Molecular Phylogenetic Diversity and Biological Characterization of Diaporthe Species Associated with Leaf Spots of Camellia sinensis in Taiwan

Four new endophytic species of Diaporthe (Diaporthaceae, Diaporthales) isolated from Cameroon

The genus Diaporthe (Diaporthaceae, Diaporthales) is a large group of fungi frequently reported as phytopathogens, with ubiquitous distribution across the globe. Diaporthe have traditionally been characterized by the morphology of their ana- and teleomorphic state, revealing a high degree of heterogeneity as soon as DNA sequencing was utilized across the different members of the group. Their relevance for biotechnology and agriculture attracts the attention of taxonomists and natural product chemists alike in context of plant protection and exploitation for their potential to produce bioactive secondary metabolites. While more than 1000 species are described to date, Africa, as a natural habitat, has so far been under-sampled. Several endophytic fungi belonging to Diaporthe were isolated from different plant hosts in Cameroon over the course of this study. Phylogenetic analyses based on DNA sequence data of the internal transcribed spacer region and intervening 5.8S nrRNA gene, and partial fragments of the calmodulin, beta-tubulin, histone and the translation elongation factor 1-α genes, demonstrated that these isolates represent four new species, i.e. D.brideliae, D.cameroonensis, D.pseudoanacardii and D.rauvolfiae. Moreover, the description of D.isoberliniae is here emended, now incorporating the morphology of beta and gamma conidia produced by two of our endophytic isolates, which had never been documented in previous records. Moreover, the paraphyletic nature of the genus is discussed and suggestions are made for future revision of the genus.

Insights into the Isolation, Identification, and Biological Characterization Analysis of and Novel Control Strategies for Diaporthe passiflorae in Postharvest Passion Fruit

Postharvest diseases seriously restrict developments in the passion fruit industry. In this study, we aimed to identify the postharvest pathogen affecting passion fruit, investigate its pathogenicity, and explore relevant control methods. The pathogen was isolated from rotting passion fruit and identified using morphological characteristics, ITS sequences, and phylogenetic tree analyses. Additionally, preliminary studies were conducted to assess the biological characteristics of the pathogen and evaluate the efficacy of various treatments for disease control. The fungus on the passion fruit called B4 was identified as Diaporthe passiflorae. Optimal conditions for mycelial growth were observed at 25-30 °C and pH 5-6, with starch as the carbon source and peptone as the nitrogen source. Infection by D. passiflorae accelerated fruit decay, reduced the h° value of the peel, and increased the peel cell membrane permeability when compared to the control. Notably, treatments with appropriate concentrations of ɛ-poly-l-lysine, salicylic acid, and melatonin showed inhibitory effects on the pathogen's growth in vitro and may thus be potential postharvest treatments for controlling brown rot caused by D. passiflorae in passion fruit. The results provide a scientific basis for the development of strategies to control postharvest decay and extend the storage period of passion fruit.

Unprecedented Antimicrobial and Cytotoxic Polyketides from Cultures of Diaporthe africana sp. nov

Four unprecedented polyketides named isoprenylisobenzofuran B (2), isoprenylisobenzofuran C₁/C₂ (3), diaporisoindole F₁/F₂ (4), and isochromophilonol A₁/A₂ (7) were isolated from ethyl acetate extracts of the newly described endophytic fungus Diaporthe africana. Additionally, the previously reported cyclic depsipeptide eucalactam B (1) was also identified, along with the known compounds diaporisoindole A/B (5), tenellone B (6) and beauvericin (8). The taxonomic identification of the fungus was accomplished using a polyphasic approach combining multi-gene phylogenetic analysis and microscopic morphological characters. The structures 1-8 were determined by a detailed analysis of their spectral data, namely high-resolution electrospray ionization mass spectrometry (HR-ESIMS), 1D/2D nuclear magnetic resonance (NMR) spectroscopy, as well as electronic circular dichroism (ECD) spectra. In addition, chemical methods such as Marfey's analysis were also employed to determine the stereochemistry in compound 1. All the compounds obtained were evaluated for antimicrobial and in vitro cytotoxic properties. Compounds 3-8 were active against certain fungi and Gram-positive bacteria with MIC values of 8.3 to 66.6 µg/mL. In addition, 3-5 displayed cytotoxic effects (22.0 ≤ IC₅₀ ≤ 59.2 µM) against KB3.1 and L929 cell lines, whereas compounds 6-8 inhibited the growth of seven mammalian cancer cell lines with IC₅₀ ranging from 17.7 to 49.5 µM (6), 0.9 to 12.9 µM (7) and 1.9 to 4.3 µM (8).

Linoleic acid from the endophytic fungus Diaporthe sp. HT-79 inhibits the growth of Xanthomonas citri subsp. citri by destructing the cell membrane and producing reactive oxygen species (ROS)

Citrus canker disease caused by Xanthomonas citri subsp. citri (Xac) severely influences the quality and quantity of citrus fruits. The current management of this disease mainly relies on the application of copper-associated chemicals, which poses a threat to human health and the environment. The present study isolated an endophytic fungus HT-79 from the healthy navel orange tree, whose crude fermentation product significantly inhibited the growth of Xac. The strain HT-79 was identified as a species of the Diaporthe genus. The petroleum ether extract (PEE) of the crude fermentation product of HT-79 exhibited remarkable activity against Xac with a MIC (minimum inhibitory concentration) value of 0.0625 mg/mL, significantly better than the positive control CuSO₄ (MIC = 0.125 mg/mL). Bioassay-guided isolation of PEE resulted in the discovery of one highly potent anti-Xac subfraction, namely fraction 5 (MIC = 0.0156 mg/mL). Gas chromatography-mass spectrometry (GC-MS) analysis revealed that fraction 5 mainly consisted of palmitic acid (18.17%), ethyl palmitate (15.66%), linoleic acid (6.80%), oleic acid (18.32%), ethyl linoleate (21.58%), ethyl oleate (15.87%), and ethyl stearate (3.60%). Among these seven compounds, linoleic acid (MIC = 0.0078 mg/mL) was found to be the most potent against Xac, followed by oleic acid (MIC = 0.0156 mg/mL), while all others were less pronounced than CuSO₄. Linoleic acid highly inhibited the growth of Xac via the destruction of the cell membrane and overproduction of reactive oxygen species (ROS). A preliminary in vivo experiment revealed that linoleic acid was effective in the control of citrus canker disease.

10th Anniversary of Plants-Recent Advances and Further Perspectives

Published for the first time in 2012, Plants will celebrate its 10th anniversary [...].

Taxonomy and Phylogeny of Fungi Associated with Mangifera indica from Yunnan, China

During investigations of saprobic fungi associated with mango (Mangifera indica) in Baoshan and Honghe of Yunnan Province (China), fungal taxa belonging to the orders Botryosphaeriales, Calosphaeriales, Chaetothyriales, Diaporthales, and Xylariales were recorded. Morphological examinations coupled with phylogenetic analyses of multigene sequences (ITS, LSU, SSU, tef1-α, rpb1, rpb2, β-tubulin and CAL) were used to identify the fungal taxa. A new genus viz. Mangifericola, four new species viz. Cyphellophora hongheensis, Diaporthe hongheensis, Hypoxylon hongheensis, and Mangifericola hongheensis, four new host and geographical records viz. Aplosporella artocarpi, Hypomontagnella monticulosa, Paraeutypella citricola and Pleurostoma ootheca, and two new collections of Lasiodiplodia are reported.

Endophytic Diaporthe Associated with Morinda officinalis in China

Diaporthe species are endophytes, pathogens, and saprobes with a wide host range worldwide. However, little is known about endophytic Diaporthe species associated with Morinda officinalis. In the present study, 48 endophytic Diaporthe isolates were obtained from cultivated M. officinalis in Deqing, Guangdong Province, China. The nuclear ribosomal internal transcribed spacer (ITS), partial sequences of translation elongation factor 1-α (tef1-α), partial calmodulin (cal), histone H3 (his), and Beta-tubulin (β-tubulin) gene regions were sequenced and employed to construct phylogenetic trees. Based on morphology and combined multigene phylogeny, 12 Diaporthe species were identified, including five new species of Diaporthe longiconidialis, D. megabiguttulata, D. morindendophytica, D. morindae, and D. zhaoqingensis. This is the first report of Diaporthe chongqingensis, D. guangxiensis, D. heliconiae, D. siamensis, D. unshiuensis, and D. xishuangbanica on M. officinalis. This study provides the first intensive study of endophytic Diaporthe species on M. officinalis in China. These results will improve the current knowledge of Diaporthe species associated with this traditional medicinal plant. Furthermore, results from this study will help to understand the potential pathogens and biocontrol agents from M. officinalis and to develop a disease management platform.