Abstract
BACKGROUND: Xanthium spinosum is one of the most abundant and aggressively invasive plants in the world. Cuscuta australis parasitism hinders X. spinosum growth and development by absorbing nutrients, leading to reduced reproductive performance. However, which metabolite changes contribute to stunted growth and diminished reproductive performance in X. spinosum? Additionally, what genes regulate these metabolites? These underlying mechanisms remain largely unknown. RESULTS: X. spinosum was used to determine the physiological relevance of C. australis parasitism to alleviate host plant growth and explore the molecular mechanism, with a focus on metabolic pathways. The results revealed that C. australis significantly reduced the growth potential of X. spinosum, with a particularly notable decrease in seed quantity, which decreased by 92.07%. C. australis parasitism increased the activities of the peroxidase (POD) and superoxide dismutase (SOD) enzymes in the stems of X. spinosum. Integrated transcriptome and metabolome analysis revealed that C. australis influenced lignin synthesis in the stem through the phenylpropanoid biosynthesis pathway. Concurrently, the majority of differentially expressed genes in the galactose metabolism pathway were upregulated, leading to increased sugar accumulation and disrupted metabolism. Furthermore, all differentially expressed genes in the autophagy-other pathway were upregulated, resulting in excessive autophagy and a significant reduction in the reproductive performance of X. spinosum. CONCLUSIONS: The results provide a theoretical foundation for the development of targeted pesticides aimed at controlling X. spinosum.