Diaporthe Phaseolorum Research Articles

A Novel Strain Burkholderia theae GS2Y Exhibits Strong Biocontrol Potential Against Fungal Diseases in Tea Plants (Camellia sinensis).

Tea plants (Camellia sinensis) are widely cultivated cash crops. However, fungal diseases lead to significant reductions in both the yield and quality of tea. Therefore, searching for economical, eco-friendly, and efficient biological control measures is crucial for protecting tea plants from pathogenic fungi. The confrontation assays were performed to identify the antagonistic bacteria against tea pathogenic fungi and evaluate the antifungal activity of these bacteria. Here, three tea pathogenic fungi were identified: Colletotrichum siamense HT-1, Diaporthe phaseolorum HT-3, and Fusarium fujikuroi HT-4. Notably, D. phaseolorum was the first to be reported in tea plants in China. Some tea pathogenic fungi showed a high relative abundance, suggesting a potential disease risk in tea plantations. Strain GS2Y, isolated from tea rhizosphere soil, exhibited strong antifungal activity against tea pathogenic fungi and represented a novel species within the genus Burkholderia, designated as Burkholderia theae. GS2Y could directly inhibit tea pathogenic fungi by disrupting the cellular structures and protect tea plants from fungal diseases caused by C. siamense HT-1 and D. phaseolorum HT-3. B. theae GS2Y might function as a potentially valuable resource for biocontrol agents, laying the foundation for the development of strategies to manage fungal diseases in tea plants.

Development of ‘TN16‐520R1’: A drought‐tolerant soybean cultivar with glyphosate resistance

AbstractThe glyphosate‐tolerant soybean [Glycine max (L.) Merr.] line ‘TN16‐520R1’ (Reg. no. CV‐560, PI 703273) was released as a high‐yielding cultivar by University of Tennessee Agricultural Research in 2018. TN16‐520R1 is a BC4F2 cultivar derived from the recurrent parent ‘Ellis’, with drought tolerance and a maturity group (MG) of V‐early. It has white flowers, gray pubescence, tan podwall, and a determinate growth habit. The seed has buff hila, is yellow with smooth seed coat, and contains 40% protein and 22% oil on a dry weight basis. TN16‐520R1 has good resistance to lodging and good seed quality (1.8 and 1.6, respectively, on 1–5 scale), and a seed size of 11.8 g per 100 seed. Like Ellis, TN16‐520R1 has performed competitively throughout much of the mid‐South United States over several years, with testing occurring over a 6‐year period in 100 environments. Further, TN16‐520R1 is remarkably like the recurrent parent Ellis for yield, maturity, lodging, height, protein, and oil. Also, like Ellis, TN16‐520R1 is resistant to stem canker [caused by Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. caulivora K.L. Athow & R.M. Caldwell] and southern root‐knot nematode [Meloidogyne incognita (Kofoid and White) Chitwood] and has field tolerance to frogeye leafspot [caused by Cercospora sojina (Hara)]. This combination of beneficial traits and broad adaptability make TN16‐520R1 an excellent choice as a soybean cultivar for producers or a crossing parent for breeders.

Diaporthe phaseolorum causing dieback disease on Melia dubia cav. in Karnataka state (India).

Melia dubia is an important tree species grown worldwide for its medicinal and timber values. It is widely used in timber and pulp industry and also as an organic pesticide, fertilisers, agro-forestry and herbal formulations. During 2019-2022, a dieback disease in plantations of M. dubia was recorded in Mysore, Mandya, Chamarajanagar, Hassan and Tumkur districts of Karnataka state (India) with disease incidence of 26.25%. The associated pathogen was isolated on PDA medium and its morpho-cultural characteristics were studied. The genomic DNA of the pathogen was isolated, and rDNA was amplified and sequenced using universal primers. Based on the microscopic, morpho-cultural, sequence data and phylogenetic analysis, the pathogen was identified as Diaporthe phaseolorum (Cooke & Ellis) Sacc. Koch's postulates were performed both in vitro and in vivo and the typical symptoms of dieback disease were recorded on post-inoculated saplings. The dieback disease is responsible for the poor growth of Melia species in the region, and hence, there is an urgent need to manage the disease in plantations using integrated management practices. This is the first report of the occurrence of D. phaseolorum on M. dubia plantations in India.

In-vitro evaluation of fungicides and essential oils against Diaporthe phaseolorum causing dieback of Melia dubia

In-vitro evaluation of fungicides and essential oils against Diaporthe phaseolorum causing dieback of Melia dubia

Quadruplex and q-PCR based diagnostic assay to delineate the major quarantine and other seed-borne fungal pathogens of soybean.

Soybean is one of the most important crops grown worldwide and accounting for significant global trade including transgenic soybean. The crop is attacked by several seed-borne fungal pathogens and some of them are of quarantine concern for India. Keeping in view of the risks associated with movement of soybean seeds, sensitive and reliable molecular diagnostics have been developed for precise and simultaneous detection of three pathogens of quarantine concern for India namely, Diaporthe phaseolorum (stem blight), D. longicolla (seed decay), Peronospora manshurica (downy mildew), along with Macrophomina phaseolina causing dry root rot. The targeted pathogens after isolation from imported transgenic and non-transgenic soybean seeds were identified. Quadruplex and qPCR assays were developed targeting the sequences of different genes such as Histone-3 for detection of D. longicolla and M. phaseolina. The markers DlHisF2&R2 and MpHisF1&R1 produced 265 and 309bp amplicons for D. longicolla and M. phaseolina, respectively. Actin gene based marker DpActF1&R2 was developed for D. phaseolorum which provided 113bp amplicon whereas, COX2 based marker PmCoxF2&R2 was developed for P. manshurica with amplified product of 152bp. During qPCR analysis, these markers proved highly specific and sensitive for detection of these pathogens up to 0.1 pg of template DNA. Quadruplex PCR protocol was also developed by combining these specific markers which could distinguish all the targeted pathogens simultaneously in a single reaction. The developed diagnostic protocols are extremely valuable for quarantine clearance and to ensure the safe transboundary exchange and healthy conservation of germplasm in the National Genebank.

Priming crop plants with rosemary (Salvia rosmarinus Spenn, syn Rosmarinus officinalis L.) extract triggers protective defense response against pathogens

Plant bioactive compounds provide novel straightforward approaches to control plant diseases. Rosemary (Salvia rosmarinus)-derived extracts carry many prominent pharmacological activities, including antimicrobial and antioxidant, mainly due to its phenolic compounds, rosmarinic acid (RA), carnosic acid and carnosol. However, the effects of these extracts on plant diseases are still unknown, which constrains its potential application as bioprotectant in the agricultural production. In this study we demonstrate the antiviral effect of the aqueous rosemary extract (ARE) against tobacco necrosis virus strain A (TNVA) in ARE-treated tobacco (Nicotiana tabacum) plants. Our results show that ARE-treatment enhances plant defense response, contributing to reduce virus replication and systemic movement in tobacco plants. RA, the main phenolic compound detected in this extract, is one of the main inducers of TNVA control. The ARE-induced protection in TNVA-infected plants was characterized by the expression of H2O2 scavengers and defense-related genes, involving salicylic acid- and jasmonic acid-regulated pathways. Furthermore, treatment with ARE in lemon (Citrus limon) and soybean (Glycine max) leaves protects the plants against Xanthomonas citri subsp. citri and Diaporthe phaseolorum var. meridionalis, respectively. Additionally, ARE treatment also promotes growth and development, suggesting a biostimulant activity in soybean. These results open the way for the potential use of ARE as a bioprotective agent in disease management.

First report of Diaporthe phaseolorum infecting Indian trumpet flower (Oroxylum indicum) from India

Seed health testing, using the blotter method, revealed some fungal growth on the seed surface of one accession of Indian trumpet flower/Broken bones tree (Oroxylum indicum (L.) Kurz) collected from Kokrajhar, Assam, India. The fungus was identified as Diaporthe phaseolorum (Cooke & Ellis) Sacc. based on morphological characters. Later, the identity was re-confirmed by DNA sequencing using ITS gene sequencing (NCBI Sequence Id: MT154253.1) and a large subunit of rRNA (NCBI Sequence Id: OL798081.1). Literature reveals that D. phaseolorum is a destructive pathogen causing severe yield losses in various host crops. However, detection of D. phaseolorum in Indian trumpet flower seed followed by pathogenicity on its seedlings confirms that O. indicum is a new host record. Being a destructive pathogen of several other crops, such as seed decay and stem canker in soybean, it may pose a serious threat to future cultivation of this herbal plant.

Preliminary Identification of New Fungal Pathogen Isolated from Black Pepper Disease

Black pepper (Piper nigrum L.) is one of important spice crop that has been grown and traded globally. In this few years, black pepper industry had recorded unsatisfactory yield production as its has been hampered with disease attacks. Almost all parts of the plant are susceptible to disease infections particularly disease that has been caused by fungal pathogens. This present study aims to isolate and identify fungal pathogen associated with black pepper disease in peninsular Malaysia. In one of sampling location in Jelebu, Negeri Sembilan, two fungus were isolated from symptomatic leaves and berries of black peppers. The leaves produced yellowish to brownish lesions while the berries produce blackish lesions. Morphological identification based on macroscopic and microscopic characteristics showed that the isolates produced similar characteristics with Fusarium and Diaporthe species. The pathogenicity was confirmed by an artificial inoculation test on healthy black pepper plants in which similar simptoms were observed on inoculated plant. Molecular identification based on DNA sequence analysis of the Internal Transcribed Spacers (ITS1 and ITS2) regions was conducted to confirm the identity of both isolates. The sequences were compared with other sequences from the NCBI GenBank database and the blast results indicate 99% percent similarity with Diaporthe phaseolorum and Fusarium polyphialidicum species. Constructed Phylogenetic tree also showed that the isolates were grouped together with the reference strain of Diaporthe phaseolorum and Fusarium polyphialidicum species. This is the first report of the occurrence of both species as pathogen of black pepper plant in peninsular Malaysia.

Identification of Pathogens and Laboratory Activity Test of Kiwifruit Rot Disease in Guizhou Province, China

Kiwifruit (Actinidia spp.) postharvest decay is common in China, which can cause serious economic losses to kiwifruit industry. In order to further clarify the pathogen of kiwifruit rot disease in Guizhou Province, the rotten fruits of kiwifruit (cultivar “Jinyan”) were collected, and the pathogenic fungi were identified by isolation and purification, pathogenicity test, morphological characteristics, and analysis of rDNA-ITS sequences. The results showed that the pathogenic fungi of kiwifruit rot disease were Diaporthe phaseolorum and Fusarium tricinctum. Meanwhile, the results showed that all the tested agents had a certain inhibitory effect on Diaporthe phaseolorum and Fusarium tricinctum. Among them, 33.5% quinolone SC had the best inhibitory effect on Diaporthe phaseolorum with an EC50 value of 9.67 mg/L, and 25% fludioxonil SC had the best inhibitory effect on Fusarium tridentatus with the EC50 value of 13.13 mg/L. The results will provide a reference for the control of kiwifruit rot disease.

Effects of endophytic fungi on parasitic process of Taxillus chinensis

Taxillus chinensis (DC.) Danser is an extensively used medicinal shrub 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 were screened out from 72 endophytic fungi of T. chinensis which with high enzyme activities for lignocellulosic degradation. 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 sp., Nigerrospora sphaerica, Exserohilum sp., Diaporthe phaseolorum and Pestalotiopsis sp., respectively, according to their morphological and molecular biology properties. The endophytic fungi may secrete efficient cell wall degradation enzymes, which promote the dissolution and relaxation of the cell wall between T. chinensis and host, thus contributing to the parasitism of T. chinensis.

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.

Registration of ‘TN14‐5021’, a conventional soybean cultivar with elevated seed protein and resistance to soybean cyst nematode races 2, 3, and 5

Abstract‘TN14‐5021’ (Reg. no. CV‐543, PI 699124) is a late maturity group IV (relative maturity 4.9) determinate conventional soybean [Glycine max (L.) Merr.] cultivar developed and released by the University of Tennessee soybean breeding program. Soybean cultivars with resistance to soybean cyst nematode (SCN) race 2 are rare, but race 2 is becoming a predominant SCN population infecting farmers’ fields in regions of the U.S. Southeast and Mid‐South. TN14‐5021 also conveys resistance to stem canker [caused by Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. caulivora K.L. Athow & R.M. Caldwell] and strong resistance to SCN races 3 and 5. In replicated trials across 70 environments from the Mid‐South to the Southeast, TN‐5021 showed high yield potential and adaptation to a broad range of growing conditions. TN14‐5021 has white flowers and gray pubescence. The pods have a tan pod coat, and the seeds are yellow with smooth seed coats. Across 48 environments over a 4‐yr period, with testing locations from Kansas to Alabama, TN14‐5021 averaged 406 and 226 g kg–1 protein and oil content, respectively. In comparison, the average protein and oil content of commercial cultivars grown in the same tests averaged 397 and 224 g kg–1, respectively. Its high yield coupled with elevated seed protein concentration and nematode resistance package make TN14‐5021 a valuable cultivar for Tennessee and the Mid‐South region.

First report of soybean stem blight caused by Diaporthe phaseolorum in Sichuan province, China.

In September 2020, a disease resembling stem blight on soybean was found in Chengdu city, Sichuan province, southwestern of China. Symptoms began as a brown lesion on the stems, usually at the nodes, then lesions expanded, darkened, and even girdled the stems, causing wilt of the above stems (Figure 1A). In three 0.33-ha fields, a total of 300 soybean plants (20 plants/site × 5 sites/filed × 3 fields) were investigated, and 3% of the plants showed the disease symptoms. The symptoms were consistent with those previously reported for stem canker and stem blight on soybean caused by Diaporthe complex (Cui et al. 2009; Mena et al. 2019; Santos et al. 2011). The tissues of symptomatic soybean stems were rinsed by water, disinfected by submerging them in 75% ethanol for 30 s and in 2% sodium hypochlorite solution for 2 min, then followed by washing with sterile distilled water. Small diseased tissue fragments were placed on selective potato dextrose agar (PDA) containing rifampicin and ampicillin (both 50 mg/μl). Plates were sealed and incubated at 26°C for two days. Developing mycelia of isolates were transferred to fresh PDA and purified by single hyphal tip. For the five obtained isolates (Figure 1B), five markers, including the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA, parts of the translation elongation factor 1-α (TEF1), part of the histone H3 (HIS) gene, the calmodulin gene (CAL), and the beta-tubulin gene (TUB), were amplified using the established primers ITS4/ITS5 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999), CYLH3F (Crous et al. 2006) and H3-1b (Glass and Donaldson 1995), CAL228F/CAL737R (Carbone and Kohn 1999), and Bt-2a/Bt-2b (Glass and Donaldson 1995), respectively, and sequenced (GenBank IDs: MW595761-MW595780 and MW624472-MW624476). Phylogenetic trees were constructed based on concatenated sequences of the five markers using the maximum-likelihood (ML) method in MEGA-5.2.2. Based the results of morphological (Figure 1C-E) and phylogenetic analysis (Figure 2), the five isolates were all identified as D. phaseolorum. Pathogenicity tests for the isolates were conducted on 7-day-old soybean seedlings (cv. Shangdou 1310) using a hypocotyl slit inoculation method. At the stem 2-cm below cotyledon, a 6-mm long slit was cut with a sterile scalpel, and placed inside with a 3 mm × 3 mm PDA plug with or without mycelia of pathogen. Ten plants were assayed for each treatment, and the plants were maintained in greenhouse at 26°C, with humidity higher than 90% for the first two days. The assay was repeated at least three times. Typical brown lesions on the stems were observed four days after inoculation (Figure 1F), even 20% treated plants died. The D. phaseolorum was reisolated from these stem lesions. No disease symptom was observed on control plants (Figure 1G). Thus D. phaseolorum was the pathogen causing the soybean stem blight in field. To our knowledge, this is the first report of D. phaseolorum causing this disease in Sichuan province, China. The result may provide useful information for soybean disease control in this region of China. The authors declare no conflict of interest. Funding: China Agriculture Research System (CARS-004-PS14).

Metabolomic Analysis of Combretum lanceolatum Plants Interaction with Diaporthe phaseolorum and Trichoderma spirale Endophytic Fungi through 1 H-NMR.

Endophytic fungi are an important class of microorganisms, able to interact with a host plant via a mutualistic mechanism without visible symptoms of the fungal colonization. The synergy between endophytic fungi and their host plant can promote morphological, physiological and biochemical changes through the expression of bioactive metabolites. This work aims to correlate metabolic changes in the Combretum lanceolatum plant metabolome with its endophytic fungi Diaporthe phaseolorum (Dp) and Trichoderma spirale (Ts), and to discover corresponding metabolite-biomarkers, with the principal focus being on its primary metabolism. The 1 H-NMR metabolomic analysis of qualitative and quantitative changes was performed through multivariate statistical analysis and the identification of primary metabolites was achieved on the Madison Metabolomics Consortium Database. The presence of Dp significantly impacted the plant's metabolic pathways, improving the biosynthesis of primary metabolites such as threonine, malic acid and N-acetyl-mannosamine, which are precursors of special metabolites involved in plant self-defence. This work represents a valuable contribution to advanced studies on the metabolic profiles of the interaction of plants with endophytes.

Registration of three soybean germplasms with novel cyst nematode resistance from PI 567516C

AbstractSoybean [Glycine max (L.) Merr.] germplasm lines JTN‐5316 (Reg. no. GP‐443, PI 691524), JTN‐5416 (Reg. no. GP‐444, PI 691525), and JTN‐5516 (Reg. no. GP‐445, PI 691526) were released by the USDA‐ARS in 2019 and trace 25% of their pedigree to PI 567516C. These F6–derived sister lines are the first releases derived from this accession. The new lines were developed to provide broad genetic resistance to the predominant damaging pest of soybean in the United States, soybean cyst nematode (SCN; Heterodera glycines Ichinohe), by combining the novel genetic resistance of PI 567516C with the established resistance of ‘Hartwig’. Development of these lines was characterized by intensive selection of F3 plants based on agronomic characteristics and simple sequence repeat markers associated with SCN resistance quantitative trait loci (QTL) in PI 567516C and Hartwig. The new lines have inherited resistance alleles at five QTL: two originating from PI 567516C and three originating from Hartwig, across four chromosomes. The lines were evaluated for and exhibit varying levels of resistance to other economically important pathogens of soybean, including: reniform nematode (Rotylenchulus reniformis Linford & Oliveira), frogeye leaf spot (caused by Cercospora sojina Hara), and southern stem canker (caused by Diaporthe phaseolorum var. meridionalis F. A. Fernández). JTN‐5316, JTN‐5416, and JTN‐5516 were field tested for multiple years in Jackson and Milan, TN, and produce moderate seed yield. These determinate maturity group (MG) V germplasm lines are excellent parent material for breeding programs with an interest in incorporating broad genetic resistance to SCN.

First Report of Diaporthe phaseolorum Causing Stem Canker of Hemp (Cannabis sativa).

Hemp is an annual herbaceous plant that is used for its fiber and oil in a variety of commercial and industrial products. In Florida, it is currently being explored as a new specialty crop. During a field trial from October to January 2019 in Wimauma, FL, a stem canker was observed on up to 60% of three-month-old plants of 'Eletta Campana', 'Carmagnola Selezionata', and 'Tygra'. Symptoms started on the main stems with light-to-dark brown lesions of different sizes and shapes. Over time, the lesions coalesced into large necrotic areas and bore pycnidia. Isolations were made from diseased stem tissues on General Isolation medium (Amiri et al. 2018) after surface disinfestation (Marin et al. 2020). The plates were placed in a growth chamber at 25°C under a 12/12 photoperiod. A fungus with white, floccose, aerial mycelium and pycnidia producing alpha and beta conidia was consistently isolated. Three single spore isolates were chosen for identification and pathogenicity tests. Pycnidia on PDA were globose to irregular and ranged from 170 to 250 μm long (210 ± 2.5, n = 50) and 140 to 220 μm wide (180 ± 2.7, n = 50). The alpha conidia were unicellular, hyaline, ellipsoidal to fusiform and ranged from 5.3 to 7.7 μm long (6.5 ± 1.6, n = 50) and 1.5 to 4.6 μm wide (2.8 ± 1.8, n = 50). The beta conidia were hyaline, elongated, filiform, straight or curved and ranged from 10.2 to 17.7 μm long (16.1 ± 2.2, n = 50) and 0.5 to 1.8 μm wide (0.8 ± 0.2, n = 50). Perithecia were not observed. Based on morphological features, the fungus was similar to anamorphs of Diaporthe spp. (Santos et al. 2011; Udayanga et al. 2015). DNA from the same three isolates was extracted using the FastDNA kit, and the ribosomal internal transcribed spacer (ITS), β-tubulin (TUB), and calmodulin (CAL) regions were amplified following Udayanga et al. (2014), and Sanger sequenced by Genewiz. Sequences were deposited in GenBank (accession no. MT497039 to MT497047 for ITS, TUB, and CAL). BLASTn searches revealed isolates 20-58, 20-59, and 20-60 were 96.34% identical to the epitype isolate D. phaseolorum AR4203 for ITS (KJ590738.1, 527 bp out of 547 bp), 100% for TUB (KJ610893.1, 459 bp out of 459 bp), and 100% for CAL (KJ612135.1, 522 bp out of 522 bp) (Udayanga et al. 2015). Their identity was confirmed by phylogenetic analyses using maximum likelihood and Bayesian inference methods. To complete Koch's postulates, pycnidia of the same three isolates were harvested and crushed in 2 mL Eppendorf tubes containing 0.01% Tween 20. Conidia suspensions were adjusted to 106 spores/mL. Three 5-week-old potted plants of 'Eletta Campana' and 'Carmagnola Selezionata' per isolate were inoculated using a 1 mL syringe with a needle by injecting 200 µL of the suspension into the stem. Plants were placed inside clear plastic bags for 48 h and maintained in the greenhouse. Control plants were injected with sterile deionized water and kept under the same conditions. The pathogenicity test was repeated once. Four weeks after inoculation, inoculated plants developed stem cankers from which the same pathogen was isolated, whereas controls remained healthy. To our knowledge, this is the first report of D. phaseolorum causing stem canker on hemp. This pathogen has been reported causing canker on sunflower and Phaseolus spp. (Gomzhina and Gannibal 2018; Udayanga et al. 2015; Vrandecic et al. 2009). This discovery may help shape future research into disease epidemiology and management for a crop in which very limited disease information is available at the moment.

Phylogenetic Diversity, Antimicrobial and Antioxidant Potential and Identification of Bioactive Compounds from Culturable Endophytic Fungi Associated with Mangrove Bruguiera sexangula (Lour.) Poir.

A total of 96 isolates were obtained from 375 segments, isolated from the healthy roots, stems, leaves, hypocotyls and flowers of Bruguiera sexangula (Lour.) Poir. collected at the Dong Zhai Gang Mangrove Garden on Hainan Island, and 20 independent representative isolates were identified using a combination of morphological and molecular approaches. The most frequent endophytic fungal species isolated were Diaporthe phaseolorum (relative frequency = 31.2%). The Shannon-Wiener diversity and Simpson's diversity index both showed that stems possessed the highest diversity compared to the other tissues estimated. Ethyl acetate extracts and the isolated metabolites were tested for antimicrobial activity using the serial dilution technique and for antioxidant activity using 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) radical-scavenging capacity assays, respectively. The fungal isolate HL18 (Gelasinospora endodonta) cultured on Czapek's agar (CA) displayed a broad spectrum of antimicrobial activities and was significantly active against Escherichia coli (MIC = 0.0625mgml-1). Antioxidant assays showed that most of the fungal isolates (60.0%) exhibited some degree of antioxidant capacity (%RSA > 50%). The stain HL14 (Pestalotiopsis mangiferae) grown on potato dextrose agar (PDA) exhibited the highest DPPH and ABTS radical-scavenging capability with IC50 values of 0.717 ± 0.012mgml-1 and 0.787 ± 0.027mgml-1, respectively. Furthermore, five known secondary metabolites 1-5 were isolated and identified from HL-14. Compounds 1 and 5 exhibited weak antioxidant activity.

Ligninolytic enzymes production by endophytic fungus Diaporthe phaseolorum (Desm.) Sacc. under the influence of different carbon and nitrogen sources

Ligninolytic enzymes production by endophytic fungus Diaporthe phaseolorum (Desm.) Sacc. under the influence of different carbon and nitrogen sources

Bioactive metabolites from tomato endophytic fungi with antibacterial activity against tomato bacterial spot disease

Endophytic fungi are potential antimicrobial agents that play an important role in improving plant growth. Endophytic fungi from healthy tomato plants have been evaluated for their potential antibacterial activity against Xanthomonas vesicatoria causing bacteria spot disease of tomato Thirty-eight different endophytic fungal isolates were isolated, and their extracts were screened for antibacterial activity using the well diffusion method. Three isolates showed strong antibacterial activity, which were molecularly identified as Diaporthe phaseolorum (USt1), Aspergillus fumigatus (USt2) and Aspergillus versicolor (USt3), respectively. Comparison of the components of the extracts between three isolates was made using a gas chromatography-mass spectrometry. Thirty eight compounds were found in A. fumigatus, thirty six compounds in D. phaseolorum and fourty two compounds were found in A. versicolor. The most prevalent compounds were acetol, hexanoic acid and acetic acid in all three fungi. Hexanoic acid (39.52%), acetic acid (8.95%) and acetol (8.10%), were found in A. fumigatus. However, the D. phaseolorum extract contained mainly hexanoic acid (42.35%) and acetic acid (11.89%) and acetol (9.52%), while A. versicolor contained hexanoic acid (34.44%), acetic acid (13.44%) and acetol (10.61%). Our results suggest that the three active endophytic fungi isolates provide a basis for the identification of new bioactive compounds, and for the effective biocontrol of bacterial spot of tomato.

Auxin-producing fungal endophytes promote growth of sunchoke

Endophytic fungi were able to protect their host plants against pathogens and promote plant growth. No previous studies have been conducted on the growth promotion of sunchoke by endophytic fungi. This research was the first to characterize plant growth promoting properties of endophytic fungi including, Macrophomina phaseolina BUP2/3 and Diaporthe phaseolorum BUP3/1 isolated from sunchoke and Daldinia eschscholtzii 2NTYL11, Trichoderma koningii ST-KKU1, Trichoderma erinaceum ST-KKU2, Macrophomina phaseolina SS1L10 and Macrophomina phaseolina SS1R10 from medicinal plants. Also, their plant growth promoting efficiency in artichoke plants under greenhouse condition was evaluated. The highest phosphate solubility and production of extracellular enzymes including amylase, protease, cellulase and xylanase were found after 5 and 21 days of incubation, respectively. Moreover, Indole-3-Acetic Acid (IAA) in the crude extracts of fungi isolated from Jerusalem artichoke was higher than that from medicinal plants (p ≤ 0.05). HPLC analysis suggested the putative IAA biosynthesis pathways in our fungi were via Indole-3-lactic acid (ILA) and Indole-3-acetamide (IAM). In the pot experiment, the values of height, diameter, chlorophyll content and leaf dry weight in sunchoke plants inoculated with fungal endophytes were significantly higher than those of un-inoculated plants. Therefore, this study suggested that fungal endophytes could be used as a biofertilizer for promoting growth of sunchoke.