Diversity and spatial distribution of endophytic fungi in Cinnamomum longepaniculatum of Yibin, China

Identification and Characterization of Neocosmospora silvicola Causing Canker Disease on Pinus armandii in China

Chinese white pine, Pinus armandii, is a source of high-quality timber and an afforestation tree in China, which plays an important ecological and social role in water and soil conservation. Recently, a new canker disease has been reported in Longnan City, Gansu Province, where P. armandii is mainly distributed. In this study, the causal agent was isolated from diseased samples and identified as a fungal pathogen, Neocosmospora silvicola, based on morphological characteristics and molecular analyses (internal transcribed spacer, large subunit, RNA polymerase II, and translation elongation factor-1α). Pathogenicity tests on P. armandii revealed that N. silvicola isolates caused a 60% average mortality rate in artificially inoculated 2-year-old seedlings. The pathogenicity of these isolates was also observed on the branches of 10-year-old P. armandii trees with a 100% mortality rate. These results agree with the isolation of N. silvicola from diseased plants, suggesting the possible role of this fungus in the decline of P. armandii plants. Mycelial growth of N. silvicola was fastest on potato dextrose agar medium, and growth occurred at pH values ranging from 4.0 to 11.0 with temperatures between 5 and 40°C. The fungus also grew rapidly in complete darkness compared with other light conditions. Of the eight carbon and seven nitrogen sources tested, starch and sodium nitrate, respectively, were highly efficient in supporting the mycelial growth of N. silvicola. The ability of N. silvicola to grow at low temperatures (5°C) may explain its occurrence in the Longnan area of Gansu Province. This article is the first report of N. silvicola as an important fungal pathogen causing branch and stem cankers on Pinus tree species, which remains a threat to the forests.

Six Additions to the Genus Periconia (Dothideomycetes: Periconiaceae) from Graminaceous Plants in China

Periconia is a polyphyletic and asexual morphic genus within the family Periconiaceae (Pleosporales). The genus is characterized by a pale to dark brown stipe with an apical conidial head and ellipsoidal to oblong conidia. Species of Periconia are widely distributed throughout the world in various hosts, while most species are isolated from graminaceous plants. During our investigations of microfungal in Sichuan Province, China, 26 Periconia isolates were collected from a wide variety of graminaceous plants. These isolates corresponded to 11 species based on the examination of morphology and multi-locus phylogenetic analysis (SSU, ITS, LSU, TEF1, RPB2). This includes six new species (P. chengduensis, P. cynodontis, P. festucae, P. imperatae, P. penniseti, and P. spodiopogonis) and five new records (P. byssoides, P. chimonanthi, P. cookie, P. pseudobyssoides, and P. verrucosa). A comprehensive description and illustrations of the new species are provided and discussed with comparable taxa. These discoveries expand our knowledge of the species diversity of Periconia taxa in graminaceous plants in China.

Cytogenetic Characterization and Metabolomic Differences of Full-Sib Progenies of Saccharum spp

Sugarcane smut is a worldwide fungal disease. Disease resistance breeding is the most economical and effective measure to prevent and control sugarcane smut. The cytogenetic characteristics and metabolomic differences of sugarcane F₁s are closely related to disease resistance. Zhongzhe 1 and G160 sugarcane from the same parents (ROC25 and Yunzhe89-7) were used; the plants were grown in accordance with the barrel method. When the seedlings had 4-5 leaves, genomic in situ hybridization (GISH) was performed; digoxigenin (DIG)-labeled female parental (ROC25)DNA and biotin-labeled male parental (Yunzhe89-7) DNA were used as probes, and the karyotypes of two hybrids were analyzed. The new sugarcane smut-resistant variety (Zhongzhe 1) and the susceptible variety (G160) derived from the same parent were analyzed via gas chromatography-mass spectrometry technology (GC-MS) to compare the metabolomic differences between them. GISH analysis revealed that the chromosome ploidy number of Zhongzhe 1 sugarcane and G160 sugarcane were 114 and 110, respectively. However, the two contain different numbers of chromosomes from the female (ROC25) and male (Yunzhe89-7) parents. Moreover, 258 significantly changed metabolites were identified in smut-resistant Zhongzhe 1, as compared with the smut-susceptible G160 sugarcane: 56 flavonoids, 52 phenolic acids, 30 lipids, 26 organic acids, 26 amino acids and derivatives, 19 nucleotides and derivatives, 5 alkaloids, 9 terpenoids, and 35 others. Multivariate statistical analysis revealed a distinct difference in metabolic pathways between Zhongzhe 1 sugarcane and G160, and both of these varieties had unique functional metabolites. Differences in chromosome composition may constitute the genetic basis for the difference in resistance to smut disease between Zhongzhe 1 sugarcane and G160 sugarcane, and a high accumulation of flavonoids, lipids, terpenoids and tannins may constitute the basis of resistance to smut disease for the Zhongzhe 1 variety.

Four New Species of Torula (Torulaceae, Pleosporales) from Sichuan, China

Torula is an asexual and hyphomycetous genus in the family Torulaceae. Torula species are generally saprophytic. They have a worldwide distribution and abound in humid or freshwater habitats. In order to better understand this genus, we carried out several field collections from Sichuan, China. As a result, we obtained nine Torula isolates from dead woody substrates in terrestrial and freshwater habitats. Based on a biphasic approach of morphological examination and multi-locus phylogenetic analyses (ITS, SSU, LSU, TEF, RPB2), these collections were identified as belonging to seven Torula species. Four of them were new species (Torula chinensis, T. longiconidiophora, T. sichuanensis and T. submersa), and the other three belonged to existing species, though one was found for the first time in China (T. masonii). Morphological and updated phylogenetic delamination of the new discoveries is also discussed. This study provides further insights into our understanding of wood-based Torula species in China.

Diversity of endophytic fungal community in Huperzia serrata from different ecological areas and their correlation with Hup A content

Background

Huperzine A (Hup A) has attracted considerable attention as an effective therapeutic candidate drug used to treat Alzheimer’s disease. Whereas, the production of Hup A from wild plants faced a major challenge, which is the wild Huperzia Serrata harbor a low Hup A content, has a long-life cycle, and has a small yield. At present, several reports showed that Hup A is produced by various endophytic fungal strains isolated from H. serrata, thereby providing an alternative method to produce the compound and reduce the consumption of this rare and endangered plant. However, till now, very few comprehensive studies are available on the biological diversity and structural composition of endophytic fungi and the effects of endophytic fungi on the Hup A accumulation in H. serrata.

Results

In this research, the composition and diversity of fungal communities in H. serrata were deciphered based on high-throughput sequencing technology of fungal internal transcribed spacer regions2 (ITS2). The correlation between endophytic fungal community and Hup A content was also investigated. Results revealed that the richness and the diversity of endophytic fungi in H. serrata was various according to different tissues and different ecological areas. The endophytic fungal communities of H. serrata exhibit species-specific, ecological-specific, and tissue-specific characteristics. There are 6 genera (Ascomycota_unclassified, Cyphellophora, Fungi_unclassified, Sporobolomyces, and Trichomeriaceae_unclassified) were significantly positively correlated with Hup A content in all two areas, whereas, there are 6 genera (Auricularia, Cladophialophora, Cryptococcus, Mortierella, and Mycena) were significantly negatively correlated with Hup A content of in all two areas.

Conclusions

This study indicated a different composition and diverse endophytic fungal communities in H. serrata from different organs and ecological areas. The current study will provide the realistic basis and theoretical significance for understanding the biological diversity and structural composition of endophytic fungal communities in H. serrata, as well as providing novel insights into the interaction between endophytic fungi and Hup A content.

Synhelminthosporium gen. et sp. nov. and Two New Species of Helminthosporium (Massarinaceae, Pleosporales) from Sichuan Province, China

Helminthosporium is a polyphyletic genus in Massarinaceae (Pleosporales). Species of Helminthosporium are characterized by having septate and erect conidiophores, acro-pleurogenous and distoseptate conidia with a ring-shaped scar at the base. During a survey of fungal diversity in Sichuan Province, China, six Helminthosporium-like isolates were collected from dead branches of unknown trees. Five barcodes, including ITS (ITS1-5.8S-ITS2), SSU, LSU, TEF1, and RPB2 were amplified and sequenced. Morphological examination and multi-locus phylogenetic analyses revealed two new Helminthosporium species (H. chengduense sp. nov., and H. chinense sp. nov.), a new genus (Synhelminthosporium gen. nov.) with a type species Synhelminthosporium synnematoferum sp. nov., and two known species (Helminthosporium submersum and H. velutinum) within Massarinaceae. The new genus Synhelminthosporium differs from the phylogenetically closest genus Helminthosporium by producing synnematous conidiophores. This work expands our understanding of the diversity of Helminthosporium-like taxa in Sichuan Province, China.

Transcriptome and metabolome reveal the accumulation of secondary metabolites in different varieties of Cinnamomum longepaniculatum

BACKGROUND

Cinnamomum longepaniculatum (Gamble) N. Chao ex H. W. Li, whose leaves produce essential oils, is a traditional Chinese medicine and economically important tree species. In our study, two C. longepaniculatum varieties that have significantly different essential oil contents and leaf phenotypes were selected as the materials to investigate secondary metabolism.

RESULT

The essential oil content and leaf phenotypes were different between the two varieties. When the results of both transcriptome and metabolomic analyses were combined, it was found that the differences were related to phenylalanine metabolic pathways, particularly the metabolism of flavonoids and terpenoids. The transcriptome results based on KEGG pathway enrichment analysis showed that pathways involving phenylpropanoids, tryptophan biosynthesis and terpenoids significantly differed between the two varieties; 11 DEGs (2 upregulated and 9 downregulated) were associated with the biosynthesis of other secondary metabolites, and 12 DEGs (2 upregulated and 10 downregulated) were related to the metabolism of terpenoids and polyketides. Through further analysis of the leaves, we detected 196 metabolites in C. longepaniculatum. The abundance of 49 (26 downregulated and 23 upregulated) metabolites differed between the two varieties, which is likely related to the differences in the accumulation of these metabolites. We identified 12 flavonoids, 8 terpenoids and 8 alkaloids and identified 4 kinds of PMFs from the leaves of C. longepaniculatum.

CONCLUSIONS

The combined results of transcriptome and metabolomic analyses revealed a strong correlation between metabolite contents and gene expression. We speculate that light leads to differences in the secondary metabolism and phenotypes of leaves of different varieties of C. longepaniculatum. This research provides data for secondary metabolite studies and lays a solid foundation for breeding ideal C. longepaniculatum plants.