Xin-Lei Fan

Cytospora species associated with walnut canker disease in China, with description of a new species C. gigalocus.

Cytospora species associated with canker disease are presently difficult to identify because of lack of ex-types cultures with molecular data, few distinguishable characters, and only Internal transcribed spacer (ITS) sequence data is available for most Cytospora strains in GenBank. We report on Cytospora species from the walnut tree in China. Collections were subjected to morphological and phylogenetic study. The relatedness of species associated with walnut canker were established using combined ITS, nrLSU, β-tubulin, and actin gene sequence data. Cytospora atrocirrhata, Cytospora chrysosperma, Cytospora sacculus, and a new species, Cytospora gigalocus, were identified causing canker disease of walnut. Cytospora gigalocus is formally described and compared with most similar species. Cytospora chrysosperma and C. sacculus have previously been recorded from walnut, whereas C. atrocirrhata is reported as associated with walnut canker for the first time. This is the first study that has established the Cytospora species causing walnut canker in China using a multi-phasic approach. All species are recorded as being associated with walnut canker disease in China for the first time.

Diaporthe rostrata, a novel ascomycete from Juglans mandshurica associated with walnut dieback

Diaporthe rostrata sp. nov., collected from Juglans mandshurica in China, is described and illustrated in this paper. The new species is introduced based on its holomorphic morphology plus support from phylogenetic analysis. The sexual and asexual morphs produce rostrate host tissue around the necks on infected branches or twigs and have aseptate alpha conidia, while the sexual morph produces 1-septate ascospores. The new species is compared with other taxa from Juglans spp.

Phylogeny and taxonomy of the scab and spot anthracnose fungus Elsinoë (Myriangiales, Dothideomycetes)

Species of Elsinoë are phytopathogens causing scab and spot anthracnose on many plants, including some economically important crops such as avocado, citrus, grapevines, and ornamentals such as poinsettias, field crops and woody hosts. Disease symptoms are often easily recognisable, and referred to as signature-bearing diseases, for the cork-like appearance of older infected tissues with scab-like appearance. In some Elsinoë-host associations the resulting symptoms are better described as spot anthracnose. Additionally the infected plants may also show mild to severe distortions of infected organs. Isolation of Elsinoë in pure culture can be very challenging and examination of specimens collected in the field is often frustrating because of the lack of fertile structures. Current criteria for species recognition and host specificity in Elsinoë are unclear due to overlapping morphological characteristics, and the lack of molecular and pathogenicity data. In the present study we revised the taxonomy of Elsinoë based on DNA sequence and morphological data derived from 119 isolates, representing 67 host genera from 17 countries, including 64 ex-type cultures. Combined analyses of ITS, LSU, rpb2 and TEF1-α DNA sequence data were used to reconstruct the backbone phylogeny of the genus Elsinoë. Based on the single nomenclature for fungi, 26 new combinations are proposed in Elsinoë for species that were originally described in Sphaceloma. A total of 13 species are epitypified with notes on their taxonomy and phylogeny. A further eight new species are introduced, leading to a total of 75 Elsinoë species supported by molecular data in the present study. For the most part species of Elsinoë appear to be host specific, although the majority of the species treated are known only from a few isolates, and further collections and pathogenicity studies will be required to reconfirm this conclusion.

Cytospora from Ulmus pumila in Northern China

Cytospora species are cosmopolitan, and commonly associated with dieback and canker diseases of numerous hosts. In the present study, isolates were collected and identified from diseased branches or twigs of Ulmus pumila in northern China. The morphological characteristics and multilocus phylogeny (act1, ITS, LSU, tefA and tubB) indicate four distinct lineages with high branch support, i.e., C. carbonacea, C. chrysosperma, C. ribis and C. pruinopsis sp. nov. Cytospora pruinopsis is distinguishable from the other Cytospora spp. on Ulmus by its single conidiomatal locule with one ostiole per disc, and its smaller conidia. This study represents the first attempt to clarify the taxonomy of Cytospora spp. associated with canker and dieback symptoms of Ulmus pumila in northern China.

Melanconis (Melanconidaceae) associated with Betula spp. in China

Melanconis is a monotypic genus in Melanconidaceae and mostly restricted to hardwood trees in Betulaceae, as endophytes and plant pathogens. During a routine forest pathogens investigation of canker disease in China, some melanconidaceous fungi were observed on Betula spp. with various symptoms. The primary objective of the present study was to identify species of Melanconidaceae associated with canker and dieback of Betula spp. in China. In the present study, we investigated 45 isolates using morphology and multi-gene phylogenetic analyses based on the internal transcribed spacers (ITS), nuclear large subunit rDNA (LSU), RNA polymerase II subunit 2 (rpb2), translation elongation factor 1-α (tef1-α) and β-tubulin (tub). Three melanconidaceous taxa were identified: Melanconis betulae sp. nov., M. itoana and M. stilbostoma. This is the first phylogenetic study evaluating species of Melanconis associated with canker and dieback disease of Betula spp. in China, resulting in the description of a novel species and the report of M. itoana as a new record.

Families and genera of diaporthalean fungi associated with canker and dieback of tree hosts

In this study we accept 25 families in Diaporthales based on phylogenetic analyses using partial ITS, LSU, rpb2 and tef1-α gene sequences. Four different families associated with canker and dieback of tree hosts are morphologically treated and phylogenetically compared. These include three new families (Diaporthostomataceae, Pseudomelanconidaceae, Synnemasporellaceae), and one new genus, Dendrostoma (Erythrogloeaceae). Dendrostoma is newly described from Malus spectabilis, Osmanthus fragrans and Quercus acutissima having fusoid to cylindrical, bicellular ascospores, with three new species namely D. mali, D. osmanthi and D. quercinum. Diaporthostomataceae is characterised by conical and discrete perithecia with bicellular, fusoid ascospores on branches of Machilus leptophylla. Pseudomelanconidaceae is defined by conidiogenous cells with apical collarets and discreet annellations, and the inconspicuous hyaline conidial sheath when mature on Carya cathayensis, compared to morphologically similar families Melanconidaceae and Juglanconidaceae. Synnemasporellaceae is proposed to accommodate fungi with synnematous conidiomata, with descriptions of S. toxicodendri on Toxicodendron sylvestre and S. aculeans on Rhus copallina.

Diaporthe from walnut tree ( Juglans regia ) in China, with insight of the Diaporthe eres complex

Species of Diaporthe are important plant pathogenic fungi that commonly occur on a wide range of hosts. They are relatively difficult to identify due to their extreme similarity in morphology and confusing multigene phylogeny, especially in the Diaporthe eres complex. In the present study, isolates were collected from diseased branches of Juglans regia in China. Most strains were clustered into the D. eres species complex based on the combined internal transcribed spacer (ITS) region, partial calmodulin (CAL), histone H3 (HIS), translation elongation factor 1-alpha (TEF1-α) and beta-tubulin (TUB) genes. To focus on this complex, CAL, TEF1-α and TUB were selected in further phylogenetic analyses that showed a better topology compared with combined five-gene phylogeny. Results revealed that all strains which clustered in the Diaporthe eres complex from Juglans regia in China were Diaporthe eres. Results suggested a revised species criterion in the Diaporthe eres complex. The current study uncovered a new species here described as Diaporthe. tibetensis.

Mycological Diversity Description I

Here, Quambalaria fabacearum and Neopestalotiopsis brasiliensis are introduced as new species from Brazil, isolated as endophyte from Mimosa tenuiflora and causing post-harvest rot disease on fruits of Psidium guajava, respectively. Diaporthe inconspicua is emended to include a more detailed morphological description. Neopestalotiopsis egyptiaca is reported as new to the Americas and as causing post-harvest rot disease on fruits of Psidium guajava, while Umbelopsis isabellina is reported as endophyte.

Identification of phytopathogens from a taxonomic view, an example of Cryphonectriaceae

Plant diseases cause lots of losses worldwide, and pathogens identification is essential during diseases studies. Traditional identification of phytopathogens mainly relied on host information and pathogen morphological characteristics, which limited the discovery of similar pathogens on the same hosts. Recently, the application of phylogenetics to plant pathology greatly promotes the discovery of larvaceous fungi. For example, novel genera in Cryphonectriaceae were described as phytopathogens continuously in the past two decades.

High diversity of Diaporthe species associated with dieback diseases in China, with twelve new species described

Abstract Diaporthe species have often been reported as important plant pathogens, saprobes and endophytes on a wide range of plant hosts. Although several Diaporthe species have been recorded in China, little is known about species able to infect forest trees. Therefore, extensive surveys were recently conducted in Beijing, Heilongjiang, Jiangsu, Jiangxi, Shaanxi and Zhejiang Provinces. The current results emphasised on 15 species from 42 representative isolates involving 16 host genera using comparisons of DNA sequence data for the nuclear ribosomal internal transcribed spacer (ITS), calmodulin (cal), histone H3 (his3), partial translation elongation factor-1α (tef1) and β-tubulin (tub2) gene regions, as well as their morphological features. Three known species, D.biguttulata, D.eres and D.unshiuensis, were identified. In addition, twelve novel taxa were collected and are described as D.acerigena, D.alangii, D.betulina, D.caryae, D.cercidis, D.chensiensis, D.cinnamomi, D.conica, D.fraxinicola, D.kadsurae, D.padina and D.ukurunduensis. The current study improves the understanding of species causing diebacks on ecological and economic forest trees and provides useful information for the effective disease management of these hosts in China.