Cornus officinalis is a valuable traditional Chinese medicinal (TCM) plant species with both therapeutic and ornamental attributes. It is widely used in TCM prescriptions to nourish the liver and kidneys and constitutes a critical component of numerous classical formulas. In recent years, the large-scale cultivation of this medicinal plant has been expanded in Xixia County, Henan Province, China. Field investigations have revealed widespread brown leaf spot, accompanied by reductions in yield and quality. In this study, symptomatic leaves were collected for pathogen isolation. Tissue isolations consistently yielded a Colletotrichum fungus, and morphology combined with multi-locus phylogenetic analyses (the internal transcribed spacer, glyceraldehyde-3-phosphate dehydrogenase, chitin synthase, actin, and β-tubulin) identified the pathogen as Colletotrichum siamense. Pathogenicity assays (conducted by either wounding and inoculating detached leaves with a mycelium plug or spraying a conidium suspension on healthy potted plants) reproduced field symptoms, and the pathogen was re-isolated, thereby fulfilling Koch’s postulates. In vitro fungicide assays showed that carbendazim, tebuconazole, and prochloraz were highly effective against the pathogen, providing preliminary information for chemical management. This is the first documentation of C. siamense causing leaf anthracnose on C. officinalis and provides a basis for developing targeted control strategies to mitigate disease impacts and preserve yield and quality.

Fungal diseases pose significant threats to forestry species such as Tectona grandis (teak), as well as other important forestry and agricultural crops, highlighting the need for early and accurate identification of fungal spores, which serve as primary agents of dissemination and infection. Although Artificial Intelligence (AI) has enabled automated spore recognition, its effectiveness depends on the availability of large, diverse, and well-annotated datasets. However, publicly available datasets targeting fungal taxa associated with commercially valuable timber species remain scarce. To address this gap, we introduce a microscopic image dataset of fungal spores isolated from symptomatic teak foliage, including Olivea tectonae, Colletotrichum siamense, and Neopestalotiopsis sp. The dataset was developed through systematic field sampling, direct microscopic observation, and axenic culturing, followed by high-resolution imaging and manual annotation by experts. This annotated dataset serves as a foundational resource for AI-assisted spore detection across both field-based and atmospheric surveillance workflows, supporting applications such as sample-based analysis, air-based monitoring, and real-time diagnostics. Its cross-species utility and future extensibility enhance its value for plant disease management.

Draft genome sequence data of Colletotrichum siamense isolated from Camellia japonica in the United States

Potassium phosphite effectively controls rubber tree anthracnose by inhibiting melanin biosynthesis of Colletotrichum siamense.

Citrus sinensis (sweet orange) is an economically important horticultural commodity in global fruit markets owing to its excellent organoleptic qualities, coupled with a rich nutritional profile that includes essential vitamins, minerals, and antioxidants. While conducting a field survey (350 hectares) during the kharif season of 2023 in Maharashtra state, India, fruit rot disease was observed with an incidence of 25-30% on sweet orange fruits. Infected fruits exhibited large, circular, sunken lesions on the surface, surrounded by a slightly raised or discoloured margin. In advanced stages, fruits exhibited extensive rotting and premature fruit drop. From the diseased fruit samples collected during the survey, four fungal isolates were obtained. These isolates were designated as CS vk_mpkv_101 (Amravati-21°14′4.26″N, 78°1′14.31″E), CS vk_mpkv_102 (Nagpur-21°15′38.2″N, 78°39′35.4″E), CS vk_mpkv_103 (Chhatrapati Sambhajinagar-19°51′19.6″N, 75°28′18.8″E), and CS vk_mpkv_104 (Jalna-19°51′11.50″N, 75°40′40.21″E). Isolation of the fungus was performed on PDA medium using the standard tissue isolation method, followed by purification using the single spore isolation method (Johnston and Booth 1983). Microscopic examination revealed that all four isolates of the pathogen produced septate mycelium and conidia. The conidia were unicellular, hyaline, cylindrical to fusiform, with a round apex and were guttulate. The size of conidia of all four isolates ranged from 11.5-15.9 × 2.9-5.5 μm. Cultural studies of all the isolates of fungi revealed that the colony colour varied from cream to greyish with whitish to slight yellowish pigmentation. Texture was cottony and fluffy with raised mycelial growth. Pathogenicity of all four isolates was confirmed on fresh sweet orange fruits by using the pin-prick method, satisfying Koch’s postulates. The characteristic rotting symptoms as observed on naturally infected fruits were reproduced during the pathogenicity test. All the isolates of the pathogen exhibited similar morphological and cultural characteristics. Based on these morphological and cultural characteristics, all four isolates were identified as Colletotrichum siamense (Fayyaz et al. 2020; Kaur et al. 2024). Among the four isolates, Colletotrichum siamense isolate vk_mpkv_101 was the most virulent, inducing severe rotting symptoms within the shortest incubation period (5 days), compared to other isolates. Consequently, the isolate vk_mpkv_101 was selected for molecular identification using ITS, β-tubulin, Actin, and GAPDH gene sequences, which were amplified with standard primers (White et al., 1990; Templeton et al., 1992; Glass and Donaldson, 1995). Blast analysis of the sequences generated from all four gene regions showed the highest sequence similarity with Colletotrichum siamense, thereby confirming the molecular identity of the isolate as C. siamense. Sequences were deposited in NCBI GenBank, and accession numbers received are PX248333 (ITS), PX113340 (Actin), PX117002 (β-tubulin), and PX113339 (GAPDH). The pure fungal culture was submitted to the National Fungal Culture Collection of India, and the accession number received for the culture is NFCCI-5995. Earlier, this fungus was reported as a causal agent of fruit rot on Kinnow fruit by Fayyaz et al. (2020) in Pakistan, on citrus by Wang et al. (2021) in Australia and on Kinnow fruit by Kaur et al. (2024) in India. To our knowledge, this is the first report of Colletotrichum siamense causing fruit rot in sweet orange (Citrus sinensis) in India. Identification of the pathogen provides a foundation for future research on effective management strategies, as it poses a significant threat to Citrus sinensis production in India.

Strawberry anthracnose caused by Colletotrichum siamense threatens global strawberry production. Traditional chemical control faces environmental and safety challenges, making resistant cultivar development critical for sustainability. This study aimed to rank 10 cultivars’ resistance to C. siamense Cs.4J and clarify temporal redox and transcriptomic drivers of resistance. We evaluated resistance using the disease index (DI), observed oxidative stress indicators [peroxidase (POD), hydrogen peroxide (H2O2), malondialdehyde (MDA), catalase (CAT)], and conducted Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and weighted gene coexpression network analysis (WGCNA). Significant resistance differences emerged: ‘Tianxianzui’ (TXZ) was resistant (DI 10.0–20.0%), while ‘Miaoxiang7’ (MX7) was highly susceptible (DI > 50%). ‘MX7’ showed sustained POD overactivation, progressive H2O2 accumulation, and high MDA (severe oxidative damage); ‘TXZ’ maintained redox balance via earlier CAT activation. KEGG identified 5 key pathways (e.g., phenylpropanoid biosynthesis), and Weighted Gene Co-expression Network Analysis (WGCNA) revealed 2 core modules (resistance-related red, susceptibility-related brown) plus 2 hub genes (FvRNF144B-like [Fragaria vesca RING Finger Protein 144B-like], FaPHR1-like [Fragaria × ananassa PHR1-like]). ‘TXZ’ and ‘MX7’ represent resistant/susceptible cultivars; early CAT activation for redox balance is a key resistance trait. The 5 pathways and 2 hub genes provide a theoretical basis for future functional validation and exploring strawberry–C. siamense interaction mechanisms.

Molecular, morphophysiological, and pathogenic characterization of Colletotrichum isolates from strawberry plants in Santa Catarina, Brazil.

ABSTRACT In July 2021, desert rose plants were consistently observed with symptoms of brown spots on the leaves, which coalesced and promoted leaf fall. The causal agent of the disease was unknown. This study aimed to identify the pathogen responsible for the symptoms through morphological and molecular characterisation, as well as pathogenicity tests. The pathogens were identified as Colletotrichum siamense and a novel species of Lasiodiplodia representing the first report of these fungi causing leaf spot on desert rose in Brazil and worldwide.

First report of Lithocarpus henryi leaf blight caused by Colletotrichum siamense in China

A new cytochalasan, sophochalasin (1), together with ten known analogous compounds were obtained from the co-culture of two endophytic fungi Aspergillus spelaeus and Xylaria sp. The structure and the absolute configuration of 1 were established via NMR and ECD spectral analysis. In antifungal assay, aspochalasin B (2) exhibited notable antifungal activity against Fusarium oxysporum, Colletotrichum siamense, Alternaria alternata and Fusarium oxysporium f. sp. cucumberinum with MICs of 16 μg/mL.

New observations in the spores and hyphae of Colletotrichum siamense exposed to nanochitosan particles.

First report of Michelia maudiae leaf blight caused by Colletotrichum siamense in China

Investigation into the biochemical properties of loquat fruits and their optical properties of hyperspectral imaging spectral correlation during the progression of postharvest fungal infection.

First report of leaf spot caused by Colletotrichum siamense on Bauhinia purpurea from India

Disinfestants are an important sanitation tool used to eliminate plant pathogens. Disinfestant product labels, as well as university and company literature, provide instructions and guidance for the proper usage of disinfestants, yet recent research reviews have shown that inconsistencies in efficacy occur even when these information sources are followed. The efficacy of hypochlorite, isopropyl alcohol, quaternary ammonium, and peroxygen compounds against Colletotrichum siamense was evaluated relative to substrate porosity, contact time, and disinfestant wettability properties in a series of in vitro studies in which disinfestants were sprayed on six substrates (concrete, galvanized metal, polypropylene ground fabric, polyethylene plastic sheet, pressure-treated pine, and twin-wall clear polycarbonate) commonly found in ornamental plant production systems. Bayesian generalized linear mixed models were used to calculate posterior distributions of the median point estimate and 95% equal-tailed credible intervals representing uncertainty about the means. Control of C. siamense was consistently achieved on the nonporous surfaces with all six disinfestants, but the level of control was variable when treating porous surfaces. The natural duration of evaporatively declining coverage over 1 to 20 min after disinfestants were sprayed on surfaces and the initial coverage from disinfestants that innately spread out or bead up on surfaces were not prominent factors that affected efficacy. Control outcomes were improved on porous substrates by making two sequential applications of a label dose or one application of a high dose, although two applications of a label dose, which does not violate disinfestant product label guidance, more consistently achieved the lowest recovery of C. siamense. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2025.

Anthracnose, caused by Colletotrichum spp., significantly threatens rubber trees globally. The nucleotide-binding and leucine-rich repeat (NLR) protein family constitutes one of the largest and most widespread classes of plant immune receptors. However, the specific relationship between NLR genes and anthracnose resistance in rubber trees remains poorly understood. This study comprehensively identified all NLR family members in the reference genome of the wild rubber tree accession MT/VB/25A 57/8. From 39,340 annotated proteins, 253 were classified as NLRs, including 155 coiled-coil NLR (CNL) and 35 Toll/interleukin-1 receptor NLR (TNL) proteins. Conserved motifs were identified in both CNL and TNL proteins. Notably, TNL proteins had a higher occurrence of conserved motif 8 in C-terminal leucine-rich repeat domains than CNL proteins. Chromosomal mapping indicated that CNL and TNL protein-coding genes largely localized on chromosomes 1, 3, 8, 12, and 14. The observed NLR distribution and diversity likely resulted from tandem, ectopic, and segmental gene duplications, with tandem duplications being the most common. Comparative transcriptome and quantitative RT-PCR analyses revealed two specific CNL genes (LOC110667987 and LOC110668014) preferentially expressed in a resistant genotype upon infection by Colletotrichum siamense. Identification of these genes provides insight into the molecular mechanisms of anthracnose resistance and will facilitate the development of resistant rubber trees.

ABSTRACT The 42 kDa chitinase of T. asperellum SH16 has been regarded with considerable interest in promising biotechnological applications due to its antifungal activities. However, poor thermostability limits most practical applications. This study investigated the expression of various 42 kDa chitinase mutants in E. coli. Findings indicate that the recombinant chitinase I168L mutant demonstrated markedly improved thermostability compared to the native enzyme, retaining substantial activity even at elevated temperatures. Additionally, both in vitro and in vivo antifungal tests showed that the I168L mutant exhibited a greater inhibitory effect on the growth of Colletotrichum siamense strains, which are responsible for anthracnose in chili fruits, when compared to the native chitinase at 35°C. This mutant can prevent fungal infection for up to four days following pretreatment with 80 units of I168L. These findings highlight the potential of the I168L mutant as a biocontrol agent against anthracnose diseases caused by Colletotrichum species in fruits.

Camu-camu (Myrciaria dubia (Kunth) McVaugh) is an Amazonian fruit with high economic potential due to its reported health-promoting properties, including elevated antioxidant and anti-inflammatory compound levels. Since 2018, anthracnose-like lesions, starting as small dark spots and coalescing into large irregular or circular lesions, were observed in up to 60% of camu-camu plants in an experimental field located in the city of Boa Vista, Roraima, Brazil (2°52'20.7″ N; 60°42'44.2″ W) and in a natural population in Rorainópolis, Roraima, Brazil (0°54'128″ N,60°36'226″ W). Fifty symptomatic leaves were collected from 10 plants. Small (5×5 mm) lesion tissue fragments were surface disinfected in 70% ethanol (1 min), 2.5% sodium hypochlorite (1 min), rinsed in sterile water, and placed on water agar. After 4 days at 25°C, mycelium was transferred to potato dextrose agar (PDA). After 7 days, 10 morphologically similar isolates were obtained, showing grayish-white colonies with orange spore masses. Conidia were hyaline, unicellular, cylindrical, smooth-walled, straight with rounded apices, measuring 15.3 ± 0.8 × 6.95 ± 1.4 μm (n = 30). Appressoria were brown, irregular or ovoid, measuring 6.4 ± 1.5 × 4.9 ± 1.2 μm (n = 30). Single-spore cultures were deposited in the EMBRAPA Roraima Microorganism Culture Collection. Four representative isolates (MTG07, MTG08 from Boa Vista; DXV01, DXV02 from Rorainópolis) were selected for phylogenetic and pathogenicity analysis. Total DNA was extracted and portions of actin (ACT), calmodulin (CAL), chitin synthase 1 (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and β-tubulin 2 (TUB2) genes were amplified (Weir et al. 2012) and Sanger sequenced (GenBank accession numbers ACT: PV463490-PV463493; CAL: PV463498-PV463501; CHS-1: PV055675-PV055678; GAPDH: PV430301-PV430304; TUB2: PV463494-PV463497). Sequences showed 96 to 99% identity with sequences of Colletotrichum siamense published in GenBank. Phylogenetic Bayesian inference analysis based on a combined data set showed that the isolates clustered with the ex-holotype specimen of C. siamense (ICMP 18578) with high support (posterior probability = 0.98). To confirm pathogenicity, five seedlings of camu-camu per isolate were sprayed with 106 conidia/mL spore suspension (15 mL/plant). Control seedlings were sprayed with sterile water. All seedlings were covered with plastic bags 24 h after inoculation and maintained at 27°C in a greenhouse with a 12-h photoperiod. After 6 days, inoculated leaves exhibited small dark brown spots with yellow halo, which enlarged and coalesced into regular or irregular brown necrotic lesions. The control plants showed no symptoms. The pathogenicity test was performed twice with similar results. The fungus was successfully reisolated from the inoculated leaves and its identify was confirmed by cultural morphology and DNA sequence. C. siamense is a known anthracnose agent on diverse hosts (Weir et al. 2012), but in camu-camu, only C. gloeosporioides, C. aeschynomenes, C. tropicale, and C. theobromicola (Perez et al., 2006; Matos et al., 2020; Sachet et al., 2024) have been reported. To our knowledge, this is the first report of C. siamense causing anthracnose in camu-camu. The identification of the pathogen enables future research on management strategies, as this pathogen can cause serious damage to camu-camu production in the region.

First report of anthracnose caused by Colletotrichum siamense on Cinnamomum burmanni

Anthracnose is a disease caused by phytopathogenic fungi such as Colletotrichum siamense that attacks plants and fruits causing great postharvest losses. Different alternatives for the control of this fungus have been studied. In the present study, we evaluated the in vitro antifungal activity of the methanolic extracts of Baccharis glutinosa (ExB) and Jacquinia macrocarpa (ExJ) individually, as well as in combination with chitosan (CS), along with their toxicity in different models. Using the radial growth technique, it was observed that the mycelial development of C. siamense was altered and reduced during exposure to the different treatments evaluated during the first hours of incubation, indicating a fungistatic effect. While the cell viability, by colorimetric assay using the XTT salt, showed alteration since the chitosan reduced proliferation by 50%, while the plant extracts and their mixtures with chitosan reduced approximately 40% indicating cell damage, which was confirmed by fluorescence microscopy. In addition, toxicity tests demonstrated that the J. macrocarpa extract significantly affected the germination percentage of Lactuca sativa seeds, whereas radicle length was reduced in all treatments except for chitosan. The larval survival test for Artemia salina with the extracts indicated their potential toxicity by causing up to 60% mortality. The results indicate that ExB and ExJ mixed with CS are a good option for controlling C. siamense; however, at the concentrations used, they exhibit a toxic effect on the evaluated models.