Coniella lustricola, a new species from submerged detritus

Taxonomy and Multigene Phylogeny of Diaporthales in Guizhou Province, China

In a study of fungi isolated from plant material in Guizhou Province, China, we identified 23 strains of Diaporthales belonging to nine species. These are identified from multigene phylogenetic analyses of ITS, LSU, rpb2, tef1, and tub2 gene sequence data coupled with morphological studies. The fungi include a new genus (Pseudomastigosporella) in Foliocryphiaceae isolated from Acer palmatum and Hypericum patulum, a new species of Chrysofolia isolated from Coriaria nepalensis, and five new species of Diaporthe isolated from Juglans regia, Eucommia ulmoides, and Hypericum patulum. Gnomoniopsis rosae and Coniella quercicola are newly recorded species for China.

First report of Coniella vitis causing white rot on Virginia creeper (Parthenocissus quinquefolia [L.] Planch.) in China

Virginia creeper (Parthenocissus quinquefolia [L.] Planch.) belongs to the genus of Parthenocissus and Vitaceae family, which is very common in vineyards and where wild grape occurs (Bergh et al., 2011). In September of 2021, a severe white rot disease was observed on Virginia creeper around the vineyard of wine grapevine (Cabernet Sauvignon) located in Penglai city (37º 75'38" N, 120º 84'28" E), Shandong province of China. The disease incidence was about 75%, and infected leaf of Virginia creeper exhibited irregular necrotic lesion with brown center, and most lesion occurred on leaf margin, black pycnidia were also observed on the infected leaf at the late stage of infection. To determine the causal agent, symptomatic leaves with typical lesions were cut into small pieces (5 mm × 3 mm), surface sterilized with 75% ethanol for 1 min, followed by three times rinsed in sterile water. Leaf sections were plated onto potato dextrose agar (PDA) medium and incubated at 28°C for 3 days. Totally, five isolates (referred to as JD01, JD07, JD09, JD12 and JD16) were collected and transferred on to fresh PDA medium for incubation at 28°C. Seven days later, colonies on PDA plates had crenulated edges with concentric rings, the upper surface of colonies was mostly flat and white with many pycnidia. The conidia were hyaline at immature and became brown later, spherical or ellipsoid, aseptate, and 7.92 ± 1.20 μm × 5.18 ± 0.61 μm (n=50), length : width ratio is nearly 2. Morphologically, the isolates were identified as Coniella vitis (Chethana et al., 2017). Further to confirm the fungal species, the internal transcribed spacer region (ITS) of the ribosomal RNA gene, large subunit rRNA gene (LSU) and the translation elongation factor 1-alpaha gene (TEF1-α) were amplified using primers ITS1/ ITS4, LR7/ LROR, and TEF1- 728F/ TEF1- 986R (Chethana et al., 2017; Raudabaugh et al., 2018). The amplification products were sequenced and deposited in GenBank database. The sequences were compared to type sequences in GenBank. The results showed that ITS (GenBank accession numbers ON329769, ON329770, ON329771, ON329772 and ON329773), LSU (ON358423，ON358424, ON358425, ON358426 and ON358427) and TEF (ON297671, ON229071, ON229072, ON229073 and ON297672) sequences of the five isolates were 99.66%, 96.90% and 98.79% identical with the sequences data from C. vitis isolates in GeneBank (MFLUCC 18-0093, JZB3700020 and MFLUCC 18-0093, respectively). Furthermore, concatenated sequences of the three genes (ITS, LSU and TEF) were used to conduct a phylogenetic tree using maximum likehood MEGA-X (Raudabaugh et al., 2018). The phylogenetic analysis showed that the five isolates (JD01, JD07, JD09, JD12 and JD16) belong to C. vitis clade among the 41strains of Coniella spp. In the pathogenicity tests, detached leaves of Virginia creeper (1-year-old) were inoculated with mycelia plugs (5 mm diameter) (form 3-day-old of isolate JD07 culture), and control were inoculated with PDA plugs (5 mm diameter). Virginia creeper live plants (1-year-old) were inoculated with conidial suspension (2.5×106 spores/ml) of the isolate JD07 of one week old, and control plants were inoculated with sterile water. All treated Virginia creeper plants (detached leaves) were placed in a greenhouse maintained at 28°C and 95% relative humidity. Virginia creeper plants (detached leaves) inoculated with the conidial suspension (fungal mycelia) had brown lesion on leaves, the disease symptoms were similar to those observed in field. No such symptoms were observed on control plants (detached leaves). The pathogen was reisolated from inoculated Virginia creeper plants and re-identified, thus fulfilling Koch's postulates. C. vitis had been reported to cause grape white rot in China (Chethana et al., 2017). Virginia creeper, as an excellent host of C. vitis, will increase the transmission risk of the pathogens. To our knowledge, this is the first report of C. vitis causing white rot on Virginia creeper, and this finding will provide useful information for developing effective control strategies for white rot disease.

Fungal succession on the decomposition of three plant species from a Brazilian mangrove

Leaf decomposition is the primary process in release of nutrients in the dynamic mangrove habitat, supporting the ecosystem food webs. On most environments, fungi are an essential part of this process. However, due to the peculiarities of mangrove forests, this group is currently neglected. Thus, this study tests the hypothesis that fungal communities display a specific succession pattern in different mangrove species and this due to differences in their ecological role. A molecular approach was employed to investigate the dynamics of the fungal community during the decomposition of three common plant species (Rhizophora mangle, Laguncularia racemosa, and Avicennia schaueriana) from a mangrove habitat located at the southeast of Brazil. Plant material was the primary driver of fungi communities, but time also was marginally significant for the process, and evident changes in the fungal community during the decomposition process were observed. The five most abundant classes common to all the three plant species were Saccharomycetes, Sordariomycetes, Tremellomycetes, Eurotiomycetes, and Dothideomycetes, all belonging to the Phylum Ascomycota. Microbotryomycetes class were shared only by A. schaueriana and L. racemosa, while Agaricomycetes class were shared by L. racemosa and R. mangle. The class Glomeromycetes were shared by A. schaueriana and R. mangle. The analysis of the core microbiome showed that Saccharomycetes was the most abundant class. In the variable community, Sordariomycetes was the most abundant one, mainly in the Laguncularia racemosa plant. The results presented in this work shows a specialization of the fungal community regarding plant material during litter decomposition which might be related to the different chemical composition and rate of degradation.

Antifungal Activity and DNA Topoisomerase Inhibition of Hydrolysable Tannins from Punica granatum L

Punica granatum L. (pomegranate) fruit is known to be an important source of bioactive phenolic compounds belonging to hydrolysable tannins. Pomegranate extracts have shown antifungal activity, but the compounds responsible for this activity and their mechanism/s of action have not been completely elucidated up to now. The aim of the present study was the investigation of the inhibition ability of a selection of pomegranate phenolic compounds (i.e., punicalagin, punicalin, ellagic acid, gallic acid) on both plant and human fungal pathogens. In addition, the biological target of punicalagin was identified here for the first time. The antifungal activity of pomegranate phenolics was evaluated by means of Agar Disk Diffusion Assay and minimum inhibitory concentration (MIC) evaluation. A chemoinformatic analysis predicted for the first time topoisomerases I and II as potential biological targets of punicalagin, and this prediction was confirmed by in vitro inhibition assays. Concerning phytopathogens, all the tested compounds were effective, often similarly to the fungicide imazalil at the label dose. Particularly, punicalagin showed the lowest MIC for Alternaria alternata and Botrytis cinerea, whereas punicalin was the most active compound in terms of growth control extent. As for human pathogens, punicalagin was the most active compound among the tested ones against Candida albicans reference strains, as well as against the clinically isolates. UHPLC coupled with HRMS indicated that C. albicans, similarly to the phytopathogen Coniella granati, is able to hydrolyze both punicalagin and punicalin as a response to the fungal attack. Punicalagin showed a strong inhibitory activity, with IC₅₀ values of 9.0 and 4.6 µM against C. albicans topoisomerases I and II, respectively. Altogether, the results provide evidence that punicalagin is a valuable candidate to be further exploited as an antifungal agent in particular against human fungal infections.

Genome Assembly and Transcriptome Analysis of the Fungus Coniella diplodiella During Infection on Grapevine (Vitis vinifera L.)

Grape white rot caused by Coniella diplodiella (Speg.) affects the production and quality of grapevine in China and other grapevine-growing countries. Despite the importance of C. diplodiella as a serious disease-causing agent in grape, the genome information and molecular mechanisms underlying its pathogenicity are poorly understood. To bridge this gap, 40.93 Mbp of C. diplodiella strain WR01 was de novo assembled. A total of 9,403 putative protein-coding genes were predicted. Among these, 608 and 248 genes are potentially secreted proteins and candidate effector proteins (CEPs), respectively. Additionally, the transcriptome of C. diplodiella was analyzed after feeding with crude grapevine leaf homogenates, which reveals the transcriptional expression of 9,115 genes. Gene ontology enrichment analysis indicated that the highly enriched genes are related with carbohydrate metabolism and secondary metabolite synthesis. Forty-three putative effectors were cloned from C. diplodiella, and applied for further functional analysis. Among them, one protein exhibited strong effect in the suppression of BCL2-associated X (BAX)-induced hypersensitive response after transiently expressed in Nicotiana benthamiana leaves. This work facilitates valuable genetic basis for understanding the molecular mechanism underlying C. diplodiella-grapevine interaction.

The Effect of Polyphenols on Pomegranate Fruit Susceptibility to Pilidiella granati Provides Insights into Disease Tolerance Mechanisms

Pilidiella granati, also known as Coniella granati, is the etiological agent of pomegranate fruit dry rot. This fungal pathogen is also well-known as responsible for both plant collar rot and leaf spot. Because of its aggressiveness and the worldwide diffusion of pomegranate crops, the selection of cultivars less susceptible to this pathogen might represent an interesting preventive control measure. In the present investigation, the role of polyphenols in the susceptibility to P. granati of the two royalties-free pomegranate cultivars Wonderful and Mollar de Elche was compared. Pomegranate fruit were artificially inoculated and lesion diameters were monitored. Furthermore, pathogen DNA was quantified at 12-72 h post-inoculation within fruit rind by a real time PCR assay setup herein, and host total RNA was used in expression assays of genes involved in host-pathogen interaction. Similarly, protein extracts were employed to assess the specific activity of enzymes implicated in defense mechanisms. Pomegranate phenolic compounds were evaluated by HPLC-ESI-MS and MS2. All these data highlighted 'Wonderful' as less susceptible to P. granati than 'Mollar de Elche'. In the first cultivar, the fungal growth seemed controlled by the activation of the phenylpropanoid pathway, the production of ROS, and the alteration of fungal cell wall. Furthermore, antifungal compounds seemed to accumulate in 'Wonderful' fruit following inoculation. These data suggest that pomegranate polyphenols have a protective effect against P. granati infection and their content might represent a relevant parameter in the selection of the most suitable cultivars to reduce the economic losses caused by this pathogen.