Colletotrichum species associated with mango in southern China

Prevalence of Neofusicoccum parvum Associated with Fruit Rot of Mango in South Italy and Its Biological Control Under Postharvest Conditions

Botryosphaeriaceae species were recently found to be responsible for heavy mango crop losses worldwide. In 2020, mango fruit samples showing fruit decay symptoms were collected from Glenn, Kent, Irwin, Palmer, Brokaw 2, and Gomera 3 accessions in 4 orchards located in Sicily (Italy). A molecular analysis of the ITS and tub2 regions performed on 41 representative isolates allowed for the identification of mainly Neofusicoccum parvum and occasionally Botryosphaeria dothidea (1/41) as the causal agents of fruit decay. Pathogenicity proofs were satisfied for both fungal pathogens. Ripe and unripe Gomera 3 mango fruits were used to compare the virulence among the N. parvum isolates. Postharvest experiments performed on Gomera 3 fruits and by using different biocontrol agents (BCAs) showed that the performance of treatments in reducing fruit decay depends on N. parvum virulence. The data show that unregistered Wickerhamomyces anomalus WA-2 and Pichia kluyveri PK-3, followed by the trade bioformulate Serenade™ (Bacillus amyloliquefaciens QST713), were the most effective in managing mango fruit rot. This paper shows, for the first time, the potential of different BCAs, including Trichoderma spp., for the controlling of postharvest decay caused by N. parvum on mango fruits.

Dimethyl trisulfide reduces postharvest anthracnose and enhances mango quality, and a potential molecular mechanism against Colletotrichum gloeosporioides

Mango anthracnose, mainly caused by Colletotrichum gloeosporioides, is the major destructive postharvest disease of mango during storage and transport. Dimethyl trisulfide (DMTS), an organic volatile found in some microorganisms or plants, inhibited growth of C. gloeosporioides in vitro, but its effects on mango anthracnose and its molecular mechanisms of action have not been well characterized. In this study, the EC50 of DMTS against Colletotrichum spp. from mango mainly ranged from 2.3 to 20.0 μL/L. In vivo, the fumigation rates of 20 μL/L of DMTS for 24 h, or 80 μL/L for 3 h or 6 h could effectively reduce severity of anthracnose (natural inoculum) on postharvest mangoes with inhibitory effects of 61.7 %, 65.7 %, and 69.4 %, respectively, as observed 10 days after treatment. Furthermore, there was no detectable DMTS residue in mango skin or flesh, and an overall improvement in the quality of the fruit with higher soluble solids, total sugars, vitamin c, and β-carotene, and lower titratable acidity than the non-treated control. In addition, DMTS could significantly reduce ergosterol content in mycelia of C. gloeosporioides, and gene expression analysis showed DMTS significantly suppressed expression of ergosterol biosynthesis-related genes Cgerg6 and Cgerg11 after mycelia were exposed to DMTS. Knock-out mutants for each of these two genes showed reduced sensitivity to DMTS. After gene complementation in situ, the sensitivity of complementary transformants to DMTS was restored to that of the parental strain. Therefore, we concluded that the genes Cgerg6 and Cgerg11 are involved in an interaction with the antifungal activity of DMTS. This is the first study to demonstrate a control effect of DMTS on mango postharvest anthracnose resulting in reduced disease severity and enhanced fruit quality. Transformant studies also revealed some potential molecular mechanisms of the antifungal activity of DMTS that may lead to improved management of mango postharvest anthracnose.

Identification and Characterization Colletotrichum spp. Causing Mango Dieback in Indonesia

Dieback disease in mango trees has been observed in Indonesia, particularly in Java Island, with the causal agent remaining unidentified. One of the important pathogens that are responsible for causing mango dieback is Colletotrichum. Field surveys were conducted in various mango cultivating areas in Java Island, Indonesia to assess prevalence of Colletotrichum as dieback disease pathogen. Eleven Colletotrichum isolates were recovered from symptomatic dieback twigs and morphologically characterized. Genetic diversity fingerprint analysis was carried out using rep-PCR. Phylogenetic analysis identified isolates as belonging to Colletotrichum asianum and Colletotrichum cairnsense using partial sequences of four gene regions, including ITS, ACT, GAPDH, and TUB2. Pathogenicity tests on mango seedlings cv. Arumanis showed that all fungal isolates were responsible for causing dieback symptoms. Subsequently, symptomatic tissue was reisolated to fulfill Koch's Postulate. This study represented new funding for two species of Colletotrichum causing mango dieback in Indonesia.

Biological characterization of emerging fungal pathogen Colletotrichum associated with mango (Mangifera indica L.) post-harvest anthracnose from Vietnam

BACKGROUND

Post-harvest anthracnose (PHA) of mango is a devastating disease, which results in huge loss to mango producers and importers. Various species of PHA, diverse pathogenicity, and different resistance towards fungicides make it essential to evaluate the pathogen taxonomic status and biological characterization.

METHODS AND RESULTS

Two strains DM-1 and DM-2 isolated from the fruit of DaQing mango from Vietnam were identified as Colletotrichum fructicola and C. asianum respectively, based on the morphological features, along with the phylogenetic tree of ITS and ApMat combined sequences. The growth status of different Colletotrichum strains under different conditions was analyzed to reveal the biological characteristics. The optimum growth temperature of DM-1 and DM-2 was 28 °C and mycelia grew rapidly in the dark. Both strains could grow in media with pH 4-11, while the optimum pH value was 6. Maltose and soluble starch were the most suitable carbon source for DM-1 and DM-2 respectively, and the peptone was the most suitable nitrogen source for both strains. The lethal temperatures were recorded as 55 °C 5 min for DM-1, and 50 °C 10 min for DM-2.

CONCLUSIONS

To the best of our knowledge, it is the first study reporting the identification of the pathogens: C. fructicola and C. asianum responsible for postharvest fruit anthracnose of mango in Vietnam.

Re-identification of Colletotrichum gloeosporioides Species Complex Isolates in Korea and Their Host Plants

The Colletotrichum gloeosporioides species complex includes many phytopathogenic species, causing anthracnose disease on a wide range of host plants and appearing to be globally distributed. Seventy-one Colletotrichum isolates in the complex from different plants and geographic regions in Korea were preserved in the Korean Agricultural Culture Collection (KACC). Most of them had been identified based on hosts and morphological features, this could lead to inaccurate species names. Therefore, the KACC isolates were re-identified using DNA sequence analyses of six loci, comprising internal transcribed spacer, gapdh, chs-1, his3, act, and tub2 in this study. Based on the combined phylogenetic analysis, KACC strains were assigned to 12 known species and three new species candidates. The detected species are C. siamense (n = 20), C. fructicola (n = 19), C. gloeosporioides (n = 9), C. aenigma (n = 5), C. camelliae (n = 3), C. temperatum (n = 3), C. musae (n = 2), C. theobromicola (n = 2), C. viniferum (n = 2), C. alatae (n = 1), C. jiangxiense (n = 1), and C. yulongense (n = 1). Of these, C. jiangxiense, C. temperatum, C. theobromicola and C. yulongense are unrecorded species in Korea. Host plant comparisons showed that 27 fungus-host associations are newly reported in the country. However, plant-fungus interactions need to be investigated by pathogenicity tests.

First Report of Colletotrichum fructicola, C. rhizophorae sp. nov. and C. thailandica sp. nov. on Mangrove in Thailand

Colletotrichum, a genus within the phylum Ascomycota (Fungi) and family Glomerellaceae are important plant pathogens globally. In this paper, we detail four Colletotrichum species found in mangrove ecosystems. Two new species, Colletotrichum rhizophorae and C. thailandica, and a new host record for Colletotrichum fructicola were identified in Thailand. Colletotrichum tropicale was collected from Taiwan's mangroves and is a new record for Rhizophora mucronata. These identifications were established through a combination of molecular analysis and morphological characteristics. This expanded dataset for Colletotrichum enhances our understanding of the genetic diversity within this genus and its associations with mangrove ecosystems. The findings outlined herein provide data on our exploration of mangrove pathogens in Asia.

Gas barrier coating based on cellulose nanocrystals and its preservation effects on mango

Mango is the "king of tropical fruits" because of its attractive appearance, delicious taste, rich aroma, and high nutritional value. However, mango keeps fast metabolizing after harvest, leading to water loss, starch conversion into sugar, texture softening, and decay. Here, a gas barrier coating based on cellulose nanocrystals (CNCs) is proposed to control the post-harvest metabolism of mango. The results of gas barrier permeability show that CNCs enhance the barrier ability of the chitosan (CS) membrane on mango by 202 % and 63 % for oxygen and water vapor, respectively. The gas-barrier coating reduces the climb in pH and the decrease in firmness by 84.9 % and 45.8 %, respectively, decelerating the conversion process from starch to sugar. Besides, introducing clove essential oil (CEO), the CEO mainly adsorbs and crystalizes on the hydrophobic facets of CNCs, presenting high compatibility, increases the antibacterial rate to nearly 100 %. As a consequence, the preservation period of the mango coated by the CNC-based membrane is at least 7-day longer than the control group. Such a gas-barrier coating based on eco-friendly composites must have excellent potential in the preservation of mango, and even for other tropical fruits.

Characterization of Colletotrichum Species Infecting Litchi in Hainan, China

Litchi (Litchi chinensis) is an evergreen fruit tree grown in subtropical and tropical countries. China accounts for 71.5% of the total litchi cultivated area in the world. Anthracnose disease caused by Colletotrichum species is one of the most important diseases of litchi in China. In this study, the causal pathogens of litchi anthracnose in Hainan, China, were determined using phylogenetic and morphological analyses. The results identified eight Colletotrichum species from four species complexes, including a proposed new species. These were C. karsti from the C. boninense species complex; C. gigasporum and the proposed new species C. danzhouense from the C. gigasporum species complex; C. arecicola, C. fructicola species complex; C. arecicola, C. fructicola and C. siamense from the C. gloeosporioides species complex; and C. musicola and C. plurivorum from the C. orchidearum species complex. Pathogenicity tests showed that all eight species could infect litchi leaves using a wound inoculation method, although the pathogenicity was different in different species. To the best of our knowledge, the present study is the first report that identifies C. arecicola, C. danzhouense, C. gigasporum and C. musicola as etiological agents of litchi anthracnose.

The evolution of mini-chromosomes in the fungal genus Colletotrichum

Anthracnose diseases caused by Colletotrichum species are among the most common fungal diseases. These symptoms typically manifest as dark, sunken lesions on leaves, stems, and fruit. In China, mango anthracnose seriously affects fruit yield and quality. Genome sequencing of several species shows the presence of mini-chromosomes. These are thought to contribute to virulence, but their formation and activity remain to be fully elucidated. Here, we assembled 17 Colletotrichum genomes (16 isolated from mango plus one from persimmon) through PacBio long-read sequencing. Half of the assembled scaffolds had telomeric repeats at both ends indicating full-length chromosomes. Based on comparative genomics analysis at interspecies and intraspecies levels, we identified extensive chromosomal rearrangements events. We analyzed mini-chromosomes of Colletotrichum spp. and found large variation among close relatives. In C. fructicola, homology between core chromosomes and mini-chromosomes suggested that some mini-chromosomes were generated by recombination of core chromosomes. In C. musae GZ23-3, we found 26 horizontally transferred genes arranged in clusters on mini-chromosomes. In C. asianum FJ11-1, several potential pathogenesis-related genes on mini-chromosomes were upregulated, especially in strains with highly pathogenic phenotypes. Mutants of these upregulated genes showed obvious defects in virulence. Our findings provide insights into the evolution and potential relationships to virulence associated with mini-chromosomes. IMPORTANCE Colletotrichum is a cosmopolitan fungal genus that seriously affects fruit yield and quality of many plant species. Mini-chromosomes have been found to be related to virulence in Colletotrichum. Further examination of mini-chromosomes can help us elucidate some pathogenic mechanisms of Colletotrichum. In this study, we generated novel assemblies of several Colletotrichum strains. Comparative genomic analyses within and between Colletotrichum species were conducted. We then identified mini-chromosomes in our sequenced strains systematically. The characteristics and generation of mini-chromosomes were investigated. Transcriptome analysis and gene knockout revealed pathogenesis-related genes located on mini-chromosomes of C. asianum FJ11-1. This study represents the most comprehensive investigation of chromosome evolution and potential pathogenicity of mini-chromosomes in the Colletotrichum genus.

Mango anthracnose disease: the current situation and direction for future research

Mango anthracnose disease (MAD) is a destructive disease of mangoes, with estimated yield losses of up to 100% in unmanaged plantations. Several strains that constitute Colletotrichum complexes are implicated in MAD worldwide. All mangoes grown for commercial purposes are susceptible, and a resistant cultivar for all strains is not presently available on the market. The infection can widely spread before being detected since the disease is invincible until after a protracted latent period. The detection of multiple strains of the pathogen in Mexico, Brazil, and China has prompted a significant increase in research on the disease. Synthetic pesticide application is the primary management technique used to manage the disease. However, newly observed declines in anthracnose susceptibility to many fungicides highlight the need for more environmentally friendly approaches. Recent progress in understanding the host range, molecular and phenotypic characterization, and susceptibility of the disease in several mango cultivars is discussed in this review. It provides updates on the mode of transmission, infection biology and contemporary management strategies. We suggest an integrated and ecologically sound approach to managing MAD.

Two Newly Identified Colletotrichum Species Associated with Mango Anthracnose in Central Thailand

Anthracnose caused by Colletotrichum spp. is one of the major problems in mango production worldwide, including Thailand. All mango cultivars are susceptible, but Nam Dok Mai See Thong (NDMST) is the most vulnerable. Through a single spore isolation method, a total of 37 isolates of Colletotrichum spp. were obtained from NDMST showing anthracnose symptoms. Identification was performed using a combination of morphology characteristics, Koch's postulates, and phylogenetic analysis. The pathogenicity assay and Koch's postulates on leaves and fruit confirmed that all Colletotrichum spp. tested were causal agents of mango anthracnose. Multilocus analysis using DNA sequences of internal transcribed spacer (ITS) regions, β-tubulin (TUB2), actin (ACT), and chitin synthase (CHS-1) was performed for molecular identification. Two concatenated phylogenetic trees were constructed using either two-loci of ITS and TUB2, or four-loci of ITS, TUB2, ACT, and CHS-1. Both phylogenetic trees were indistinguishable and showed that these 37 isolates belong to C. acutatum, C. asianum, C. gloeosporioides, and C. siamense. Our results indicated that using at least two loci of ITS and TUB2, were sufficient to infer Colletotrichum species complexes. Of 37 isolates, C. gloeosporioides was the most dominant species (19 isolates), followed by C. asianum (10 isolates), C. acutatum (5 isolates), and C. siamense (3 isolates). In Thailand, C. gloeosporioides and C. acutatum have been reported to cause anthracnose in mango, however, this is the first report of C. asianum and C. siamense associated with mango anthracnose in central Thailand.

First Report on Colletotrichum fructicola Causing Anthracnose in Chinese Sorghum and Its Management Using Phytochemicals

Sorghum bicolor is cultivated worldwide. Leaf spots on sorghum, which lead to leaf lesions and impaired growth, are prevalent and severe in Guizhou Province, Southwest China. In August 2021, new leaf spot symptoms were observed on sorghum plants growing in agricultural fields. We used conventional tissue isolation methods and pathogenicity determination tests. Inoculations of sorghum with isolate 022ZW resulted in brown lesions similar to those observed under field conditions. The original inoculated isolates were reisolated and fulfilled Koch's postulates. Based on the morphological character and phylogenetic analyses of the combined sequences of the internal transcribed spacer (ITS) region and the β-tubulin (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes, we identified the isolated fungus as C. fructicola. This paper is the first to report this fungus-causing disease in sorghum leaves. We studied the sensitivity of the pathogen to various phytochemicals. The sensitivity of C. fructicola to seven phytochemicals was measured using the mycelial growth rate method. Honokiol, magnolol, thymol, and carvacrol displayed good antifungal effects, with EC₅₀ (concentration for 50% of the maximal effect) values of 21.70 ± 0.81, 24.19 ± 0.49, 31.97 ± 0.51, and 31.04 ± 0.891 µg/mL, respectively. We tested the control effect of the seven phytochemicals on the anthracnose caused by C. fructicola: honokiol and magnolol displayed good field efficacy. In this study, we expand the host range of C. fructicola, providing a basis for controlling sorghum leaf diseases caused by C. fructicola.

Widely targeted metabolite profiling of mango stem apex during floral induction by compond of mepiquat chloride, prohexadione-calcium and uniconazole

Background

Insufficient low temperatures in winter and soil residues caused by paclobutrazol (PBZ) application pose a considerable challenge for mango floral induction (FI). Gibberellin inhibitors SPD (compound of mepiquat chloride, prohexadione-calcium and uniconazole) had a significant influence on enhancing the flowering rate and yield of mango for two consecutive years (2020-2021). Researchers have indicated that FI is regulated at the metabolic level; however, little is known about the metabolic changes during FI in response to SPD treatment.

Methods

Here, ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS)-based widely targeted metabolomic analysis was carried out to assess the metabolic differences in the mango stem apex during different stage of mango FI (30, 80, 100 days after SPD/water treatment).

Results

A total of 582 compounds were annotated and 372 metabolites showed two-fold differences in abundance (variable importance in projection, VIP ≥ 1 and fold change, FC≥ 2 or≤ 0.5) between buds at 30, 80, 100 days after SPD/water treatment or between buds under different treatment. Lipids, phenolic acids, amino acids, carbohydrates, and vitamins were among metabolites showing significant differences over time after SPD treatment. Here, 18 out of 20 lipids, including the lysophosphatidylethanolamine (12, LPE), lysophosphatidylcholine (7, LPC), and free fatty acids (1, FA), were significantly upregulated from 80 to 100 days after SPD treatment comared to water treatment. Meanwhile, the dormancy release of mango buds from 80 to 100 days after SPD treatment was accompanied by the accumulation of proline, ascorbic acid, carbohydrates, and tannins. In addition, metabolites, such as L-homocysteine, L-histidine, and L-homomethionine, showed more than a ten-fold difference in relative abundance from 30 to 100 days after SPD treatment, however, there were no significant changes after water treatment. The present study reveals novel metabolites involved in mango FI in response to SPD, which would provide a theoretical basis for utilizing SPD to induce mango flowering.

EFSA Panel on Plant Health (PLH), Bragard C, Baptista P, Chatzivassiliou E, Di Serio F, Gonthier P, Jaques Miret JA, Justesen AF, MacLeod A, Magnusson CS, Milonas P, Navas‐Cortes JA, Parnell S, Potting R, Reignault PL, Stefani E, Thulke H, Van der Werf W, Vicent Civera A, Yuen J, Zappalà L, Migheli Q, Vloutoglou I, Czwienczek E, Maiorano A, Streissl F, Reignault PL. Pest categorisation of Colletotrichum aenigma, C. alienum, C. perseae, C. siamense and C. theobromicola

The EFSA Plant Health Panel performed a pest categorisation of Colletotrichum aenigma, C. alienum, C. perseae, C. siamense and C. theobromicola, five clearly defined fungi of the C. gloeosporioides complex causing anthracnose. The pathogens are widely distributed in at least three continents. C. aenigma and C. siamense are reported from Italy and C. alienum from Portugal, including the Madeira Islands, with a restricted distribution. C. perseae and C. theobromicola are not known to be present in the EU. However, there is uncertainty on the status of the pathogens worldwide and in the EU because of the taxonomic re-evaluation of the genus Colletotrichum and the lack of specific surveys. The pathogens are not included in Commission Implementing Regulation (EU) 2019/2072 and there are no reports of interceptions in the EU. With the exception of C. perseae, which has a very limited number of hosts, the other four Colletotrichum species have relatively wide host ranges. Therefore, this pest categorisation focused on those hosts for which there is robust evidence that the pathogens were formally identified by a combination of morphology, pathogenicity and multilocus sequence analysis. Host plants for planting and fresh fruits are the main entry pathways into the EU. Host availability and climate suitability factors occurring in some parts of the EU are favourable for the establishment of the pathogens. No yield losses have been reported so far in the EU but in non-EU areas of their current distribution, the pathogens have a direct impact on cultivated hosts that are also relevant for the EU. Phytosanitary measures are available to prevent the further introduction and spread of C. aenigma, C. alienum and C. siamense into the EU as well as the introduction and spread of C. perseae and C. theobromicola. C. aenigma, C. alienum, C. perseae, C. siamense and C. theobromicola satisfy the criteria that are within the remit of EFSA to assess for these species to be regarded as potential Union quarantine pests.

Subcellular damages of Colletotrichum asianum and inhibition of mango anthracnose by dielectric barrier discharge plasma

Colletotrichum asianum (C. asianum) is a new pathogenic fungus that causes mango anthracnose. Cold plasma is a novel non-thermal decontamination technology, which has been proven to be effective in controlling postharvest fungus. Herein, dielectric barrier discharge (DBD) plasma was used to treat C. asianum spores in sterile phosphate-buffered saline, the damages in subcellular structures of C. asianum and inhibition of mango anthracnose were evaluated. Results showed that after 9 min treatment, the spore germination rate and spore viability were decreased by 95.48% and 98.82%, respectively, and the subcellular structures were damaged (P < 0.05), leading to spores death. Besides, DBD plasma treatments could control mango anthracnose and maintain mango quality, and the disease incidence and lesion diameter of mango treated for 9 min were decreased by 48.00% and 62.95%, respectively. Therefore DBD plasma inactivated C. asianum spore, providing an alternative technique for preventing and controlling mango anthracnose.

Chitosan Sensitivity of Fungi Isolated from Mango (Mangifera indica L.) with Anthracnose

In Mexico, the mango crop is affected by anthracnose caused by Colletotrichum species. In the search for environmentally friendly fungicides, chitosan has shown antifungal activity. Therefore, fungal isolates were obtained from plant tissue with anthracnose symptoms from the state of Guerrero in Mexico and identified with the ITS and β-Tub2 genetic markers. Isolates of the Colletotrichum gloeosporioides complex were again identified with the markers ITS, Act, β-Tub2, GADPH, CHS-1, CaM, and ApMat. Commercial chitosan (Aldrich, lot # STBF3282V) was characterized, and its antifungal activity was evaluated on the radial growth of the fungal isolates. The isolated anthracnose-causing species were C. chrysophilum, C. fructicola, C. siamense, and C. musae. Other fungi found were Alternaria sp., Alternaria tenuissima, Fusarium sp., Pestalotiopsis sp., Curvularia lunata, Diaporthe pseudomangiferae, and Epicoccum nigrum. Chitosan showed 78% deacetylation degree and a molecular weight of 32 kDa. Most of the Colletotrichum species and the other identified fungi were susceptible to 1 g L-1 chitosan. However, two C. fructicola isolates were less susceptible to chitosan. Although chitosan has antifungal activity, the interactions between species of the Colletotrichum gloeosporioides complex and their effect on chitosan susceptibility should be studied based on genomic changes with molecular evidence.

Taxonomy and Phylogeny of Novel and Extant Taxa in Pleosporales Associated with Mangifera indica from Yunnan, China (Series I)

Pleosporales is the largest fungal order with a worldwide distribution in terrestrial and aquatic environments. During investigations of saprobic fungi associated with mango (Mangifera indica) in Baoshan and Honghe, Yunnan, China, fungal taxa belonging to pleosporales were collected. Morphological examinations and phylogenetic analyses of ITS, LSU, SSU, rpb2 and tef1-α loci were used to identify the fungal taxa. A new genus, Mangifericomes; four new species, namely Mangifericomes hongheensis, Neomassaria hongheensis, Paramonodictys hongheensis, and Paramonodictys yunnanensis; and six new host and country records, namely Byssosphaeria siamensis, Crassiparies quadrisporus, Paradictyoarthrinium aquatica, Phaeoseptum mali, Torula fici, and Vaginatispora amygdali, are introduced. Photoplates, full descriptions, and phylogenetic trees to show the placement of new and known taxa are provided.

Identification of Colletotrichum Species Associated with Anthracnose Disease of Strawberry in Sichuan Province, China

Strawberry anthracnose, caused by Colletotrichum species, is a major fungal disease threatening the strawberry industry in Sichuan Province of southwestern China. However, research on identification of Colletotrichum species associated with strawberry anthracnose in Sichuan remains scarce. In this study, 73 representative Colletotrichum strains were isolated from diseased leaves, stolons, petioles, and crowns of 11 major strawberry-planting localities in Sichuan Province. Based on morphological characteristics and multiloci phylogenetic analysis, the Colletotrichum strains were identified as three distinct species: Colletotrichum fructicola (53 strains, 72.60%), Colletotrichum siamense (17 strains, 23.29%), and Colletotrichum gloeosporioides sensu stricto (3 strains, 4.11%). Among them, C. fructicola was the most ubiquitous and dominant species, whereas C. gloeosporioides sensu stricto was restricted to Chongzhou. Importantly, our pathogenicity tests showed that C. fructicola and C. siamense can infect both leaves and stolons, whereas C. gloeosporioides sensu stricto was only pathogenic to leaves. Interestingly, although the sexual stage of C. siamense was not observed in this study, it still exhibited the strongest virulence to strawberry compared with C. gloeosporioides sensu stricto and C. fructicola. This is the first study to characterize Colletotrichum species causing strawberry anthracnose and evaluate their pathogenicity in Sichuan Province of southwestern China, which will provide a better strategy for accurate diagnosis and management of anthracnose disease in strawberry.

First Report of Anthracnose on Jerusalem Cherry Caused by Colletotrichum liaoningense in Shandong, China

Jerusalem cherry (Solanum pseudocapsicum), which belongs to the genus Solanum and the family Solanaceae, possesses high ornamental value and is widely cultivated as an indoor ornament due to its bright red berries at maturity (Xu et al., 2018). In September 2019, leaf spot was detected on jerusalem cherry plants in Yuxiu Park, Shizhong district, Jinan, Shandong Province. Field surveys were done in a 1/15 ha park. Disease incidence was estimated at approximately 18% across the survey area. Foliar symptoms began as small white spots. As the disease progressed, lesions expanded and merged, and developed into large irregular white spots, with pale grey edge. At last, lesions were densely distributed throughout the leaves. To isolate the pathogen, twenty leaf tissues (5 × 5 mm) were cut from the border between diseased and healthy tissue, surface disinfected in 75% alcohol for 15 s, soaked in 0.1% mercuric chloride for 1 min, washed with sterile distilled water three times, and cultured on potato dextrose agar (PDA) at 25°C. Nineteen fungal isolates were obtained and were single-spored to obtain pure cultures. The colony of LCL7, a representative isolate, on PDA was initially white to orange, but turned black after 3 to 4 days incubation with black conidial masses. Conidia were single-celled, hyaline, straight, cylindrical, apex obtuse, and ranged from 13.4 to 18.3 × 3.2 to 4.9 μm (n = 50) （Diao et al., 2017）. To validate the species identification, rDNA internal transcribed spacer (ITS) region (White et al., 1990), and the partial sequences of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), β-tubulin (TUB2), and chitin synthase (CHS-1) (Damm et al., 2019; He et al., 2019), were amplified and sequenced. The ITS, GAPDH, ACT, TUB2, and CHS-1 sequences of isolate LCL7 were submitted to GenBank (MW221320, MW227217, MW227218, MW227219, and MW266988, respectively). ITS, ACT, TUB2, and CHS-1 BLAST showed 99-100% homology with sequences of Colletotrichum liaoningense (ITS, 100% to MH636504; ACT, 100% to MH622582; TUB2, 99.56% to MH622714, CHS-1, 99.33% to MH622446, respectively), although GAPDH showed 93.98% homology with sequence MH681383 (234/249bp). Neighbor-joining tree based on concatenated sequences of the five genes was constructed using MEGA7.0. The results showed the isolate was closely related to C. liaoningense. Based on morphological and molecular characteristics, the isolate LCL7 was identified as C. liaoningense. Pathogenicity tests were performed by spraying a conidial suspension (1 × 105 conidia/mL) on ten two-year-old healthy jerusalem cherry plants. Ten other plants with sterile water served as controls. All samples were incubated in a growth chamber at 25±2°C and transparent plastic bags to keep relative humidity high for 2 days. All inoculated plants showed symptoms similar to those observed in the field after 21 days, but no disease occurred on control plants. The same fungus was successfully reisolated from inoculated leaves and reidentified based on morphology and molecular characteristics, and the fungus was not isolated from the control plants, thus confirming Koch's postulates. Pathogenicity tests were repeated twice. C. liaoningense can cause anthracnose in chili and mango in China (Diao et al., 2017; Li et al., 2019).To our knowledge, this is the first report of anthracnose on jerusalem cherry caused by C. liaoningense in China, which influences ornamental value and reduces market value. Identification of the causes of the disease will help develop effective strategies for managing this disease.

First record of Colletotrichum alienum Causing postharvest Anthracnose disease of mango fruit in China

Mango (Mangifera indica L.) is one of the world's most significant economic fruit crops, and China is the second-largest producer of mango (Kuhn et al., 2017). Postharvest mango anthracnose is caused by Colletotrichum species and reduce the self-life of mature fruit (Wu et al., 2020). Colletotrichum species also cause postharvest anthracnose and fruit rot disease of Apple, Banana and Avocado (Khodadadi et al., 2020; Vieira et al., 2017; Sharma et al., 2017). In July 2019, mango fruits cv. 'Jin-Hwang' were observed at different fruit markets (39°48'42.1"N 116°20'17.0"E) of the Fengtai district, Beijing, China, exhibiting typical symptoms of anthracnose including brown to black lesions in different size (≤ 2 cm) with identified border on the mango fruit surface. Later, the lesions were coalesced and extensively cover the surface area of the fruit. The lesions were also restricted to peel the fruit and pathogen invaded in the fruit pulp. About 30% of mango fruits were affected by anthracnose disease. The margins of lesions from infected mango fruits (n=56) were cut into 2 × 2 mm pieces, surface disinfected with NaClO (2% v/v) for 30 s, rinsed thrice with distilled water for 60s. These pieces were placed on PDA medium and incubated at 25°C for 7 days. Pure culture of fungal isolates was obtained by single spore isolation technique. Initially, the fungal colony was off white, and colony extended with time, turning light gray at the center. The morphological examination revealed that conidia were hyaline, oblong, and unicellular. The conidia were measured from 10 days old culture and dimensions varied from 13.3 to 15.8 µm in length and 4.6 to 6.1 µm in width. For molecular identification, a multi-locus sequence analysis; the Internal Transcribed Spacers (ITS) region, partial actin (ACT) gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene and chitin synthase (CHS-1) gene were amplified by using the primer sets ITS1/4 (White et al. 1990), ACT-512F/ACT-783R (Carbone and Kohn 1999), GDF1/GDR1 (Guerber et al. 2003) and CHS1-79F/CHS-1-354R (Carbone and Kohn 1999) respectively. The partial sequences of MTY21 were deposited to GenBank accessions (MT921666 (ITS), MT936119 (ACT), MT936120 (GAPDH) and MT936118 (CHS-1). All obtained sequences showed 100% similarity with reported sequences of Colletotrichum alienum ICMP.18691 with accessions numbers JX010217 (ITS), JX009580 (ACT), JX010018 (GAPDH) and JX009754 (CHS-1) which represented the isolate MTY21 identified as C. alienum by constructing Maximum Likelihood phylogenetic tree analysis using Mega X (Kumar et al., 2018). For the confirmation of Koch's postulates, the pathogenicity test was conducted on 36 fresh healthy mango fruits for each treatment. Fruits were punctured with the help of a sterilized needle to create 2mm2 wounds and inoculated with 10µL inoculum (107 spores/mL) of MTY21. Control mango fruits were inoculated with 10µL sterilized distilled water and incubated at 25 °C with 90% relative humidity. The lesions appeared at the point of inoculation and gradually spread on the fruit surface after 7 days post inoculation. The symptoms were similar to the symptoms on original fruit specimens. The re-isolated fungus was identified as C. alienum based on morphological and molecular analysis. Mango anthracnose disease caused by several Colletotrichum species has been reported previously on mango in China (Li et al., 2019). Liu et al. (2020) reported C. alienum as the causal organism of anthracnose disease on Aquilaria sinensis in China. C. alienum has been previously reported causing mango anthracnose disease in Mexico (Tovar-Pedraza et al., 2020) To our knowledge, this is the first report of C. alienum causing postharvest anthracnose of mango in China. The prevalence of C. alienum was 30% on mango fruit which reflects the importance of this pathogen as a potential problem of mango fruit in China.

Fusarium species associated with leaf spots of mango in China

Mango is one of the important commercially cultivated fruit crops in southern China. In continuing research on foliar diseases of mango in south of China during 2016-2017, leaf spot disease was common at all mango orchards investigated. The purpose of this study was to investigate Fusarium species associated with leaf spots of mango in the main production areas of China, and to identify them to species. Twenty-two Fusarium isolates were obtained from diseased leaves from seven provinces (Fujian, Guangdong, Guangxi, Guizhou, Hainan, Sichuan and Yunnan), and then identified using morphological characteristics and phylogenetic analysis. These isolates were from seven species: F. concentricum, F. hainanense, F. mangiferae, F. pernambucanum, F. proliferatum, F. sulawesiense, and F. verticillioides. We found all 22 isolates to be capable of causing leaf spot symptoms on artificially wounded leaves. To our knowledge, this is the first report of F. concentricum, F. hainanense, F. mangiferae, F. pernambucanum, F. sulawesiense and F. verticillioides associated with leaf spots on mango in China, and the first for F. concentricum, F. hainanense, F. pernambucanum, F. sulawesiense from mango worldwide. This is one of the few reports on Fusarium species as potential causal agents of mango leaf spots.

Diversity and pathogenicity of Colletotrichum species causing strawberry anthracnose in Taiwan and description of a new species, Colletotrichum miaoliense sp. nov

Strawberry is a small fruit crop with high economic value. Anthracnose caused by Colletotrichum spp. poses a serious threat to strawberry production, particularly in warm and humid climates, but knowledge of pathogen populations in tropical and subtropical regions is limited. To investigate the diversity of infectious agents causing strawberry anthracnose in Taiwan, a disease survey was conducted from 2010 to 2018, and Colletotrichum spp. were identified through morphological characterization and multilocus phylogenetic analysis with internal transcribed spacer, glyceraldehyde 3-phosphate dehydrogenase, chitin synthase, actin, beta-tubulin, calmodulin, and the intergenic region between Apn2 and MAT1-2-1 (ApMAT). Among 52 isolates collected from 24 farms/nurseries in Taiwan, a new species, Colletotrichum miaoliense sp. nov. (6% of all isolates), a species not previously known to be associated with strawberry, Colletotrichum karstii (6%), and three known species, Colletotrichum siamense (75%), Colletotrichum fructicola (11%), and Colletotrichum boninense (2%), were identified. The predominant species C. siamense and C. fructicola exhibited higher mycelial growth rates on potato dextrose agar and caused larger lesions on wounded and non-wounded detached strawberry leaves. Colletotrichum boninense, C. karstii, and C. miaoliense only caused lesions on wounded leaves. Understanding the composition and biology of the pathogen population will help in disease management and resistance breeding.

Characterization of Colletotrichum ocimi Population Associated with Black Spot of Sweet Basil (Ocimum basilicum) in Northern Italy

Black spot is a major foliar disease of sweet basil (Ocimum basilicum) present in a typical cultivation area of northern Italy, including the Liguria and southern Piedmont regions, where this aromatic herb is an economically important crop. In this study, 15 Colletotrichum isolates obtained from sweet basil plants with symptoms of black spot sampled in this area were characterized morphologically and by nuclear DNA analysis using internal transcribed spacers (ITS) and intervening 5.8S nrDNA as well as part of the β-tubulin gene (TUB2) regions as barcode markers. Analysis revealed all but one isolate belonged to the recently described species C. ocimi of the C. destructivum species complex. Only one isolate was identified as C. destructivum sensu stricto (s.s.). In pathogenicity tests on sweet basil, both C. ocimi and C. destructivum s.s. isolates incited typical symptoms of black spot, showing that although C. ocimi prevails in this basil production area, it is not the sole causal agent of black spot in northern Italy. While no other hosts of C. ocimi are known worldwide, the close related species C. destructivum has a broad host range, suggesting a speciation process of C. ocimi within this species complex driven by adaptation to the host.