Auswahl der wissenschaftlichen Literatur zum Thema „Pestalotiopsis theae“

A novel disease characterized by small brown-black spots (1 to 2 mm in diameter) on tender tea leaves (Camellia sinensis) has been observed in many regions of Hubei Province, China, which severely affects the yield and quality of tea. Tea leaf samples with typical symptoms were collected from three major tea-cultivation regions of Hubei, and were subjected to pathogen isolation for etiological analysis. As a result, 34 Pestalotiopsis isolates were obtained from 20 samples, and they were identified as Pestalotiopsis theae (14 isolates), P. camelliae (12), and P. clavispora (8), determined by morphologies and phylogenetic analysis based on internal transcribed spacer, and partial β-tubulin and translation elongation factor 1-alpha genes. Pathogenicity tests on detached tea leaves showed that no matter what mycelial discs or conidium suspensions were used, inoculation of the Pestalotiopsis fungi could result in small brown-black spots (1 to 2 mm in diameter) on wounded leaves, similar to those observed in the field in the sizes and colors. It also revealed that only P. theae had pathogenicity on unwounded tea leaves, and P. theae and P. clavispora showed significantly higher virulence than P. camelliae. Inoculation test with conidium suspension on intact tea leaves in the field further confirmed that P. theae as the pathogen of brown-black spots. Reisolation of the pathogens from diseased leaves confirmed that the symptom was caused by the inoculation of Pestalotiopsis fungi. The P. theae isolates responsible for brown-black spots were also compared with those for tea gray blight disease in growth rate, pathogenicity, and molecular characteristics in parallel. To our knowledge, this is the first report that the Pestalotiopsis fungi cause brown-black spot disease on tender tea leaves. The results provide important implications for the prevention and management of this economically important disease.

Kejadian penyakit gugur daun karet (GDK) Pestalotiopsis sp. yang ditemukan menyerang Sumatera pada tahun 2019 membuat perhatian banyak pihak karena serangan penyakit ini mampu menurunkan produktivitas karet hingga 80%. Berbagai informasi dikumpulkan terkait penyebaran serangan di Indonesia dan teknik pengendalian guna memperoleh pendekatan yang tepat dalam pengelolaan penyakit GDK Pestalotiopsis sp. Tulisan ini bertujuan mengkonfirmasi keberadaan Pestalotiopsis sp. penyebab penyakit GDK, dan mengetahui kejadian penyakit di wilayah Kalimantan Barat sebagai kantong serangan penyakit. Pengambilan sampel dilaksanakan pada sentra produksi karet di Kalimantan Barat, dengan metode survei kilat dengan cara mengamati secara intensif, mengidentifikasi gejala, dan menemukan/mendeteksi semua OPT yang ditemukan. Data luas serangan diperoleh dengan melakukan pengamatan langsung dan dengan metode wawancara dengan pemilik kebun. Hasil surveilans menunjukkan penyakit GDK Pestalotiopsis sp. telah menyerang hampir di seluruh wilayah sentra tanaman karet dan wilayah lainnya di Kalimantan Barat, meliputi 9 (sembilan) kabupaten yaitu Sintang, Melawi, Sanggau, Landak, Kapuas Hulu, Mempawah, Bengkayang, Kubu Raya, dan Singkawang dengan hasil sekuensing DNA menunjukkan spesies Pestalotiopsis theae, dan Pseudopestalotiopsis theae. Faktor iklim dan cara budidaya petani diduga memengaruhi tingkat keparahan penyakit. Untuk menurunkan serangan penyakit dilakukan teknik pengendalian pada kantong serangan dalam bentuk kegiatan demplot sehingga diharapkan dapat mencegah perluasan serangan GDK pada wilayah lain.

New plant growth regulators, named chloroisosulochrin, chloroisosulochrin dehydrate and pestheic acid, have been isolated from the culture filtrate of Pestalotiopsis theae grown on a Raulin-Thom medium. Their structures have been established by spectroscopic and chemical methods. The biological activities of these compounds have been examined using bioassay methods with lettuce and rice seedlings

During July 1998, a leaf blight caused by Pestalotiopsis theae (Saw.) Stey. was observed at an incidence of 18 to 20% in sweet persimmon (Diospyros kaki L.fil.) orchards in Huelva Province (southwestern Spain). Symptoms appeared on leaves as large grayish brown circular ringspots. Usually, they were solitary, but occasionally, two to three spots occurred on an affected leaf. In severe cases, lesions developed on more than one-third of the leaf, resulting in defoliation. Small black acervular conidiomata were visible in the surface of spots. These conidiomata produced fusiform conidia that were straight or rarely curved, four five-celled euseptate, including three olivaceous or dark brown median cells, and hyaline apical and basal cells with appendages that were slightly constricted at septa. Conidiomata were up to 240 μm in diameter; conidiogenous cells were 6 to 13 × 1.2 to 2.8 μm; conidia were 24.7 × 7.8 μm; three median cells were 16.7 μm long; two to three apical appendages (rarely four) were 28.3 μm long; and straight basal appendage was 5.7 μm. P. theae was consistently isolated on potato dextrose agar from diseased leaves and conidiomata. To confirm pathogenicity, both mycelial plugs and a conidial suspension (1.5 × 106 conidia per ml) of the fungus were used as inocula. Young completely developed leaves from persimmon tree cvs. Sharon and Hanafuyu were inoculated in the laboratory and maintained in a moist chamber for 5 days. Lesions resembling symptoms that occurred in the field were observed on leaves after 5 days. Symptoms were not observed on control leaves inoculated with agar media or sprayed with water. The fungus reisolated from diseased leaves was identical to the original isolates. Based on the morphological characteristics of conidiomata and conidia as well as pathogenicity, the fungus was identified as P. theae (1). This is the first report of this fungus as a pathogen of D. kaki in Europe. Possibly the introduction of P. theae to Spain has been through young imported persimmon plants. Unusual climatic conditions (heavy rainfalls during 1997 in southwestern Spain) have been favorable for disease development. The hot and dry conditions that usually occur during flowering, growing, and maturation of persimmon fruits normally prevent dissemination of inoculum and infection of leaves. For these reasons, the wet areas of southwestern Spain could be more favorable for “grey blight” of persimmon trees. Reference: (1) T.-H. Chang et al. Korean J. Plant Pathol. 12:377, 1996.

Four new dimeric sorbicillinoids (1–3 and 5) and a new monomeric sorbicillinoid (4) as well as six known analogs (6–11) were purified from the fungal strain Hypocrea jecorina H8, which was obtained from mangrove sediment, and showed potent inhibitory activity against the tea pathogenic fungus Pestalotiopsis theae (P. theae). The planar structures of 1–5 were assigned by analyses of their UV, IR, HR-ESI-MS, and NMR spectroscopic data. All the compounds were evaluated for growth inhibition of tea pathogenic fungus P. theae. Compounds 5, 6, 8, 9, and 10 exhibited more potent inhibitory activities compared with the positive control hexaconazole with an ED50 of 24.25 ± 1.57 µg/mL. The ED50 values of compounds 5, 6, 8, 9, and 10 were 9.13 ± 1.25, 2.04 ± 1.24, 18.22 ± 1.29, 1.83 ± 1.37, and 4.68 ± 1.44 µg/mL, respectively. Additionally, the effects of these compounds on zebrafish embryo development were also evaluated. Except for compounds 5 and 8, which imparted toxic effects on zebrafish even at 0.625 μM, the other isolated compounds did not exhibit significant toxicity to zebrafish eggs, embryos, or larvae. Taken together, sorbicillinoid derivatives (6, 9, and 10) from H. jecorina H8 displayed low toxicity and high anti-tea pathogenic fungus potential.

Loquat, Eriobotrya japonica (Thunb.) Lindl., is an important fruit that is widely planted and used as an ornamental in Jingxian, Anhui Province, China. Loquat branches with severely spotted leaves and fruits were observed in this region in 2012. Symptoms on leaves consisted of small (0.5 to 1.2 cm in diameter), circular to oblong, greenish-brown lesions that coalesced to form isolated or confluent, dark brown spots. On fruit, the disease appeared as circular to elongated, sunken spots. Expanding lesions spread over the surface resulting in death of the fruit. Acervuli were observed within lesions. Isolations from symptomatic tissue onto potato dextrose agar (PDA) medium consistently yielded white fungal colonies of sparse aerial mycelium with acervuli containing black, slimy spore masses on the surface. The colony reached 8.0 cm diameter after 7-day culture on PDA at 24°C. Conidia produced in the culture were five-celled, narrow fusiform, straight or slightly curved, with a tapering base and 2 to 4 hyaline appentages (apical appentages measured 15 to 34 μm long and a single basal appentage was 5 to 9 μm long). Conidia were 24 to 32 × 5 to 8 μm with median cells 15 to 20 μm and two hyaline, cylindrical to conical apical cells typical of Pestalotiopsis spp. (3). A total of 12 isolates were obtained by isolation from the diseased fruit or leaves. Genomic DNA from the fungal isolates was purified using a DNA Gel Extraction Kit (AxyPrep, Hangzhou, China), and applied to a DNA Engine System PTC-200 (BIO-RAD, Watertown, MA) with ITS1 and ITS4 internal transcribed spacer (ITS) universal primers. The amplified sequences (533 bp) were analyzed together with other Pestalotiopsis sequences (1). ITS from all 12 of the fungal isolates were identical (99.5% similarity) to each other and to isolates of Pestalotiopsis theae, which infects tea trees in China (2). To demonstrate pathogenicity, suspensions (prepared in distilled water) of 106 conidia ml–1 of each isolate were sprayed on the loquat leaves in vivo and mature fruits in vitro. Distilled water was used as the control. More than 20 leaves and 10 mature fruits were sprayed for the treated and control plants, respectively, and the inoculation tests were repeated twice. The inoculated plants and fruit were kept in a humidity chamber for 7 days. Approximately 50% of the inoculated leaves and fruits developed blight symptoms similar to natural infections. P. theae was reisolated from diseased plants to complete Koch's postulates. Control plants sprayed with distilled water remained symptomless. There is a previous study reporting that P. guepini infected loquat in Argentina (4); however, to our knowledge, this is the first report of P. theae causing leaf and fruit spots on loquat in China. References: (1) R. Jeewon et al. Mol. Phylogenet. Evol. 25:378, 2002. (2) J. Y. Lu. Diagnosis of plant diseases. Page 194 in: Pestalotiopsis. J. Y. Lu, Z. G. Xu, Y. X. Chen, D. R. Shen, X. B. Zheng, and Y. Q. Cao, eds. China Agriculture Press, Beijing, 1995. (3) T. R. Nag Raj. Coelomycetous Anamorphs with Appendage-Bearing Conidia. Mycologue Publications, Waterloo, Canada, 1993. (4) A. E. Perelló and S. Larran. Plant Dis. 83:695, 1999.

Fungi and bacteria that live in the internal tissues of the plant are referred to as endophytes. They have no harmful effects on their host plant. Endophytic fungi synthesise metabolites that are structurally and functionally similar to those of their host plants. They are able to create a wide range of biomolecules from different classes with countless applications. Fungal endophytes such as Penicillium, Fusarium, Aspergillus, Sclerotium, Myxormia, Alternaria, Colletotrichum, Cladosporium, Diaporthe, and other endophytic species are well recognized to produce bioactive chemicals that have a crucial role in the management of disease. Bioactive compounds derived from endophytic fungi were classified as alkaloids, steroids, flavonoids, phenolic acids, benzopyranones, quinines, tannins, xanthones, terpenoids and they possess antimicrobial, antioxidant, cytotoxic, immunosuppressive, and anti-inflammatory activities. The deadliest illness, cancer kills thousands of individuals annually. In this scenario, the scientific community is searching for new anticancer drugs to combat cancer. Studies on the discovery of anti-cancer drugs from endophytes began in the early 90s and gained prominence in the twenty-first century. More than 200 novel cytotoxic chemicals have been discovered in the last thirty years from endophytic fungi of both terrestrial and marine plants. The majority of these cytotoxic substances fall into the following categories: polyketides, terpenoids, sterols, macrolides, lactones, azaphilones, alkaloids, preussomerins, p-terphenyls, hybrid structures, and other substances. The most important anti-cancer drugs are from endophytes, including taxol, podophyllotaxin, camptothecin, vinca alkaloids, cytochalasin 1-3, malformin, graphislactone A, etc. Discovery of taxol and its analogue from endophytes marked a significant advance in cancer drugs research. Studies have reported the production of taxol by Pestalotiopsis versicolor, and an apoptotic experiment using the isolated fungal taxol demonstrated high cytotoxic action against tested human cancer cells in in vitro culture, demonstrating that an increase in taxol concentration causes more cell death. In this review we have referred a total of sixty-one research papers during the year 2010 to 2022 and tried to highlight the significance of fungal endophytes and the bioactive substances produced by them in cancer treatment