Nano-enhanced defense: Titanium-enriched Alginate–Bentonite coating augments Bacillus amyloliquefaciens D203 efficacy against Magnaporthe oryzae in Kenyan rice cultivation

Abstract

Rice blast disease, caused by Magnaporthe oryzae, poses a significant threat to global rice pro duction, necessitating the development of effective and sustainable management strategies. Biological control using beneficial microbes like Bacillus amyloliquefaciens has emerged as a promising approach due to its ability to enhance plant resistance and reduce disease incidence. Nano-encapsulation of bacteria, which involves embedding beneficial microbes within nanomaterials, offers a novel method to improve the stability, survival, and efficacy of these biocontrol agents. This study evaluated the capacity of encapsulated Bacillus amyloliquefaciens D203, embedded within an alginate-bentonite coating infused with titanium nanoparticles (TNs), to stimulate defense responses in rice seedlings challenged by the Magnaporthe oryzae the causal agent of rice blast disease. Encapsulation was achieved using the extrusion technique, with some modifications. Using a completely randomized design, the experiment was conducted in a greenhouse, with four treatments replicated four times. The experiment used the popular Kenyan rice variety "BASMATI 370”. The study investigated the impact of strain D203 on the incidence, severity, and area under disease progress curves related to M. oryzae, as well as the expression of defense-related enzymes. The results demonstrated that rice plants derived from seeds coated with the D203 encapsulated B. amyloliquefaciens strain exhibited higher levels of defense-related enzyme expression, including peroxidase (POD), phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD) and catalase (CAT), compared to controls. In addition, the incidence and severity of the disease were markedly lower in plants treated with encapsulated B. amyloliquefaciens compared to controls, sometimes paralleling the efficacy of hexaconazole treatment. These findings suggest that the encapsulation of strain D203 has the potential to enhance resistance against rice blast disease by inducing systemic resistance through the pro duction of antioxidant enzymes.