Identification and application of fungal biocontrol agent cladosporium cladosporioides against bemisia tabaci

The entomopathogenic fungus Cladosporium cladosporioides is a potential candidate for biocontrol of insect pests. We isolated a strain of C. cladosporioides BOU1 from an infected brown plant hoper (BPH) of rice and characterized it using morpho-physiological and molecular analyses. Internal transcribed spacer regions and intervening 5.8S rRNA gene (ITS) sequencing and morphopathogenic analyses confirmed that BOU1 is a strain of C. cladosporioides. To select the suitable medium for this fungus, a single condium of BOU1 was grown in potato dextrose agar (PDA), potato dextrose agar with yeast (PDAY), Sabouraud dextrose agar (SDA) and synthetic nutrient-poor agar (SNA) media. The suitable medium for this fungal isolate was determined by fungal growth (colony area and conidiogenesis), and enzymatic activities (protease and lipase). The fungal growth parameters including enzymatic activities showed that the PDA medium is most suitable culture medium for C. cladosporioides. Finally, the pathogenicity of this fungal isolate was evaluated against whitefly, Bemisia tabaci through direct contact toxicity assay on eggplant leaves by dipping under laboratory conditions. The BOU1 strain caused mortality in B. tabaci in a dose-dependent manner, the highest mortality being 71% at 1 × 108 conidia/mL. To the best of our knowledge, this is the first report of isolation and molecular characterization of an entomopathogenic fungus C. cladosporioides from a BPH of rice. This study suggests that BOU1 is a potential candidate for biological control of whitefly for the promotion of sustainable agriculture

Chitosan biostimulant controls infection of cucumber by Phytophthora capsici through suppression of asexual reproduction of the pathogen

The biopolymer chitosan is a derivative of chitin, which can promote plant growth and protect plants from phytopathogens. This study aimed to evaluate the efficacy of chitosan as a biostimulant and a biorational agent to protect cucumber plants from damping-off disease caused by Phytophthora capsici. Cucumber seeds were treated with a range of chitosan concentrations, viz. 0, 125, 250, and 500 ppm, to evaluate effect on seed germination and fresh root and shoot weight of the seedlings. Chitosan significantly (p ≤ 0.05) enhanced seed germination and root and shoot growth of cucumber in a dose-dependent manner up to 500 ppm. Application of in vitro chitosan suspension onto P. capsici mycelial plug suppressed growth of mycelia, formation of sporangia, and release of P. capsici zoospores at 125–500 ppm concentrations. Cucumber seedlings from chitosan-treated seeds showed enhanced resistance to damping-off disease caused by P. capsici compared to untreated control. Cucumber seedlings from 500 ppm chitosan seed treatment showed 100% disease resistance against damping off caused by P. capsici. These results suggest that chitosan could be used as a natural and environmentally safe alternative to a synthetic growth promoter and pesticide for sustainable production of cucumber

Data_Sheet_1_Role of seed infection for the near and far distance dissemination of wheat blast caused by Magnaporthe oryzae pathotype Triticum.pdf

Magnaporthe oryzae pathotype Triticum (MoT) is a devastating fungal phytopathogen causing wheat blast disease which threatens wheat production particularly in warmer climate zones. Effective disease control is hampered by the limited knowledge on the life cycle, epidemiology, and pathogenicity of MoT. Since MoT mainly infects and colonizes the inflorescences of wheat, infection, invasion routes and colonization of MoT on wheat ears and in wheat seeds were investigated in order to assess potential seed transmission pathways. MoT was spray inoculated on two wheat cultivars (Sumai 3, susceptible and Milan, resistant) at three ear maturity stages [full ear emergence, growth stage (GS) 59; mid flowering, GS 65; and end of flowering, GS 69]. Incidence of MoT on Sumai 3 seeds was 100% and 20–25% on Milan. MoT sporulation rate on Sumai 3 contaminated seeds was more than 15 times higher than on Milan. Repeated washes of seed samples for removing paraffin fixation hampers seed microscopy. To overcome the damage of seed samples, we used hand-sectioned seed samples instead of paraffin-fixed microtome samples to facilitate microscopy. The colonization of MoT within various seed tissues was followed by light and confocal laser scanning microscopy (CLSM). Invasion of MoT in seeds predominantly occurred in the caryopsis germ region, but entry via other seed parts was also observed, confirming the potential of intense colonization of MoT in wheat grains. Fungal spread in wheat plants growing from MoT infected seeds was monitored through plating, microscopic and molecular techniques. Under greenhouse conditions, no spread of MoT from infected seeds to seedlings later than GS 21 or to ears was detected, neither in Milan nor in Sumai 3. We therefore conclude, that MoT may not systemically contaminate inflorescences and seeds in neither susceptible nor resistant wheat cultivars. However, initial blast symptoms, only found on seedlings of Sumai 3 but not Milan, resulted in the formation of new conidia, which may serve as inoculum source for plant-to-plant dissemination by airborne infection of plant stands in the field (short distance spread). Ultimately the inoculum may infect young inflorescences in the field and contaminate seeds. Our findings again stress the risk of long-distance dissemination of wheat blast across continents through MoT-contaminated seeds. This underlines the importance of mandatory use of healthy seeds in strategies to control any further spread of wheat blast.</p

Macrocyclic Trichothecenes from Myrothecium roridum Strain M10 with Motility Inhibitory and Zoosporicidal Activities against Phytophthora nicotianae

The cytotoxicity of the extract obtained from Myrothecium roridum M10 and a characteristic ¹H signal at δ_H ∼8 led to the assumption that verrucarin/roridin-type compounds were present. Upscaling on rice medium led to the isolation of four new metabolites: verrucarins Y (<b>1</b>) and Z (<b>6</b>) (macrocyclic trichothecenes), bilain D (<b>12</b>) (a diketopiperazine derivative), and hamavellone C (<b>14</b>) (an unusual cyclopropyl diketone). In addition, nine known trichothecenes [verrucarin A (<b>3</b>), 16-hydroxyverrucarin A (<b>5</b>), verrucarin B (<b>7</b>), 16-hydroxyverrucarin B (<b>8</b>), verrucarin J (<b>2</b>), verrucarin X (<b>4</b>), roridin A (<b>9</b>), roridin L-2 (<b>10</b>), and trichoverritone (<b>11</b>)] and a bicyclic lactone [myrotheciumone A (<b>15</b>)] were identified. Their structures and configurations were determined by spectroscopic methods, published data, Mosher’s method, and considering biosyntheses. Some trichothecenes showed motility inhibition followed by lysis of the zoospores against devastating Phytophthora nicotianae within 5 min. Compounds <b>2</b>, <b>3</b>, <b>7</b>, and <b>9</b> also exhibited potent activities against Candida albicans and Mucor miehei

Plant probiotic bacteria suppress wheat blast fungus Magnaporthe oryzae Triticum pathotype

<b>Biological control of fearsome wheat blast by bacterial antagonist from native environment.</b

Genome sequences of candidate wheat blast biocontrol bacteria

In an effort to combat wheat blast disease in Bangladesh, Prof. Tofazzal Islam and team have identified several biocontrol bacteria that have the ability to inhibit fungal growth in wheat (Surovy et al., 2017). They have isolated a number of these agents and we have sequenced the genomes of four bacterial strains to 30x coverage. The genome sequence data is now available to download from links in the tables included in the document.<br

Suitable methods for isolation, culture, storage and identification of wheat blast fungus Magnaporthe oryzae Triticum pathotype

Wheat blast disease caused by a South American lineage of Magnaporthe oryzae Triticum (MoT) pathotype has emerged as a serious threat to wheat production in Bangladesh since its first emergence in 2016. Efficient and suitable methods for isolation, storage, inoculum production and molecular characterization of the pathogen can help in achieving the target of sustainable management of the disease in a relatively short period of time. In this study, we aimed to develop suitable methods for isolation, storage and morphological characterization and molecular identification of MoT isolates collected from the blast-infected wheat fields in Bangladesh. This process included modification of existing protocols that were available for a related fungal pathogen M. oryzae or de novo method development and validation. We developed suitable methods for isolation of MoT from field-infected plant samples using modified monoconidial isolation technique and produced abundant conidia from a single mycelial plate for in vivo pathogenicity assay in a reproducible manner. Cultural and morphological characterization of the isolates revealed that all Bangladeshi MoT isolates are of a single clonal lineage with similar cultural and morphological characters. Molecular detection of isolates with M. oryzae-specific primers Pot1 and Pot2 and MoTspecific primers MoT3F and MoT3R produced bands with the expected size from all wheat-infecting isolates. We also successfully established a PCR-based detection system based on a commercially available detection kit for fieldinfected leaf and seed samples by detecting Pot2- and MoT3-specific bands. Additionally, the simple method we developed in our study for producing abundant conidia in a very short period of time will be very helpful in studying biology of the wheat blast fungus. This method was also proven to be more user-friendly and costeffective than previously available methods. Successful characterization of MoT isolates at morphological and molecular levels coupled with detection of the pathogen in infected field and seed lots should be useful for efficient surveillance and management of the fearsome wheat blast disease

Fragments d’intime. Amours, corps, et solitudes aux marges urbaines

Dans les espaces urbains marqués par la précarisation, les sphères de l’intime se fragilisent. Cet ouvrage explore la vie émotionnelle, affective et sociale de personnes de toutes origines, souvent marquées par l’épreuve de l’exil, dans un quartier « chaud » de Bruxelles, où les relations hommes/femmes, les quêtes affectives et sexuelles sont d’une grande complexité. L’auteure y a longuement fréquenté des prostituées, des errants avec ou sans papiers, des jeunes issus des anciennes et nouvelles migrations, turques en particulier. Elle restitue ici, avec finesse et délicatesse, leurs histoires et contextes de vie, qui contribuent à façonner leurs rapports au corps, à l’autre sexe et à la solitude. Éprouvés mais altiers, marginalisés mais créatifs, brisés mais tenaces, les interlocuteurs de l’ethnologue font face à l’insécurité sociale et intime. Celle-ci peut devenir une quête initiatique, où s’invente une autre vie urbaine, souterraine et alternative. Il en va ainsi de la prostitution libre et courtisane, vécue comme un métier de service ; des squats semi-organisés qui protègent de la rue les couples et les grands célibataires ; des couples mixtes et des inventions transculturelles qui décloisonnent les ghettos urbains. À travers la vie intérieure et secrète de ses interlocuteurs, Pascale Jamoulle nous invite à découvrir les mondes off des grandes métropoles, à voir comment s’invente la mondialisation par le bas de l’échelle sociale