Impact of Combining Chitosan Nanoparticles and Cyproconazole in Controlling Wheat Stem Rust

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is a devastating disease that inflicts significant global damage annually. To combat this disease, chitosan nanoparticles (CNPs) were combined with the fungicide cyproconazole (CYP) and applied as a foliar spray 24 h postinoculation (hpi) with fungal urediniospores. Plant samples were analyzed to assess fungal progression by examining pustule formation and quantifying fungal DNA content in leaf tissues. Treatment with CNPs and the cyproconazole-chitosan nanocomposite (C-CYP) resulted in significantly smaller pustules or their absence and reduced fungal DNA levels compared to controls. Additionally, enzyme assays revealed that the activities of peroxidase, catalase, polyphenol oxidase, and phenylalanine ammonia-lyase significantly increased 24 h post-treatment with CNPs compared to controls. Furthermore, transcription levels of WAK-2, NPR-1, and Chitinase genes were notably upregulated in plants treated with CNPs and C-CYP at 24 h post-treatment. These findings suggest that the combination of chitosan nanoparticles and cyproconazole not only effectively controls wheat stem rust but also reduces environmental hazards by requiring lower chemical dosages.