New species and records of Diaporthe from Jiangxi Province, China

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, little is known about species able to infect forest trees in Jiangxi Province. Hence, extensive surveys were recently conducted in Jiangxi Province, China. A total of 24 isolates were identified and analysed 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. Results revealed five novel taxa, D. bauhiniae, D. ganzhouensis, D. schimae, D. verniciicola, D. xunwuensis spp. nov. and three known species, D. apiculatum, D. citri and D. multigutullata.

First Report of Dieback Caused by Lasiodiplodia pseudotheobromae on Ormosia pinnata in China

Ormosia pinnata (Lour.) Merr. is an important tree used for landscape and plant recovery of barren slopes in China. During an investigation of plant disease on landscape trees in 2018, a dieback was observed on O. pinnata trees in Guangzhou, Guangdong Province, China. Symptoms were characterized by initial dryness of the twigs and eventual death of the whole branch of the tree. Isolations from symptomatic branches yielded 13 isolates including two main morphotypes. Pathogenicity tests showed that isolate GDOP1 from Type I caused dieback of O. pinnata. Based on morphological characteristics and molecular analysis of the internal transcribed spacer rDNA (ITS1-5.8S-ITS2) and partial sequence of the translation elongation factor 1α (EF1-α), the fungus causing dieback on O. pinnata was identified as Lasiodiplodia pseudotheobromae. This is the first report of L. pseudotheobromae infecting O. pinnata in the world.

Gnomoniopsis chinensis (Gnomoniaceae, Diaporthales), a new fungus causing canker of Chinese chestnut in Hebei Province, China

Chinese chestnut (Castanea mollissima) is an important crop tree species in China. However, branch canker and fruit rot are two kinds of severe diseases, which weaken the host and decrease chestnut production. During our investigations into chestnut diseases in China, several fungi have been confirmed as casual agents in previous studies, namely Aurantiosacculus castaneae, Cryphonectria neoparasitica, Cry. parasitica, Endothia chinensis and Gnomoniopsis daii. In this study, a new canker pathogen is introduced based on morphology, phylogeny and pathogenicity. Typical Gnomoniopsis canker sign of wide, orange tendrils emerging from hosts’ glaucous lenticels were obvious on the diseased trees in the field. Symptomatic branches or bark on stems from different chestnut plantations were sampled and isolated, then strains were identified by comparisons of DNA sequence data for the nuclear ribosomal internal transcribed spacer (ITS), partial translation elongation factor-1α (tef1) and β-tubulin (tub2) gene regions as well as morphological features. As a result, these strains appeared different from any known Gnomoniopsis species. Hence, we propose a novel species named Gnomoniopsis chinensis. Pathogenicity was further tested using the ex-type strain (CFCC 52286) and another strain (CFCC 52288) on both detached branches and 3-year-old chestnut seedlings. The inoculation results showed that Gnomoniopsis chinensis is mildly pathogenic to Chinese chestnut. However, further studies are required to confirm its pathogenicity to the other cultivated Castanea species in America, Europe and Japan.

Three new Diaporthe species from Shaanxi Province, China

Diaporthe species (Sordariomycetes, Diaporthales) are often reported as important plant pathogens, saprobes and endophytes on a wide range of plant hosts. In this study, Diaporthe specimens were collected from symptomatic twigs and branches at the Huoditang Forest Farm in Shaanxi Province, China. Identification was done using a combination of morphology and comparison of DNA sequence data of the nuclear ribosomal internal transcribed spacer (ITS), calmodulin (cal), histone H3 (his3), partial translation elongation factor-1α (tef1) and β-tubulin (tub2) gene regions. Three new Diaporthe species are proposed: D. albosinensis, D. coryli and D. shaanxiensis. All species are illustrated and their morphology and phylogenetic relationships with other Diaporthe species are discussed.

Phylogeny and morphology of Lasiodiplodia species associated with Magnolia forest plants

Two new species of Lasiodiplodia (Lasiodiplodia endophytica and Lasiodiplodia magnoliae) are described and illustrated from Magnolia forests in Yunnan, China. Endophytic and saprobic Lasiodiplodia pseudotheobromae and endophytic L. thailandica are new records from this host. The internal transcribed spacers (ITS), part of the translation elongation factor-1α (tef1) and partial β-tubulin (tub2) sequence data were analyzed to investigate the phylogenetic relationships of the new species with other Lasiodiplodia species. Lasiodiplodia magnoliae is phylogenetically sister to L. mahajangana and L. pandanicola but morphologically distinct from L. mahajangana in having larger conidia. Lasiodiplodia endophytica is most closely related to L. iraniensis and L. thailandica and the three species can be distinguished from one another by 2 base pair differences in ITS and three or four base pair differences in tef1. The new collections suggest that Magnolia forest plants are good hosts for Lasiodiplodia species with endophytic and saprobic life-styles.

Identification and Pathogenicity of Fungal Species Associated with Canker Diseases of Pistachio in California

A survey was conducted during 2015 and 2016 in pistachio orchards throughout the San Joaquin Valley of California to investigate the occurrence of canker diseases and identify the pathogens involved. Cankers and dieback symptoms were observed mainly in orchards aged >15 years. Symptoms of canker diseases included brown to dark brown discoloration of vascular tissues, wood necrosis, and branch dieback. In total, 58 fungal isolates were obtained from cankers and identified based on multilocus phylogenetic analyses (internal transcribed spacer, glyceraldehyde 3-phosphate dehydrogenase, β-tubulin, calmodulin, actin 1, and translation elongation factor 1α) representing 11 fungal species: Colletotrichum karstii, Cytospora californica, Cytospora joaquinensis, Cytospora parapistaciae, Cytospora pistaciae, Diaporthe ambigua, Didymella glomerata, Diplodia mutila, Neofusicoccum mediterraneum, Phaeoacremonium canadense, and Schizophyllum commune. Pathogenicity tests conducted in the main pistachio cultivars Kerman, Golden Hills, and Lost Hills using the mycelium-plug method indicated that all fungal species were pathogenic to Pistacia vera. All species tested caused cankers in pistachio branches, although virulence among species varied from high to moderate. Overall, N. mediterraneum and Cytospora spp. were the most widespread and virulent species associated with canker diseases of pistachio in California.

A New European Species of The Opportunistic Pathogenic GenusSaksenaea–S. dorisiaeSp. Nov.

A new speciesSaksenaea dorisiae(Mucoromycotina, Mucorales), recently isolated from a water sample originating from a private well in a rural area of Serbia (Europe), is described and illustrated. The new taxon is well supported by phylogenetic analysis of the internal transcribed spacer region (ITS), domains D1 and D2 of the 28S rRNA gene (LSU), and translation elongation factor-1α gene (TEF-1α), and it is resolved in a clade withS. oblongisporaandS. trapezispora. This fungus is characteristic by its moderately slow growth at 15 and 37°C, sparse rhizoids, conical-shaped sporangia and short-cylindrical sporangiospores.S. dorisiaeis a member of the opportunistic pathogenic genus often involved in severe human and animal mucormycoses encountered in tropical and subtropical regions. Despite its sensitivity to several conventional antifungals (terbinafine and ciclopirox), the fungus is potentially causing clinically challenging infections. This is the first novel taxon of the genusSaksenaeadescribed from the moderately continental climate area of Europe.

Phylogeny and Mycotoxin Characterization of Alternaria Species Isolated from Wheat Grown in Tuscany, Italy

Wheat, the main source of carbohydrates worldwide, can be attacked by a wide number of phytopathogenic fungi, included Alternaria species. Alternaria species commonly occur on wheat worldwide and produce several mycotoxins such as tenuazonic acid (TA), alternariol (AOH), alternariol-monomethyl ether (AME), and altenuene (ALT), provided of haemato-toxic, genotoxic, and mutagenic activities. The contamination by Alternaria species of wheat kernels, collected in Tuscany, Italy, from 2013 to 2016, was evaluated. Alternaria contamination was detected in 93 out of 100 field samples, with values ranging between 1 and 73% (mean of 18%). Selected strains were genetically characterized by multi-locus gene sequencing approach through combined sequences of allergen alt1a, glyceraldeyde-3-phosphate dehydrogenase, and translation elongation factor 1α genes. Two well defined groups were generated; namely sections Alternaria and Infectoriae. Representative strains were analyzed for mycotoxin production. A different mycotoxin profile between the sections was shown. Of the 54 strains analyzed for mycotoxins, all strains included in Section Alternaria produced AOH and AME, 40 strains (99%) produced TA, and 26 strains (63%) produced ALT. On the other hand, only a very low capability to produce both AOH and AME was recorded among the Section Infectoriae strains. These data show that a potential mycotoxin risk related to the consumption of Alternaria contaminated wheat is high.

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

Diaporthespecies have often been reported as important plant pathogens, saprobes and endophytes on a wide range of plant hosts. Although severalDiaporthespecies 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.eresandD.unshiuensis, were identified. In addition, twelve novel taxa were collected and are described asD.acerigena,D.alangii,D.betulina,D.caryae,D.cercidis,D.chensiensis,D.cinnamomi,D.conica,D.fraxinicola,D.kadsurae,D.padinaandD.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.