A method for designing primer sets for speciation studies in filamentous ascomycetes

Morpho-molecular characterization of phoma-like fungi from Morus alba in northern Thailand; a novel species (Boeremia albae) and a new host record (B. maritima)

Boeremia was established to accommodate phoma-resembling fungi. Its species occur in terrestrial ecosystems as endophytes, saprobes and pathogens, except one species reported from a marine ecosystem. Boeremia species are characterized by hyaline, thin-walled, and aseptate (occasionally 1(-2)-septate) conidia that are variable in shape, and hyaline, straight or slightly curved, thick-walled, and 1-septate ascospores that are usually constricted at the septum. In the past, host associations were used to delimit Boeremia species. However, since Boeremia taxa have overlapping morphological characters and are cryptic, it renders taxonomic identification arduous. Therefore, the use of other approaches including multi-gene phylogenetic analyses are imperative. Recommended DNA markers for species delineation are the internal transcribed spacer (ITS, nuclear rDNA consisting of ITS1-5.8S-ITS2) and large subunit (28S, D1-D2 domains of nuclear 28S rDNA) loci, and the genes for actin (ACT1), beta-tubulin (TBB1), RNA polymerase 2 (RPB2) and translation elongation factor 1α (TEF1). Here, we applied morphological and molecular phylogenetic analyses to establish a new taxon (B. albae), and a new host and geographical record for B. maritima associated with leaf spots of Morus alba (Moraceae) in northern Thailand. By providing sequence data for three additional gene regions, our phylogenetic analyses impart a stable phylogenetic placement of the ex-type strain of B. maritima, as illustrated. This is the first study that reports Boeremia species from M. alba, and B. maritima from a terrestrial habitat.

Two new species of Cytospora (Diaporthales, Cytosporaceae) causing canker disease of Malusdomestica and M.sieversii in Xinjiang, China

Apple tree canker is a serious disease caused by species of Cytospora. Xinjiang Uygur Autonomous Region is one of the most important apple-producing areas in China. However, losses due to apple Cytospora canker have seriously damaged the apple industry and affected the economic development of the apple growers in this region. In this study, we used morphological characteristics combined with multilocus phylogenetic analyses of the ITS, act, rpb2, tef1 and tub2 loci to identify isolates from apple (Malusdomestica) and wild apple (M.sieversii). As a result, C.hippophaopsis sp. nov. from M.sieversii and C.shawanensis sp. nov. from M.domestica were discovered and proposed herein. Pathogenicity tests were further conducted on 13 varieties of apple and wild apple, which confirmed C.hippophaopsis and C.shawanensis as canker pathogens. Meanwhile, C.hippophaopsis is generally more aggressive than C.shawanensis on the tested varieties of apple and wild apple.

From marine neglected substrata new fungal taxa of potential biotechnological interest: the case of Pelagia noctiluca

Introduction

The marine environment is extremely complex and exerts strong evolutionary pressure often leading to the appearance of microbial strains with new metabolic competencies. Microorganisms in marine ecosystems are still largely unknown and should be explored and conserved for biodiversity preservation, possible ecosystem restoring, and other applications. Biodiversity conservation should become a basic ecological strategy of particular significance in relation to global change. In this context, the present research aimed at exploring the culturable mycobiota associated with the jellyfish Pelagia noctiluca, never studied before. In addition, the isolated strains were tested for potential application (antimicrobial activity and presence of genes related to the production of secondary metabolites).

Methods

Five jellyfishes were collected in the coastal area of Giglio Island and processed to isolate epizoic fungi. The strains were identified using a polyphasic approach (morphological, physiological, and molecular) and their salt preference was also investigated. The antifungal and antibacterial activity were tested for each strain with agar plug diffusion test. The presence of some key genes related to the main pathways for the production of secondary metabolites in fungi, polyketide synthases (PKSs), and non-ribosomal peptide synthase (NRPSs), was also assessed.

Results

A total of 164 isolates were obtained; after the dereplication, 40 morphotypes, and 23 species were identified. The phylogenetic analyses suggested the presence of new taxa belonging to Pleosporales: two new genera and species, and a new species of Tamaricicola. The detected mycobiota showed a relatively high diversity, if compared to other epizoic fungal communities. All isolated strains were marine fungi as confirmed by their salt preference and marked euryhalinism. The genes related to the two main pathways for the production of secondary metabolites in fungi, PKSs and NRPSs, were identified in four and nine strains, respectively. The antimicrobial activity was revealed in 70% of the strains, including the new taxa. The abundance of bioactive strains may be related to the potential involvement of epizoic fungi in host defense strategies. Moreover, these strains could show a high potential for further biotechnological applications particularly in the case of new taxa. All strains are maintained in culture collections.

New Helminthosporium (Massarinaceae, Dothideomycetes) and Nigrospora (Incertae sedis, Sordariomycetes) species associated with walnut (Juglansregia L.) in China

Six collections of ascomycetes were obtained from samples collected from dead branches and leaves of Juglansregia in Guizhou and Yunnan provinces, China. By incorporating multigene phylogenetic analysis (ITS, LSU, rpb2, SSU, tef1-α, tub2) supplemented by morphological data, we establish two novel species, namely Helminthosporiumguizhouense and Nigrosporayunnanensis. In morphology, H.guizhouense can be distinguished from H.caespitosum by its narrower conidia (13-16 µm vs. 27.3-35.5 µm), and N.yunnanensis is characterized by black, globose conidia (16.2 × 14.4 µm). The phylogenetic results further substantiated them as novel taxa. The present study contributes to our comprehension of the range of fungi found in Juglansregia, thereby expanding our knowledge of the diversity of fungi within this host.

Morpho-phylogenetic identification and characterization of new causal agents of Fusarium species for postharvest fruit rot disease of muskmelon in northern Thailand and their sensitivity to fungicides

A significant global problem affecting muskmelon (Cucumis melo L.) is fruit rot caused by phytopathogenic fungi, which results in unsaleable products and substantial financial losses. In 2022 and 2023, fruit rot on muskmelon was found during the postharvest storage period in Phayao Province of northern Thailand. The aim of the current study was to isolate the species of fungi causing the fruit rot lesions. Out of the rot lesions on muskmelons, nine fungal isolates were received. All isolates of fungi were identified through a combination of morphological characteristics and molecular analyses. Based on their morphological traits, all isolated fungal isolate was assigned to the genus Fusarium. All the fungal isolates were determined to belong to the Fusarium incarnatum-equiseti species complex through multi-gene phylogenetic analysis employing the calmodulin (cam), RNA polymerase second largest subunit (rpb2), and translation elongation factor 1-alpha (tef1-α) genes. These isolates were identified as F. compactum (SDBR-CMU483), F. jinanense (SDBR-CMU484, SDBR-CMU485, and SDBR-CMU486), F. mianyangense (SDBR-CMU487 and SDBR-CMU488), and F. sulawesiense (SDBR-CMU489, SDBR-CMU490, and SDBR-CMU491). Moreover, pathogenicity tests were subsequently carried out, and the results indicated that all fungal isolates caused symptoms of fruit rot on inoculated muskmelon fruits. Notably, this result was consistent with the symptoms observed throughout the postharvest storage period. In the fungicide screening test, all fungal isolates showed sensitivity to copper oxychloride. However, all isolates showed insensitivity to benalaxyl-M + mancozeb, carbendazim, mancozeb, and metalaxy. To the best of our knowledge, the present study is the first to identify F. compactum, F. jinanense, and F. mianyangense as new causative agents of muskmelon fruit rot in Thailand and other regions globally. This is also the first report of postharvest fruit rot on muskmelons caused by F. sulawesiense in Thailand. Furthermore, the fungicide screening results indicate that fungicide resistance can be beneficial in developing potential management strategies against postharvest fruit rot disease of muskmelon caused by these four pathogenic Fusarium species.

Morphological and phylogenetic analyses reveal eight novel species of Pestalotiopsis (Sporocadaceae, Amphisphaeriales) from southern China

Plants play an important role in maintaining the ecological balance of the biosphere, but often suffer from pathogenic fungi during growth. During our continuing mycological surveys of plant pathogens from terrestrial plants in Jiangxi and Yunnan provinces, China, 24 strains of Pestalotiopsis isolated from diseased and healthy tissues of plant leaves represented eight new species, viz. P.alpinicola, P.camelliicola, P.cyclosora, P.eriobotryae, P.gardeniae, P.hederae, P.machiliana and P.mangifericola. Multi-locus (ITS, tef1-α and tub2) phylogenetic analyses were performed using maximum-likelihood and Bayesian inference to reveal their taxonomic placement within Pestalotiopsis. Both molecular phylogenetic analyses and morphological comparisons supported them as eight independent taxa within Pestalotiopsis. Illustrations and descriptions of these eight taxa were provided, in conjunction with comparisons with closely related taxa in the genus. This work highlights the large potential for new fungal species associated with diseased plant leaves.

Biological characterization and in vitro fungicide screening of a new causal agent of walnut leaf spot in Guizhou Province, China

Walnut (Juglans regia L.) is a widely grown nut plant worldwide, including in Guizhou Province, located in southwest China. The high quality and special taste make Guizhou walnuts, particularly those produced in Hezhang County, a "Chinese National Geographical Indication Product" that substantially contributes to the local economy and grower's income. In July 2022, a serious occurrence of leaf spot disease was observed in a walnut plantation area, Shuitang Town, Hezhang County, Guizhou Province, China (27°07'67″N, 104°64'61″E). The causal agent was identified as Didymella segeticola through morphological characterization and amplification and sequencing of the internal transcribed spacer (ITS) region, beta-tubulin (TUB) gene, and glyceraldehyde-3-phosphate dehydrogenase (G3PD) gene. Koch's postulates, including re-isolation and identification, were performed to confirm its pathogenicity on healthy leaves. To our knowledge, this is the first report of D. segeticola causing leaf spot on walnuts worldwide. Further, to determine its biological characteristics, which could be utilized for future disease management, the effects of temperature, light, and carbon and nitrogen resources on mycelial growth, conidia production, and conidia germination and the effects of humidity on conidia germination were studied. The optimum temperature for mycelial growth of representative strain D. segeticola C27 was 20°C. Increasing the light period significantly decreased conidia production and conidia germination. Maltose and beef extract were the best carbon and nitrogen sources, respectively, for the pathogen. Conidia germination was enhanced at 90% humidity. In vitro screening of effective fungicides was conducted. Among the 20 screened fungicides, difenoconazole showed the best inhibition rate, with an EC50 (concentration for 50% of the maximal effect) of 0.0007 μg/mL. Tetramycin also showed sufficient inhibitory effects against D. segeticola, with an EC50 value of 0.0009 μg/mL. Our study provides new insights into the causal agent of walnut leaf spot in Guizhou, China, as well as the first pathogen characteristics and promising candidate fungicides for its management.

Calonectria eucalyptorum sp. nov., a new leaf blight pathogen of Eucalyptus from India

In this study, Calonectria eucalyptorum sp. nov. is described from the blighted leaves of Eucalyptus in India using morphological and multi-locus phylogenetic analyses. The new species belongs to the Calonectria cylindrospora species complex, and its unique microscopic features and DNA sequence information enable clear separation from the 12 currently accepted species in this complex. Conidia of the new taxon are slightly longer than those of its phylogenetic neighbors. Additionally, this species produces central as well as lateral stipe extensions, which is a feature not known for the other members of the C. cylindrospora species complex. Analyses of the combined partial calmodulin, histone, translation elongation factor-1α, and β-tubulin gene regions revealed a distinct phylogenetic position for C. eucalyptorum. Recombination analysis provided additional support for the new species hypothesis. Koch's postulates for the new taxon as a foliar pathogen of Eucalyptus were fulfilled. The discovery of novel and pathogenic Calonectria species is important because it sheds light on species diversity, potential threats, and disease control.

Molecular phylogenetic and estimation of evolutionary divergence and biogeography of the family Schizoparmaceae and allied families (Diaporthales, Ascomycota)

The Diaporthales includes 32 families, many of which are important plant pathogens, endophytes and saprobes, e.g., members of the families Pseudoplagiostomataceae, Pyrisporaceae and Schizoparmaceae. Nucleotide sequences derived from five genetic loci including: ITS, LSU, TEF1-α, TUB2 and RPB2 were used for Bayesian evolutionary analysis to determine divergence times and evolutionary relationships within the Schizoparmaceae. Molecular clock analyses revealed that the ancestor of Schizoparmaceae split during the Upper Cretaceous period approximately 75.7 Mya (95 % highest posterior density of 60.3-91.3 Mya). Reconstructing ancestral state in phylogenies (RASP) with using the Bayesian Binary Markov chain Monte Carlo (BBM) Method to reconstruct the historical biogeography for the family Schizoparmaceae indicated its most likely origin in Africa. Based on taxonomic and phylogenetic analyses, the Pseudoplagiostomataceae and Pyrisporaceae relationships were clarified and a total of four species described herein. For Pseudoplagiostomataceae, three new species and one known species that include, Pseudoplagiostoma fafuense sp. nov., Ps. ilicis sp. nov., Ps. sanmingense sp. nov. and Ps. bambusae are described and a key of Pseudoplagiostomataceae is provided. With respect to Pyrisporaceae, we considered Pseudoplagiostoma castaneae to be a synonym of Pyrispora castaneae. In addition, a new species of Schizoparmaceae, Coniella fujianensis sp. nov. is described and illustrated.

Effect of temperature on in vitro germination and growth of Colletotrichum fioriniae, a new emerging pathogen of olive fruits

Olive anthracnose induced by different Colletotrichum species causes dramatic losses of fruit yield and oil quality. The increasing incidence of Colletotrichum fioriniae (Colletotrichum acutatum species complex) as causal agent of olive anthracnose in Italy, is endorsing new studies on its biology, ecology, and environmental factors such as temperature. Five isolates from different sampling sites in Lazio region (Central Italy) were studied under controlled laboratory conditions aiming to better understand the differences of thermal development among the isolates and to lay the foundations of a future mathematical model able to describe the key aspects of the pathogen's life cycle. The mycelial growth rate and the conidial germination rate were assessed at seven different constant temperatures (5, 10, 15, 20, 25, 30, and 35°C) and fixed relative humidity (100% RH). The obtained dataset was analysed to estimate the parameters of mathematical functions that connect the mycelial growth rate and the spore germination with the environmental temperature. The parameters set provided as the result of this study constitute a key step forward in the biological knowledge of the species and the basis for future formulations of mathematical models that might be the core of decision support systems in an integrated pest management framework.

Re-identification of Korean Isolates in the Colletotrichum dematium, C. magnum, C. orchidearum, and C. orbiculare Species Complexes

A large number of species in the genus Colletotrichum have been reported as causal agents of anthracnose on crops and wild plants in Korea. Many Colletotrichum isolates from the country preserved in the Korean Agricultural Culture Collection (KACC) were previously identified based on host plants and morphological characteristics, and it may lead to species misidentification. Thus, accurate fungal species identification using multilocus sequence analyses is essential for understanding disease epidemiology and disease management strategies. In this study, combined DNA sequence analyses of internal transcribed spacer, gapdh, chs-1, his3, act, tub2, and gs were applied to re-identify 27 Colletotrichum isolates in KACC. The phylogenetic analyses showed that the isolates resulted in 11 known species, they belong to the C. dematium species complex (C. hemerocallidis, C. jinshuiense, and C. spinaciae), the C. magnum complex (C. kaifengense and C. cf. ovatense), the C. orchidearum complex (C. cattleyicola, C. plurivorum, C. reniforme, and C. sojae) and the C. orbiculare complex (C. malvarum and C. orbiculare). Of them, C. cattleyicola, C. hemerocallidis, C. kaifengense, and C. reniforme were unrecorded species in Korea. In the view of host-fungus combinations, 10 combinations are newly reported in the world and 12 are new reports in Korea, although their pathogenicity on the host was not confirmed.

Antifungal activity of 2-chloro-5-trifluoromethoxybenzeneboronic acid and inhibitory mechanisms on Geotrichum candidum from sour rot Xiaozhou mustard root tuber

Xiaozhou mustard (Brassica napiformis) root tuber, a traditional fermented vegetable, has a long history in Rongan County, Guangxi Province. However, the frequent occurrence of root tuber sour rot by Geotrichum candidum (G. candidum) has seriously reduced Xiaozhou mustard production and quality in recent years. The objective of the present study is to investigate the antifungal efficacy of 2-chloro-5-trifluoromethoxybenzeneboronic acid (Cl-F-BBA) against G. candidum and its possible mechanisms. The results revealed that a concentration of 0.25 mg/mL Cl-F-BBA completely halted mycelial growth and spore germination. Furthermore, a slightly lower concentration of 0.20 mg/mL was sufficient to compromise the integrity of the plasma membrane in mycelia and mitochondria, leading to a reduction in respiratory rate, activities of malate dehydrogenase (MDH), and succinate dehydrogenase (SDH), ATP content, and energy charge. This concentration also significantly disordered antioxidant metabolism, resulting in the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), and caused intracellular leakage in mycelia. In vivo experiments further demonstrated that Xiaozhou mustard root tubers treated with Cl-F-BBA exhibited markedly lower decay rates and lesion diameters compared to the control group. In summary, Cl-F-BBA presents a promising solution for controlling root tuber sour rot in Xiaozhou mustard caused by G. candidum.

Evaluating Treatments for the Protection of Grapevine Pruning Wounds from Natural Infection by Trunk Disease Fungi

Infection of grapevines by fungal pathogens causing grapevine trunk diseases (GTDs) primarily arises from annual pruning wounds made during the dormant season. While various studies have showcased the efficacy of products in shielding pruning wounds against GTD infections, most of these investigations hinge on artificial pathogen inoculations, which may not faithfully mirror real field conditions. This study aimed to evaluate and compare the efficacy of various liquid formulation fungicides (pyraclostrobin + boscalid) and paste treatments, as well as biological control agents (BCA: Trichoderma atroviride SC1, T. atroviride I-1237, and T. asperellum ICC012 + T. gamsii ICC080), for their potential to prevent natural infection of grapevine pruning wounds by trunk disease fungi in two field trials located in Samaniego (Northern Spain) and Madiran (Southern France) over three growing seasons. Wound treatments were applied immediately after pruning in February. One year after pruning, canes were harvested from vines and brought to the laboratory for assessment of Trichoderma spp. and fungal trunk pathogens. More than 1,200 fungal isolates associated with five GTDs (esca, Botryosphaeria, Diaporthe and Eutypa diebacks, and Cytospora canker) were collected from the two vineyards each growing season. Our findings reveal that none of the products under investigation exhibited complete effectiveness against all the GTDs. The efficacy of these products was particularly influenced by the specific year of study. A notable exception was observed with the biocontrol agent T. atroviride I-1237, which consistently demonstrated effectiveness against Botryosphaeria dieback infections throughout each year of the study, irrespective of the location. The remaining products exhibited efficacy in specific years or locations against particular diseases, with the physical barrier (paste) showing the least overall effectiveness. The recovery rates of Trichoderma spp. in treated plants were highly variable, ranging from 17 to 100%, with both strains of T. atroviride yielding the highest isolation rates. This study underscores the importance of customizing treatments for specific diseases, taking into account the influence of environmental factors for BCA applications.

Diaporthe species causing shoot dieback of Acer (maple) in Henan Province, China

BACKGROUND

Maple is an important ornamental plant in China. With the increasing use of maple trees in landscaping, a symptom of shoot dieback has been observed in Henan province, China.

RESULTS

In this study, 28 Diaporthe isolates were obtained from symptomatic shoots of maple trees between 2020 and 2023. Phylogenetic analyses based on five loci (ITS, TEF, CAL, HIS and TUB) coupled with morphology of 12 representative isolates identified three known species (D. eres, D. pescicola and D. spinosa) and one new species, namely D. pseudoacerina sp. nov. Koch's postulates confirmed that all these species were pathogenic. Additionally, D. pseudoacerina was able to infect China wingnut (Pterocarya stenoptera), pear (Pyrus sp.), and black locust (Robinia pseudoacacia). This study marks the first report of Diaporthe spinosa and D. pescicola pathogens infecting maple trees.

CONCLUSIONS

These findings enhance the existing knowledge of the taxonomy and host diversity of Diaporthe species as, while also providing valuable information for managing of maple shoot dieback in Henan Province, China.

Colletotrichum Species Associated with Apple Bitter Rot and Glomerella Leaf Spot: A Comprehensive Overview

Species of the genus Colletotrichum are among the most important plant pathogens globally, as they are capable of infecting many hosts-apple (Malus spp.) and other fruit and woody plant species-but also vegetable crops, cereals, legumes, and other annual and perennial herbaceous plants. The apple (Malus spp.) is attacked by various species from the genus Colletotrichum, whereby 27 different species from this genus have been described as the causative agents of apple bitter rot (ABR) and 15 as the cause of Glomerella leaf spot (GLS). These species generally belong to one of three species complexes: Colletotrichum acutatum, Colletotrichum gloeosporioides, and Colletotrichum boninense. The largest number of apple pathogens of the genus Colletotrichum belong to the species complex C. acutatum and C. gloeosporioides. However, further data on these species and the interactions between the species complexes of the genus Colletotrichum that cause these two apple diseases is needed for the development of effective control measures, thus ensuring successful and profitable apple cultivation. To contribute to this endeavor, a comprehensive review of the causative agents of ABR and GLS from the genus Colletotrichum is provided. In addition to presenting the species' current names, distribution, economic significance, and the symptoms they cause in apple, their development cycle, epidemiology, and molecular detection strategies are described, with a particular emphasis on control measures.

New species of Diaporthe (Diaporthaceae, Diaporthales) from Bauhiniavariegata in China

Diaporthe species are known as endophytes, saprobes and pathogens infecting a wide range of plants and resulting in important crop diseases. In the present study, four strains of Diaporthe were obtained from diseased leaves of Bauhiniavariegata in Guangdong Province, China. Phylogenetic analyses were conducted to identify these strains using five gene regions: internal transcribed spacer (ITS), calmodulin (cal), histone H3 (his3), translation elongation factor 1-α (tef1) and β-tubulin (tub2). The results combined with morphology revealed two new species of Diaporthe named D.bauhiniicola in D.arecae species complex and D.guangzhouensis in D.sojae species complex.

Two new species of Dendrostoma (Erythrogloeaceae, Diaporthales) associated with Castaneamollissima canker disease in China

The genus Dendrostoma is known to inhabit tree barks associated with branch canker diseases in China and several countries of Europe. Previous studies indicated that species of Dendrostoma prefer inhabiting fagaceous hosts, especially species of Castanea. In the present study, we obtained four isolates from cankered branches of Chinese chestnut (C.mollissima) in Rizhao City, Shandong Province, China. Morphological comparisons and phylogenetical analyses of a combined ITS-tef1-rpb2 sequence matrix were conducted, which revealed two new species named Dendrostomarizhaoense sp. nov. and D.tianii sp. nov. The new taxa are compared with other Dendrostoma species and comprehensive descriptions and illustrations are provided herein.

Novel Helicoma and Neohelicosporium (Tubeufiaceae, Tubeufiales) species and two new host records of Helicoma on tropical palms (Arecaceae) from China

Asexual species of Tubeufiaceae are characterised as helicosporous hyphomycetes and are abundantly discovered in tropical and subtropical regions. The present study collected helicosporous fungal samples from rotting tissues of Caryotamitis, Elaeisguineensis and E.oleifera in Xishuangbanna, Yunan Province, China. Fungal isolates were identified, based on the morphological characteristics and multi-gene phylogeny with DNA sequence data of the internal transcribed spacer (ITS), part of the large subunit nuclear rRNA gene (LSU), translation elongation factor 1-alpha gene (tef 1-α) and RNA polymerase II second largest subunit gene (rpb2). Herein, we introduce three new species viz. Helicomaoleifera, Neohelicosporiumguineensis and N.xishuangbannaensis. In addition, we introduce two new host records of Helicomaguttulatum and H.rufum on Caryotamitis. The illustrations of all identified species, detailed descriptions and in-depth phylogenetic analyses are provided. Our results add new knowledge of fungal species associated with palm hosts in southern China. Moreover, our data will contribute to the biodiversity of fungi in tropical China.

Identification and pathogenicity of Alternaria and Fusarium species associated with bagged apple black spot disease in Shaanxi, China

Apple is an economically important fruit crop in northern Shaanxi Province in China. In recent years, a new type of apple black spot disease, "bagged apple black spot disease," has occurred in the main apple production area of Yan'an City, Shaanxi Province, during the apple ripening season. It seriously affects the appearance quality and commercial value of apples. In this study, 120 isolates recovered from symptomatic apples were identified based on morphological characteristics, pathogenicity, and multilocus sequence analyses of the internal transcribed spacer of ribosomal DNA (rDNA-ITS), translation elongation factor 1-α (EF1-α), RNA polymerase II subunit B (RPB2), endopolygalacturonase (endo-PG), and anonymous region OPA1-3. Alternaria alternata was the most abundant species (64%), followed by Fusarium acuminatum (36%). Pathogenicity assays were conducted by inoculating them individually and together on detached apples (Venus Golden and Fuji varieties). The results showed that the two fungal species could infect apples individually and together. Co-infection enhanced the disease severity. F. acuminatum led to increased severity and speed of disease development compared to A. alternata. This is the first report of Fusarium and Alternaria co-infection causing apple black spot disease worldwide, and the first report of F. acuminatum affecting apples. The optimal growth of A. alternata occurred at 25-30°C and pH 7; the optimal growth of F. acuminatum occurred at 25°C and pH 7. The results of this study can provide a theoretical basis for exploring the occurrence and epidemiology of apple black spot disease and strategies for its control.

Three new species of Colletotrichum (Glomerellales, Glomerellaceae) associated with walnut (Juglansregia) anthracnose from China

Colletotrichum species are significant pathogens of various economic plant hosts worldwide. In this study, 45 Colletotrichum isolates were obtained from symptomatic walnut leaves of walnut anthracnose in Shaanxi and Sichuan Provinces. In conjunction with morphological evidence and multi-gene phylogenetic analyses of internal transcribed spacer (ITS), actin (act), chitin synthase 1 (chs1), glyceraldehyde-3-phosphate dehydrogenase (gapdh) and beta-tubulin (tub2) sequences support the introduction of three new species, namely Colletotrichumcordae, C.guangyuanense and C.juglandium. Five species of Colletotrichum were identified to be C.fioriniae of the C.acutatum species complex, C.karsti of the C.boninense species complex, C.gloeosporioides, C.mengyinense and C.siamense of the C.gloeosporioides species complex. The three new species are described and illustrated in this paper and compared with taxa in the Colletotrichumgloeosporioides species complex. The current results improve the understanding of Colletotrichum species causing walnut anthracnose in China.

Genome-wide search and gene expression studies reveal candidate effectors with a role in pathogenicity and virulence in Fusarium graminearum

Fusarium graminearum causes Fusarium head blight (FHB) disease in wheat worldwide. Although F. graminearum is reported to secrete several effectors, their role in virulence and pathogenicity is unknown. The study aimed at identifying candidate genes with a role in pathogenicity and virulence using two different host systems, Arabidopsis thaliana and wheat, challenged with F. graminearum TN01. Detached leaf assay and histological studies revealed the virulent nature of TN01. A genome-wide in silico search revealed several candidate genes, of which 23 genes were selected based on reproducibility. Gene expression studies by reverse transcriptase-polymerase chain reaction (RT-PCR) in leaf tissues of Arabidopsis and the two wheat genotypes, the susceptible (Sonalika) and the resistant (Nobeoka Bozu/Nobeoka), compared with mock-treated controls in a time-course study using fungal- and plant-specific genes as internal controls revealed that these genes were differentially regulated. Further, expression of these candidates in F. graminearum-inoculated Sonalika and Nobeoka spikes compared with mock-treated controls revealed their role in pathogenicity and virulence. Gene ontology studies revealed that some of these secretory proteins possessed a role in apoptosis and ceratoplatanin and KP4 killer toxin syntheses. A three-dimensional protein configuration was performed by homology modeling using trRosetta. Further, real-time quantitative PCR (RT-qPCR) studies in F. graminearum-inoculated Arabidopsis and wheat at early time points of inoculation revealed an increased expression of the majority of these genes in Sonalika, suggesting their possible role in pathogenicity, whereas low mRNA abundance was observed for 11 of these genes in the resistant genotype, Nobeoka, compared with Sonalika, indicating their role in virulence of F. graminearum.

Diversity and Aggressiveness of the Diaporthe Species Complex on Sunflower in Serbia

This study aimed to investigate the Diaporthe species associated with Phomopsis stem canker of sunflower (Helianthus annuus L.) in Serbia. The significant increase in sunflower and soybean (Glycine max [L.] Merr.) cultivation may have created the bridge favorable conditions for the distribution of Diaporthe species in this region. The present study identified five Diaporthe species on sunflower: D. gulyae, D. helianthi, D. pseudolongicolla, D. stewartii, and the newly identified D. riccionae based on morphological, molecular, and pathogenic characteristics. The research emphasizes the importance of effective inoculation methods and evaluates the aggressiveness of isolates. Sunflower plants were inoculated using the stem wound method, while seeds of sunflower and soybean were inoculated using the standard seed method. Most of the tested isolates demonstrated high aggressiveness, resulting in more than 80% premature wilting of sunflower plants. Additionally, this research examined the aggressiveness of Diaporthe species on sunflower seeds, highlighting D. stewartii and D. pseudolongicolla as common pathogens of both sunflower and soybean. The most aggressive species on seeds was D. stewartii, causing seed decay of up to 100% in sunflower and 97% in soybean. The findings suggest the development of resilient sunflower genotypes through breeding programs and the implementation of strategies to manage cross-contamination risks between sunflower and soybean crops. Furthermore, this study provides insights into the interactions between Diaporthe species and the seeds of sunflower and soybean. Future research will enhance our understanding of the impact of Diaporthe species on sunflower and soybean.

The Origin of the Problem: Characterization of Paraguayan Septoria steviae, Causal Agent of Septoria Leaf Spot of Stevia, Based on Multilocus Sequence Analysis

Septoria leaf spot is a significant disease affecting cultivated stevia, potentially reducing yields by > 50%. The disease is caused by Septoria steviae, first identified in 1978 in Japan as a new pathogen of stevia. Understanding the origin of S. steviae could clarify how it spread to new production areas. To investigate this, 12 isolates of Septoria sp. were obtained from stevia's native range in the Amambay forests and field plantings in Paraguay from 2018 to 2020. These isolates underwent colony morphology and molecular characterization of Actin, β-Tubulin, Calmodulin, ITS, LSU, RPB2, and TEF1α loci. GenBank sequences from S. steviae isolates collected in France, Japan, and the United States were included. Multilocus sequence phylogenetic analysis generated a maximum likelihood (ML) tree. The morphological characteristics of Paraguayan isolates were similar to those of previously reported S. steviae type cultures from Japan. The ML analysis showed that Paraguayan isolates formed a monophyletic group with S. steviae isolates from France, Japan, and the United States. During blotter tests, pycnidia and cirri of S. steviae were observed on multiple stevia seed surfaces from different sources. Further characterization confirmed viable pathogenic conidia of S. steviae. This observation suggests that S. steviae could be associated with stevia seed, possibly spreading from the center of origin to other countries. This research is the first to genetically characterize S. steviae from Paraguay and propose its potential spread mechanism from the center of origin to the rest of the world.

Identity, Pathogenicity, and Genetic Diversity of Lasiodiplodia Species Associated with Stem-End Rot of Avocado in China

Stem-end rot (SER) causes brown necrotic lesions in the pulp near the base of the fruit pedicel and is one of the most devastating postharvest diseases of avocados in all avocado-growing regions of the world. China's avocado industry is growing very rapidly, and the planting area is expanding, but little is known about the pathogens and genetic diversity of avocado SER. To determine the causal agents of SER, avocado fruits were sampled from the main avocado-producing areas in China during 2020 and 2021. Fungal isolates were obtained from SER symptomatic avocado fruits and identified by morphology combined with phylogenetic analysis of internal transcribed spacer (ITS), translation elongation factor 1-α (EF1-α), and β-tubulin (TUB2) gene sequences. All 101 isolates belonged to Lasiodiplodia spp.; four Lasiodiplodia species were identified, namely, L. pseudotheobromae (59.41%), L. theobromae (24.75%), L. mahajangana (7.92%), and L. euphorbiaceicola (1.98%); and six others are classified as Lasiodiplodia sp. (5.94%). There were only slight morphological differences in colonies and conidia of these four species of Lasiodiplodia. The pathogenicity tests showed symptoms of SER, and 92.08% of the isolates exhibited a high level of virulence on avocado (disease index >70), related to the disease severity on avocado fruits. All tested isolates grew well under the temperature ranging from 23 to 33°C. There was a significant difference in mycelial growth between the four species of Lasiodiplodia after treatment with high or low temperatures. The growth of L. pseudotheobromae was the fastest at 13 to 18°C but was the lowest at 38°C (P < 0.05). The red pigment could be produced by all tested isolates after culturing for 7 days at 38°C. The mycelial growth rate was the fastest on PDA medium, and the slowest on the OMA medium but promoted spore formation (P < 0.05). In addition, the genetic diversity of pathogenic Lasiodiplodia species associated with SER collected from avocado, mango, guava, and soursop fruits was determined. A total of 74 isolates were clustered into four main ISSR groups by the unweighted pair-group method with arithmetic mean analysis, and the classification of this group was related to the host. Extensive diversity was detected in the Lasiodiplodia populations. The diverse geographical origins and host species significantly influenced the population differentiation, and most of the genetic variation occurred within populations (P < 0.001). This is the first study to identify the major pathogens of avocado SER in China, survey their occurrence and pathogenicity, and include a comparative analysis of genetic diversity with Lasiodiplodia spp. causing SER on other fruit hosts. Collectively, the Lasiodiplodia species complex affecting avocado showed high pathogenicity and diversity, while L. pseudotheobromae was the most frequently isolated species in China. The results of this study provide insights into the aspects of the epidemic of SER disease caused by Lasiodiplodia species, which will help in developing strategies for the management and control of SER in avocado.

Identification and Characterization of Colletotrichum Species Associated with Anthracnose Disease of Plum

Plum (Prunus salicina Lindl.) is commercially cultivated worldwide for the high levels of nutrients in the fruit. In recent years, anthracnose has been severe in some plum planting areas in China, resulting in a large number of necrotic leaves, blight, and premature leaf fall. In this study, anthracnose samples of plum leaves were collected from Hezhou, Guilin, and Lipu in Guangxi Province and Meishan, Abe Tibetan, and Qiang Autonomous Prefecture of Sichuan Province. Characteristics of mycelia on potato dextrose agar, morphology of appressoria and conidia, and analysis of sequences of several marker regions (internal transcribed spacer [ITS] region, glyceraldehyde-3-phosphate dehydrogenase [GAPDH], chitin synthase [CHS-1], histone H3 [HIS3], actin [ACT], β-tubulin [TUB2], and the intergenic region between apn2 and MAT1-2-1 [ApMat]). The resulting 101 Colletotrichum isolates obtained were identified as eight species: C. fructicola (50.5%), C. siamense (24.8%), C. karsti (8.9%), C. plurivorum (7.9%), C. aeschynomenes (3.9%), C. gloeosporioides (2%), C. celtidis (1%), and C. phyllanthi (1%). Representatives of all eight Colletotrichum species were found to cause disease on wounded leaves of plum seedlings in pathogenicity assays. As far as we are aware, this is the first report of anthracnose of plum caused by C. celtidis and C. phyllanthi in China.

Revision of Alternaria sections Pseudoulocladium and Ulocladioides: Assessment of species boundaries, determination of mating-type loci, and identification of Russian strains

Alternaria is a large genus within Pleosporaceae and consists of fungi that have up to recently been considered to be 15 separate genera, including Ulocladium. The majority of Ulocladium species after incorporation into Alternaria were placed in three sections: Ulocladioides, Pseudoulocladium, and Ulocladium. In this study, phylogeny of 26 reference strains of 22 species and 20 Russian Ulocladium-like isolates was recovered. The partial actin gene (act), Alternaria major allergen (alta1), calmodulin (cal), glyceraldehyde-3-phosphate dehydrogenase (gapdh), RNA polymerase II second largest subunit (rpb2), and translation elongation factor 1-α (tef1) were sequenced for Russian isolates. All these fungi were examined using multilocus phylogenetic analysis according to the genealogical concordance phylogenetic species recognition (GCPSR) principle and the coalescent-based model Poisson tree processes (PTP, mPTP) and evaluated for the presence of recombination. All strains were combined into two clades that corresponded to the Pseudoulocladium and Ulocladioides sections. The Pseudoulocladium clade included four reference strains and nine local isolates and considered to be a single species, whereas the Ulocladioides section comprises 11 species, instead of 17 names previously adopted. Nine species were abolished by joining four other species. Species A. atra and A. multiformis were combined into the single species A. atra. Five species, A. brassicae-pekinensis, A. consortialis, A. cucurbitae, A. obovoidea, and A. terricola, were united in the species A. consortialis. Alternaria heterospora and A. subcucurbitae were combined into one species, A. subcucurbitae. Alternaria aspera, A. chartarum, A. concatenata, and A. septospora were combined into a single species, A. chartarum. Also, amplification with two different primer sets was performed to define mating-type locus 1 (MAT1) idiomorph. All studied isolates were heterothallic, contradicting some prior studies. Twenty Russian Ulocladium-like isolates were assigned to five species of two sections, A. atra, A. cantlous, A. chartarum, A. consortialis, and A. subcucurbitae. Species A. cantlous and A. subcucurbitae were found in Russia for the first time.

Colletotrichum species (Glomerellales, Glomerellaceae) causing walnut anthracnose in China

Colletotrichum species can function as plant pathogens, saprobes or endophytes on a wide variety of plant hosts and are considered amongst the ten most significant genera of plant pathogens globally. China contributes almost half the walnut production in the world. However, Colletotrichum species occurring on walnut remain largely unresolved in China. To explore the Colletotrichum species found on walnut in China, 470 walnut fruit or leaf samples with anthracnose were collected from 14 main walnut-producing regions across seven provinces. A total of 165 Colletotrichum strains were isolated from these samples. The Colletotrichum isolates were identified, based on morphological characteristics and sequence analyses of ACT, CHS-1, GAPDH, ITS and TUB2. Twelve species, including 11 known Colletotrichum species (C.boninense, C.citrulli, C.fioriniae, C.fructicola, C.godetiae, C.juglandicola, C.karsti, C.mengyinense, C.pandanicola, C.peakense and C.siamense) and a novel species (C.chinensis sp. nov.) were identified. The species distribution revealed regional prevalence as follows: C.mengyinense was the most dominant species in Gansu, C.mengyinense and C.siamense in Shandong, C.chinensis in Beijing, C.pandanicola in Shaanxi and C.godetiae in Yunnan. Colletotrichumsiamense was the sole species isolated in Sichuan and Xinjiang Provinces. Koch's postulates were fulfilled, demonstrating that all 12 species cause anthracnose on walnut. This is the first report of C.boninense, C.citrulli and C.karsti as pathogens of walnut anthracnose worldwide.

Genetic diversity and population structure of Botryosphaeria dothidea and Neofusicoccum parvum on English walnut (Juglans regia L.) in France

Botryosphaeriaceae species are the major causal agents of walnut dieback worldwide, along with Diaporthe species. Botryosphaeria dothidea and Neofusicoccum parvum are the only two Botryosphaeriaceae species associated with this recently emergent disease in France, and little is known about their diversity, structure, origin and dispersion in French walnut orchards. A total of 381 isolates of both species were genetically typed using a sequence-based microsatellite genotyping (SSR-seq) method. This analysis revealed a low genetic diversity and a high clonality of these populations, in agreement with their clonal mode of reproduction. The genetic similarity among populations, regardless of the tissue type and the presence of symptoms, supports the hypothesis that these pathogens can move between fruits and twigs and display latent pathogen lifestyles. Contrasting genetic patterns between N. parvum populations from Californian and Spanish walnut orchards and the French ones suggested no conclusive evidence for pathogen transmission from infected materials. The high genetic similarity with French vineyards populations suggested instead putative transmission between these hosts, which was also observed with B. dothidea populations. Overall, this study provides critical insight into the epidemiology of two important pathogens involved in the emerging dieback of French walnut orchards, including their distribution, potential to mate, putative origin and disease pathways.

The effect of natural herbicide from Fusarium equiseti crude extract on the aquatic weed water hyacinth (Eichornia crassipes (Mart.) Solms)

In this study, Fusarium equiseti was isolated from the weed plant Tridax procumbens in an agricultural field and a crude extract produced with 75% ethanol for use as active ingredient material in natural herbicides. The herbicidal effect of F. equiseti extract was tested on water hyacinth (Eichornia crassipes), an invasive aquatic weed, by leaf disk assay at concentrations of 0.05%, 0.1%, and 0.2% w/v crude extract. Dose-dependent visual toxicity symptoms were evident after three days, namely chlorosis, yellow leaves surrounded by dark brown edges. Photosynthetic pigments (chlorophyll a, b, and carotenoids) and membrane integrity (as electrolyte leakage and malondialdehyde content) were evaluated following the leaf disk test. 3 days after treatment, photosynthetic pigment contents showed dose-dependent decreases, while both measures of membrane integrity showed dose-dependent increases with increasing extract concentration. In addition, a cytogenetic assay was conducted on Allium cepa L. root, in which mitotic index reduction and depigmentation were evident as early as 24 h after herbicide application. Finally, anatomical analysis of treated E. crassipes leaves revealed degradation or damage of the ground tissue. All told, our results support the F. equiseti crude-based natural herbicide cloud as a sustainable alternative in agriculture.

Etiology of Foliar Blight of Indian Paintbrush (Castilleja tenuiflora) in Mexico

Castilleja tenuiflora is a native perennial plant used in traditional Mexican medicine. In June 2022, leaf blight symptoms were observed in a wild population of C. tenuiflora plants. Disease incidence was 80% and disease intensity reached up to 5% of the leaf area. Currently, there are no reports of pathogens causing leaf blight in this plant; therefore, this work aimed to identify the fungi responsible for the disease. The fungi recovered from the diseased tissue were characterized by means of pathogenicity tests and cultural, morphological, and molecular characterization. The information obtained revealed that Alternaria alternata and Alternaria gossypina are the pathogens responsible for the disease. This is the first report implicating species of Alternaria in causing leaf blight of C. tenuiflora in Mexico, as well as the first report of Alternaria gossypina also in Mexico. These pathogens may threaten the in situ conservation of native C. tenuiflora populations and limit their in vitro propagation. Future research lines should focus on determining the effect of these pathogens on metabolite production.

Diversity and Pathogenicity of Six Diaporthe Species from Juglans regia in China

Walnut (Juglans regia L.) is cultivated extensively in China for its substantial economic potential as a woody oil species. However, many diseases caused by Diaporthe greatly affect the health of Juglans regia trees. The present study revealed the presence of Diaporthe species from Juglans regia. A total of six species of Diaporthe were isolated from twigs of Juglans regia in three provinces in China, including two known species (Diaporthe gammata and D. tibetensis) and four novel species (D. chaotianensis, D. olivacea, D. shangluoensis and D. shangrilaensis). Phylogenetic relationships of the new species were determined by multilocus phylogenetic analyses based on partial sequences of the internal transcribed spacer (ITS) region, calmodulin (cal) gene, histone H3 (his3) gene, translation elongation factor 1-α (tef1-α) gene and β-tubulin (tub2) gene. Pathogenicity tests indicated that all Diaporthe species obtained in this study were confirmed as pathogens of Juglans regia. This study deepens the understanding of species associated with several disease symptoms in Juglans regia and provides useful information for effective disease control.

Identification of Pathogen Causing Bulb Rot in Fritillaria taipaiensis P. Y. Li and Establishment of Detection Methods

Fritillaria taipaiensis P. Y. Li (F. taipaiensis) is a traditional Chinese herbal medicine that has been used for over two millennia to treat cough and expectoration. However, the increasing cultivation of F. taipaiensis has led to the spread of bulb rot diseases. In this study, pathogens were isolated from rotten F. taipaiensis bulbs. Through molecular identification, pathogenicity testing, morphological assessment, and microscopy, Fusarium solani was identified as the pathogen causing bulb rot in F. taipaiensis. The colonization of F. solani in the bulbs was investigated through microscopic observation. The rapid and accurate detection of this pathogen will contribute to better disease monitoring and control. Loop-mediated isothermal amplification (LAMP) and qPCR methods were established to quickly and specifically identify this pathogen. These results provide valuable insights for further research on the prediction, rapid detection, and effective prevention and control of bulb rot in F. taipaiensis.

Novel discoveries of Xylariomycetidae (Ascomycota) taxa from peat swamp forests and other terrestrial habitats in Thailand

In a comprehensive survey of fungi conducted in the northern (Chiang Rai Province) and southern (Narathiwat Province) regions of Thailand, several xylariales-like specimens were discovered. Through the integration of molecular phylogeny and morphological analyses, one previously undocumented taxon, Oxydothisnarathiwatensis sp. nov., was identified, along with Xylariabawanglingensis and Hypoxylonhypomiltum as new host and geographical records from Afzeliaxylocarpa, and Dalbergiacana, respectively. In addition, Annulohypoxylonthailandicum was identified as a new host record from Swieteniamacrophylla in Thailand. The morphological characters, including ascomata, asci, and ascospores, were compared with known Oxydothis, Xylaria, Hypoxylon, and Annulohypoxylon species. Multi-locus phylogenetic analyses based on ITS, LSU, and SSU (for Oxydothidaceae), ITS, rpb2, tub2, and act (for Xylariaceae), and ITS, LSU, rpb2, and tub2 (for Hypoxylaceae) gene regions were carried out to refine the taxonomic classifications of these specimens further. This research contributes to understanding fungal diversity in these ecologically significant regions, highlighting insights into the relationships among xylariales-like species.

Phylogenetic Insights Reveal New Taxa in Thyridariaceae and Massarinaceae

Pleosporales is a highly diverse (and the largest) order in Dothideomycetes, and it is widespread in decaying plants in various environments around the world. During a survey of fungal diversity in Sichuan Province, China, specimens of hyphomycetous and Thyridaria-like fungi were collected from dead branches of pine trees and cherry trees. These taxa were initially identified as members of Massarinaceae and Thyridariaceae through morphological examination. Phylogenetic analyses of the Thyridariaceae, combining ITS, SSU, LSU, RPB2, and TEF1 sequence data, indicated a distinct clade sister to Pseudothyridariella and Thyridariella, distinct from any genus in the family. Thus, a new genus, Vaginospora, is proposed to accommodate the type species Vaginospora sichuanensis, which is characterized by semi-immersed globose to oblong ascomata with an ostiolar neck, cylindrical to clavate asci with an ocular chamber, and hyaline to dark brown, fusiform, 3-5-transversely septate ascospores with an inconspicuous mucilaginous sheath. Based on the morphological comparisons and multi-locus phylogenetic analyses (ITS, SSU, LSU, RPB2, and TEF1) of the Massarinaceae, we have identified three collections belonging to the genus Helminthosporium, leading us to propose H. filamentosa sp. nov., H. pini sp. nov., and H. velutinum as a new host record. According to Phylogenetic analysis, H. pini formed an independent clade sister to H. austriacum and H. yunnanense, and H. filamentosa represents the closest sister clade to H. quercinum. Helminthosporium pini is distinct from H. austriacum by the shorter conidiophores and H. yunnanense by the longer and wider conidia. The H. filamentosa differs from H. quercinum in having longer conidiophores and smaller conidia. This study extends our understanding of diversity within Thyridariaceae and Helminthosporium. Our findings underscore the rich biodiversity and potential for discovering novel fungal taxa within these groups.

Antifungal activity of Serratia plymuthica against the phytopathogenic fungus Alternariatenuissima

The antifungal activity of Serratia plymuthica CCGG2742, a bacterial strain isolated from grapes berries skin, against a phytopathogenic fungus isolated from blueberries was evaluated in vitro and in vivo. In order to characterize the wild fungal isolate, phylogenetic analysis using concatenated DNA sequences from the RPB2 and TEF1 genes and of the ITS region was performed, allowing the identification of the fungal isolate that was called Alternaria tenuissima CC17. Hyphae morphology, mycelium ultrastructure, conidia and reproductive structures were in agreement with the phylogenetic analysis. The antifungal activity of the S. plymuthica strain was dependent on the composition of the culture medium. The greatest inhibition of mycelial growth of A. tenuissima CC17 by S. plymuthica CCGG2742 was observed on YTS medium, which lacks of an easily assimilable carbon source. Fungal growth medium supplemented with 50 % of bacterial supernatant decreased the conidia germination of A. tenuissima CC17 up to 32 %. Preventive applications of S. plymuthica CCGG2742 to blueberries and tomato leaves at conidia:bacteria ratio of 1:100, protected in 77.8 ± 4.6 % and 98.2 ± 0.6 % to blueberries and tomato leaves from infection caused by A. tenuissima CC17, respectively. To the best of our knowledge, this is the first report on the antifungal activity of S. plymuthica against A. tenuissima, which could be used as a biological control agent of plant diseases caused by this fungal species. In addition, the results of this work could be a starting point to attribute the real importance of A. tenuissima as a pathogen of blueberries in Chile, which until now had been considered almost exclusively to A. alternata. Likewise, this research could be relevant to start developing highly effective strategies based on S. plymuthica CCGG2742 for the control of this important phytopathogenic fungus.

Discovery of Botryosphaeria eucalypti sp. nov. from blighted Eucalyptus leaves in India

Eucalyptus spp. are undoubtedly one of the most favored plantation trees globally. Accurately identifying Eucalyptus pathogens is therefore crucial for timely disease prevention and control. Recently, symptoms of a leaf blight disease were observed on Eucalyptus trees in plantations at Jhajjar and Karnal in the state of Haryana, northern India. Asexual morphs resembling the features of the Botryosphaeriaceae were consistently isolated from the symptomatic leaves. Morphological features coupled with DNA sequence analysis confirmed a novel species, which is described and illustrated here as Botryosphaeria eucalypti sp. nov. Conidia of the new taxon are longer and wider than those of its phylogenetic neighbors. A distinct phylogenetic position for the new taxon was established through combined analysis of the internal transcribed spacer (ITS), partial translation elongation factor-1α (tef1) and partial β-tubulin (tub2) regions. Recombination analysis provided additional support for the new species hypothesis. The pathogenicity of the novel species was proved on Eucalyptus leaves, and Koch's postulates were fulfilled. The discovery of new Botryosphaeria species is important because it will help in understanding the species diversity, host range, possible threats and disease control in the long run.

Exhaustive identification and characterization of Colletotrichum siamense and Colletotrichum fructicola as causative agents of circular leaf spot disease of rubber tree (Hevea brasiliensis) in India

The rubber tree (Hevea brasiliensis) is one of the major domesticated crops planted commercially for the production of natural rubber (NR) worldwide. In recent years, rubber trees in the Southern states of India and other rubber-producing countries have experienced a severe leaf spot disease, characterized by the appearance of several brown circular spots in the initial stage, which later spread all over the lamina of fully matured leaves, leading to yellowing and defoliation. The causal organism of this Circular Leaf Spot (CLS) disease has not been conclusively identified in any previous studies. In this study, we collected infected leaf samples from various locations in the South Indian states. We aimed to identify the actual fungal pathogen that causes the CLS disease on rubber trees. Based on the morphological and molecular analysis of the most frequently isolated fungi from infected leaf samples were identified as Colletotrichum siamense and Colletotrichum fructicola. Pathogenicity tests also confirmed the involvement of isolated Colletotrichum spp. in the development of CLS disease. These findings provide valuable insights into understanding the CLS disease and its impact on rubber cultivation. To our knowledge, it is the first report of C. siamense and C. fructicola associated with CLS disease of rubber trees in India.

Cercospora polygonatum, a New Species Causing Gray Leaf Spot Disease in Polygonatum cyrtonema

This study identified a new species (Cercospora polygonatum) that causes gray leaf spot (GLS) disease in cultivated Polygonatum cyrtonema. This fungal species was isolated from the affected region of GLS on P. cyrtonema leaves. Pathogenicity bioassays were conducted based on Koch's postulates. Morphology was examined based on the features of conidiomata, conidiogenous loci, conidia/conidiophores, and conidiogenous cells. The rDNA internal transcribed spacer region, calmodulin, translation elongation factor 1-alpha, and histone genes were subjected to phylogenetic analysis using the MrBayes tool in Phylosuite. Bootstrap support analysis for phylogenetic placement confirmed the new species, which was significantly different from the closely related species C. senecionis-walkeri and C. zeae-maydis. The morphological characteristics also supported this finding, with the conidiogenous cells of C. polygonatum being considerably shorter than those of C. senecionis-walkeri or C. zeae-maydis. In addition, C. polygonatum was distinguished by its cultural characteristics. As this fungus was isolated from P. cyrtonema, it was named C. polygonatum F.Q. Yin, M. Liu & W.L. Ma, sp. nov. The type specimen (H8-2) was preserved at the China General Microbiological Culture Collection Center. This is the first report of GLS caused by C. polygonatum on P. cyrtonema leaves in China. The current study enriches the knowledge regarding Cercospora sp., contributes to the identification of a species causing GLS in P. cyrtonema, and provides useful information for the effective management of this disease.

Three Alternaria Species, Including a New Species, Causing Leaf Spot Disease of Loquat (Eriobotrya japonica) in China

Loquat (Eriobotrya japonica) is an economically important subtropical fruit crop in China. Field surveys conducted in different loquat orchards located in Chongqing, Sichuan, and Fujian provinces between 2017 and 2020 resulted in a collection of 56 Alternaria-like isolates from trees exhibiting symptoms of loquat leaf spot. Multigene phylogenetic analyses using seven gene regions, namely, ITS, gapdh, RPB2, tef1, Alt a 1, endoPG, and OPA10-2, showed that all the isolates belonged to the genus Alternaria, and supporting morphological analysis identified them as members of species A. alternata, A. gaisen, and A. chongqingensis sp. nov. In vitro and in vivo pathogenicity tests showed all the identified species to be pathogenic and able to cause leaf spot disease on loquat. Moreover, comprehensive phylogenetic analyses employing all combinations of the above seven gene sequences revealed the capability of Alt a 1-tef1-endoPG to provide a well-resolved gene tree for Alternaria spp. at the species level. This study adds to the current knowledge on an unknown species (A. chongqingensis sp. nov.) and is the first report of A. gaisen in loquat worldwide.

Recent advances in the population biology and management of maize foliar fungal pathogens Exserohilum turcicum, Cercospora zeina and Bipolaris maydis in Africa

Maize is the most widely cultivated and major security crop in sub-Saharan Africa. Three foliar diseases threaten maize production on the continent, namely northern leaf blight, gray leaf spot, and southern corn leaf blight. These are caused by the fungi Exserohilum turcicum, Cercospora zeina, and Bipolaris maydis, respectively. Yield losses of more than 10% can occur if these pathogens are diagnosed inaccurately or managed ineffectively. Here, we review recent advances in understanding the population biology and management of the three pathogens, which are present in Africa and thrive under similar environmental conditions during a single growing season. To effectively manage these pathogens, there is an increasing adoption of breeding for resistance at the small-scale level combined with cultural practices. Fungicide usage in African cropping systems is limited due to high costs and avoidance of chemical control. Currently, there is limited knowledge available on the population biology and genetics of these pathogens in Africa. The evolutionary potential of these pathogens to overcome host resistance has not been fully established. There is a need to conduct large-scale sampling of isolates to study their diversity and trace their migration patterns across the continent.

Morphological and phylogenetic analyses reveal two new Alternaria species (Pleosporales, Pleosporaceae) in Alternaria section from Cucurbitaceae plants in China

Alternaria species are commonly found as saprophytes, endophytes and plant pathogens. During a survey of small-spored Alternaria in China, two new species were discovered from Cucurbitaceae plants collected in Hubei and Sichuan provinces. This study identified two new species of Alternaria using seven genes (ITS, GAPDH, TEF1, RPB2, Alt a 1, EndoPG, and OPA10-2) for phylogenetic analyses and morphological characteristics. The two new species A.jingzhouensis and A.momordicae were described and illustrated. Alternariajingzhouensis sp. nov., associated with Citrulluslanatus, is characterized by producing muriform, ellipsoidal, flask-shaped, rostrate, and beaked conidia. It differs from A.koreana, A.ovoidea, and A.baoshanensis by bearing conidia in a simple conidiogenous locus with occasionally longer beaks in a chain, and from A.momordicae sp. nov. by having shorter beaks. Alternariamomordicae sp. nov. from Momordicacharantia was distinct from A.koreana, A.ovoidea, and A.baoshanensis by producing muriform, long ellipsoid or ovoid to obclavate, sometimes inverted club-shaped conidia on a single conidiogenous locus with a wider body and longer beak in a chain, and distinct from A.jingzhouensis sp. nov. by a longer beak conidia. These two species were clearly distinguished from other species in the section Alternaria based on DNA based phylogeny and morphological characteristics. The morphological features were discussed and compared to relevant species in the present paper.

Outbreak of Alternaria Black Spot of Pomegranate (Punica granatum L.) in Italy as a Consequence of Unusual Climatic Conditions

Alternaria black spot of pomegranate (Punica granatum) was reported for the first time in Italy. In spring 2023, an outbreak of this disease was noticed in commercial pomegranate 'Wonderful' orchards of the municipality of Misterbianco (Sicily), following an unusually rainy period. A total of 30 randomly selected Alternaria isolates recovered from typical necrotic spots of leaves and fruits were characterized. Based on the colony morphology on solid agar media (PDA and MEA), isolates were separated into three distinct morphotypes (1, 2, and 3). The first two morphotypes comprised only isolates from fruits, while morphotype 3 comprised only isolates from leaves. Multigene phylogenetic analysis of four DNA regions, including internal transcribed spacer (ITS), translation elongation factor 1-α (EF-1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and a SCAR marker (OPA10-2), identified the isolates of morphotypes 1 and 2 as Alternaria alternata and morphotype 3 isolates as A. arborescens. In pathogenicity tests on unwounded leaves and fruit, the isolates of all three morphotypes produced symptoms on the leaves of three pomegranate cultivars, 'Acco', 'Wonderful', and 'Etna'. The symptoms on 'Acco' leaves were the least severe. Conversely, the fruits of 'Acco' were the most susceptible. The isolates of morphotypes 2 and 3 were not pathogenic on the fruits of 'Wonderful' and 'Etna'. This is the first report of Alternaria black spot in Italy and of A. arborescens associated with Alternaria black spot of pomegranate worldwide.

Pathogenicity Differentiation of Fusarium spp. Causing Fusarium Basal Rot and Wilt Disease in Allium spp

Here, 12 Fusarium strains, previously described as F. oxysporum f. sp. cepae (Foc), were examined via multi-locus sequencing of calmodulin (cmdA), RNA polymerase II second largest subunit (rpb2), and translation elongation factor 1-alpha (tef1), to verify the taxonomic position of Foc in the newly established epitype of F. oxysporum. The strains in this study were divided into two clades: F. nirenbergiae and Fusarium sp. To further determine the host specifications of the strains, inoculation tests were performed on onion bulbs and Welsh onion seedlings as potential hosts. Four strains (AC145, AP117, Ru-13, and TA) isolated from diseased onions commonly possessed the secreted in xylem (SIX)-3, 5, 7, 9, 10, 12, and 14 genes and were pathogenic and highly aggressive to onion bulbs, whereas all strains except for one strain (AF97) caused significant inhibition of Welsh onion growth. The inoculation test also revealed that the strains harboring the SIX9 gene were highly aggressive to both onion and Welsh onion and the gene was expressed during infection of both onions and Welsh onions, suggesting the important role of the SIX9 gene in pathogenicity. This study provides insights into the evolutionary pathogenicity differentiation of Fusarium strains causing Fusarium basal rot and wilt diseases in Allium species.

An Emerging Disease of Chickpea, Basal Stem Rot Caused by Diaporthe aspalathi in China

Chickpea (Cicer arietinum L.) is an important legume crop worldwide. An emerging disease, basal stem rot with obvious wilt symptoms, was observed in the upper part of chickpea plants during the disease survey in Qiubei County of Yunnan Province. Three fungal isolates (ZD36-1, ZD36-2, and ZD36-3) were obtained from the diseased tissue of chickpea plants collected from the field. Those isolates were morphologically found to be similar to Diaporthe aspalathi. Molecular sequence analyses of multiple gene regions (ITS, tef1, tub2, cal, and his3) indicated that the three isolates showed a high identity with D. aspalathi. Pathogenicity and host range tests of the isolates were performed on the original host chickpea and eight other legume crops. The isolates were strongly pathogenic to chickpea and appeared highly pathogenic to soybean, cowpea, and mung bean; moderated or mild pathogenic to adzuki bean and common bean; however, the isolates did not cause symptoms on grass pea (Lathyrus sativus). Diaporthe aspalathi was previously reported as a main pathogen causing the southern stem canker in soybean. To our knowledge, this is the first report of D. aspalathi inducing basal stem rot on chickpea worldwide.

Three new species of Pestalotiopsis (Amphisphaeriales, Sporocadaceae) were identified by morphology and multigene phylogeny from Hainan and Yunnan, China

Pestalotiopsis fungi are widely distributed all over the world, mainly as plant pathogens, endophytes or saprobes from multiple hosts. In this study, the sequence data analysis based on internal transcribed spacer (ITS), partial beta-tubulin (tub2) and partial regions of translation elongation factor 1 alpha (tef1α) combined with morphological characteristics was used to identify strains isolated from the diseased leaves of Aporosadioica and Rhaphiolepisindica, as well as some rotted leaves from Yunnan and Hainan Provinces in China as three new species, viz., Pestalotiopsisaporosae-dioicae sp. nov., P.nannuoensis sp. nov. and P.rhaphiolepidis sp. nov.

Updating the Species Diversity of Pestalotioid Fungi: Four New Species of Neopestalotiopsis and Pestalotiopsis

Pestalotioid fungi are associated with a wide variety of plants around the world as pathogens, endophytes, and saprobes. In this study, diseased leaves and branches of plants were collected from Guizhou and Sichuan in China. Here, the fungal isolates were identified based on a phylogenetic analysis of the internal transcribed spacer region (ITS), the translation elongation factor 1-alpha (tef1-α) and the beta-tubulin (tub2) of ribosomal DNA, and the morphological characteristics. Ten Neopestalotiopsis isolates and two Pestalotiopsis isolates were obtained, and these isolates were further confirmed as four novel species (N. acericola, N. cercidicola, N. phoenicis, and P. guiyangensis) and one known species, N. concentrica.

Characterization of the fungal genus Sphaerellopsis associated with rust fungi: species diversity, host-specificity, biogeography, and in-vitro mycoparasitic events of S. macroconidialis on the southern corn rust, Puccinia polysora

Sphaerellopsis species are putative hyperparasites of rust fungi and may be promising biological control agents (BCA) of rust diseases. However, few detailed studies limit potential BCA development in Sphaerellopsis. Here, we explored the biogeography, host-specificity, and species diversity of Sphaerellopsis and examined the early infection stage of one species, S. macroconidialis, to infer its trophic status. We randomly screened 5,621 rust specimens spanning 99 genera at the Arthur Fungarium for the presence of Sphaerellopsis. We identified 199 rust specimens infected with Sphaerellopsis species on which we conducted morphological and multi-locus phylogenetic analyses. Five Sphaerellopsis species were recovered, infecting a total of 122 rust species in 18 genera from 34 countries. Sphaerellopsis melampsorinearum sp. nov. is described as a new species based on molecular phylogenetic data and morphological features of the sexual and asexual morphs. Sphaerellopsis paraphysata was the most commonly encountered species, found on 77 rust specimens, followed by Sphaerellopsis macroconidialis on 56 and S. melampsorinearum on 55 examined specimens. The type species, Sphaerellopsis filum, was found on 12 rust specimens and Sphaerellopsis hakeae on a single specimen. We also recovered and documented for the first time, the sexual morph of S. macroconidialis, from a specimen collected in Brazil. Our data indicate that Sphaerellopsis species are not host specific and furthermore that most species are cosmopolitan in distribution. However, S. paraphysata is more abundant in the tropics, and S. hakeae may be restricted to Australia. Finally, we confirm the mycoparasitic strategy of S. macroconidialis through in-vitro interaction tests with the urediniospores of Puccinia polysora. Shortly after germination, hyphae of S. macroconidialis began growing along the germ tubes of P. polysora and coiling around them. After 12 days of co-cultivation, turgor loss was evident in the germ tubes of P. polysora, and appressorium-like structures had formed on urediniospores. The interaction studies indicate that Sphaerellopsis species may be more effective as a BCA during the initial stages of rust establishment.

Geographical variations, prevalence, and molecular dynamics of fastidious phloem-limited pathogens infecting sugar beet across Central Europe

In Europe, two fastidious phloem-limited pathogens, 'Candidatus Phytoplasma solani' (16SrXII-A) and 'Candidatus Arsenophonus phytopathogenicus', are associated with rubbery taproot disease (RTD) and syndrome basses richesses (SBR) of sugar beet, respectively. Both diseases can significantly reduce yield, especially when accompanied by root rot fungi. This study investigates the presence, geographic distribution and genetic traits of fastidious pathogens and the accompanying fungus, Macrophomina phaseolina, found on sugar beet across four geographically separated plains spanning seven countries in Central Europe. The survey revealed variable incidences of symptoms linked to these fastidious pathogens in the Pannonian and Wallachian Plains, sporadic occurrence in the North European Plain, and no symptomatic sugar beet in the Bohemian Plain. Molecular analyses unveiled the occurrence of both 'Ca. P. solani' and 'Ca. A. phytopathogenicus' throughout Central Europe, with a predominance of the phytoplasma. These fastidious pathogens were detected in all six countries surveyed within the Pannonian and Wallachian Plains, with only a limited presence of various phytoplasmas was found in the North European Plain, while no fastidious pathogens were detected in Bohemia, aligning with observed symptoms. While 16S rDNA sequences of 'Ca. P. solani' remained highly conserved, multi-locus characterization of two more variable loci (tuf and stamp) unveiled distinct variability patterns across the plains. Notably, the surprising lack of variability of tuf and stamp loci within Central Europe, particularly the Pannonian Plain, contrasted their high variability in Eastern and Western Europe, corresponding to epidemic and sporadic occurrence, respectively. The current study provides valuable insights into the genetic dynamics of 'Ca. P. solani' in Central Europe, and novel findings of the presence of 'Ca. A. phytopathogenicus' in five countries (Slovakia, Czech Republic, Austria, Serbia, and Romania) and M. phaseolina in sugar beet in Slovakia. These findings emphasize the need for further investigation of vector-pathogen(s)-plant host interactions and ecological drivers of disease outbreaks.

Biological Control of Avocado Branch Blight Caused by Lasiodiplodia theobromae Using Bacillus velezensis

In recent years, avocado branch blight has gradually become one of the major diseases causing mortality of avocado trees, which seriously affects the economic development of avocado planting regions. In order to investigate the cause of the disease, the pathogens were isolated from the interroot of avocado trees with the onset of the disease and identified as Lasiodiplodia theobromae. At the same time, three Bacillus velezensis strains, YK194, YK201, and YK268, with better antagonistic effects and high stability against L. theobromae, were isolated from the rhizospheric soil of healthy avocado plants. The results of branch experiments and field trials showed that the avocado leaves as well as branches treated with the strains YK194, YK201, and YK268 did not develop disease, and the incidence of avocado trees was significantly reduced. In the branch experiments, the biological control effect of the strains YK194, YK201, and YK268 reached 62.07, 52.70, and 72.45%, respectively. In the field experiments, it reached 63.85, 63.43, and 73.86%, respectively, which indicated that all these three strains possessed good biological control effects on avocado branch blight. Further investigation on the mechanism of action of antagonistic strains revealed that B. velezensis YK268 could produce lipopeptides, namely, surfactin, fengycin, and iturin, which could significantly inhibit the spore germination of L. theobromae. Consequently, these three isolates have potential as biocontrol agents against L. theobromae.

Diversity and Pathogenicity of Botryosphaeriaceae Species Isolated from Olives in Istria, Croatia, and Evaluation of Varietal Resistance

During 2021 and 2022, a field investigation was conducted in Istria, Croatia, searching for trees exhibiting signs of Botryosphaeria dieback. Samples of symptomatic trees were collected from 26 different locations and analysed. Isolates that morphologically corresponded to species from the Botryosphaeriaceae family were selected, and detailed morphological characterisation and molecular identification of the isolates were conducted. Based on morphological characteristics and phylogenetic analysis using the internal transcribed spacer (ITS), beta-tubulin (TUB2), and translation elongation factor 1-alpha (TEF1-α) regions, six species of fungi from the Botryosphaeriaceae family were identified: Botryosphaeria dothidea (Moug. ex Fr.) Ces. & De Not.; Diplodia mutila (Fr.) Fr.; Diplodia seriata De Not.; Dothiorella iberica A.J.L. Phillips, J. Luque & A. Alves; Dothiorella sarmentorum (Fr.) A.J.L. Phillips, Alves & Luque; and Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips. This is the first report of D. mutila, Do. sarmentorum, and Do. iberica causing Botryosphaeria dieback on olive trees in Croatia, and the first study investigating the resistance of Croatian olive varieties to species from the Botryosphaeriaceae family. Pathogenicity testing of selected isolates and assessment of variety resistance were conducted on four different olive varieties, namely Buža, Istarska bjelica, Leccino, and Rosinjola, using representative isolates of the mentioned species. The most aggressive species was found to be N. parvum. Olive varieties exhibited differences in susceptibility depending on the fungus they were infected with.