scholarly journals Foliar endophytic fungi of Theobroma cacao stimulate more than inhibit Moniliophthora spp. growth and behave more as an endophytes than pathogens.

Author(s):  
Miriam Villavicencio ◽  
Laura Schuller ◽  
Fernando Espinosa ◽  
Carlos Noceda ◽  
Daynet Sosa del Castillo ◽  
...  

Abstract The two most disastrous diseases of Theobroma cacao in Ecuador are caused by the pathogenic fungi Moniliophthora roreri (MR, Frosty pod) and M. perniciosa (MP, Witches' broom). Both diseases are prevalent in Ecuador since its detection in 1916 and 1921, respectively. One hundred and twenty-six isolates were isolated from healthy T. cacao leaves, originated from five nurseries in the Ecuadorian Coast. Isolates were screened in vitro for their stimulation/inhibition of growth of MR & MP. The endophytic fungi influenced the growth of Moniliophthora spp. in different manners, 91/126 of the tested isolates stimulated somehow the colony growth of both pathogens, and only 30 and 5 isolates always inhibited the mycelial growth of MR & MP, respectively. The highest percentage of growth inhibitions against MR was 71%, but quite lower for MP (18%). Only two isolates caused symptoms of chlorosis and necrosis in leaves and fruits Phomopsis spp. (Ascomycota) and Psathyrella sp. (Basidiomycota). Twenty-four isolates from 11 taxa caused necrosis only fruits (Ascomycota: Phomopsis spp., Phoma sp., Colletotrichum gloeosporioides s.l., Fusarium decemcellulare, F. equiseti, F. solani, Nectria pseudotrichia, Pestalotiopsis microspora, Didymosphaeria futilis, Xylaria venosula and Basidiomycota: Ceriporia lacerata) and four isolates/taxa infected only leaves (Phomopsis spp., Pestalotiopsis microspora, Nigrospora sphaerica and one unidentifiable isolate of Xylariaceae sp.). The non-pathogenic isolate, Hypoxylon investiens, inhibited MR in 71%, but also stimulate the growth of MP in 3%. The second-best isolate (Lasiodiplodia theobromae) only inhibit MR and MP in 58 y 15%, respectively; and, although the isolate was not pathogenic, the specie is risky to develop a biological control agent. There was no promising isolate against both MR & MP.

2018 ◽  
Vol 13 (5) ◽  
pp. 161
Author(s):  
Evan Purnama Ramdan ◽  
Efi Toding Tondok ◽  
Suryo Wiyono ◽  
Sri Hendrastuti Hidayat ◽  
Widodo Widodo

Stem rot disease caused by Phytophthora capsici is an important disease on chilli. Eight endophytic fungi that had been isolated and screened based on pathogenecity test were further tested for their potential as the biological control agent of the stem rot disease of chilli. The endophytic fungi suspension was applied twice during the trial. The first application was on 100 seed lot, by soaking them in 100 mL of suspension. The second application was on the 3 weeks-old chili seedlings by drenching them with 10 mL suspension per plant. The concentration of endophytic fungi  in the suspension was 2.8 × 106 cfu mL-1. The disease intensity and AUDPC value were measured for 4 weeks after the pathogen inoculation. The growth inhibition test of P. capsici  was performed in vitro and the colonization abilities of endophytic fungi were observed at 4 weeks-old chilli seedlings. Eight endophytic fungi  inhibited the growth of the P. capsici, and two of those isolates namely Penicillium strain MAG1 and Penicillium strain PAB2 showed antibiosis mechanism. Endophytic fungi has the ability more to colonize at the root (26–60%) than in the stem (20–40%). Fusarium strain MAGR1 has the highest level of endophytic colonization i.e. 60% compared to others.  Based on in vivo assay, six endophytic fungi isolates, i.e. Fusarium strain MAGR1, Penicillium strain MAG1, Penicillium strain PAB2, sterile hyphae HAJ1, sterile hyphae HAJ2, and  sterile hyphae PBG7, showed the potency to control stem rot disease with inhibition level of 25.5–35.5%


2017 ◽  
Vol 29 (1) ◽  
pp. 111
Author(s):  
Babar Khan ◽  
Zuniara Akash ◽  
Shahzad Asad ◽  
Nazir Javed ◽  
Nasir A. Rajput ◽  
...  

Fusarium oxysporum f. sp. cubense is a soil loving pathogen of banana that can cause distortion of vascular system. It is responsible for the disease Fusarium wilt of bananas also renowned as panama wilt disease that has responsible of immense losses in the banana industry worldwide. In this study, diseased samples were collected from rhizosphere of banana plants in the research area of National Agriculture Research Centre (NARC), Islamabad and cultured on PDA to isolate pathogenic strains of F. oxysporium f. sp. cubense. Antagonistic potential of Trichoderma harzianum against F. oxysporum f. sp. cubense was evaluated under controlled conditions. T. harzianum produced up to 75.5% inhibition of colony growth of the pathogen followed by incubation for 72 h at 28+2°C in vitro. In pot culture T. harzianum considerably reduced disease severity. It proves that it is a potential biological control agent against banana wilt pathogen.


Biologija ◽  
2017 ◽  
Vol 63 (3) ◽  
Author(s):  
Larysa O. Kriuchkova

A new Bacillus amyloliquefaciens subsp. plantarum strain IMV B-7404 was selected by an in-vitro agar plate assay as a potential biological control agent. The strain strongly inhibited the growth of 12 important plant pathogenic fungi. In growth chamber assays, the severity of spot blotch of barley decreased when culture filtrate was applied on leaves or was introduced into the plant growth medium before fungal inoculation. Apparently, the metabolites of strain IMV B-7404 play a role in disease prevention, which indicates that the strain can stimulate induced systemic resistance (ISR). When the cell suspension was sprayed onto leaves, the disease severity depended on environmental and, probably, some other conditions. We suggest that effective biological control by Bacillus-based products depends on spraying leaves with the cell suspension to co-ordinate with the process of plant infection by the pathogen. The ecological behaviour and biology of both the antagonist and the target pathogen are the key elements in enhancing the efficacy of biocontrol products. It is necessary to know the stage of infection that is most vulnerable. This information needs to be identified individually for each pathosystem and in relation to environmental conditions.


2004 ◽  
Vol 94 (12) ◽  
pp. 1305-1314 ◽  
Author(s):  
O. Carisse ◽  
D. Rolland

Field and in vitro trials were conducted to establish the influence of the biological control agent Microsphaeropsis ochracea on the ejection pattern of ascospores by Venturia inaequalis and on apple scab development, and to establish the best timing of application. The ejection pattern of ascospores was similar on leaves sprayed with M. ochracea and on untreated leaves. Fall application of M. ochracea combined with a delayed-fungicide program was evaluated in orchards with intermediate and high scab risk. For both orchards, it was possible to delay the first three and two infection periods in 1998 and 1999, respectively, without causing significant increase or unacceptable leaf and fruit scab incidence. To evaluate the best timing of application, sterile leaf disks were inoculated with V. inaequalis and then with M. ochracea 0, 2, 4, 6, 8, 10, 12, 14, and 16 weeks later. After incubation under optimal conditions for pseudothecia development, the number of ascospores was counted. Similarly, M. ochracea was sprayed on scabbed leaves on seven occasions from August to November 1999 and 2000. Leaves were overwintered on the orchard floor and ascospore production was evaluated the following spring. Ascospore production was reduced by 97 to 100% on leaf disks inoculated with M. ochracea less than 6 weeks after inoculation with V. inaequalis, but ascospore production increased with increasing period of time when M. ochracea was applied 8 to 16 weeks after the inoculation with V. inaequalis. In the orchard, the greatest reduction in production of ascospores (94 to 96% in 2000 and 99% in 2001) occurred on leaves sprayed with M. ochracea in August. The production of ascospores was reduced by 61 to 84% in 2000 and 93% in 2001 on leaves sprayed with M. ochracea in September, reduced by 64 to 86% in 2000 and 74 to 89% in 2001 on leaves sprayed in October, and reduced by 54 and 67% in 2000 and 2001, respectively, on leaves sprayed in November. It was concluded that M. ochracea should be applied in August or September and that ascospore maturation models and delayed-fungicide program could be used in orchards treated with this biological control agent.


2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
M. M. Rahman ◽  
M. E. Ali ◽  
A. A. Khan ◽  
A. M. Akanda ◽  
Md. Kamal Uddin ◽  
...  

A total of 91 isolates of probable antagonistic bacteria of potato soft rot bacteriumErwinia carotovorasubsp.carotovora(Ecc) were extracted from rhizospheres and endophytes of various crop plants, different soil varieties, and atmospheres in the potato farming areas of Bangladesh. Antibacterial activity of the isolated probable antagonistic bacteria was testedin vitroagainst the previously identified most common and most virulent soft rot causing bacterial strain Ecc P-138. Only two isolates E-45 and E-65 significantly inhibited thein vitrogrowth of Ecc P-138. Physiological, biochemical, and carbon source utilization tests identified isolate E-65 as a member of the genusBacillusand the isolate E-45 asLactobacillussp. The stronger antagonistic activity against Ecc P-138 was found in E-65in vitroscreening and storage potatoes. E-65 reduced the soft rot infection to 22-week storage potatoes of different varieties by 32.5–62.5% in model experiment, demonstrating its strong potential to be used as an effective biological control agent for the major pectolytic bacteria Ecc. The highest (62.5%) antagonistic effect of E-65 was observed in the Granola and the lowest (32.7%) of that was found in the Cardinal varieties of the Bangladeshi potatoes. The findings suggest that isolate E-65 could be exploited as a biocontrol agent for potato tubers.


Agrociencia ◽  
2020 ◽  
Vol 54 (6) ◽  
pp. 813-824
Author(s):  
Dario De la Cruz-Ricardez ◽  
Carlos F. Ortiz-García ◽  
Luz del C. Lagunes-Espinoza ◽  
Magdiel Torres-de la Cruz

Uno de los principales problemas fitosanitarios en la producción de cacao (Theobroma cacao L.) en Latinoamérica y en México es la moniliasis, causada por Moniliophthora roreri. Este fitopatógeno causa más del 75% de pérdidas en la producción anual. Los metabolitos secundarios del género Capsicum tienen efectos antifúngicos, por lo que se pueden usar para el control de M. roreri. El objetivo de este experimento fue evaluar el efecto in vitro de extractos metanólicos (EM) de tres especies de Capsicum sobre M. roreri. Los EM extraídos de frutos inmaduros de C. chinense, C. frutescens, y dos morfotipos de C. annuum var. glabriusculum se probaron a dos concentraciones: 1000 y 2500 mg L-1, y se evaluaron en la inhibición del crecimiento micelial, la esporulación y la viabilidad de conidios producidos de M. roreri. Ambas dosis (tratamientos) se establecieron bajo un diseño experimental completamente al azar con cinco repeticiones; cada caja de Petri fue una unidad experimental, los datos se analizaron con ANDEVA y las medias se compararon con la prueba de Tukey (p≤0.05). Moniliophthora roreri fue sensible a los EM de las tres especies. Los EM de C. annuum var. glabriusculum en sus morfotipos amashito (AM) y garbanzo (GA) a 2500 mg L-1 inhibieron el crecimiento micelial hasta en 95%. Los EM de C. annuum var. glabriusculum AM y GA a 2500 mg L-1 inhibieron totalmente la producción de conidios en ambas concentraciones. Los EM de C. chinense y C. annuum var. glabriusculum GA inhibieron hasta 35% la viabilidad de conidios de M. roreri. La sensibilidad in vitro de M. roreri a EM de C. annuum var. glabriusculum AM y GA permite sugerir el efecto de los extractos en el campo de cultivo.


2004 ◽  
Vol 23 (12) ◽  
pp. 1169-1176 ◽  
Author(s):  
Ida E. Yates ◽  
Judy W. Arnold ◽  
Charles W. Bacon ◽  
Dorothy M. Hinton

2002 ◽  
Vol 68 (9) ◽  
pp. 4383-4389 ◽  
Author(s):  
Pingsheng Ji ◽  
Mark Wilson

ABSTRACT Bacterial speck of tomato, caused by Pseudomonas syringae pv. tomato, was used to determine whether similarity in carbon source utilization between a preemptive biological control agent and the pathogen was significant in determining the ability of the bacterium to suppress disease. Similarity in carbon source utilization was quantified as the ratio of the number of tomato carbon sources utilized in vitro by the biological control agent to the number of tomato carbon sources utilized in vitro by the target pathogen (the niche overlap index [NOI]). Suppression of the disease was quantified as the percent reduction in disease severity compared to the pathogen-only control when nonpathogenic bacteria were applied to foliage 48 h prior to the pathogen. In the collection of 36 nonpathogenic bacterial strains, there was a significant (P < 0.01), but weak (r2 = 0.25), correlation between reduction in disease severity and similarity in carbon source utilization, suggesting that similarity in carbon source use was significant in determining ability to suppress disease. The relationship was investigated further using catabolic mutants of P. syringae strain TLP2, an effective biological control agent of speck. Catabolic mutants exhibited lower levels of similarity (NOI = 0.07 to 0.90) than did wild-type TLP2 (NOI = 0.93). With these catabolic mutants there was a significant (P < 0.01), and stronger (r2 = 0.42), correlation between reduction in disease severity and similarity in carbon source utilization. This suggests that similarity in carbon source utilization was a more important component of biological control ability for the catabolic mutants than for the nonpathogenic bacteria. Together, these studies indicate that suppression of bacterial speck of tomato was correlated with nutritional similarity between the pathogenic and nonpathogenic bacteria and suggest that preemptive utilization of carbon sources was probably involved in the biological control of the disease by both the naturally occurring nonpathogenic bacteria and the catabolic mutants.


2012 ◽  
Vol 61 (3) ◽  
pp. 185-193 ◽  
Author(s):  
K.P. Singh ◽  
S.S. Vaish ◽  
Niranjan Kumar ◽  
K.D. Singh ◽  
Minakshi Kumari

2017 ◽  
Vol 16 (2) ◽  
pp. 115
Author(s):  
Johanna Taribuka ◽  
Christanti Sumardiyono ◽  
Siti Muslimah Widyastuti ◽  
Arif Wibowo

Exploration and identification of endophytic Trichoderma in banana. Endophytic fungi Trichoderma is an organism that can used as biocontrol agent. This study aims to isolate and identify endophytic Trichoderma in roots of healthy banana plants from three districts in Yogyakarta, which will be used as biological control agent against the pathogen Fusarium oxysporum f.sp. cubense. Isolation was conducted using TSM (Trichoderma Selective Medium). We obtained six isolates of endophytic Trichoderma spp., i.e., Swn-1, Swn-2, Ksn, Psr-1, Psr-2, and Psr-3. Molecular identification was done by using ITS1 and ITS2 primer pain and sequenced. The sequence of DNA obtained was analysed and compared with NCBI database by using BLAST-N programe. The results showed that all isolates were amplified at 560-bp. Phylogenetic analysis showed that isolates Swn-1, Swn-2 and Psr-1 are homologous to Trichoderma harzianum, isolate Ksn homologous to Trichoderma asperrellum, isolate Psr-2 homologous to Trichoderma gamsii, and isolate Psr-3 homologous to Trichoderma koningiopsis, with the homologous value of 99%.


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