Antifungal activity of microbial nanoparticles derived from Chaetomium spp. against Magnaporthe oryzae causing rice blast

The Magnaporthe oryzae isolate PO2 was proven to cause rice blast var. PSL 2 in this study. Chaetomium elatum, Chaetomium lucknowense and Chaetomium brasiliense were antagonised to M. oryzae. The hexane extract of C. brasiliense gave the highest inhibition of the spore production with an ED₅₀ of 35 ppm, the EtOAC extract of C. lucknowense inhibited the spore production at 57 ppm and the EtOAC extracts of C. elatum inhibited the spore production at 106 ppm. The nano-CLM (C. lucknowense) inhibited the spore production at 5.24 ppm, the nano-CBH (C. brasiliense) inhibited the spore production at 6.86 ppm and the nano-CEE (C. elatum) inhibited the spore production at 7.89 ppm. The rice leaves treated with nano-CBH from C. brasiliense produced Sakuranertin and Oryzalexin B as seen on the thin layer chromatography where the Rf value was 0.08 assumed to be Sakuranertin, and the Rf value of 0.28 supposed to be Oryzalexin B. It was found that the nanoparticles act as elicitors to induce immunity in rice plants through the production of phytoalexin.

Stress priming affects fungal competition – evidence from a combined experimental and modeling study

Priming, an inducible stress defense strategy that prepares an organism for an impending stress event, is common in microbes and has been studied mostly in isolated organisms or populations. How the benefits of priming change in the microbial community context and, vice versa, whether priming influences competition between organisms, remains largely unknown. In this combined experimental and modeling study, we developed a cellular automaton model based on dedicated data of different isolates of soil fungi in isolation and pairwise competition experiments. With the model, we simulated growth of the ascomycete Chaetomium elatum competing against other fungi to understand which species traits influence the benefit of priming and the effect of priming on competition. We showed that competition changes the priming benefit compared to isolated growth, and that it depends not only on the primeable species itself, but also on the competitors’ traits such as growth rate, primeability and stress susceptibility. In addition, we showed that priming benefits were not always reflected in the competitive outcome. With this study, we transferred insights on priming from studies in isolation to the community context. This is an important step towards understanding the role of inducible defenses in microbial community assembly and composition.

Chaetomium elatum. [Descriptions of Fungi and Bacteria].

C. elatum is described and illustrated. Information on host range (mainly field and horticultural crops, trees, wood, nematode, dung and artefacts), geographical distribution (South Africa; Manitoba, Ontario and Saskatchewan, Canada; California, Kansas, Louisiana, Massachusetts, New Jersey, New Mexico, New York, Oregon, Pennsylvania and Washington DC, USA; Chile; Ecuador; Venezuela; Gansu and Jiangsu, China; India; Pakistan; Philippines; Japan; Russia; Turkey; Uzbekistan; New South Wales, Victoria and Western Australia; New Zealand; Dominican Republic; Austria; Belgium; Croatia; Czech Republic; Denmark; France; Germany; Great Britain; Greece; Hungary; Ireland; Italy; Netherlands; Poland; Romania; Russia; Sweden; Switzerland; Ukraine; Cyprus; Iraq; and Kuwait), biology, and conservation status is presented.