the filamentous fungus P. microspora.

Cover: Journal of Basic Microbiology. 12/2021

Journal of Basic MicrobiologyVolume 61, Issue 12 p. 1046-1046 COVER PICTUREFree Access Cover: Journal of Basic Microbiology. 12/2021 First published: 03 December 2021 https://doi.org/10.1002/jobm.202170037AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Cover illustration: A sexual reproduction of the grey leaf spot causing fungus Pestalotiopsis microspora. The conidia can be either composed of two upper median cells that are darker than the lowest median cell, i.e. versicolourous. Or concolorous conidia are found with similar pigmentation in the median cells. (Photo: Nasrin Sultana and Md. Abdullahil Baki Bhuiyan, Department of Plant Pathology, BSMRAU, Gazipur, Bangladesh) Volume61, Issue12December 2021Pages 1046-1046 RelatedInformation