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Plant Disease May 2023Pandanus amaryllifolius, also known as pandan, is a perennial herb, growing in Indonesia, China and the Maluku Islands (Wakte et al. 2009). It is the only plant with...
Pandanus amaryllifolius, also known as pandan, is a perennial herb, growing in Indonesia, China and the Maluku Islands (Wakte et al. 2009). It is the only plant with aromatic leaves in the Pandanaceae. It is widely used in food, medicine, cosmetics and other industries, and is also known as "Oriental Vanilla." Pandan is planted in Hainan province over 1,300 ha and is the main plant intercropped among the forest trees. From 2020, the leaf spot was surveyed for three years. Diseased leaves occurred on 30 to 80% of the surveyed plants, with an incidence of 70% and yield losses of 40%. The disease occured from mid-November to April and was most severe at low temperatures and humidity. Initial symptoms were pale green spots, that formed dark brown, nearly circular lesions. As the lesions expanded, their centers became greyish white, with yellow halos at the junction of the diseased and healthy tissue. When the humidity was high, there were small black spots scattered in the center of the lesion. Symptomatic leaf samples were collected from four different sites. The leaf surface was disinfested with 75% ethyl alcohol for 30 s and washed with sterile distilled water three times. Samples from the junction of diseased and healthy tissue (0.5 × 0.5 cm) were removed and placed on potato dextrose agar (PDA) medium containing 100 µg/mL of cefotaxime sodium and cultivated in a dark incubator at 28°C. After two days, hyphal tips from the edges of growing colonies were transferred to fresh PDA plates for further purification. Following Koch's postulates, colonies from strains were used as inoculum in pathogenicity tests. Colonies with 5 mm diameter were inoculated upside onto fresh and healthy pandan leaves via wounding method (pinpricked by sterilized needles) and non-wounding method. Sterilized PDA was used as control. All plants were setted three replicates and were incubated at 28℃ for 3 to 5 days. When symptoms on leaves similar to those in the field appeared, the fungus were reisolated The colonies formed on PDA were also consistent with the original isolate (Scandiani et al, 2003). After seven days, the colony covered the whole petri dish with white, petal-shaped growth with a slight concentric, annular bulge in the center, irregular edges, with black acervuli emerging at a later stage of colony growth. Conidia were fusiform, 18.1±1.6 × 6.4±0.3 μm, showing four septations and five cells, the middle three cells were brownish black to olivaceous, and the apical cell colorless with two to three filaments, 21.8±3.5 μm long. The caudate cell was colorless with one stalk 5.9±1.8 μm long (Zhang et al. 2021; Shu et al. 2020). According to the colony and conidia characteristics, the pathogen was initially identified as Pestalotiopsis spp. (Benjamin et al. 1961). To confirm the pathogen identity, we used the universal primers ITS1/ITS4, targeting primers EF1-728F/EF1-986R and Bt2a/Bt2b sequences (Tian et al. 2018). The sequences of the PCR products were deposited in NCBI GenBank with accession numbers OQ165166 (ITS), OQ352149 (TEF1-α) and OQ352150 (TUB2). BLAST results showed that the sequences of the ITS, TEF1-α and TUB2 genes shared 100% homology with the sequences of Pestalotiopsis clavispora. The maximum likelihood method was used in the phylogenetic analysis. The result showed that LSS112 was clustered with Pestalotiopsis clavispora with a support rate of 99%. Based on morphological and molecular characteristics, the pathogen was confirmed as Pestalotiopsis clavispora. To our knowledge, this is the first report of leaf spot of pandan caused by Pestalotiopsis clavispora in China. This research will be immediately helpful for the diagnosis and control the disease on pandan.
PubMed: 37157095
DOI: 10.1094/PDIS-02-23-0302-PDN -
Plant Disease Apr 2023Faba bean (Vicia faba L.) is a cool-season legume crop, planted worldwide as an essential source of protein-rich foods, vegetables, and animal feeds. In China, the total...
Faba bean (Vicia faba L.) is a cool-season legume crop, planted worldwide as an essential source of protein-rich foods, vegetables, and animal feeds. In China, the total cultivated area of faba bean in 2019 was 839,618 square hectometers (hm2) and the production was 1,740,945 tons (t) (Ji et al. 2022). In May 2021, a leaf spot disease on faba bean plants with about 80% disease incidence was observed in a 0.3 ha commercial field located at Zunyi City (27°31'43.80″ N, 106°23'34.27″ E), Guizhou Province, China. The leaves of the early affected plants appeared circular dark brown spots, which then rapidly develop into large irregular shaped lesions if conditions remain favorable. Severe infection can result in extensive defoliation of plants and lesions on pods. Symptomatic leaves were collected and cut into small pieces, surface sterilized with 75% ethanol for 30 s followed by 2% NaClO for 1 min, rinsed with sterile distilled water three times, and incubated on PDA plates amended with streptomycin sulfate (0.5 mg/L) at 25°C for 2-4 days. Two purified cultures were obtained through single-spore culture. Colonies on PDA attaining 62 mm diam after 2 weeks, white or pale red, edge undulate, with dense aerial mycelium on the surface, fruiting bodies black to reddish brown. Conidia fusoid to ellipsoid, 4-septate, straight to slightly curved, 18.5-22 × 6-7 μm (av. = 20 × 7 μm, n = 30); basal cell obconic, hyaline, 3.5-5 μm long, with a single appendage, 2.5-6 μm; three median cells doliiform, verruculose, olivaceous with slightly red (second cell from base 4-5 μm long; third cell 4.5-5.5 μm long; fourth cell 3-5.5 μm long); apical cell conical, hyaline, 2.5-4 μm long, with 1-3 tubular appendages, 13-22.5 μm long. The morphological characters of our studied specimens fit well with Pestalotiopsis rosea (Maharachchikumbura et al. 2012). For molecular identification, the internal transcribed spacer (ITS) region, partial β-tubulin (tub2) and translation elongation factor 1-alpha (tef1-α) genes were amplified and sequenced using primer pairs ITS5/ITS4 (White et al. 1990), T1/Bt-2b (Glass and Donaldson 1995) and EF1-728F/EF-2 (Carbone and Kohn 1999). The DNA sequences of two isolates GUCC 195257 (OP364052, OP391714, OP391713) and GUCC 195258 (OP364053, OP391716, OP391715) were deposited in GenBank. The BLAST searches revealed that these sequences had 99% (537/539 bp), 100% (453/453 bp), 99% (591/593 bp), 99% (537/539 bp), 100% (453/453 bp) and 99% (574/576 bp) nucleotide identity to the ex-type strain of P. rosea (JX399005, JX399036, JX399069), respectively. In addition, multi-locus phylogenetic analysis showed that both isolates clustered with P. rosea with full statistical support. The phylogenetic relationship of Pestalotiopsis species supported the identification of our isolates as P. rosea. In the pathogenicity test, the leaves of ten healthy 2-week-old faba bean plants were spray inoculated with a conidial suspension (1 × 106 conidia/ml) of the two isolates. Another set of five plants that were sprayed with sterilized distilled water served as the controls. Treated plants were kept at 25°C in a greenhouse with a photoperiod of 12 h and 70% relative humidity. After one week, all inoculated leaves showed symptoms similar to those of the infected faba bean observed in the field, whereas controls were symptomless. The pathogenicity test was performed twice with similar results. The fungus was reisolated from the inoculated plants and identified as P. rosea by morphological and molecular evidence, thus confirming Koch's postulates. To our knowledge, this is the first report of P. rosea causing leaf spot on faba bean in the world. Pestalotiopsis species are well-known phytopathogens that can cause a variety of diseases, including leaf spots, chlorosis, and various postharvest (Wang et al. 2019). The results of this study not only contribute to accurately identify this disease in the fields of faba bean production, but also provide an important reference for developing specific control measures.
PubMed: 37081628
DOI: 10.1094/PDIS-12-22-2920-PDN -
Archives of Microbiology Mar 2023A macrolide antibiotic, lasiodiplodin was isolated from the endophytic fungus (EF) Lasiodiplodia pseudotheobromae J-10 associated with the medicinal plant Sarcandra...
In vitro antifungal activity of lasiodiplodin, isolated from endophytic fungus Lasiodiplodia pseudotheobromae J-10 associated with Sarcandra glabra and optimization of culture conditions for lasiodiplodin production.
A macrolide antibiotic, lasiodiplodin was isolated from the endophytic fungus (EF) Lasiodiplodia pseudotheobromae J-10 associated with the medicinal plant Sarcandra glabra. In vitro antifungal assay demonstrated the inhibitory activity of lasiodiplodin against the growth of six phytopathogenic fungi, with the IC values ranging between 15.50 and 52.30 μg/mL. The highest antifungal activities were recorded against Exserohilum turcicum, Colletotrichum capsici, and Pestalotiopsis theae, with IC values of 15.50, 15.90, and 17.55 μg/mL, respectively. The underlying mechanism of the antifungal activity of lasiodiplodin against E. turcicum included the alteration of its colony morphology and disturbance of its cell membrane integrity. In addition, the optimization of L. pseudotheobromae J-10 culture conditions increased lasiodiplodin yield to 52.33 mg/L from 0.59 mg/L at pre-optimization. This is the first report on the isolation and identification of antifungal compound from the EF L. pseudotheobromae J-10 associated with S. glabra, as well as on the optimization of L. pseudotheobromae J-10 culture conditions to increase lasiodiplodin yield. The results of this study support that lasiodiplodin is a natural compound with high potential bioactivity against phytopathogens, and provide a basis for further study of the EF associated with S. glabra.
Topics: Antifungal Agents; Zearalenone; Plants, Medicinal
PubMed: 36964826
DOI: 10.1007/s00203-023-03440-z -
International Journal of Molecular... Feb 2023The effectiveness of nitric oxide (NO) for control of grey spot rot cause by in harvested loquat fruit and its probable mechanisms have been investigated. The results...
The effectiveness of nitric oxide (NO) for control of grey spot rot cause by in harvested loquat fruit and its probable mechanisms have been investigated. The results showed that NO donor sodium nitroprusside (SNP) did not evidently inhibit mycelial growth and spore germination of , but resulted in a low disease incidence and small lesion diameter. SNP resulted in a higher hydrogen peroxide (HO) level in the early stage after inoculation and a lower HO level in the latter period by regulating the activities of superoxide dismutase, ascorbate peroxidase and catalase. At the same time, SNP enhanced the activities of chitinase, β-1,3-glucanase, phenylalanine ammonialyase, polyphenoloxidase, and total phenolic content in loquat fruit. However, SNP treatment inhibited the activities of cell wall-modifying enzymes and the modification of cell wall components. Our results suggested that NO treatment might have potential in reducing grey spot rot of postharvest loquat fruit.
Topics: Nitric Oxide; Disease Resistance; Hydrogen Peroxide; Eriobotrya; Nitroprusside; Fruit
PubMed: 36901799
DOI: 10.3390/ijms24054369 -
Plant Disease Mar 2023American ginseng ( L.) is an herbaceous perennial understory plant. It was listed as endangered species by the Convention on International Trade in Endangered Species of...
American ginseng ( L.) is an herbaceous perennial understory plant. It was listed as endangered species by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (McGraw et al. 2013). Leaf spot symptoms were observed on 6-year-old cultivated American ginseng on a research plot (8 x 12 ft raised bed under a tree canopy) in Rutherford Co., TN in July 2021 (Fig. 1a). Symptomatic leaves were exhibiting light brown leaf spots with chlorotic haloes 0.5 to 0.8 cm in diameter, mostly confined within or bounded by veins. As the disease progressed, leaf spots expanded and coalesced into irregular shapes with necrotic centers, resulting in a tattered appearance of the leaf. Disease severity was about 50 to 80% of leaf area and incidence was 10% out of 20 plants. Plant tissues were surface sterilized with 10% NaOCl for 60s and washed thrice with sterile water and plated on potato dextrose agar (PDA). Colony growth of the isolates FBG880 and FBG881 on PDA were round, white, thick, and flocculent at the front of the plate and showed a yellowish-ringed shape on the back 10 days after incubation at 25°C (light/dark: 12/12h). Acervular conidiomata containing abundant conidia were observed on PDA. They were globose, 1.0 to 1.8 mm in diameter, and found as solitary or aggregated clusters. Conidia contained five cells (average 13.03±3.50 x 14.31±3.93 µm, = 30). The middle three cells were light brown to brown. The basal and apical cells were nearly triangular, and transparent, with two to three (7:3 ratios, respectively) apical appendages (average 13.27±3.27 µm) and a basal appendage (average 4.50±0.95 µm, = 30). To determine pathogen identity, total DNA was extracted using DNeasy PowerLyzer Microbial Kit from fungal colonies on PDA (isolates FBG880 and FBG881). The ribosomal internal transcribed spacer (ITS) region, beta-tubulin (BT), and translation elongation factors 1-α (EF1) genetic markers were amplified using ITS1/ITS4 (White et al. 1990), T1/T2 (Stefańczyk et al. 2016), and EF1/EF2 (O'Donnell et al. 1998), respectively. The sequences (GenBank accession nos. ITS: OQ102470 and OQ103415; BT: OQ107059 and OQ107061; and EF1: OQ107060 and OQ107062) are 100% similar to (CSUFTCC16 and CFCC53882) (Jiang et al. 2022; Li et al. 2021) (Fig. 2). Based on morphology and molecular characteristics, the isolates were identified as . To conduct the pathogenicity trial, six healthy 1-year-old American ginseng plants, germinated from seeds and grown in the greenhouse were spray inoculated with a conidial suspension (1×10 conidia/ml) (FBG880). Six control plants were sprayed with sterile water. All plants were covered with plastic bags and incubated in a greenhouse set at 21 to 23°C, 70% relative humidity and 16-h photoperiod. After 48 h, bags were removed and plants were maintained under the same conditions. After one month, while control plants remained asymptomatic (Fig. 1b), inoculated plants started to exhibit symptoms resembling those in the research plot (Fig. 1c). Fungal isolates resembling in cultural characters were consistently recovered from inoculated plants and their identity as was confirmed by DNA sequencing. To our knowledge, this is the first report of leaf spot disease caused by on American ginseng. Identification of this pathogen and confirmation of its pathogenicity are fundamental to future disease management approaches.
PubMed: 36890123
DOI: 10.1094/PDIS-01-23-0078-PDN -
Journal of Fungi (Basel, Switzerland) Feb 2023tolerates the dry and frigid climate of Beijing, China, and effectively filters out particles during the winter. However, fungal infestation frequently causes extreme...
tolerates the dry and frigid climate of Beijing, China, and effectively filters out particles during the winter. However, fungal infestation frequently causes extreme illness and can even lead to shrub death. In this study, 104 diseased specimens were collected from seven districts in Beijing. Seventy-nine isolates were identified as 22 fungal species in seven genera. The species were , , , , , , , , , , , , , , , , , , , , , and . On the basis of morphological and phylogenetic analyses, , , , and were introduced as novel species. , , and were subsequently confirmed as pathogens of leaves by pathogenicity testing. This study provides an important assessment of the fungi associated with diseases of in Beijing, China.
PubMed: 36836386
DOI: 10.3390/jof9020271 -
Doklady Biological Sciences :... Dec 2022European blueberry is a common plant in coniferous and mixed forests that grows in Russia, Northern Europe, Asia, United States, and Canada. Among the fungi that cause...
European blueberry is a common plant in coniferous and mixed forests that grows in Russia, Northern Europe, Asia, United States, and Canada. Among the fungi that cause blueberry diseases, the most harmful are Diaporthe vaccinii and Colletotrichum acutatum. These fungi are included in the consolidated list of quarantine objects of the Eurasian Economic Union and their occurrence and spread in the territory of countries of this Union is subject to strict control. Most taxa of micromycetes, particularly, Diaporthe and Colletotrichum species, can be correctly identified to the species level based on solely molecular phylogenetic features. The aim of the present work was to assess the biodiversity of fungi associated with blueberry growing in North-Western Russia and in Finland using morphological and molecular genetic features. Altogether, the study included 17 specimens of wild blueberry exhibiting necrotic spots on leaves and stem lesions that were collected in 2017 in St. Petersburg and in five districts of Leningrad region, as well as in the Republic of Karelia and in Finland. Analysis of the morphological and molecular genetic features of the fungal strains isolated from these blueberry specimens led to identification of 11 species: Boeremia exigua, Colletotrichum salicis, Diaporthe eres, Fusarium avenaceum, F. incarnatum, F. sporotrichioides, Heterophoma sylvatica, Kalmusia longispora, Microsphaeropsis olivacea, Neocucurbitaria cava, and Sporocadus rosigena. There were also fungi representing two sections of the genus Alternaria: Alternaria and Infectoriae, and micromycetes of the genera Chaetomium, Cladosporium, Coniothyrium, Curvularia, Epicoccum, Penicillium, Pestalotiopsis, Sordaria, and Trichoderma. The species Colletotrichum salicis, Heterophoma sylvatica, Kalmusia longispora, Microsphaeropsis olivacea, and Neocucurbitaria cava were for the first time found in Russia. The species Sporocadus rosigena was for the first time detected in Finland. Fusarium avenaceum, F. incarnatum, and F. sporotrichioides were for the first time observed in association with blueberry plants. The species Diaporthe vaccinii and Colletotrichum acutatum included in the consolidated list of quarantine objects of the Eurasian Economic Union were not detected in this study.
Topics: Blueberry Plants; Phylogeny; Finland; Biodiversity
PubMed: 36781539
DOI: 10.1134/S0012496622060047 -
Taxonomic Advances from Fungal Flora Associated with Ferns and Fern-like Hosts in Northern Thailand.Plants (Basel, Switzerland) Feb 2023Ferns are one of the most significant plant groupings that comprise a substantial proportion of the plant flora due to the fact of their great diversity, especially in...
Ferns are one of the most significant plant groupings that comprise a substantial proportion of the plant flora due to the fact of their great diversity, especially in tropical areas. The biodiversity of fungi associated with ferns and fern-like hosts has also received little attention in studies. Plant samples were collected from diseased and dead plants of ten fern or fern-like species from Chiang Rai in northern Thailand. Forty-one isolates were selected from the obtained isolates for molecular and morphological analysis, with a focus on pathogenic fungal genera and consideration of the diversity in host and geographical location. Twenty-six species belonging to seven genera (, , , , , , and ) in six families were identified. Thirty new hosts, eight new geographical hosts, and one new species, , are described. , , , , and were isolated for the first time from leaf spots. Additionally, new reservoirs and geographical locations for species previously isolated from leaf spots or whose pathogenicity was established were found. However, more studies are necessary to prove the pathogenicity of the fungi isolated from the leaf spots and to identify the fungi associated with other species of ferns.
PubMed: 36771768
DOI: 10.3390/plants12030683 -
Plants (Basel, Switzerland) Feb 2023Multidrug-resistant bacteria such as (MRSA) cause infections that are difficult to treat globally, even with current available antibiotics. Therefore, there is an...
Multidrug-resistant bacteria such as (MRSA) cause infections that are difficult to treat globally, even with current available antibiotics. Therefore, there is an urgent need to search for novel antibiotics to tackle this problem. Endophytes are a potential source of novel bioactive compounds; however, the harnessing of novel pharmacological compounds from endophytes is infinite. Therefore, this study was designed to identify endophytic fungi (from ) with antibacterial activity against multidrug-resistant bacteria. Using fungal morphology and ITS-rDNA, endophytic fungi with antibacterial activities were isolated from . The results of the ITS rDNA sequence analysis showed that a total of 124 morphotype strains were identified. In addition, Species richness (, 52), Margalef index (, 7.3337), Shannon-Wiener index (,3.6745), and Simpson's diversity index (, 0.9304) showed that have abundant endophytic fungi resources. Furthermore, the results of the agar well diffusion showed that the , , and endophytic fungi's ethyl acetate extracts showed moderate antibacterial and bactericidal activities, against methicillin-resistant (MRSA) SMU3194, with a MIC of 0.5-1 mg/mL and a MBC of 1-2 mg/mL. In summary, contains endophytic fungi resources that can be pharmacologically utilized, especially as antibacterial drugs.
PubMed: 36771733
DOI: 10.3390/plants12030650 -
Journal of Experimental Botany Mar 2023Microorganisms associated with the phyllosphere play a crucial role in protecting plants from diseases, and their composition and diversity are strongly influenced by...
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.
Topics: Cadmium; Populus; Soil; Metals, Heavy; Microbiota; Fungi
PubMed: 36738293
DOI: 10.1093/jxb/erad034