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

Table_1_Biological control potential of worrisome wheat blast disease by the seed endophytic bacilli.DOCX

Crop production often faces challenges from plant diseases, and biological control emerges as an effective, environmentally friendly, cost-effective, and sustainable alternative to chemical control. Wheat blast disease caused by fungal pathogen Magnaporthe oryzae Triticum (MoT), is a potential catastrophic threat to global food security. This study aimed to identify potential bacterial isolates from rice and wheat seeds with inhibitory effects against MoT. In dual culture and seedling assays, three bacterial isolates (BTS-3, BTS-4, and BTLK6A) demonstrated effective suppression of MoT growth and reduced wheat blast severity when artificially inoculated at the seedling stage. Genome phylogeny identified these isolates as Bacillus subtilis (BTS-3) and B. velezensis (BTS-4 and BTLK6A). Whole-genome analysis revealed the presence of genes responsible for controlling MoT through antimicrobial defense, antioxidant defense, cell wall degradation, and induced systemic resistance (ISR). Taken together, our results suggest that the suppression of wheat blast disease by seed endophytic B. subtilis (BTS-3) and B. velezensis (BTS-4 and BTLK6A) is liked with antibiosis and induced systemic resistance to wheat plants. A further field validation is needed before recommending these endophytic bacteria for biological control of wheat blast.</p