The genus Cryptosphaeria in the western United States: taxonomy, multilocus phylogeny and a new species, C. multicontinentalis

Additions to Diatrypaceae (Xylariales): Novel Taxa and New Host Associations

Diatrypaceae members have a broad distribution and are commonly found on decaying wood. Despite taxonomic and morphological challenges within this group, there has been a growing interest in Diatrypaceae in recent years. The dead branches of several plant hosts with fungal fruiting bodies were collected from Doi Tung National Park, Chiang Rai, and the Narathiwat Provinces in Thailand. Their morphological characteristics, coupled with a molecular phylogeny of combined ITS and tub2 sequence data, were used to introduce two novel Allodiatrype species (A. dalbergiae and A. eleiodoxae) and one new Melanostictus species (M. chiangraiensis). Moreover, four new host records, Diatrypella heveae, D. major, Melanostictus thailandicus, and Paraeutypella citricola on Microcos paniculata, Nayariophyton zizyphifolium, Dalbergia cultrata, and M. paniculata, respectively, as well as a new geographical record of D. major are reported. This research provides detailed descriptions of macro- and microcharacteristics, coupled with a phylogenetic tree for the newly introduced species and host records. The morphological features of Allodiatrype and Melanostictus are listed in the synoptic table.

Prediction of Suitable Habitat Distribution of Cryptosphaeria pullmanensis in the World and China under Climate Change

Years of outbreaks of woody canker (Cryptosphaeria pullmanensis) in the United States, Iran, and China have resulted in massive economic losses to biological forests and fruit trees. However, only limited information is available on their distribution, and their habitat requirements have not been well evaluated due to a lack of research. In recent years, scientists have utilized the MaxEnt model to estimate the effect of global temperature and specific environmental conditions on species distribution. Using occurrence and high resolution ecological data, we predicted the spatiotemporal distribution of C. pullmanensis under twelve climate change scenarios by applying the MaxEnt model. We identified climatic factors, geography, soil, and land cover that shape their distribution range and determined shifts in their habitat range. Then, we measured the suitable habitat area, the ratio of change in the area of suitable habitat, the expansion and shrinkage of maps under climate change, the direction and distance of range changes from the present to the end of the twenty-first century, and the effect of environmental variables. C. pullmanensis is mostly widespread in high-suitability regions in northwestern China, the majority of Iran, Afghanistan, and Turkey, northern Chile, southwestern Argentina, and the west coast of California in the United States. Under future climatic conditions, climate changes of varied intensities favored the expansion of suitable habitats for C. pullmanensis in China. However, appropriate land areas are diminishing globally. The trend in migration is toward latitudes and elevations that are higher. The estimated area of possible suitability shifted eastward in China. The results of the present study are valuable not only for countries such as Morocco, Spain, Chile, Turkey, Kazakhstan, etc., where the infection has not yet fully spread or been established, but also for nations where the species has been discovered. Authorities should take steps to reduce greenhouse gas emissions in order to restrict the spread of C. pullmanensis. Countries with highly appropriate locations should increase their surveillance, risk assessment, and response capabilities.

Diversity, morphology, and molecular phylogeny of Diatrypaceae from southern China

During an investigation of Diatrypaceae from southern China, 10 xylariales-like taxa have been collected. Morphological and multi-gene analyses confirmed that these taxa reside in Diatrypaceae and represent eight novel taxa and two new records belonging to six genera (viz., Allocryptovalsa, Diatrype, Diatrypella, Paraeutypella, Peroneutypa, and Vasilyeva gen. nov.). Vasilyeva gen. nov. was proposed to accommodate Vasilyeva cinnamomi sp. nov. Among the other collections, seven new species were introduced (viz., Diatrype camelliae-japonicae sp. nov., Diatrype rubi sp. nov., Diatrypella guiyangensis sp. nov., Diatrypella fatsiae-japonicae sp. nov., Paraeutypella subguizhouensis sp. nov., Peroneutypa hainanensis sp. nov., and Peroneutypa qianensis sp. nov.), while two were reported as new records from China (Allocryptovalsa rabenhorstii and Diatrype enteroxantha). For Diatrypaceae, the traditional taxonomic approach based on morphology may not be applicable.

Taxonomic and phylogenetic contributions to Diatrypaceae from southeastern Tibet in China

In this study, we investigated the diversity of diatrypaceous fungi from southeastern Tibet in China. The phylogenetic analyses were carried out based on ITS and β-tubulin sequences of 75 taxa of Diatrypaceae from around the world. Based on a combination of morphological features and molecular evidence, a new genus—Alloeutypa, with three new species—A. milinensis, Diatrype linzhiensis, and Eutypella motuoensis, and a new combination—A. flavovirens, were revealed by the materials in China. Alloeutypa is characterized by stromatal interior olivaceous buff, stromata producing well-developed discrete, and ascospores allantoid, subhyaline. These characteristics separate the new genus from the similar genus Eutypa. Comprehensive morphological descriptions, illustrations, and a phylogenetic tree to show the placement of new taxa are provided. All novelties described herein are morphologically illustrated and phylogeny investigated to better integrate taxa into the higher taxonomic framework and infer their phylogenetic relationships as well as establish new genera and species. Our results indicate that the diatrypaceous fungi harbor higher species diversity in China.

Whole genome sequence of Cryptosphaeria pullmanensis, an important pathogenic fungus potentially threatening crop and forestry production

Many fungal members of the Diatrypaceae family are pathogenic towards plants and are widely distributed globally. Cryptosphaeria pullmanensis is a pathogenic fungus that infects populus and walnut trees, causing their death. We sequenced the genome of C. pullmanensis based on a combination of Nanopore PromethION and Illumina NovaSeq PE150 platforms, and functionally annotated the sequences using a number of open-access databases. This is the first report of the genome-scale assembly and annotation for C. pullmanensis, the first species of the genus Cryptosphaeria to be sequenced. We obtained 13 contigs with an N50 contig size of 7,095,780 bp, a GC content ratio of 43.23% and a genome size of 56.72 Mb with 10,474 putative coding genes. Comparative genomic analysis against the genomes of seven Ascomycetes fungal strains was performed. Among the seven species tested, the Eutypa lata genome displayed the highest similarity to the C. pullmanensis genome in terms of collinearity and homologous gene content. This study has provided a genetic resource that offers extensive information and a framework for future investigations into the transcriptome, proteome, and metabonome of C. pullmanensis to understand its molecular pathogenesis.

Phytotoxic Metabolites Produced by Fungi Involved in Grapevine Trunk Diseases: Progress, Challenges, and Opportunities

Grapevine trunk diseases (GTDs), caused by fungal pathogens, are a serious threat to vineyards worldwide, causing significant yield and economic loss. To date, curative methods are not available for GTDs, and the relationship between the pathogen and symptom expression is poorly understood. Several plant pathologists, molecular biologists, and chemists have been investigating different aspects of the pathogenicity, biochemistry, and chemical ecology of the fungal species involved in GTDs. Many studies have been conducted to investigate virulence factors, including the chemical characterization of phytotoxic metabolites (PMs) that assist fungi in invading and colonizing crops such as grapevines. Moreover, multidisciplinary studies on their role in pathogenicity, symptom development, and plant-pathogen interactions have also been carried out. The aim of the present review is to provide an illustrative overview of the biological and chemical characterization of PMs produced by fungi involved in Eutypa dieback, Esca complex, and Botryosphaeria dieback. Moreover, multidisciplinary investigations on host-pathogen interactions, including those using cutting-edge Omics techniques, will also be reviewed and discussed. Finally, challenges and opportunities in the role of PMs for reliable field diagnosis and control of GTDs in vineyards will also be explored.

Phylogenetic placement of Iodosphaeriaceae (Xylariales, Ascomycota), designation of an epitype for the type species of Iodosphaeria, I. phyllophila, and description of I. foliicola sp. nov

The Iodosphaeriaceae is represented by the single genus, Iodosphaeria, which is composed of nine species with superficial, black, globose ascomata covered with long, flexuous, brown hairs projecting from the ascomata in a stellate fashion, unitunicate asci with an amyloid apical ring or ring lacking and ellipsoidal, ellipsoidal-fusiform or allantoid, hyaline, aseptate ascospores. Members of Iodosphaeria are infrequently found worldwide as saprobes on various hosts and a wide range of substrates. Only three species have been sequenced and included in phylogenetic analyses, but the type species, I. phyllophila, lacks sequence data. In order to stabilize the placement of the genus and family, an epitype for the type species was designated after obtaining ITS sequence data and conducting maximum likelihood and Bayesian phylogenetic analyses. Iodosphaeria foliicola occurring on overwintered Alnus sp. leaves is described as new. Five species in the genus form a well-supported monophyletic group, sister to the Pseudosporidesmiaceae in the Xylariales. Selenosporella-like and/or ceratosporium-like synasexual morphs were experimentally verified or found associated with ascomata of seven of the nine accepted species in the genus. Taxa included and excluded from Iodosphaeria are discussed.

New contributions to Diatrypaceae from karst areas in China

In this study, fungal specimens of the family Diatrypaceae were collected from karst areas in Guizhou, Hainan and Yunnan Provinces, China. Morpho-molecular analyses confirmed that these new collections comprise a new genus Pseudodiatrype, three new species (Diatrypelancangensis, Diatrypellapseudooregonensis and Eutypacerasi), a new combination (Diatrypellaoregonensis), two new records (Allodiatrypethailandica and Diatrypellavulgaris) from China and two other known species (Neoeutypellabaoshanensis and Paraeutypellacitricola). The new taxa are introduced, based on multi-gene phylogenetic analyses (ITS, β-tubulin), as well as morphological analyses. The new genus Pseudodiatrype is characterised by its wart-like stromata with 5-20 ascomata immersed in one stroma and the endostroma composed of thin black outer and inner layers of large white cells with thin, powdery, yellowish cells. These characteristics separate this genus from two similar genera Allodiatrype and Diatrype. Based on morphological as well as phylogenetic analyses, Diatrypelancangensis is introduced as a new species of Diatrype. The stromata of Diatrypelancangensis are similar to those of D.subundulata and D.undulate, but the ascospores are larger. Based on phylogenetic analyses, Diatrypeoregonensis is transferred to the genus Diatrypella as Diatrypellaoregonensis while Diatrypellapseudooregonensis is introduced as a new species of Diatrypella with 8 spores in an ascus. In addition, multi-gene phylogenetic analyses show that Eutypacerasi is closely related to E.lata, but the ascomata and asci of Eutypacerasi are smaller. The polyphyletic nature of some genera of Diatrypaceae has led to confusion in the classification of the family, thus we discuss whether the number of ascospores per asci can still be used as a basis for classification.

The Hidden Diversity of Diatrypaceous Fungi in China

In this study, we investigated the diversity of diatrypaceous fungi from six regions in China based on morpho-molecular analyses of combined ITS and tub2 gene regions. We accept 23 genera in Diatrypaceae with 18 genera involved in the phylogram, and the other five genera are lacking living materials with sequences data. Eleven species included in four genera (viz. Allocryptovalsa, Diatrype, Diatrypella, and Eutypella) have been isolated from seven host species, of which nine novel species (viz. Allocryptovalsa castaneae, A. castaneicola, Diatrype betulae, D. castaneicola, D. quercicola, Diatrypella betulae, Da. betulicola, Da. hubeiensis, and Da. shennongensis), a known species of Diatrypella favacea, and a new record of Eutypella citricola from the host genus Morus are included. Current results show the high diversity of Diatrypaceae which are wood-inhabiting fungi in China.

Paraeutypella guizhouensis gen. et sp. nov. and Diatrypella longiasca sp. nov. (Diatrypaceae) from China

Background

In this study, we introduce a novel genus, Paraeutypella, of the family Diatrypaceae comprising three species viz. Paraeutypellaguizhouensis sp. nov. and P.citricola (basionym: Eutypellacitricola) and P.vitis (basionym: Sphaeriavitis). Diatrypellalongiasca sp. nov. is also introduced, which forms a distinct clade in Diatrypella sensu stricto. The discovery of this new genus will contribute to expanding the knowledge and taxonomic framework of Diatrypaceae (Xylariales).

New information

Generic delimitations in Diatrypaceae are unsettled because the phylogeny has yet to be resolved using extensive taxon sampling and sequencing of ex-type cultures. During an investigation of xylarialean fungi, we collected eutypella-like fungi which is distinct from Eutypella sensu stricto in our phylogenetic analyses (ITS and β-tubulin), thus, introduced as Paraeutypellaguizhouensis gen. et sp. nov.. Paraeutypella is characterised by having 4–25 perithecia in a stroma each with 3–6 sulcate, long ostiolar necks. Paraeutypellacitricola comb. nov. (basionym: Eutypellacitricola) is introduced on Acer sp. from China. Diatrypellalongiasca sp. nov. is introduced as a new species in Diatrypella sensu stricto. which has 2–5 ascomata per stroma and long ascospores, unusual when compared to other Diatrypella species and distinct phylogenetically.

Botryosphaeriaceae species associated with dieback and canker disease of bay laurel in northern California with the description of Dothiorella californica sp. nov

Members of the Botryosphaeriaceae are cosmopolitan fungi that may exist as seemingly innocuous endophytes or as destructive pathogens of numerous woody hosts, including fruit and nut crops, urban ornamental trees and shrubs, and forest trees. Surveys of bay laurel in northern California have revealed symptoms of dieback and branch canker of unknown aetiology. The goals of this study were to identify and clarify the species of Botryosphaeriaceae associated with these symptoms and to confirm their pathogenicity. To understand the role of members of the Botryosphaeriaceae in the dieback and canker disease of bay laurel, 23 isolates were isolated from symptomatic wood. Phylogenetic analyses of ITS, translation elongation factor 1-α, and beta-tubulin revealed three species: Botryosphaeria dothidea, Neofusicoccum nonquaesitum, and the newly described and typified species Dothiorella californica sp. nov. When select isolates were inoculated to 2- to 3-year-old branches of Umbellularia californica in a natural forest, both B. dothidea and N. nonquaesitum were pathogenic with N. nonquaesitum producing the largest lesions at 12- and 18-months post inoculation, respectively, while Do. californica did not cause wood lesions significantly greater than the mock-inoculated controls. This study represents the first attempt to identify and test the pathogenicity of Botryosphaeriaceae species associated with dieback and canker disease of bay laurel in a northern California forest.

Cryptosphaeria Dieback of Fremont Cottonwood Caused by Cryptosphaeria pullmanensis and C. multicontinentalis in California

Fremont cottonwood is a large and tall tree native to riparian areas in the southwestern United States. It grows along streams, rivers, and wetlands and serves many ecological and socioeconomic functions. In recent years, we observed a severe decline of Fremont cottonwood trees in California. Trees showed branches dying back, with dark-brown internal discoloration and decay of the wood of twigs, branches, or trunks. Eventually, the cambium and the bark were killed, causing a canker. The fungus Cryptosphaeria pullmanensis was isolated consistently from the necrotic wood of branches and twigs. On rare occasion, C. multicontinentalis was also isolated from symptomatic wood. Therefore, we investigated the pathogenicity in Fremont cottonwood of C. pullmanensis and C. multicontinentalis. Koch's postulates were completed in saplings and both species appeared highly virulent, producing internal necrosis and staining of the wood. This study is the first to report Cryptosphaeria dieback of Populus fremontii caused by C. pullmanensis and C. multicontinentalis. Symptoms and signs of this new disease are described and illustrated.