Antagonistic Fungi Research Articles

Comparative Analysis of Rhizospheric Fungi Using High-Throughput Sequencing between Wild, Ex Situ, and Reintroduced Pinus squamata, a Plant Species with Extremely Small Populations in Yunnan Province, China

Pinus squamata is a rare and endangered tree endemic to northeastern Yunnan Province, China, and it is listed as a Plant Species with Extremely Small Populations (PSESP) in China for requiring urgent conservation. Furthermore, the actions of ex situ conservation and reintroduction based on artificial propagation have been carried out since some 15 years ago. The rhizosphere microbiome plays an important role in soil quality and plant health. However, how the fungal communities of the rhizosphere differ between wild, ex situ, and reintroduced examples of Pinus squamata remains unclear. Illumina sequencing of the internal transcribed spacer 2 (ITS2) region was used to investigate fungal communities in the P. squamata rhizosphere soil. Rhizospheric fungal community composition, structure, diversity, and ecological function in the soil surrounding wild, ex situ, and reintroduced P. squamata individuals were elucidated. The ex situ site Kunming (EK) had the highest fungal community richness and diversity. The samples collected from six different sites were well separated (R = 0.95, p = 0.001), suggesting significant differences between the sites. Soil total potassium (TK), available phosphorus (AP), and pH were the main factors driving fungal community (0.01 < p ≤ 0.05). Prediction of fungal functional guild in the P. squamata rhizosphere demonstrated that the fungi could be classified as ectomycorrhizal, endophyte, and plant pathogenic fungi. Our research will provide a basis to guide the further selection of conservation sites for P. squamata based on fungal diversity and offer guidance on the antagonistic fungi and plant pathogenic fungi that may be of relevance to the conservation of this rare plant.

Biological control of some wood-decay fungi with antagonistic fungi.

One of the most important biological factors that damage wood materials are wood-decay fungi (WDF). Chemical preservatives have traditionally been the most effective method for controlling WDF. However, due to environmental pressures, scientists are working on alternative protection methods. The aim of this study was to investigate the potential of some antagonistic fungi against wood-decay fungi as a biological control agent (BCA). For this purpose, the antagonistic effects of Trichoderma harzianum, Trichoderma viride, Aspergillus niger, and Penicillium brevicompactum fungi were investigated against the Trametes versicolor, Trametes hirsuta, Stereum hirsutum, Coniophora puteana, Neolentinus lepideus, and Postia placenta species of wood-decay Basidiomycetes fungi. In the study, firstly, inhibition rates were determined by comparing dual culture tests on agar medium, and then the performance of BCAs was compared by performing decay tests on wood blocks. As a result of the study, it was determined that the species belonging to the genus Trichoderma showed a very effective performance on WDF, increased the inhibition rate to 76-99%, and reduced the weight loss to 1.9-5.8%. Considering the inhibition rates, it was determined that the most effective rate of the BCAs was on P. placenta and the least on S. hirsutum species. According to the results obtained, it has been determined that some BCAs were very effective biological control agents of rot fungi on agar and wood blocks in vitro. However, in order to more clearly determine the effectiveness of BCAs in practice, this study, which was carried out in the laboratory environment, should be supported by tests performed in contact with the external field and soil.

Metabolomics analysis of mycelial exudates provides insights into fungal antagonists of Armillaria

ABSTRACT The genus Armillaria has high edible and medical values, with zones of antagonism often occurring when different species are paired in culture on agar media, while the antagonism-induced metabolic alteration remains unclear. Here, the metabolome of mycelial exudates of two Chinese Armillaria biological species, C and G, co-cultured or cultured separately was analysed to discover the candidate biomarkers and the key metabolic pathways involved in Armillaria antagonists. A total of 2,377 metabolites were identified, mainly organic acids and derivatives, lipids and lipid-like molecules, and organoheterocyclic compounds. There were 248 and 142 differentially expressed metabolites between group C-G and C, C-G, and G, respectively, and fourteen common differentially expressed metabolites including malate, uracil, Leu-Gln-Arg, etc. Metabolic pathways like TCA cycle and pyrimidine metabolism were significantly affected by C-G co-culture. Additionally, 156 new metabolites (largely organic acids and derivatives) including 32 potential antifungal compounds, primarily enriched into biosynthesis of secondary metabolites pathways were identified in C-G co-culture mode. We concluded that malate and uracil could be used as the candidate biomarkers, and TCA cycle and pyrimidine metabolism were the key metabolic pathways involved in Armillaria antagonists. The metabolic changes revealed in this study provide insights into the mechanisms underlying fungal antagonists.

Перспективные штаммы антагонисты возбудителя фомоза на подсолнечнике: оценка фитотоксичности и ростостимулирующей активности

The phytotoxicity and growth stimulating activity of promising strains antagonists of a Phoma pathogen on sunflower seedlings were estimated. Soaking of sunflower seeds and seedlings in suspensions of fungi and bacteria-antagonists did not have a depressing effect on seed germination and wilting of seedlings. Three bacterial strains antagonists from a genus Bacillus: 5-3, K 1-2, and 5B-1 Bacillus sp., and two strains from a genus Pseudomonas: Oif 2-1 and 14-3 Pseudomonas sp. showed the maximal authentic increase (by 10.0–14.0%) in seed germination (94.0–98.0% at germination in a control 84.0%). Only two fungal strains antagonists: Xk-1 Chaetomium sp. and A-1 Basidiomycota, showed verifiable increase (by 6%) in seed germination (90%). The verifiable stimulating effect of antagonists on root weight was stated. The bacterial strains 11-1, D-10, and 5-3 Bacillus sp. (150.0–166.7%) and fungal ones Xk-1 Chaetomium sp. and Pbc-1 Penicillium sp. (133.3–150.0%) showed the best results comparing to the control.

Aktivitas Cendawan Antagonis Trichoderma terhadap Fusarium dari Tanaman Kentang di Kecamatan Pakis Kabupaten Magelang

Potato is one of the common plants cultivated in Indonesia and used as a food ingredient besides rice. One of the pathogens that can attack potatoes is Fusarium. Farmers usually use synthetic fungicides to inhibit Fusarium infection, but this method is not environmentally friendly. One of the countermeasures for Fusarium can be done with the antagonistic fungus Trichoderma. This study aims to examine the antagonistic of Trichoderma spp. toward isolate Fusarium spp. from potato plants showing wilting symptoms. The method was carried out by isolating the fungus from potatoes with wilting symptoms, identifying it, and testing 4 Trichoderma strains using a double culture method. The fusarium obtained was identified as F. begoniae, F. foetens, F. mooniliforme, and F. oxysporum. A total of 2 Trichoderma strains originating from litter and trash cans were able to inhibit all Fusarium tests on day 2 and achieve 100% growth inhibition on day 4, while the other 2 Trichoderma strains only showed inhibition on day 4 to day 7. Further tests are needed to understand the mechanism of Fusarium attack, and to identify the antifungal compounds produced by Trichoderma.

Surveying potentially antagonistic fungi to myrtle rust (Austropuccinia psidii) in Brazil: fungicolous Cladosporium spp.

The myrtle rust (MR), caused by Austropuccinia psidii, is a worldwide threat to the cultivated and wild Myrtaceae. Originally from the neotropics, it has spread to North America, Africa, and Asia and has reached geographically isolated areas in the Pacific and Australasia. It is attacking native species in those new ranges and is still spreading and causing great concern for the damage caused to endemic Myrtaceae, and to the environment. Classical biological control is regarded as the most sustainable management option for mitigating such biological invasions. However, there are no examples of introductions of host-specific co-evolved natural enemies of plant pathogens, from their native range, as a management strategy for plant pathogens. In order to explore this neglected approach, a survey of potential fungal natural enemies of A. psidii was initiated recently in the state of Minas Gerais (Brazil). Several purported mycoparasites have been collected from A. Psidii pustules formed on myrtaceous hosts. This included some isolates of dematiaceous fungi recognized as having a Cladosporium-like morphology. Here we present the results of the investigation aimed at elucidating their identity through a polyphasic taxonomic approach. Besides morphological and cultural features, molecular analyses using sequences of translation elongation factor 1-α (EF1) and actin (ACT) were performed. The combination of data generated is presented herein and placed all Cladosporium-like isolates in six species of Cladosporium, namely, Cladosporium angulosum, C. anthropophilum, C. bambusicola, C. benschii, C. guizhouense, and C. macadamiae. None of these have ever been recorded in association with A. psidii. Now, with the identification of these isolates at hand, an evaluation of biocontrol potential of these fungi will be initiated. In contrast with the ready finding of fungicolous (possibly mycoparasitic) fungi on MR in this study, no evidence of those was recorded from Australasia until now.

Test Fungi Growth Physiology of Trichoderma sp. and Gliocladium sp. from Citrus Plants

One of the problems of citrus cultivation is disease attack which can cause a decrease in production during harvest. There are antagonistic fungi from citrus plants that can be used to control pathogens, namely Gliocladium sp. and Trichoderma sp. Antagonistic fungi will be able to control pathogens optimally if they have growth conditions that match their environment. This study aims to determine the growth development of Trichoderma sp. and Gliocladium sp. at several temperatures, media, exposure lengths, and types of light. The treatments used were four different temperatures (20°C, 25°C, 30°C, 35°C), three media (PDA, PDAY, and CMA), several exposure times (24 hours of light and 24 hours of dark, 8 hours of light and 16 hours of darkness, 16 hours of light and 8 hours of darkness) and the type of light (light from a reading lamp placed very close, light from a lamp placed habitually, and dark wrapped in carbon). The treatment used a completely randomized design (CRD) and was repeated 5 times. The test results showed that the two isolates could develop optimally on PDA and PDAY media with the best temperature of 20°C-25°C. In addition, testing of various rays showed the results of the fastest development by Trichoderma sp. under natural light treatment. Furthermore, the best length exposure test was Trichoderma sp. with a lighting time of 12 hours light and 12 hours dark. In general, the development of the two antagonistic fungal isolates had relatively the same optimal development conditions, but Trichoderma sp. has better development on various tests.

Evaluation of Trichoderma harzianum, Bacillus subtilis and Aspergillus species efficacy in controlling Pythium ultimum associated with apple seedlings decline in nurseries and their growth promotion effect

BackgroundApple decline diseases, responsible for seedlings root and collar rot in nurseries, are an important disease. Different fungal and bacterial antagonists were evaluated to control Pythium ultimum associated with this serious disease using in vitro and in vivo greenhouse assays.ResultsThe in vitro test of ten Aspergillus spp. and ten Trichoderma harzianum isolates showed their efficacy to reduce the radial growth of P. ultimum. The isolates, A. niger A10, A. candidus A5, T. harzianum Tr9 and Tr10, were the most effective with a high inhibition percent that exceeded 50%. The in vivo test of the four most effective antagonists and a strain of Bacillus subtilis (B) showed that the combination of the two Aspergillus isolates (A5 and A10) gave the best result with a decrease in root browning index by 55.55%. Results showed also the efficacy of all tested antagonists and their combinations on the sanitary state index of the inoculated plants except the combination between T. harzianum (Tr10) and B. subtilis (B). The two treatments, T. harzianum (Tr10) and B. subtilis (B), significantly improved the height of inoculated plants by 173.19 and 191.3%, respectively. Regarding the efficacy of antagonists on apple seedlings root weight, A. niger (A10) was the only treatment that significantly increased this parameter by 363.17%.ConclusionsA. niger A10, A. candidus A5, T. harzianum Tr9 and Tr10 exhibited the highest value of in vitro inhibition to growth of P. ultimum. The combination of A. niger A10 and A. candidus A5 was the most effective in vivo treatment in reducing the disease severity index. However, T. harzianum (Tr10), B. subtilis (B) and A. niger (A10) revealed to be able to stimulate the apple seedlings growth.

Mycotoxigenic fungal growth inhibition and multi-mycotoxin reduction of potential biological control agents indigenous to grain maize.

The present work investigated the potential of fungal species from grain maize farms in Malaysia as antagonists against the indigenous mycotoxigenic fungal species and their subsequent mycotoxin production. Dual-culture assay was conducted on grain maize agar (GMA) with 12 strains of potential fungal antagonists namely Bjerkandra adusta, Penicillium janthinellum, Schizophyllum commune, Trametes cubensis, Trichoderma asperelloides, Trichoderma asperellum, Trichoderma harzianum, and Trichoderma yunnanense against seven mycotoxigenic strains namely Aspergillus flavus, Aspergillus niger, Fusarium verticillioides, and Fusarium proliferatum producing aflatoxins, ochratoxin A, and fumonisins, respectively. Based on fungal growth inhibition, Trichoderma spp. showed the highest inhibitory activity (73-100% PIRG, Percentage Inhibition of Radial Growth; 28/0 ID, Index of Dominance) against the tested mycotoxigenic strains. Besides, B. adusta and Tra. cubensis showed inhibitory activity against some of the tested mycotoxigenic strains. All fungal antagonists showed varying degrees of mycotoxin reduction. Aflatoxin B1 produced by A. flavus was mainly reduced by P. janthinellum, Tra. cubensis, and B. adusta to 0ng/g. Ochratoxin A produced by A. niger was mainly reduced by Tri. harzianum and Tri. asperellum to 0ng/g. Fumonisin B1 and FB2 produced by F. verticillioides was mainly reduced by Tri. harzianum, Tri. asperelloides, and Tri. asperellum to 59.4 and 0µg/g, respectively. Fumonisin B1 and FB2 produced by F. proliferatum were mainly reduced by Tri. asperelloides and Tri. harzianum to 244.2 and 0µg/g, respectively. This is the first study that reports on the efficacy of Tri. asperelloides against FB1, FB2, and OTA, P. janthinellum against AFB1, and Tra. cubensis against AFB1.

Effects of Colletotrichum gloeosporioides and Poplar Secondary Metabolites on the Composition of Poplar Phyllosphere Microbial Communities.

Poplar anthracnose caused by Colletotrichum gloeosporioides is a common disease affecting poplars globally that causes the destruction and alteration of poplar phyllosphere microbial communities; however, few studies have investigated these communities. Therefore, in this study, three species of poplar with different resistances were investigated to explore the effects of Colletotrichum gloeosporioides and poplar secondary metabolites on the composition of poplar phyllosphere microbial communities. Evaluation of the phyllosphere microbial communities before and after inoculation of the poplars with C. gloeosporioides revealed that both bacterial and fungal OTUs decreased after inoculation. Among bacteria, the most abundant genera were Bacillus, Plesiomonas, Pseudomonas, Rhizobium, Cetobacterium, Streptococcus, Massilia, and Shigella for all poplar species. Among fungi, the most abundant genera before inoculation were Cladosporium, Aspergillus, Fusarium, Mortierella, and Colletotrichum, while Colletotrichum was the main genus after inoculation. The inoculation of pathogens may regulate the phyllosphere microorganisms by affecting the secondary metabolites of plants. We investigated metabolite contents in the phyllosphere before and after the inoculation of the three poplar species, as well as the effects of flavonoids, organic acids, coumarins, and indoles on poplar phyllosphere microbial communities. We speculated that coumarin had the greatest recruitment effect on phyllosphere microorganisms, followed by organic acids through regression analysis. Overall, our results provide a foundation for subsequent screening of antagonistic bacteria and fungi against poplar anthracnose and investigations of the mechanism by which poplar phyllosphere microorganisms are recruited. IMPORTANCE Our findings revealed that the inoculation of Colletotrichum gloeosporioides has a greater effect on the fungal community than the bacterial community. In addition, coumarins, organic acids, and flavonoids may have recruitment effects on phyllosphere microorganisms, while indoles may have inhibitory effects on these organisms. These findings may provide the theoretical basis for the prevention and control of poplar anthracnose.

Effects of fungicides and antagonistic marine-derived fungi on rice seedling promotion and rice sheath blight control

Fourteen fungicides and three marine-derived fungi were tested for their activities in the promotion of rice seedling development and their efficacy in controlling rice sheath blight disease in two rice varieties, RD43 and KMDL105, under greenhouse conditions. The results showed that the rice seeds treated with carbendazim 50%SC and azoxystrobin 25%SC displayed the best promotion of rice growth in root length and shoot height at seven and 14 days in rice var. RD43. Rice seeds from var. KMDL105 treated with thiophanate-methyl 70%WP exhibited significant stimulation of rice seedling growth resulting in the greatest increase in root length and shoot height at seven and 14 days. In pot experiments with rice var. RD43, spraying with triforine 19%EC, propiconazole 25%EC, trifloxystrobin 50%WG, and validamycin 3%SL showed a high level of fungicidal activity in controlling sheath blight disease, with this evidenced by significant suppression of the disease severity by 71–75% and 61–73% at seven and 14 days after inoculation, respectively. The treatment of rice var. KMDL105 with validamycin 3%SL exhibited the best activity in controlling sheath blight disease by reducing disease severity by up to 62% and 64% at seven and 14 days, respectively. The antagonistic marine fungi tested in this study displayed low activity against sheath blight disease and low effects on rice seedling promotion compared to fungicides. Specifically, Trichoderma harzianum KUFA 0689 and T. asperellum KUFA 0677 reduced sheath blight disease severity by 42–46% and 27–37% at seven and 14 days, respectively.

Identification of antagonistic fungi and their antifungal activities against aconite root rot pathogens

ABSTRACT Root rot is one of the main diseases affecting Aconitum carmichaelii Debx. during cultivation, seriously limiting yields of this herb. Currently, there is no effective control measure for aconite root rot. The antifungal activities of antagonistic strains against aconite root rot pathogens (Fusarium proliferatum, Fusarium solani, and Fusarium oxysporum) were investigated in this study. Three antagonistic strains, JKT7, JKT28 and JKT39, were screened and identified as Trichoderma asperellum, Trichoderma hamatum and Trichoderma virens, respectively. Dual culture tests showed that the inhibition rates of the three Trichoderma strains on the pathogens were all approximately 70%. The volatile metabolites had inhibitory effects on the mycelial growth of pathogens, while the nonvolatile metabolites in the culture filtrates did not show significant inhibitory effects. The volatile components analyzed by GC‒MS were mainly ketones, esters, and alcohols. These results indicate that these strains of Trichoderma and their secondary metabolites have antimicrobial activities against the pathogens of aconite root rot. This study could provide a scientific basis for the biocontrol of aconite root rot.

Systematic induced resistance in Solanum lycopersicum (L.) against vascular wilt pathogen (Fusarium oxysporum f. sp. lycopersici) by Citrullus colocynthis and Trichoderma viride.

The antifungal effects of Citrullus colocynthis extract (Hexane, chloroform, methanol, and water) were tested in vitro on Fusarium oxysporum f. sp. lycopersici (Sacc.) W. C. Snyder & H. N. Hans (FOL), the causal agent of Fusarium wilt. Of these, methanol and water extract at 10% showed the highest inhibition of mycelial growth of FOL by 12.32 and 23.61 mm respectively. The antifungal compounds were identified through Fourier transform infrared (FT-IR) spectroscopy and gas chromatography-mass spectroscopy (GC-MS). The methanol extract was compatible with the biocontrol agent Trichoderma viride. The antagonistic fungi were mass-cultured under laboratory conditions using sorghum seeds. Both T. viride and C. colocynthis methanol extract was also tested alone and together against FOL under both in vitro and in vivo conditions. The combination of T. viride and C. colocynthis showed the highest percentage of antifungal activity (82.92%) against FOL under in vitro conditions. This study revealed that induced systemic resistance (ISR) in enhancing the disease resistance in tomato plants against Fusarium wilt disease. The combined treatment of T. viride and C. colocynthis significantly reduced the disease incidence and index by 21.92 and 27.02% in greenhouse conditions, respectively. Further, the induction of defense enzymes, such as peroxidase (PO), polyphenol oxidase (PPO), β-1,3-glucanase, and chitinase were studied. The accumulation of defense enzyme was greater in plants treated with a combination of T. viride and C. colocynthis compared to the control. Reduction of wilt disease in tomato plants due to the involvement of defense-related enzymes is presumed through this experiment.

Differences in time of application of Trichoderma sp on shallot varieties on growth and disease development for seed production

Soil-borne diseases in shallots are the main diseases that can cause weight loss, especially for seeds. One of the biological agents that can control the disease is Trichoderma sp. So far, the use of Trichoderma often does not seem effective because the application time is not right. Trichoderma already exists and grows outside and inside plant tissues. This is due to the nature and character of Trichoderma for its antagonistic fungus that competent to colonize the rhizosphere quickly and protect roots from pathogen attack. This study aims to determine the interaction between the application time of Trichoderma sp and varieties on growth and disease development for seed production. The research was carried out at the Margahayu Experimental Garden, Institute Vegetable Research Indonesian (1,250 m.asl), from September to December 2021. The experiment used was a factorial randomized block with two factors and three replications. The first factor is the time of application of Trichoderma (without Trichoderma, before planting, before planting + 2 weeks after planting, and before planting + 2, 4 weeks after planting). The second factor is several varieties of shallots (Violetta, Ambassador, Maja Cipanas, Bima and Trisula). The results showed that there was no interaction between application time and variety on growth, disease attack, and yield of shallot bulbs for seed. However, application time and varieties affected the intensity of the disease of Stemphylium vesicarium and Peronospora destructor. Maja Cipanas showed the highest plant growth (plant height, number of leaves and number of tillers) with dry weight, weight of one month of storage and weight of two months of storage per clump each of 60.19 g; 50.27 g and 39.49 g.

Blast and Bacterial Diseases of Some Seed-dressed Rice Varieties in Yogyakarta.

Pyricularia grisea (blast disease) and bacterial diseases resulted rice yield loss. Tolerant varieties and seed-dressing are expected reduces the disease. This research was aimed to define the effect of tolerant varieties and seed - dressing to the incidence of blast and bacterial diseases. Research was conducted at endemic area in Yogyakarta Indonesia from November 2021 to March 2022. The experiment was designed in randomized block with 2 factors and 4 replications. Factor 1 was variety: Inpari 32 HDB, Inpari 45 Dirgahayu and Inpari 48 Blas as tolerant variety and Sunggal as common variety. Factor 2 was seed treatment: Pseudomonas fluorencens solutions, consortia of antagonist fungi and bacterium, and fungicide Trisiklazol 225 g l−1 and Azoksistrobin 75 g l−1. Results showed that tolerant varieties was significantly reduced blast and BLB. The highest incidence of blast and bacterial diseases were found at Sunggal, while not found at Inpari 45 Dirgahayu and Inpari 48 Blas. Meanwhile, bacterial diseases was found at low level at the 3 tolerant varieties. Bacterial disease found in this research was BLB (Bacterial Leaf Blight), BRS (Bacterial Red Stripe) and BLS (Bacterial Leaf Streak). Result also showed that seed treatment did not affect the reduction of blast and bacterial disease. At other site, highest yield (10.18 ton ha−1) was obtained from Inpari 32 HDB which was treated with consortia of antagonist fungi and bacterium. Hence, the 3 tested tolerant varieties was promising to be established at the endemic area in the agro ecosystem of irrigated rice in Yogyakarta Indonesia.

Efficacy of Antagonistic Fungi, Trichoderma asperellum in The Control of Fungal Diseases on Leaves of Oil Palm Seedlings

This study tested the efficacy of Trichoderma asperellum strains NST-009 and CB-Pin-01 in controlling of palm leaf fungal disease. Plant pathogenic fungi were isolated from leaves of oil palm seedlings by tissue transplanting technique. A total of 12 isolates of plant pathogenic fungi were obtained including Alternaria sp. 1 isolate, Botryodiplodia spp. 2 isolates, Colletotrichum spp. 2 isolates, Curvularia spp. 3 isolates, Drechslera spp. 2 isolates and Pestalotia spp. 2 isolates. Pathogenicity test on oil palm leaves by detached leaf method showed that all isolates caused lesions of 2.3-4.1 mm in diameter, Curvularia sp.-03 and Botryodiplodia sp.-01 respectively caused the largest lesion of 4.1 mm and the lesion of 3.5 mm. When testing the efficacy of antagonist fungi in the laboratory, it was found that both antagonistic fungi were able to inhibit and cover the mycelium Botryodiplodia sp.-01 and Curvularia sp.-03. T. asperellum NST-009 had the highest inhibition of Botryodiplodia sp.-01 and Curvularia sp.-03 at 89.1 and 84.9%, respectively, and covering such fungi at 67.4 and 58.3%, respectively. Tests on the efficacy of antagonistic fungi in disease control showed that both strains were able to reduce the severity of the disease. That is, T. asperellum NST-009 showed significantly better efficacy to reduce the severity of Botryodiplodia sp.-01 and Curvularia sp.-03 than T. asperellum CB-Pin-01. By using T. asperellum NST-009, the diseases were found at 12.9 and 17.1%, respectively. While using T. asperellum CB-Pin-01, the diseases were found at 16.8 and 25.5%, respectively. According to Trichoderma spp. quantification on oil palm leaves, it was found that T. asperellum NST-009 was detected at the highest level of 1.3×104 and 2.3×104 CFU/1 g of the oil palm leaves when it was used for controlling Botryodiplodia sp.-01 and Curvularia sp.-03, respectively.

Isolation and identification of antagonistic fungi of fungi associated with chili wilt in southern Guanajuato, Mexico

The chili crop (Capsicum annuum) in Mexico represents an important economic source; however, every year there are losses in production of 40 to 100% due to the root disease known as wilt, which causes premature death of plants, this disease is caused by the fungi complex formed by Rhizoctonia solani, Fusarium oxysporum, Fusarium solani and Phytophthora capsici. The objective of this research was to isolate antagonistic fungi to the pathogens causing wilt from soil samples obtained in the southern of the state of Guanajuato, Mexico. Antagonistic fungi potential against Rhizoctonia spp., Fusarium spp. and Phytophthora spp. were isolated. Then three fungi isolates presented antagonistic potential, inhibiting mycelial growth by 41 to 83%. Molecular identification of the antagonist fungi was performed by amplifying the intergenic transcriptional regions (ITS) of the 18S ribosomal DNA component of fungi. This research contributes to the study of biological control of root pathogens using beneficial native microorganisms present in crop soils affected by pathogens associated with chili wilt in southern Guanajuato, Mexico.

Fungal Community Associated with the Leaf-Cutting Ant Acromyrmex crassispinus (Hymenoptera: Formicidae) Colonies: a Search for Potential Biocontrol Agents.

The leaf-cutting ant Acromyrmex crassispinus is considered an important pest in forest plantations in southern Brazil. This work aimed to study the fungal community associated with A. crassispinus colonies, subjected to treatments with subdoses of granulated baits (sulfluramid), which might reduce the ability of the ants to care for their symbiotic fungus and other fungi (maybe biocontrol fungi) would take over, to prospect for potential biological control agents. Samplings of fungus gardens and dead ants allowed the identification of 195 fungal isolates, distributed in 29 families, 36 genera, and 53 species. The most frequent genera were Trichoderma (49.2%), Penicillium (13.8%), Chaetomium (6.2%), and Fusarium (3.6%). This is the first study that conducted a survey of antagonistic and entomopathogenic fungi to A. crassispinus and its symbiotic fungus, reporting for the first time the occurrence of potential biological control agents. Escovopsis weberi, Fusarium oxysporum, Rhizomucor variabilis, Trichoderma atroviride, Trichoderma harzianum, Trichoderma koningiopsis, and Trichoderma spirale are considered some of the potential biocontrol organisms.

The endophytobiome of wild Rubiaceae as a source of antagonistic fungi against the American Leaf Spot of coffee (Mycena citricolor).

The American leaf spot, caused by Mycena citricolor, is an important disease of coffee (Coffea arabica), mostly in Central America. Currently, there are limited pathogen control alternatives that are environment friendly and economically accessible. The use of fungi isolated from the plant endomycobiota in their native habitats is on the rise because studies show their great potential for biological control. To begin to generate a green alternative to control M. citricolor, the objectives of the present study were to (i) collect, identify, screen (in vitro and in planta), and select endophytic fungi from wild Rubiaceae collected in old-growth forests of Costa Rica; (ii) confirm endophytic colonization in coffee plantlets; (iii) evaluate the effects of the endophytes on plantlet development; and (iv) corroborate the antagonistic ability in planta. Through in vitro and in planta antagonism assays, we found that out of the selected isolates (i.e. Daldinia eschscholzii GU11N, Nectria pseudotrichia GUHN1, Purpureocillium aff. lilacinum CT24, Sarocladium aff. kiliense CT25, Trichoderma rifaii CT5, T. aff. crassum G1C, T. aff. atroviride G7T, T. aff. strigosellum GU12, and Xylaria multiplex GU14T), Trichoderma spp. produced the highest growth inhibition percentages in vitro. Trichoderma isolates CT5 and G1C were then tested in planta using Coffea arabica cv. caturra plantlets. Endophytic colonization was verified, followed by in planta growth promotion and antagonism assays. Results show that Trichoderma isolates CT5 and G1C have potential for plant growth promotion and antagonism against Mycena citricolor, reducing incidence and severity, and preventing plant mortality.

The nematicidal potential of novel fungus, Trichoderma asperellum FbMi6 against Meloidogyne incognita

One of the most damaging pests in vegetable crops is the root-knot nematode (Meloidogyne incognita) worldwide. The continuous use of nematicide is costly and has unintended consequences for human and environmental health. To minimize nematicides, eco-friendly integrated nematode management is required. Trichoderma, an antagonistic fungus has been explored to control root-knot nematode. The fungal bio-control strain FbMi6 was identified as Trichoderma asperellum (accession no. MT529846.1). T. asperellum FbMi6 showed substantial nematicidal activity in the laboratory, with egg hatch suppression (96.6%) and juvenile mortality (90.3%) of M. incognita. T. asperellum FbMi6 was examined under pot and field conditions (after neem cake enrichment), both alone and in combination, and compared with controls. Application of T. asperellum FbMi6 enriched neem cake (1-ton ha-1) increased (28.3%) the okra yield and decreased (57.1%) nematode population as compared with control. T. asperellum FbMi6 enriched neem cake had higher polyphenol content (resistance enhancer) in okra compared with inoculated check.