Silver oxide nanostructures as a new trend to control strawberry charcoal rot induced by Macrophomina phaseolina.

BACKGROUND: Silver oxide (Ag2 O) nanostructures were fabricated and their ability to induce antifungal activity against Macrophomina phaseolina, which causes charcoal rot disease in strawberries, was evaluated under laboratory, greenhouse and field conditions. A real-time quantitative polymerase chain reaction was used to monitor expression of defense-related genes, which is essential to evaluate the potential of the manufactured nanoparticles to promote strawberry resistance against charcoal rot. The effect of Ag2 O nanoparticles on growth characteristics in strawberry plants was also studied. RESULTS: The results showed that Ag2 O significantly inhibited M. phaseolina growth compared with untreated controls under in vitro conditions. Strawberry plants treated with Ag2 O showed a significant decrease in the severity of charcoal rot disease in the greenhouse compared with untreated plants. Strawberry plants treated with Ag2 O nanoparticles expressed defense gene (PR-1) involved in the salicylic acid signaling pathways at levels three to five times higher than in the control group. Ag2 O nanoparticles significantly improved the growth and yield of the strawberry crop. CONCLUSION: Use of Ag2 O nanoparticles can be considered a new strategy to control M. phaseolina and this is the first report of this effect. © 2022 Society of Chemical Industry.

Host Resistance to Uromyces appendiculatus in Common Bean Genotypes.

Rust, induced by the fungus Uromyces appendiculatus, is one of the most serious bean diseases. The involved mechanisms in rust resistance were evaluated in 10 common bean genotypes during the 2019/2020 and 2020/2021 growing seasons. The disease parameters such as final rust severity (FRS%), area under the disease progress curve (AUDPC) and disease increase rate (r-value) were lower in the resistant genotypes than in highly susceptible genotypes. Biochemical compounds such as total phenols and the activity of antioxidant enzymes such as catalase, peroxidase and polyphenol oxidase were increased in the resistant genotypes compared to susceptible genotypes. In the resistance genotypes, the levels of oxidative stress markers such as hydrogen peroxide (H2O2) and superoxide (O2•-) increased dramatically after infection. The electrolyte leakage percentage (EL%), was found to be much greater in susceptible genotypes than resistant genotypes. The resistant gene SA14, which was found in genotypes Nebraska and Calypso at 800 bp, had an adequate level of resistance to bean rust with high grain yield potential. After infection, the transcriptions levels of 1,3-D-glucanases and phenylalanine ammonia lyase) were higher in the resistant genotypes than susceptible genotypes. In conclusion, the resistant genotypes successfully displayed desirable agronomic traits and promising expectations in breeding programs for improving management strategies of common bean rust disease. The resistance was mediated by antioxidant enzymes, phenolic compounds, and defense gene expressions, as well as the resistant gene SA14.