Search

Lychee pepper spot, a field disease affecting lychee fruit skin, pedicels and petioles, is caused by Colletotrichum siamense, a fungal pathogen within the gloeosporioides species complex. Members of Colletotrichum from the gloeosporioides species complex and occasionally those from the acutatum species complex also cause postharvest anthracnose of lychee. Pepper spot was first described in Australia many years after anthracnose on lychee was first described, giving rise to the hypothesis that a novel species or strain within the gloeosporioides species complex causes pepper spot. In the present study, 19 isolates of Colletotrichum spp., collected from pepper spot and anthracnose symptoms on lychee fruit, representing 13 different genotypes across five species, were inoculated onto lychee fruit in the field or on detached fruit in the laboratory, to understand more about their pathogenic diversity. We found that symptoms were specific to genotype of the pathogen, as three genetically similar isolates of C. siamense consistently caused pepper spot and anthracnose, whilst other isolates caused anthracnose only. Cross‐inoculation studies on detached fruit of lychee, banana, avocado and mango also provided some evidence of host specialization in isolates of C. siamense infecting lychee in Australia. Our experiments provided further evidence that detached fruit assays cannot be used as a reliable proxy for field inoculation studies. This research confirms that C. siamense is a causal agent of both lychee pepper spot and lychee anthracnose in Australia, and Colletotrichum alienum and Colletotrichum queenslandicum are reported as causal agents of anthracnose of lychee for the first time. [ABSTRACT FROM AUTHOR]

Natural rubber is an important national strategic and industrial raw material. The leaf anthracnose of rubber trees caused by the Colletotrichum species is one of the important factors restricting the yields of natural rubber. In this study, we isolated and identified strain Bacillus velezensis SF334, which exhibited significant antagonistic activity against both C. australisinense and C. siamense, the dominant species of Colletotrichum causing rubber tree leaf anthracnose in the Hainan province of China, from a pool of 223 bacterial strains. The cell suspensions of SF334 had a significant prevention effect for the leaf anthracnose of rubber trees, with an efficacy of 79.67% against C. siamense and 71.8% against C. australisinense. We demonstrated that SF334 can lead to the lysis of C. australisinense and C. siamense mycelia by causing mycelial expansion, resulting in mycelial rupture and subsequent death. B. velezensis SF334 also harbors some plant probiotic traits, such as secreting siderophore, protease, cellulase, pectinase, and the auxin of indole-3-acetic acid (IAA), and it has broad-spectrum antifungal activity against some important plant pathogenic fungi. The genome combined with comparative genomic analyses indicated that SF334 possesses most genes of the central metabolic and gene clusters of secondary metabolites in B. velezensis strains. To our knowledge, this is the first time a Bacillus velezensis strain has been reported as a promising biocontrol agent against the leaf anthracnose of rubber trees caused by C. siamense and C. australisinense. The results suggest that B. velezensis could be a potential candidate agent for the leaf anthracnose of rubber trees. [ABSTRACT FROM AUTHOR]

Plasma membrane H+-ATPases (PMAs) play an important role in the pathogenicity of pathogenic fungi. Lipid droplets are important storage sites for neutral lipids in fungal conidia and hyphae and can be used by plant pathogenic fungi for infection. However, the relationship between plasma membrane H+-ATPase, lipid droplets and virulence remains unclear. Here, we characterized a plasma membrane H+-ATPase, CsPMA2, that plays a key role in lipid droplet formation, appresorial development and virulence in C. siamense. Deletion of CsPMA2 impaired C. siamense conidial size, conidial germination, appressorial development and virulence but did not affect hyphal growth. ΔCsPMA2 increased the sensitivity of C. siamense to phytic acid and oxalic acid. CsPMA2 was localized to lipids on the plasma membrane and intracellular membrane. Deletion of CsPMA2 significantly inhibited the accumulation of lipid droplets and significantly affected the contents of some species of lipids, including 12 species with decreased lipid contents and 3 species with increased lipid contents. Furthermore, low pH can inhibit CsPMA2 expression and lipid droplet accumulation. Overall, our data revealed that the plasma membrane H+-ATPase CsPMA2 is involved in the regulation of lipid droplet formation and affects appressorial development and virulence in C. siamense. [ABSTRACT FROM AUTHOR]

Colletotrichum siamense is a hemibiotrophic ascomycetous fungus responsible for mango anthracnose. The key genes involved in C. siamense infection remained largely unknown. In this study, we conducted weighted gene co-expression network analysis (WGCNA) of RNA-seq data to mine key genes involved in Colletotrichum siamense-mango interactions. Gene modules of Turquoise and Salmon, containing 1039 and 139 respectively, were associated with C. siamense infection, which were conducted for further analysis. GO enrichment analysis revealed that protein synthesis, organonitrogen compound biosynthetic and metabolic process, and endoplasmic reticulum-related genes were associated with C. siamense infection. A total of 568 proteins had homologs in the PHI database, 370 of which were related to virulence. The hub genes in each module were identified, which were annotated as O-methyltransferase (Salmon) and Clock-controlled protein 6 (Turquoise). A total of 24 proteins exhibited characteristics of SCRPs. By using transient expression in Nicotiana benthamiana, the SCRPs of XM_036637681.1 could inhibit programmed cell death (PCD) that induced by BAX (BCL-2-associated X protein), suggesting that it may play important roles in C. siamense infection. A mango-C. siamense co-expression network was constructed, and the mango gene of XM_044632979.1 (auxin-induced protein 15A-like) was positively associated with 5 SCRPs. These findings help to deepen the current understanding of necrotrophic stage in C. siamense infection. [ABSTRACT FROM AUTHOR]

Onion (Allium cepa L.) is an important crop widely cultivated in the Philippines. In the Philippines, Colletotrichum gloeosporioides sensu lato and C. circinans have been reported to cause anthracnose twister disease and onion smudge, respectively. This study reports C. siamense from anthracnose‐infected onion bulbs. The fungus was identified using morpho‐cultural characterization and multi‐locus analyses of the nuclear ribosomal internal transcribed spacer with 5.8S region (ITS) glyceraldehyde‐3‐phosphate dehydrogenase gene (GAPDH) and beta‐tubulin (TUB2). Koch's postulates were established in pathogenicity assays where the fungus caused diseases in wounded and non‐wounded onion bulbs. This study is the first scientific report of C. siamense as a post‐harvest anthracnose pathogen of onion bulbs in the Philippines. [ABSTRACT FROM AUTHOR]

Viburnum odoratissimum Ker-Gawl is native to Asia and is usually used as a garden ornamental. In September 2022, a leaf blotch on V. odoratissimum was observed in Nanjing, Jiangsu, China. The disease causes the leaves of the plants to curl and dry up and defoliate early. It not only seriously affects the growth of the plants but also greatly reduces the ornamental value. The pathogenic fungus was isolated from the diseased leaves, and the fungus was identified to be Colletotrichum siamense based on morphological features and multilocus phylogenetic analyses of the internal transcribed spacer (ITS) region, actin (ACT), calmodulin (CAL), beta-tubulin 2 (TUB2), chitin synthase (CHS-1), Apn2-Mat1-2 intergenic spacer and partial mating type (ApMat), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes. Pathogenicity tests were performed by inoculating healthy leaves with conidia. C. siamense can grow at 15–35 °C, with an optimal growth temperature at 25–30 °C. The results of sensitivity to nine fungicides showed that C. siamense was the most sensitive to prochloraz in the concentration range of 0.01 μg/mL to 100 μg/mL. Therefore, spraying prochloraz before the optimum growth temperature of pathogenic fungus can achieve effective control. It provided useful information for future studies on the prevention and treatment strategies of C. siamense. This is the first report of leaf blotch caused by C. siamense on V. odoratissimum in China and worldwide. [ABSTRACT FROM AUTHOR]

Rambutan (Nephelium lappaceum) is an important fruit tree. Recently, leaf spots were observed in a tree in Los Baños, Laguna, Philippines. This study aims to identify the causal agent of rambutan leaf spot in the Philippines. Two fungal isolates, MBRAM001B and MBRAM003B, were isolated from the diseased leaves on potato dextrose agar medium. Colony growth and conidia characteristics of both isolates showed high resemblance with Colletotrichum species in the C. gloeosporioides species complex. Molecular characterisation of the isolates using the partial internal transcribed spacer rDNA and TUB2 regions identified the pathogens as C. tropicale MBRAM001B and C. siamense MBRAM003B. Leaf spots developed on rambutan leaves three days after inoculation and the same pathogens were isolated from the diseased leaves, establishing Koch's Postulate. In conclusion, this study identified C. tropicale MBRAM001B and C. siamense MBRAM003B as causal agents of leaf spots in rambutan species in the Philippines. The survival and possible infection of these two Colletotrichum species on rambutan fruits and other fruit trees are worth further investigating. [ABSTRACT FROM AUTHOR]

Colletotrichum siamense causes rubber tree anthracnose and significant losses for the natural rubber industry. Here, actinomycete strains YQ-33, QZ-9 and WZ-2 were isolated, found to have high antagonistic activity against C. siamense and preliminarily identified as Streptomyces sp. Millet broth was the optimal medium for all strains to produce antifungal metabolites against C. siamense, and the millet broth culture filtrate from each strais greatly inhibited conidial germination and appressorial formation of C. siamense. Of the three strains, QZ-9 had relatively broad antifungal activity; its culture filtrate provided inhibition rates over 80% against mycelial growth of seven plant pathogenic fungi. Culture filtrates of QZ-9 and WZ-2 also reduced lesion size on rubber tree leaves and are promising candidates for control of rubber anthracnose. [ABSTRACT FROM AUTHOR]

Previous studies have shown that the high-osmolarity glycerol mitogen-activated protein kinase (HOG MAPK) signaling pathway and its downstream transcription factor CsAtf1 are involved in the regulation of fludioxonil sensitivity in C. siamense. However, the downstream target genes of CsAtf1 related to the fludioxonil stress response remain unclear. Here, we performed chromatin immunoprecipitation sequencing (ChIP-Seq) and high-throughput RNA-sequencing (RNA-Seq) to identify genome-wide potential CsAtf1 target genes. A total of 3809 significantly differentially expressed genes were predicted to be directly regulated by CsAtf1, including 24 cytochrome oxidase-related genes. Among them, a cytochrome P450-encoding gene, designated CsCyp51G1, was confirmed to be a target gene, and its transcriptional expression was negatively regulated by CsAtf1, as determined using an electrophoretic mobility shift assay (EMSA), a yeast one-hybrid (Y1H) assay, and quantitative real-time PCR (qRT-PCR). Moreover, the overexpression mutant CsCYP51G1 of C. siamense exhibited increased fludioxonil tolerance, and the CsCYP51G1 deletion mutant exhibited decreased fludioxonil resistance, which revealed that CsCyp51G1 is involved in fludioxonil sensitivity regulation in C. siamense. However, the cellular ergosterol content of the mutants was not consistent with the phenotype of fludioxonil sensitivity, which indicated that CsCyp51G1 regulates fludioxonil sensitivity by affecting factors other than the ergosterol level in C. siamense. In conclusion, our data indicate that the transcription factor CsAtf1 negatively regulates the cytochrome P450 gene CsCyp51G1 to increase fludioxonil sensitivity in C. siamense. [ABSTRACT FROM AUTHOR]

Previous studies of the lipid droplet-coating protein Cap20 in Colletotrichum show that it plays a key role in appressorium development and virulence. In this study, the hydrophobin CsHydr1, which contains a signal peptide of 19 amino acids and a hydrophobic domain (HYDRO), was shown to interact with CsCap20 in Colletotrichum siamense. The CsHydr1 deletion mutant showed slightly enhanced mycelial growth, small conidia, slow spore germination and appressoria formation, cell wall integrity and virulence. Like CsCAP20, CsHydr1 is also localized on the lipid droplet surface of C. siamense. However, when CsCap20 was absent, some CsHydr1 was observed in other parts. Quantitative lipid determination showed that the absence of either CsHydr1 or CsCap20 reduced the content of lipids in mycelia and conidia, while the effect of CsCap20 was more obvious; these results suggest that an interaction protein CsHydr1 of CsCap20 is localized on the lipid droplet surface and involved in lipid metabolism, which affects appressorium formation and virulence in C. siamense. [ABSTRACT FROM AUTHOR]

The HOG MAPK pathway mediates diverse cellular and physiological processes, including osmoregulation and fungicide sensitivity, in phytopathogenic fungi. However, the molecular mechanisms underlying HOG MAPK pathway-associated stress homeostasis and pathophysiological developmental events are poorly understood. Here, we demonstrated that the oxalate decarboxylase CsOxdC3 in Colletotrichum siamense interacts with the protein kinase kinase CsPbs2, a component of the HOG MAPK pathway. The expression of the CsOxdC3 gene was significantly suppressed in response to phenylpyrrole and tebuconazole fungicide treatments, while that of CsPbs2 was upregulated by phenylpyrrole and not affected by tebuconazole. We showed that targeted gene deletion of CsOxdC3 suppressed mycelial growth, reduced conidial length, and triggered a marginal reduction in the sporulation characteristics of the Δ CsOxdC3 strains. Interestingly, the Δ CsOxdC3 strain was significantly sensitive to fungicides, including phenylpyrrole and tebuconazole, while the CsPbs2 -defective strain was sensitive to tebuconazole but resistant to phenylpyrrole. Additionally, infection assessment revealed a significant reduction in the virulence of the Δ CsOxdC3 strains when inoculated on the leaves of rubber tree (Hevea brasiliensis). From these observations, we inferred that CsOxdC3 crucially modulates HOG MAPK pathway-dependent processes, including morphogenesis, stress homeostasis, fungicide resistance, and virulence, in C. siamense by facilitating direct physical interactions with CsPbs2. This study provides insights into the molecular regulators of the HOG MAPK pathway and underscores the potential of deploying OxdCs as potent targets for developing fungicides. [ABSTRACT FROM AUTHOR]

In August 2020, a new fungal disease was observed on strawberry in Shandong Province, which showed that small spots of grayish‐black, near round without lesions and haloes on the adaxial of strawberry leaves. The morphological features of colonies and conida on PDA medium were consistent with Colletotrichum gloeosporioides species complex. The rDNA internal transcribed spacer, calmodulin, chitin synthase, and actin from the isolates were amplified and sequenced. BLAST analysis of these four genes showed 99.24‐100.00% identity with the corresponding sequences of C. siamense in GenBank. The result of phylogenetic analysis also indicated that the pathogen was identified as C. siamense. Similar symptoms were observed on the back of strawberry leaf after spraying conidial suspensions for 3 days, and C. siamense was reisolated which confirm the Koch's rule. This is the first report of new disease of black leaf spot on strawberry caused by C. siamense. [ABSTRACT FROM AUTHOR]

Crown rot (Colletotrichum siamense) of strawberry is a severe disease in Jingzhou, Hubei Province, China. Pathogen identification is the basis for disease prevention and resistance breeding. Nearly fifty isolates were achieved from 192 crown rot samples in this study. A number of 21 isolates were characterized as the pathogen of crown rot of strawberry by Koch’s postulates, and they were identified as Colletotrichum spp. by conidia morphology observation. The 21 isolates were divided into three groups based on colony morphology, and SCR-7, SCR-11 and SCR-16 belonged to each group were clustered into one group with C. siamense isolates by phylogenetic analysis of actin, β-Tubulin 2 and calmodulin sequences. In addition, the isolates of C. siamense SCR-7 showed the strongest pathogenicity of the three which caused highest values of lesion length and leaf temperature, and lowest leaf water content, photosynthetic rate, stomatal conductivity and even transpiration rate values. This study contributes to updating the Colletotrichum species associated with strawberry of China. [ABSTRACT FROM AUTHOR]

Areca palm, rubber tree, and coffee are always planted adjacent to each other or intercropped with each other, and Colletotrichum siamense was found to be the dominant species of Colletotrichum from these crops in Hainan, China. To study the population structure, pathogenicity, and fungicide sensitivity of C. siamense from these three crops in Hainan, isolates were first identified by their morphological characteristics and multilocus phylogeny. Then both permutational multivariate analysis of variance (PERMANOVA) and pairwise FST analysis showed that the original host and geographical origin (counties) had significant effects on genetic variation in the C. siamense population, explaining 5.6% and 16.3% of genetic variation, respectively. There were significant genetic differentiations between coffee and rubber tree populations but the genetic differentiation was small (FST = 0.04), while significant differentiations were observed among all populations from different counties except those between Haikou and Chengmai. Pathogenicity analysis using artificial inoculation showed that isolates had significantly higher disease incidence and diseased lesion diameter on wounded leaves than on nonwounded leaves. However, the original host of an isolate and geographical origin did not significantly affect the pathogenicity of the C. siamense populations from these three hosts. In vitro tests showed that there were no significant differences in the sensitivity of C. siamense populations to carbendazim, prochloraz, difenoconazole, and propiconazole from different original hosts and geographical origins. The present study suggests that host specialization of C. siamense has not occurred yet in coffee, rubber tree, and areca palm. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amino acid polymorphisms in SDH of Colletotrichum siamense impact susceptibility to SDHIs. • Double mutations (W85L and T86N) in SDHC reduce fitness and sensitivity to penthiopyrad. • Molecular docking reveals specific interactions between penthiopyrad and SDH residues. • SDHC polymorphisms arise from natural evolution, posing challenges for SDHI use in rubber plantations. Among succinate dehydrogenase inhibiter (SDHI) fungicides, penthiopyrad and benzovindiflupyr particularly inhibit Colletotrichum. Studying SDH amino acid polymorphism in Colletotrichum , along with its fungicide binding sites, is key to understanding their mechanisms of action. This study explores the SDH amino acid polymorphisms in Colletotrichum siamense strains from rubber trees in China and their interaction with SDHI fungicides, specifically penthiopyrad and benzovindiflupyr. Sequencing revealed most polymorphisms were in the SDHC subunit, particularly at positions 85 and 86, which are key to penthiopyrad resistance. Among 33 isolates, 33.3 % exhibited a substitution at position 85, and 9 % at position 86. A strain with W85L and T86N substitutions in SDHC showed reduced SDH activity, ATP content, mycelial growth, and virulence, and decreased sensitivity to penthiopyrad but not benzovindiflupyr. Molecular docking with Alphafold2 modeling suggested distinct binding modes of the two fungicides to C. siamense SDH. These findings underscore the importance of SDHC polymorphisms in C. siamense 's fitness and sensitivity to SDHIs, enhancing our understanding of pathogen-SDHI interactions and aiding the development of novel SDHI fungicides. [ABSTRACT FROM AUTHOR]

Sterculia lanceolata, an important tropical woody plant, has high ornamental and medicinal value. To our knowledge, only brown root disease in this plant has been reported. In Nanning, Guangxi, China, an outbreak of leaf blight disease was observed on S. lanceolata in June 2019, with the leaf infection rate ranging from 80% to 100%. The disease seriously affected the leaves of trees and caused economic loss. Eight isolates were recovered from the infected leaves of different trees, and the pathogenicity was then determined by the methods of mycelial disc and conidial suspension, fulfilling Koch's postulates. According to the morphological and molecular biological characteristics of isolates, the pathogen causing leaf blight on S. lanceolata was identified as Colletotrichum siamense. Accurate identification of the pathogen provides a reliable basis for the control of the disease. [ABSTRACT FROM AUTHOR]

Pomegranate is a fruit rich in vitamins and secondary metabolites used in traditional medicine and industry. However, production losses have been associated the anthracnose, disease caused by Colletotrichum species. This is an important disease of the pomegranate, as it affects the yield and the quality of the fruits. The present study aimed to investigate which species of Colletotrichum are associated with anthracnose disease in pomegranate in the Northeast region of Brazil, using multi-locus phylogenetic analysis and morpho-cultural characteristics. The total DNA extracted was amplified with GAPDH, TUB2, CAL, ACT genes and the ITS-rDNA region. The sequences obtained were used for the construction of phylogenetic trees of Bayesian inference. The mycelial growth rate, size and shape of the conidia and appressories were evaluated for the morpho-cultural characterization of the species. Six isolates were analysis and three species belonging to the C. gloeosporioides complex were identified in this study. This is the first report of C. theobromicola (2) in pomegranate fruit in Brazil and C. siamense (2) and C. fructicola (2) in the world. [ABSTRACT FROM AUTHOR]

Aims: Amorphophallus konjac is an important commercial crop grown in China because it is the only plant species which is rich in glucomannan concentration. Recently, an outbreak of anthracnose (incidence ranging from 10–15%) was observed in a field survey conducted from June to August 2018. This study aims to identify the causal agent of A. konjac anthracnose. Methods and Results: The pathogen was isolated on potato dextrose agar (PDA) medium. The fungal colony on PDA was greyish to dark grey. Conidia were falcate, one‐celled and hyaline. Based on the micro‐morphological and cultural characteristics, the pathogen was identified as Colletotrichum sp. blast search and phylogenetic analysis of the ITS, GAPDH, CHS1, ACT, CAL and TUB2 genes revealed the pathogen as Colletotrichum siamense. Koch's postulates were conducted on 2‐month konjac leaves with conidial suspension. Development of typical anthracnose disease was recorded 5 days after inoculation and the pathogen's identity was confirmed by re‐isolation and molecular identification. Conclusions: Amorphophallus konjac anthracnose was caused by C. siamense in China. Significance and Impact of the Study: Identification of causal agent of A. konjac anthracnose will be helpful in designing effective disease control strategies. [ABSTRACT FROM AUTHOR]

Litchi (Litchi chinensis) pepper spot disease results in black spotting symptoms on litchi fruits. This disease was first observed on litchi cultivar Guiwei, in Guangzhou, China, in 2009, and then found widespread in other litchi‐growing regions of China. Colletotrichum isolates were consistently recovered from typical black spot lesions of diseased fruits with frequency ranging from 83% to 100%. Three representative Colletotrichum isolates from Maoming, Guangzhou and Shenzhen were selected for identification and pathogenicity testing in the field. Based on morphology and phylogenetic analysis using the ribosomal internal transcribed spacer region (ITS), glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), calmodulin (CAL), actin (ACT), β‐tubulin (TUB2) and glutamine synthetase (GS) gene sequences, the three isolates were identified as C. siamense. In the pathogenicity experiments, typical symptoms appeared on the inoculated litchi fruits, including black spots and green patches around these black spots. These symptoms were consistent with the symptoms originally observed in the field. Colletotrichum siamense was successfully reisolated from the typical black spot lesions of the inoculated litchi fruits. To the authors' knowledge, this is the first report on characterization of C. siamense as the causal agent of litchi pepper spot disease in mainland China by successful inoculation on fruits under field conditions. [ABSTRACT FROM AUTHOR]

The Zn 2 Cys 6 transcription factor is a fungal-specific zinc finger protein, which plays an important role in regulating growth, development and pathogenicity of pathogenic fungi. In this study, we characterized two Zn 2 Cys 6 transcription factors, CsGcc1 and CgrGcc1 in Colletotrichum siamense and C. graminicola , respectively, which are homologous to Gcc1 in Magnaporthe oryzae. Both CsGcc1 and CgrGcc1 contain a typical GAL4 DNA-binding domain. Deletion of CsGCC1 or CgrGCC1 decreased the growth rate and lowered the tolerance to H 2 O 2. In addition, disrupting CsGCC1 reduced conidial yield and lowered the germination rate and appressorium formation rate of C. siamense. Cellophane assays showed that deletion of CsGCC1 also weakened the penetration ability of appressoria. In C. graminicola , CgrGcc1 did not affect the production and germination of oval conidia, but its deletion significantly decreased the yield of the falcate conidium, and led to abnormal appressorium formation. In terms of pathogenicity, CsGcc1 slightly reduced the virulence of C. siamense , while deleting CgrGcc1 did not affect virulence of C. graminicola. In conclusion, the Zn2Cys6 transcription factors CsGcc1 and CgrGcc1 are involved in the regulation of vegetative growth, oxidative stress, conidial/falcate conidial production and appressorium formation in C. siamense and C. graminicola. • The homologs of the Zn 2 Cys 6 transcription factor Gcc1 were characterized in Colletotrichum siamense and C. graminicola. • CsGcc1 regulates growth, oxidative stress, conidial production, appressorium formation and pathogenicity of C. siamense. • CgrGcc1 governs growth, oxidative stress, falcate conidial production and appressorium formation of C. graminicola. [ABSTRACT FROM AUTHOR]

Bitter rot caused by the fungal genus Colletotrichum is a well-known, common disease of apple and causes significant yield loss. In 2013, six fungal strains were isolated from Fuji apple fruits exhibiting symptoms of bitter rot from Andong, Korea. These strains were identified as Colletotrichum fructicola and C. siamense based on morphological characteristics and multilocus sequence analysis of the internal transcribed spacer rDNA, actin, calmodulin, chitin synthase, and glyceraldehyde-3-phosphate dehydrogenase Pathogenicity tests confirmed the involvement of C. fructicola and C. siamense in the development of disease symptoms on apple fruits. This is the first report of C. fructicola and C. siamense causing bitter rot on apple fruit in Korea. [ABSTRACT FROM AUTHOR]

Plant endophytic fungi have been recognized as an important and a good source of natural bioactive products with potential application in agriculture, medicine and food industry. Chemical and biological studies of fungal metabolites originating from endophytic fungi isolated in Sri Lanka are relatively less studied. Therefore we investigated the chemistry and bioactivity of endophytic fungi present in leaves ofPiper nigrumL. (black pepper) of the family Piperaceae famed as the spices king due to its pungent quality. A fungal endophyte isolated from the leaves ofP. nigrumwas identified asColletotrichum siamensethrough molecular biological means using internal transcribed spacer (ITS) region of rDNA gene. This is the first report of the isolation ofC. siamensefrom Piperaceae. The fungus was fermented in potato dextrose media and the fungal media were extracted with EtOAc. Chromatographic separation of the EtOAc extract over silica gel, Sephadex LH-20 and preparative thin layer chromatography furnished indole-3-acetic acid (IAA) and uracil. IAA showed high antifungal activity against the common plant pathogenic fungusCladosporium cladosporiodiesby TLC bioautography method and antioxidant activity against DPPH radical by spectrophotometry method. [ABSTRACT FROM PUBLISHER]

Colletotrichum siamense , a member of Colletotrichum gloeosporioides complex species, is the primary pathogen causing rubber anthracnose, which leads to significant economic loss in natural rubber production. Velvet family proteins are fungal-specific proteins and play an essential role in regulating development and secondary metabolism. In this study, we characterized two velvet proteins CsVosA and CsVelB in C. siamense as the orthologs of VosA and VelB in Aspergillus nidulans. CsVosA is located in the nucleus, and CsVelB displays a localization in both the nucleus and the cytoplasm. Deleting CsvosA or CsvelB results in a slow growth rate, and the CsvelB-knockout mutants also exhibit low mycelial density. CsVosA and CsVelB are involved in regulating chitin metabolism and distribution, leading to the variation in the cell wall integrity of C. siamense. Furthermore, disruption of CsvosA or CsvelB can decrease conidial production and viability, and the Δ CsvosA and Δ CsvelB mutants also lose the ability to produce fruiting bodies. Pathogenicity assays show that deleting CsvosA or CsvelB can lower the virulence, and the two velvet genes are essential for the full virulence of C. siamense. Based on the results of the yeast two-hybrid analysis and bimolecular fluorescence complementation assays, CsVosA can interact with CsVelB and form the complex CsVosA-CsVelB in the conidia of C. siamense , which may play essential roles in maintaining the cell wall integrity and conidial viability. In addition, CsVelB is also involved in regulating melanin production of C. siamense. In conclusion, CsVosA and CsVelB regulate vegetative growth, cell wall integrity, asexual/sexual sporulation, conidial viability and virulence in C. siamense. [ABSTRACT FROM AUTHOR]

Apple trees encounter problems such as stressful environments and pathogen infection throughout their entire growth and development, which limits apple production. WRKY transcription factors play a vital role in the defense against pathogens, but their functions in apple trees need to be further explored. In this study, the MdWRKY61 gene, which encodes the WRKY61 protein of the WRKY group II family, was isolated from GL-3 apple. Tobacco subcellular localization experiments showed that the MdWRKY61 protein is located in the nucleus. Quantitative reverse transcription PCR analysis suggested that MdWRKY61 is highly expressed in the roots and fruits of apples and is rapidly induced in response to salicylic acid, jasmonic acid and Colletotrichum siamense. We obtained MdWRKY61 overexpression lines through Agrobacterium -mediated stable genetic transformation of apple. Subsequent experiments revealed that overexpression of MdWRKY61 increased the resistance of apple to Colletotrichum siamense and promoted the upregulation of defense-related gene expression. Taken together, our data provide insights that MdWRKY61 plays an important role in apple resistance to fungal disease. • First research on the function of MdWRKY61. • MdWRKY61 was induced by Colletotrichum siamense , SA and JA. • MdWRKY61 can improve the resistance of apples to Colletotrichum siamense. [ABSTRACT FROM AUTHOR]

• CsAtf1 affects the regulation of fludioxonil resistance. • CsAtf1 deletion attenuates the virulence of C. siamense. • CsAtf1 deletion mutants showed slightly retarded mycelial growth, small conidia, slow spore germination, and abnormal appressorium formation. In phytopathogenic fungi, the HOG MAPK pathway has roles in osmoregulation, fungicide sensitivity, and other processes. The ATF1/CREB-activating transcription factor Atf1 is a regulator that functions downstream of the HOG MAPK pathway. Here, we identified a gene, designated CsAtf1 , that encodes a bZIP transcription factor in Colletotrichum siamense , which is the main pathogen that causes Colletotrichum leaf fall disease in rubber trees in China. CsAtf1 localizes to the nucleus. Its mRNA expression correlates positively with that of CsPbs2 and CsHog1 in the HOG MAPK pathway in response to activator (anisomycin), inhibitor (SB203580) and fludioxonil treatments. The CsAtf1 deletion mutant showed slightly retarded mycelial growth, small conidia, slow spore germination, and abnormal appressorium formation. This mutant showed the increased spore germination rate after fludioxonil treatment and more resistance to the fungicide fludioxonil than did the wild-type fungus. However, unlike deletion of Pbs2 or Hog1 , which resulted in greater sensitivity to osmotic stress, the CsAtf1 deletion induced slightly increased resistance to osmotic stress and the cell wall stress response. The ΔCsAtf1 strain also exhibited significantly reduced virulence on rubber tree leaves. These data revealed that CsAtf1 plays a key role in the regulation of fludioxonil sensitivity and in pathogenicity regulation in C. siamense. [ABSTRACT FROM AUTHOR]

The tridax daisy (Tridax procumbens) is a predominant weed in Thai plantations. Management of weeds in the country, both past and present, heavily relies on the use of synthetic herbicides. Here, we demonstrate the use of a phytopathogen for controlling this weed. The fungus Colletotrichum siamense isolate Cs1 was isolated from a diseased false daisy (Eclipta prostrata). Topical application of a conidial suspension of this fungus on Tridax procumbens plants led to 78–100% disease incidence on days 14–18 post-inoculation. Similar testing in the laboratory and greenhouse settings showed that C. siamense isolate Cs1 was non-pathogenic to cassava (Manihot esculenta) and eight other crops. Fluorescence microscopy of green fluorescent protein-expressing C. siamense indicated that the conidia germinated and formed appressoria for penetration on days 1–7 post-inoculation. Scanning electron microscopy showed hyphae growing on the leaf surface as well as invading the host through stomata. Trichomes of weed leaves served as important infection sites for this myco-pathogen. Oval conidia and pseudohyphae were detected inside the leaf trichomes, indicating that these cell types could help spread the fungus throughout the weed. C. siamense sporulated at high rates, at 1.7 × 1010 conidia/g, on a rice-oat mixture, suggesting a potential production recipe for commercialization. These data suggest that this weed-pathogenic fungus has potential as a bioherbicide for biological control of this weed. • Colletotrichum siamense is a mycopathogen of the weed tridax daisy. • C. siamense shows no or low pathogenic effect on 10 important crops. • The fungus can infect the weed through leaf trichomes and stomata. • Oval conidia and pseudohyphae help disperse the fungus in planta. • The fungus sporulates at high rates on rice mixed with oat. [ABSTRACT FROM AUTHOR]

Colletotrichum is an important fungal plant pathogen, yet an uncommon cause of human disease. Herein we report a case of invasive, cutaneous infection in a stem cell transplant recipient due to Colletotrichum species, with accompanying review of the literature. The infection was successfully treated with a combination of liposomal amphotericin B and voriconazole. Multilocus phylogenetic analysis revealed that the distinct isolate belongs to Colletotrichum siamense, a member of the Colletotrichum gloeosporioides species complex not previously described as a human pathogen. Colletotrichum infection remains in the differential for skin lesions in the immune compromised host. [ABSTRACT FROM AUTHOR]