Pathogenic Fungi Diversity of ‘CuiXiang’ Kiwifruit Black Spot Disease during Storage

Kiwifruit black spot disease has become increasingly widespread in many ‘CuiXiang’ kiwifruit plantings regions. This research was aimed at the pathogenic microorganisms of black spot of the ‘CuiXiang’ cultivar. Physiological, morphological and transcriptional characteristics between black spot fruit and healthy fruits were evaluated. Then, it applied a high-throughput internal transcribed spacer (ITS) sequencing to analyze the black spot disease microbial community. The cell structure showed that mycelium was attached to the surface of the kiwifruit through black spot, and that consequently the mitochondria were damaged, starch particles were reduced, and shelf life was shortened. Transcriptome revealed that different genes in kiwifruit with black spot disease were involved in cell wall modification, pathogen perception, and signal transduction. ITS sequencing results described the disease-causing fungi and found that the microbial diversity of black spot-diseased fruit was lower than that of healthy fruit. We predict that candidate pathogenic fungi Cladosporium cladosporioides, Diaporthe phaseolorum, Alternaria alternata, and Trichothecium roseum may cause black spot. This study was to explore the pathogenic fungal community of ‘CuiXiang’ kiwifruit black spot disease and to provide essential information for field prevention.

Screening and Identification of Strains With High Lignocellulose-degrading Enzyme Production From Endophytic Fungi of Taxillus Chinensis

Taxillus chinensis is an extensively used medicinal herb in the traditional as well as modern systems of medicines. It is a perennial hemiparasitic plant, which is difficult to propagate artificially because of its low parasitic rate. Successful parasitism of parasitic plants is to fuse their tissues and connect their vasculature to the host vasculature building a physiological bridge, which can efficiently withdraw water, sugars and nutrients from their host plants. It is reported that endophytic fungi play an important role in cell wall degradation and fusion, which is the key forming process of the physiological bridge. Therefore, in this study, the endophytic fungi from T. chinensis of different hosts were isolated, and then the organisms that could degrade the main components of the cell walls were screened out using a medium consisting of guaihuol and cellulose degradation capacity. The results showed that five strains with high enzyme activities for lignocellulosic degradation were screened out from 72 endophytic fungi of T. chinensis. The laccase and cellulase activities of five strains reached their peaks at day 7, and the highest enzyme activities of these two enzymes were found in strain P6, which was 117.66 and 1.66 U/mL, respectively. Manganese peroxidase of strain 4 and lignin peroxidase of strain N6 also reached their peaks at day 7 and were the highest among the 5 strains, with enzyme activities of 11.61 and 6.64 U/mL, respectively. Strains 4, 15, 31, N6 and P6 were identified as Colletotrichum acutatum, Nigerrospora sphaerica, Exserohilum rofolium, Diaporthe phaseolorum and Pestalotiopsis arceuthobii, respectively, according to their morphological and molecular biology properties.

Phaeohyphomycosis caused by Diaporthe phaseolorum in an immunocompetent patient in Thailand: a case report

Phaeohyphomycosis is caused by a large, heterogeneous group of darkly pigmented fungi. It is an infrequent infection in humans. However, the prevalence has been increasing in recent years especially in immunocompromised patients. Diaporthe phaseolorum is a common black fungal pathogen of plants, which rarely causes human infection. We report the first case of cutaneous infection caused by Diaporthe phaseolorum in an immunocompetent host and the first in Asia. Although, the review of the literature revealed two previous cases of cutaneous infection caused by this organism, both of them were in immunocompromised hosts. A slow-growing asymptomatic nodule was the major clinical feature. Histopathological examination showed granulomatous inflammation and pigmented septate hyphae and yeast-like cells. The fungal isolation was identified by morphological characteristics and DNA sequencing. The lesion was resolved after complete surgical excision and oral fluconazole for two months. This report highlights the potential role of Diaporthe phaseolorum as an emerging cause of infection in immunocompetent patients.

Diaporthe species infecting sunflower in Russia

Diaporthe is an important group of plant pathogenic fungi revealed all over the world. Early classification and species identification of this genus was mostly based on combination of morphological characteristics, cultural features, and affiliation with a host plant. According to recent investigations, valid distinction between Diaporthe species should have combined molecular techniques, morphological and cultural observations, and mating type data. In Russia a comprehensive and extensive analysis of biodiversity and geographic distribution of Diaporthe species infecting sunflower has not been performed. There were seven Diaporthe sp. strains isolated from this plant maintained in the Laboratory of Mycology and Phytopathology of All-Russian Institute of Plant Protection. In previous study a strain from Krasnodar region, based on combination of molecular and morphological features was identified as Diaporthe phaseolorum. The aim of this study was to identify all other strains using primarily molecular phylogenetic approach and traditional morphological analysis. The strains were identified as Diaporthe gulyae, Diaporthe eres, and Diaporthe helianthi. Two species - D. gulyae and D. eres are found for the first time on sunflower in Russia. Detection of D. helianthi is the first report of this fungus in Russia as confirmed by molecular analysis.

Secondary metabolites produced by endophytic fungi: novel antifungal activity of fumiquinone B

Fungi are present in the most diverse environments including the interior of plant tissues, living as endophytes without causing apparent damage. These endophytes are producers of secondary metabolites, also known as natural products, such as fungicides. Here, we evaluated the ethyl acetate fractions obtained from endophytic fungi isolated from plants in the genus Begonia. The fractions were submitted to inhibitory test against the plant pathogens Diaporthe phaseolorum and Colletotrichum gloeosporioides. From the 88 ethyl acetate fractions evaluated, 14.7 % inhibited C. gloeosporioides and 11.3 % inhibited D. phaseolorum. One fungal isolate displaying an active fraction was selected for chemical investigation. The fungus identified as Neopestalotiopsis sp., produced a compound that was active against D. phaseolorum, with a MIC of 312 µg mL-1 (1,695.3 µM). The compound was identified by mass spectrometry and 1H NMR as the known compound fumiquinone B. The results highlight that the endophytes are capable of producing compounds that may be used to control plant pathogens. The compound fumiquinone B is reported for the first time as an antifungal agent against D. phaseolorum, a relevant plant pathogen worldwide. This is also the first report of the production of fumiquinone B by the genus Neopestalotiopsis.

ANTIOXIDANT ACTIVITY of THE SECONDARY METABOLITES PRODUCED by ENDOPHYTIC FUNGI ISOLATED from JERUJU (Acanthus ilicifolius L.) PLANT

Twelve endophytic fungi were isolated from Jeruju plant. Three of which have the best antioxidant activity, namely Culvularia lunata DJS1, Diaporthe phaseolorum DJS2, and Colletotrichum siamense BJS4. The fungi can produce secondary metabolites that have the potential as antioxidant compounds. This study aims to isolate the antioxidant compound using a chromatography column and test the antioxidant activity using DPPH method. Isolation of secondary metabolites produced 40 eluates. The IC50 value of DJS111 and BJS42 eluates were 10.20 µg/ml and 20.89 µg/ml, which is an antioxidant compound with very strong activity. The IC50 value of DJS24 eluate was 54.45 µg/ml, which is strong antioxidant activity. DJS111 eluate has antioxidant activity that approaches to ascorbic acid as a standart antioxidant compound (7.76µg/ml). From TLC, DJS111 contains flavonoid compound and DJS24 and BJS42 contain terpenoid compound.