Chitin Oligosaccharides Enhance Broad-Spectrum Insect Resistance and Promote Growth in Brassica napus

Despite significant progress in understanding chitin oligosaccharides as plant immune elicitors, studies on their potential to induce insect resistance remain limited. In this study, we demonstrate that chitin oligosaccharides induce potent and broad-spectrum insect resistance in Brassica napus. NACOS treatment significantly reduced damage from both chewing insects (Plutella xylostella) and piercing-sucking insects (Myzus persicae). Multiomics analyses revealed that NACOS activated defense-related pathways, including peroxisome, phenylpropanoid biosynthesis, and glutathione metabolism, as evidenced by enhanced activities of superoxide dismutase, peroxidase, and polyphenol oxidase, as well as the accumulation of defense-related metabolites such as GABA, tannins, and oxalic acid. While inducing robust defense responses, NACOS also upregulated photosynthesis-related pathways, leading to improved photosynthetic rates and markedly promoting plant growth and yield. Our study uncovers a dual-role mechanism of NACOS in balancing defense and growth, providing a theoretical basis and practical strategies for developing oligosaccharide-based biopesticides.