Insights into the Antifungal Properties of Myxobacteria Outer Membrane ß-1,6-Glucanase.

Fungal cell wall decomposition enzymes exhibit great potential for the development of efficient antifungal agents. However, their practical application is restricted due to incomplete understanding of the action mode. In our previous study, we identified that a novel outer membrane (OM) ß-1,6-glucanase GluM is deployed by predatory myxobacteria to feed on fungi. In this work, we provide deep insights into the antifungal mechanism of ß-1,6-glucanase and its potential in improving plant disease resistance. The fungal cell wall decomposition ability of GluM resulted in irregular hyphae morphology, changed chitin distribution, increased membrane permeability, and leakage of cell constituents in Magnaporthe oryzae Guy11. Under the attack pattern, the cell wall integrity pathway was activated by strain Guy11 for self-protection. GluM exhibited a distinct endo-model toward fungal cell wall; the favorite substrate of GluM toward fungal ß-1,6-glucan may give reason for its efficient antifungal activity compared with Trichoderma ß-1,6-glucanase. Moreover, released glucans from GluM hydrolysis of fungal cell wall functioned as an elicitor and induced rice immunity by means of jasmonic acid pathway. Based on the dual roles of antifungal properties, gluM transgenic plants conferred enhanced resistance against fungal infection.

Menisporopsisaquatica sp. nov. (Sordariomycetes, Chaetosphaeriales, Chaetosphaeriaceae), from freshwater habitat in China.

Background: Freshwater fungi are an integral part of freshwater ecosystems. They promote the carbon cycle of the ecosystem by decomposing wood substrates. Menisporopsis is a fungal genus of Chaetosphaeriales in Sordariomycetes, which has been commonly collected from aquatic and marine environments. Most species of this genus are saprophytes. New information: Here, a new freshwater hyphomycetous fungus, Menisporopsisaquatica, reported from submerged rotten wood samples collected in a stream in Zhejiang Province, south-eastern China. The new species is characterised by hyaline conidia appendiculate with 1-2 setulae at each end and synnematous conidiophores growing closely around a black central seta. Molecular phylogeny of Menisporopsis was studied using a combined two-loci dataset, including the internal transcribed spacer sequences (ITS) and the nuclear ribosomal large subunit gene sequences (nrLSU). The new species is illustrated and a synopsis of the Menisporopsis species is presented in this paper.