Anti-phytopathogenic Activity Research Articles

Antifungal screening of endophytic fungi fromGinkgo bilobafor discovery of potent anti-phytopathogenic fungicides

Many endophytic fungi have been found to synthesize bioactive compounds to defend host plants against pathogenic organisms. Here we performed anti-fungal bioassay of 80 endophytic fungi isolated from Ginkgo biloba. Fifteen endophytes were active against at least one of the selected fungi, Fusarium graminearum, Sclerotinia sclerotiorum and Phytophthora capsici, using the agar diffusion method. The most bioactive strain CDW7 was identified as Chaetomium globosum by microscopic examination and ITS rRNA gene sequence data. Culture broth of CDW7 diluted 3-fold completely inhibited the mycelial growth and conidia germination of F.graminearum in vitro. Therefore, Fusarium head blight, a common disease in wheat and barley associated with Fusarium spp., was used to test the anti-phytopathogenic activity in vivo. The fermentation broth of CDW7 resulted in a protective efficacy of 54.9% and curative efficacy of 48.8%. Followed by a bioassay-guided approach, 1,2-benzenedicarboxaldehyde-3,4,5-trihydroxy-6-methyl (flavipin) was isolated and demonstrated to significantly inhibit the growth of several plant-pathogenic fungi, especially F.graminearum with an EC(50) value of 0.73μgmL(-1) comparable to the commonly used fungicide carbendazim, indicating that it could be used as a fungicide or as a lead compound of new fungicides.

Endophytic fungus Aspergillus tamarii from Ficus carica L., a new source of indolyl diketopiperazines

Abstract The indolyl diketopiperazines ( 1 – 6 ) were isolated from the endophytic fungus Aspergillus tamarii in Ficus carica L. and tested for anti-phytopathogenic activity in vitro for the first time. Their structures were identified as fumitremorgin B (1), verruculogen (2), fumitremorgin C (3), cyclotryprostatins B (4), tryprostatin A (5) and tryprostatin B (6) respectively, based on spectroscopic analysis and by comparison of their spectral data with those reported previously in the literature. The anti-phytopathogenic activity of the isolated metabolites suggests that A. tamari could protect the host by producing the bioactive metabolites.

Screening and evaluation of antiphytopathogenic activity of endophytic fungi from live foliages of Ginkgo biobla L.

Twenty-four strains of endophytic fungi were isolated from 50 fresh leaves samples ofGinkgo biobla L collected using the cultivation-dependent method from the campus of Anhui agricultural university in Hefei of China. Out of 24 endophytes investigated, 12 strains can produce in vitro substances that are inhibitory to all or a few of tested phytopathogens whereas the rest yielded nothing active, while all fermented broths of endophytes showed activities against one and more tested phytopathogens. These results indicated that endophytic fungi could play an important role in protection of G. biobla L from disease as well as an excellent resource for searching for natural antifungal compounds. Key words: Endophytic fungi, Ginkgo biobla L, antimicrobial activity.

Anti-phytopathogenic activities of macro-algae extracts.

Aqueous and ethanolic extracts obtained from nine Chilean marine macro-algae collected at different seasons were examined in vitro and in vivo for properties that reduce the growth of plant pathogens or decrease the injury severity of plant foliar tissues following pathogen infection. Particular crude aqueous or organic extracts showed effects on the growth of pathogenic bacteria whereas others displayed important effects against pathogenic fungi or viruses, either by inhibiting fungal mycelia growth or by reducing the disease symptoms in leaves caused by pathogen challenge. Organic extracts obtained from the brown-alga Lessonia trabeculata inhibited bacterial growth and reduced both the number and size of the necrotic lesion in tomato leaves following infection with Botrytis cinerea. Aqueous and ethanolic extracts from the red-alga Gracillaria chilensis prevent the growth of Phytophthora cinnamomi, showing a response which depends on doses and collecting-time. Similarly, aqueous and ethanolic extracts from the brown-alga Durvillaea antarctica were able to diminish the damage caused by tobacco mosaic virus (TMV) in tobacco leaves, and the aqueous procedure is, in addition, more effective and seasonally independent. These results suggest that macro-algae contain compounds with different chemical properties which could be considered for controlling specific plant pathogens.

Isolation and Anti-phytopathogenic Activity of Secondary Metabolites from Alternaria sp. FL25, an Endophytic Fungus in <I>Ficus carica</I><SUP>*</SUP>

Isolation and Anti-phytopathogenic Activity of Secondary Metabolites from Alternaria sp. FL25, an Endophytic Fungus in <I>Ficus carica</I><SUP>*</SUP>

Sludge and lignin as growth media for the production of antimicrobial substances by selected microorganisms

The ability of sludge, lignin and humic acid to support the growth and production of antimicrobial substances by 19 microorganism strains was tested. Organisms from seven genera: Bacillus, Pseudomonas, Streptomyces, Beauveria, Paecilomyces, Trichoderma and Trichosporon grew on the tested media. On these media, they were also examined for the production of anti-phytopathogenic activity against Fusarium oxysporum P1 BIM, Botrytis cinerea B1 BIM and Pseudomonas syringae. pv. glicinea B-280 BIM. Strains Pseudomonas aurantiaca S-1, Bacillus sp. 19 and Streptomyces sp. 11 synthesize antimicrobial metabolites on the different media. Protease, cellulase, α-amylase, xylanase and peroxidase were also produced by the same microorganisms, which can explain their ability to grow on sludge, and laccase was produced only by P. aurantiaca S-1. HPLC analysis of the lignin culture media before and after P. aurantiaca S-1 growth has shown that the major lignin peak in the culture broth disappeared.

A New Enrichment Method for the Selective Isolation of Streptomycetes from the Root Surfaces of Herbaceous Plants

Diverse rhizoplane streptomycetes with high levels of anti-phytopathogenic activity were efficiently isolated from healthy herbaceous plants using a new enrichment method, which we designated as the moist incubation and desiccation (MI&D) method. The MI&D method involves incubating root tissues on humic acid-vitamin (HV) agar, desiccating roots bearing arthrospore chains of colonized streptomycetes in dried soil particles, then liberating spores by agitation in water. Dilutions of the liquid enriched with streptomycete spores are then plated and incubated on HV agar. The desiccation stage drastically reduces bacterial contamination, thereby achieving selective isolation of streptomycetes.

Isolation of Actinomycetes from Live Plants and Evaluation of Antiphytopathogenic Activity of Their Metabolites.

Actinomycetes were isolated from live plants collected in Toyama and Miyagi prefectures, Japan. Three hundred and ninety eight actinomycete strains were obtained from the leaves, stems and roots of 11 harbaceous and 13 arbor plants of agricultural and wild species. n-Butanol extracts of the fermentation broths of these strains were screened for antiphytopathogenic activity using in vitro antimicrobial and in vivo antiinfective assays. About 10–20% of the extracts showed antagonistic activity against fungal or bacterial plant pathogens. In addition, several extracts suppressed the infection of Alternaria brassicicola TP-F0423, a fungal pathogen to seedlings of Chinese cabbages in vivo.

Isolation and Phenotypic Characterization of Plant Growth–Promoting Rhizobacteria with High Antiphytopathogenic Activity and Root-Colonizing Ability

Some bacterial strains isolated from the plant rhizosphere showed high root-colonizing ability and antiphytopathogenic activity against 6 fungal species. The antifungal activity was species-specific, which could be accounted for by the fact that the isolates differed in the ability to produce lytic enzymes (chitinases, proteases, and lipases) and to secrete cyanide. The possibility of using there rhizobacteria to control phytopathogens is discussed.