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Plant Disease Nov 2023Photinia × fraseri Dress, belonging to the Rosaceae family, is widely cultivated as an ornamental plant in China. In July 2022, the leaf spot symptoms were observed on...
Photinia × fraseri Dress, belonging to the Rosaceae family, is widely cultivated as an ornamental plant in China. In July 2022, the leaf spot symptoms were observed on over thirty P. × fraseri plants in an approximately 2-hectare park in Xinjian District, Nanchang City, Jiangxi Province, China (28°43'02″ N, 115°44'01″ E), with a disease incidences of roughly 10% . At first, small, grayish-white lesions appeared on the leaf edges, later expanding into 2 to 10 mm circular or irregular spots. These spots turned grayish-white to brown, with dark brown margins. Eventually, some lesions' centers dried and died. For fungal isolation, ten symptomatic leaves were randomly collected. The edges between the diseased and healthy tissues were cut into small pieces (4 × 4 mm). These pieces were then surface-sterilized by dipping in 70% ethanol for 30 s and 1% NaClO for 30 s. Subsequently, they were rinsed three times with sterile distilled water. Leaf pieces were then transferred to potato dextrose agar (PDA) medium and incubated at 25 °C for 3-4 days. Eight isolates with similar colony morphology were collected from diseased leaves. Colonies of this fungus on PDA were nearly round, white, and had sparse aerial mycelium on the surface with black, gregarious conidiomata. The conidia were nearly cylindrical, smooth, hyaline, and 4-septate, measuring 16.7 to 24.3 × 4.2 to 6.6 µm (mean 20.9 × 5.3 µm, n=50). The three middle cells were smooth, doliiform, and brown, with concolorous septa that were darker than the rest of the cell. They measured 11.8 to 17.0 µm long (mean 14.1 µm, n=50). The basal and apical cells were triangular and transparent. The basal cells had a mean length of 4.7 µm and were equipped with a basal appendage, while the apical cells had two appendages with a mean length of 17.7 µm(n=50). The characteristics of these isolates match those of Pestalotiopsis species (Maharachchikumbura et al. 2014). To identify them accurately, three representative isolates, namely JFRL 03-161, JFRL 03-162, and JFRL 03-226, were selected for further analysis. The internal transcriptional spacer (ITS) region, β-tubulin (TUB2) and translation elongation factor 1-alpha (TEF1-α) gene were amplified and sequenced using primers ITS1/ITS4 (White et al. 1990), BT2a/BT2b (Glass and Donaldson 1995), and EF1-526F/EF1-1567R (Maharachchikumbura et al. 2012), respectively. All sequences (ITS: OR342044-OR342046, TUB2: OR343299-OR343301, and TEF1-α: OR343302-OR343304) were deposited in GenBank. A BLASTn homology search revealed 99-100% identity to Pestalotiopsis nanjingensis CSUFTCC16 (ex-type). The sequences included ITS (OK493602, 486/486 nucleotides), TUB2 (OK562377, 438/439 nucleotides), and TEF1-α (OK507972, 478/478 nucleotides). The maximum likelihood analyses were performed for the combined ITS, TUB2 and TEF1-α data sets using IQtree web server (Trifinopoulos et al. 2016). The resulting phylogenetic tree demonstrated a strong association: the three isolates clustered tightly with P. nanjingensis forming a clade with robust 99% bootstrap support. This clustering, consistent with both morphological and molecular characteristics, confirmed the identity of the fungus as P. nanjingensis. To evaluate its pathogenicity, we obtained 3-year-old P. × fraseri 'Red Robin' plants, which were purchased then potted in a controlled climate chamber. We surface sterilized six healthy leaves of P. × fraseri with 70% ethanol and created wounds using a sterile needle. Subsequently, we inoculated a 50 μL conidial suspension (1 × 106 conidia/mL) of the isolate JFRL 03-161 on these wounded leaves. In parallel, another six leaves from P. × fraseri were inoculated with sterile distilled water, serving as the control group. All potted plants were incubated under conditions of 26 °C and 80% humidity. After seven days, all leaves inoculated with isolate JFRL 03-161 displayed symptoms similar to those observed in the field, whereas the control leaves remained unaffected. To fulfill Koch's postulates, we re-isolated P. nanjingensis plants from the symptomatic leaves and identified it based on morphological and molecular characteristics. It has been reported that two species of Pestalotiopsis, namely P. microspora and P. trachicarpicola can caused damage to the leaves of P. × fraseri in China (Xu et al. 2022; Zhu et al. 2021). However, to our best knowledge, this is the first report on leaf spot caused by P. nanjingensis on P. × fraseri in China. Therefore, it is necessary to pay more attention to the leaf spot disease of P. × fraseri caused by Pestalotiopsis species and develop appropriate control strategies.
PubMed: 38085969
DOI: 10.1094/PDIS-07-23-1469-PDN -
Plant Disease May 2024Strawberry root and crown rot caused by the fungus is an emerging disease that has caused yield losses of up to 70% in Mexico and other regions worldwide. This research...
Strawberry root and crown rot caused by the fungus is an emerging disease that has caused yield losses of up to 70% in Mexico and other regions worldwide. This research evaluated the effects of biological and chemical fungicides applied as preventive and curative applications for controlling root and crown rot caused by in strawberries under greenhouse conditions. Treatments included these chemical fungicides: prochloraz, prochloraz + thiram, cyprodinil + fludioxonil, difenoconazole + azoxystrobin, iprodione, captan, thiram, pydiflumetofen + fludioxonil, fluxapyroxad + pyraclostrobin, and hymexazol; each was applied at commercial doses. Also tested were biological treatments based on , , sp., and strain D747 (). Disease incidence, severity, plant mortality, root length, and dry weight were determined. Results showed that overall, preventive applications of the fungicides pydiflumetofen + fludioxonil, cyprodinil + fludioxonil, and prochloraz resulted in the smallest area under the disease progress curve and the lowest final disease incidence, severity, and plant mortality. An intermediate group of effective treatments entailed hymexazol, iprodione, , and (50 to 75% efficacy). Treatments with greater efficacy (99 to 100%), pydiflumetofen + fludioxonil, cyprodinil + fludioxonil, and prochloraz, also had maximal total plant biomass vis-à-vis the untreated control. By contrast, each treatment's efficacy was significantly reduced when applied curatively (0 to 37% treatment efficacy). These results suggest that certain treatments are useful for controlling strawberry root and crown rot caused by when applied preventively (as root dipping). These results will contribute to designing more effective management programs for root and crown rot caused by on strawberry.
Topics: Fragaria; Plant Diseases; Fungicides, Industrial; Plant Roots; Trichoderma; Xylariales; Ascomycota
PubMed: 38012823
DOI: 10.1094/PDIS-05-23-0958-RE -
Pathogens (Basel, Switzerland) Nov 2023The main pathogens affecting the carob () tree in the Mediterranean basin are described in this overview. The most widespread diseases periodically occurring in carob... (Review)
Review
The main pathogens affecting the carob () tree in the Mediterranean basin are described in this overview. The most widespread diseases periodically occurring in carob orchards are powdery mildew () and cercospora leaf spot (). The causal agents of "black leaf spots" (e.g., , and spp.) are responsible for symptoms similar to those previously mentioned for foliar diseases, but are reported in carob orchards at a negligible frequency. Likewise, canker and branch diebacks caused by fungal species belonging to Botryosphaeriaceae are almost never recorded. Among the rots of wood tissues that may compromise old carob specimens, "brown cubical rot" caused by is the most widespread and recurrent issue; this pathogen is also well-known for producing edible fruit bodies that are appreciated for pharmaceutical and industrial purposes. On the other hand, "white rots" caused by and species are less common and reported for the first time in this review. Gall-like protuberances on twigs of uncertain aetiology or tumors on branches associated with are described, although these symptoms are seldom detected, as they are also observed for necrotic leaf spots caused by pv. . A worldwide list of pathogens not yet recorded but at high risk of potential introduction in Italian carob-producing areas is also provided. Finally, concerns related to new phytopathogenic fungi vectored by the invasive ambrosia beetle are addressed. All the described pathogens could become limiting factors for carob production in the near future, because they could be favored by high-density orchards, the increasing global network of trade exchanges, and the high frequency at which extreme events related to climate change occur globally. Thus, symptoms and signs, causal agents, epidemiology, and, whenever applicable, recommendations for disease prevention and management are provided in this review.
PubMed: 38003821
DOI: 10.3390/pathogens12111357 -
Metabolites Nov 2023Gray blight disease, which is caused by -like species, poses significant challenges to global tea production. However, the comprehensive metabolic responses of tea...
Gray blight disease, which is caused by -like species, poses significant challenges to global tea production. However, the comprehensive metabolic responses of tea plants during gray blight infection remain understudied. Here, we employed a multi-omics strategy to characterize the temporal transcriptomic and metabolomic changes in tea plants during infection by , the causal agent of gray blight. Untargeted metabolomic profiling with ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS) revealed extensive metabolic rewiring over the course of infection, particularly within 24 h post-inoculation. A total of 64 differentially accumulated metabolites were identified, including elevated levels of antimicrobial compounds such as caffeine and (-)-epigallocatechin 3-gallate, as well as oxidative catechin polymers like theaflavins, theasinensins and theacitrins. Conversely, the synthesis of (+)-catechin, (-)-epicatechin, oligomeric proanthocyanidins and flavonol glycosides decreased. Integrated omics analyses uncovered up-regulation of phenylpropanoid, flavonoid, lignin biosynthesis and down-regulation of photosynthesis in response to the pathogen stress. This study provides novel insights into the defense strategies of tea plants against gray blight disease, offering potential targets for disease control and crop improvement.
PubMed: 37999217
DOI: 10.3390/metabo13111122 -
The Journal of Antibiotics Jan 2024New ambuic acid derivatives, pestallic acids R-V (1-5), together with ambuic acid (6), were isolated from the endophytic fungus Pestalotiopsis trachicarpicola SC-J551...
New ambuic acid derivatives, pestallic acids R-V (1-5), together with ambuic acid (6), were isolated from the endophytic fungus Pestalotiopsis trachicarpicola SC-J551 derived from the fern Blechnum orientale L., of which compound 2, being racemic, was separated to two optically pure enantiomers (+)-2 and (-)-2. The structures including absolute configurations of these new compounds were elucidated by extensive spectroscopic analysis and theoretical simulations of their ECD spectra and C NMR chemical shifts. Compounds 1 and 3 exhibited cytotoxicity against human carcinoma A549, HeLa, HepG2, and MCF-7 cells (IC: 3.6-12.5 μM) and compound 3 was also active against Staphylococcus aureus and MRSA (MIC = 20 μg ml). Compound (±)-2 showed inhibitory activity against LPS-induced NO release (IC = 21.1 μM) and t-BHP-induced ROS production (IC = 8.5 μM) in RAW264.7 macrophages.
Topics: Humans; Fungi; Pestalotiopsis; Magnetic Resonance Spectroscopy; Molecular Structure
PubMed: 37957338
DOI: 10.1038/s41429-023-00674-3 -
Data in Brief Oct 2023Bananas, one of the most widely consumed fruits globally, are highly susceptible to various leaf spot diseases, leading to significant economic losses in banana...
Bananas, one of the most widely consumed fruits globally, are highly susceptible to various leaf spot diseases, leading to significant economic losses in banana production. In this article, we present the Banana Leaf Spot Diseases (BananaLSD) dataset, an extensive collection of images showcasing three prevalent diseases affecting banana leaves: Sigatoka, Cordana, and Pestalotiopsis. The dataset was used to develop the BananaSqueezeNet model [1]. The BananaLSD dataset contains 937 images of banana leaves collected from banana fields, which were then further augmented to generate another 1600 images. The images were acquired using three smartphone cameras in diverse real-world conditions. The dataset has potential for reuse in the development of machine learning models that can help farmers identify symptoms early. It can be useful for researchers working on leaf spot diseases and serve as motivation for further researches.
PubMed: 37823069
DOI: 10.1016/j.dib.2023.109608 -
Indian Journal of Microbiology Sep 2023Members of the plant mycobiota are all associated to varying degrees with the development of plant diseases. Although many reports on the plant mycobiota are well...
Members of the plant mycobiota are all associated to varying degrees with the development of plant diseases. Although many reports on the plant mycobiota are well documented, the relationships between mycobiota of and plant diseases are poorly understood. Mutual interactions and extent of the roles of microbial communities associated with and the source of pathogens are still unclear, and more research is needed on the health benefits of this ecologically important population. Using high-throughput sequencing, we analyzed the mycobiota composition and ecological guilds of the rhizosphere, root, and phyllosphere of healthy and diseased . from the Tianfu Industrial Park in Panzhou city, Guizhou province. Analysis of community composition showed that the relative abundance of pathogens of leaf spot, including , and in the phyllosphere of diseased plant (LD), were 1.15%, 0.15% and 0.06%, and the relative abundance of and were 0.96% and 0.58% in healthy plant (LH). The alpha diversity indices indicated that fungal diversity was higher in healthy plants compared to diseased plants in each compartment. The alpha diversity index of fungi in the phyllosphere (LH) of healthy . , including Shannon, Chao-1, and Faith-pd indices, was 1.02, 81.50 and 10.42 higher than that of the diseased (LD), respectively. The fungi in the rhizosphere of healthy was 1.03, 59.00 and 5.56 higher than the diseased, respectively. The Shannon index of fungi in the root of healthy was 0.29 higher than that of diseased. Principal Coordinate analysis and ANOSIM results showed that there were significant differences in mycobiota composition between healthy and diseased phyllospheres ( < 0.05), as well as rhizosphere fungal community, while there was no significant difference between healthy and diseased roots ( > 0.05). Linear discriminant analysis effect size revealed that, at different taxonomic levels, there were significantly different taxa between the healthy and diseased plants in each compartment. The ecological guilds differed between healthy and diseased plants according to the FUNGuild analysis. For example, of healthy compared to diseased plants, the percentages of "lichenized-undefined saprotroph" were increased by 2.34%, 0.44%, and 1.54% in the phyllosphere, root, and rhizosphere, respectively. In addition, the plant pathogens existed in each compartment of . , but the percentages of "plant pathogen" were increased by 1.16% in the phyllosphere of diseased compared to healthy plants. Together, the ecological guild and co-occurrence network indicated that the potential pathogens of leaf spot were mainly found in the phyllosphere. This study explained one of pathogen origin of leaf spots of by the microbial community ecology, which will provide the new insights for identification of plant pathogens.
PubMed: 37781006
DOI: 10.1007/s12088-023-01093-6 -
The Journal of Antibiotics Nov 2023Three isocoumarins, including two new compounds, (±) pestalactone D (1) and pestapyrone F (2), as well as one known compound, pestapyrone D (3), were isolated from the...
Three isocoumarins, including two new compounds, (±) pestalactone D (1) and pestapyrone F (2), as well as one known compound, pestapyrone D (3), were isolated from the culture of the endolichenic Pestalotiopsis rhododendri LF-19-12. The planar structures of all compounds were elucidated by NMR and MS spectra. And the absolute configurations of 1 were confirmed by single crystal X-ray diffraction analysis, indicative of it as a racemate of 4S/12S and 4R/12R enantiomers. Compound 1 exhibited weak anti-coronaviral activity against human coronavirus HCoV-229E with an EC of 77.61 μM. Based on the bioinformatics analysis, the biosynthetic pathway of 1 has been proposed.
Topics: Humans; Isocoumarins; Crystallography, X-Ray; Magnetic Resonance Spectroscopy; Molecular Structure
PubMed: 37612463
DOI: 10.1038/s41429-023-00646-7 -
Plant Disease Aug 2023Morel (Morchella sextelata) is a valuable medicinal and edible mushroom, but the wild yield is seriously insufficient, so several artificial varieties have been...
Morel (Morchella sextelata) is a valuable medicinal and edible mushroom, but the wild yield is seriously insufficient, so several artificial varieties have been developed to alleviate the shortage of wild yield. However, in 2020-2022, apothecium wither symptoms were observed in Nanchong, Sichuan. A total of 30.80% of the morels in the planting base (1.3 km2) showed these symptoms. The initial symptoms were slight white lesions on the surface of apothecium, then the mycelia gradually invaded the interior of the fruiting body, and eventually leading to black and wilt apothecium (Fig. 1a). Fifteen symptomatic morels were collected and ten isolates were obtained using the single spore isolation technique developed by Chomnunti et al. (2014). The morphological characteristics of the ten isolates were similar, which showed dense aerial white mycelia colony texture on PDA, and later forming concentric black mucus (Fig. 1c). The reverse side was yellow (Fig. 1d). The acervulus was floral-shaped and discrete, with smooth walls and measured 120.0 to 400.5 × 15.5 to 40.0 μm (n=10) (Fig. 1e); the conidia were fusiform and hyaline, 21.0 to 28.6 × 6.0 to 7.6 μm in size (n=50), each contained five cells. The apical cell was hyaline, conic and with 2 to 4 tubular apical appendages on the top. The three intermediate cells were brown to olivaceous, doliform to cylindrical, constricted at septa. The basal cell was conic to acute (Fig. 1f). The morphological characteristics were consistent with the published description of Pestalotiopsis trachicarpicola (Maharachchikumbura et al., 2012). PCR was performed with primers ITS1/ITS4 for internal transcribed spacer (ITS) (White et al., 1990), BT2A/BT2B for β-tubulin gene (TUB) (Glass and Donaldson, 1995), and EF1-526F/EF1-1567R for translation elongation factor 1-alpha (TEF-1α) (Roger et al., 1999). The pairwise alignments of ITS, TUB, and TEF-1α sequences was nearly 100% identical to P. trachicarpicola with GenBank accession numbers MT889666.1 (579/585 bp, 99%), MT884145.1 (445/450 bp, 99%), and MW149930.1 (946/958 bp, 99%), respectively. The resulting sequences were deposited in GenBank (Accession no. ITS: OL362082; TUB: OL828342; and TEF-1α: OL905009). Phylogenetic analysis performed with maximum likelihood method used MEGA 7.0 (1000 bootstrap replications) classified WLM5 into the P. trachicarpicola clade (Fig. 2), so we finally confirmed the identity of WLM5 as P. trachicarpicola. To fulfill Koch's postulates, twenty morels were surface disinfected with 2% sodium hypochlorite and then artificially wounded (diameter of 0.5 mm) prior to inoculation with 200 μL conidial suspension (105 conidia/mL), while an equal amount of sterile distilled water was applied to controls. After 4 days, the inoculated fruiting bodies showed symptoms consistent with field infection (Fig. 1b) and P. trachicarpicola was re-isolated using the same protocol, while the control remained asymptomatic. This first report of P. trachicarpicola causing apothecium wither on morel will help develop robust disease management strategies against this emerging fungal pathogen.
PubMed: 37578365
DOI: 10.1094/PDIS-01-23-0027-PDN -
Frontiers in Microbiology 2023Rose black spot is an economically important disease that significantly decreases flower yield. Fungicide and biological control are effective approaches for controlling...
INTRODUCTION
Rose black spot is an economically important disease that significantly decreases flower yield. Fungicide and biological control are effective approaches for controlling rose black spot. The objective of this study was to evaluate the effect of application of biological and chemical control agents, including (GUAL210), . (LKW) and fungicide (CP) on the black spot disease and rhizosphere fungal community structure of edible rose.
METHODS
In this study, the 'Crimson Glory' was taken as the research object, and the field experiment was designed by randomized block design. The experiment contained 3 treatments (CP, GUAL210, LKW) and 1 control. The control effect and growth promoting effect of fungicide and biological control on rose black spot were compared. The composition and diversity of rhizosphere soil fungal community of different treatments of rose were studied by high-throughput sequencing method. The fungal community composition, correlation of environmental factors and differences in metabolic pathways related to rose disease were analyzed, and the correlation between rhizosphere soil fungal community of rose and biological control of disease was explored.
RESULTS AND DISCUSSION
Both disease incidence and disease index differed significantly among groups (LKW < GUAL210 < CP < CK), and disease control effect exhibited no significant difference between GUAL210 and LKW (60.96% and 63.86%, respectively). Biological control was superior to chemical control in terms of disease prevention effects and duration, and it significantly increased the number of branches and flowers of rose plants. Ascomycota and Basidiomycota accounted for more than 74% of the total fungal abundance, and the abundance of Ascomycota was highest in CK, followed by GUAL210, CP and LKW, which was consistent with the disease occurrence in each group. The analysis of metabolic pathways showed that the HSERMETANA-PWY in each experimental group was significantly lower than that in control group. The Shannon index in each experimental group was significantly lower than that in control group. PCoA analysis showed that the rhizosphere fungal community structure in each experimental group was significantly different from that in control group. in GUAL210, and in LKW replaced , and as dominant flora, and played a nonneglectable role in reducing disease occurrence. The difference in rhizosphere fungal community structure had an important impact on the incidence of rose black spot disease. Biological control is crucial for establishing environment-friendly ecological agriculture. GUAL210 has promising prospects for application and development, and may be a good substitute for chemical control agents.
PubMed: 37577414
DOI: 10.3389/fmicb.2023.1199024