-
EFSA Journal. European Food Safety... Dec 2023Following the commodity risk assessments of bonsai plants from China consisting of grafted on performed by EFSA, the EFSA Plant Health Panel performed a pest...
Following the commodity risk assessments of bonsai plants from China consisting of grafted on performed by EFSA, the EFSA Plant Health Panel performed a pest categorisation of a clearly defined plant pathogenic fungus of the family Pestalotiopsidaceae. The pathogen has been reported on herbaceous, woody and ornamental plants causing symptoms such as leaf blight, shoot blight, seedling blight, pod canker, pre- and post-harvest fruit rot, and gummosis. Moreover, the fungus was reported as an endophyte on a wide range of asymptomatic hosts. The pathogen is present in Africa, North and South America, Asia, Europe and Oceania. It has been reported from the EU, with a restricted distribution (Portugal). There is a key uncertainty on the geographical distribution of in the EU and worldwide, because of the endophytic nature of the fungus, the lack of surveys and since the pathogen might have been misidentified based only on morphology and pathogenicity tests. The pathogen is not included in Commission Implementing Regulation (EU) 2019/2072. This pest categorisation focuses on those hosts that are relevant for the EU and for which there is robust evidence that the pathogen was formally identified by a combination of morphology, pathogenicity and multilocus sequence analysis. Plants for planting, fresh fruits, bark and wood of host plants as well as soil and other plant growing media are the main pathways for the entry of the pathogen into the EU. Host availability and climate suitability factors occurring in parts of the EU are favourable for the establishment of the pathogen. Despite the low aggressiveness observed in most reported hosts, and the fact that may colonise plants as an endophyte, its introduction and spread in the EU may have an economic and environmental impact (with a key uncertainty) where susceptible hosts are grown. Phytosanitary measures are available to prevent the introduction and spread of the pathogen. The Panel cannot conclude on whether satisfies all the criteria that are within the remit of EFSA to assess for this species to be regarded as potential Union quarantine pest, because of the key uncertainties on the restricted distribution in the EU and the magnitude of the impact.
PubMed: 38116101
DOI: 10.2903/j.efsa.2023.8494 -
Biocontrol fungi induced stem-base rot disease resistance of How revealed by transcriptome analysis.Frontiers in Microbiology 2023How (MO) is a Rubiaceae plant, and its medicinal part is dried root, which is one of the "Four Southern Medicines" in China. At present, the plant MO breed seedlings...
INTRODUCTION
How (MO) is a Rubiaceae plant, and its medicinal part is dried root, which is one of the "Four Southern Medicines" in China. At present, the plant MO breed seedlings mainly by cutting methods. Long-term asexual propagation makes pathogenic fungi accumulate in MO, leading to stem-base rot, which is caused by (Fon).
METHODS
In this study, we used and sp. as biocontrol fungi to investigate their antagonistic ability to Fon through in vitro antagonism and pot experiments, and combined with transcriptome sequencing to explore the mechanism of biocontrol.
RESULTS
The results showed that both and sp. could inhibit the growth of Fon. In addition, and sp. could also enhance the basic immunity to Fon by increasing the activities of defensive enzymes such as POD and SOD, chlorophyll content, soluble sugar content, and oligosaccharide content of MO. The mechanism of biological control of stem-base rot of MO was discussed by transcriptome technology. MO was treated with two treatments, root irrigation with biocontrol fungi or inoculation with Fon after root irrigation with biocontrol fungi. Transcriptome sequencing revealed that nearly 11,188 differentially expressed genes (DEGs) were involved in the process of inducing MO systemic resistance to Fon by biocontrol fungi. Meanwhile, Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, as well as transcription factor (TFs) prediction showed that there were significant differences in the expression levels of MO roots under different treatments. Also, the genes of the "MAPK signaling pathway" and "plant hormone signaling pathway" were analyzed, in which the ERFs gene of the ethylene signal transduction pathway participated in the metabolism of glycosyl compounds. It is speculated that the ethylene signal may participate in the immune response of the sugar signal to the infection of Fon. After qRT-PCR verification of 10 DEGs related to the ethylene signal transduction pathway, the expression trend is consistent with the results of transcriptome sequencing, which proves the reliability of transcriptome sequencing.
DISCUSSION
In conclusion, this study preliminarily identified the molecular mechanism of the biological control of MO stem-base rot and provided a scientific basis for further research on the prevention and control mechanism of MO stem-base rot.
PubMed: 38107850
DOI: 10.3389/fmicb.2023.1257437 -
Polish Journal of Microbiology Dec 2023The sp. strain cr013 is a mycoparasite of , a potential biocontrol fungus for Armand pine () blister rust. A previous study showed that the strain cr013 has great...
The sp. strain cr013 is a mycoparasite of , a potential biocontrol fungus for Armand pine () blister rust. A previous study showed that the strain cr013 has great potential to produce new compounds. However, there has been no report of the whole-genome sequence of the mycoparasite sp. In this study, the BGISEQ-500 and Oxford Nanopore GridION X5 sequencing platforms were used to sequence the strain cr013 isolates and assemble the reads to obtain the complete genome. We first report the whole-genome information of the mycoparasite sp. strain cr013 (GenBank accession number: JACFXT010000000, BioProject ID: PRJNA647543, BioSample ID: SAMN15589943), and the genomic components and gene functions related to the mycoparasitism process were analyzed. This study provides a theoretical basis for understanding the lifestyle strategy of the mycoparasite sp. and reveals the mechanisms underlying secondary metabolite diversity in the strain cr013.
Topics: Pestalotiopsis; Basidiomycota; Genomics; Fungi
PubMed: 38095159
DOI: 10.33073/pjm-2023-041 -
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 -
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 -
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