Cobalt-encapsulated N-doped carbon nanotube nanozymes generate ROS to suppress Ralstonia solanacearum and prime systemic resistance in tomato

Nanomaterials offer new opportunities for sustainable control of crop diseases caused by soil-borne pathogens. Here, cobalt-encapsulated nitrogen-doped carbon nanotubes (Co@N-CNTs) with tubular and bamboo-like morphologies were synthesized and evaluated against tomato bacterial wilt. Co@N-CNTs showed strong antibacterial activity against Ralstonia solanacearum in vitro , with the tubular morphology being more effective. Mechanistic analyses indicated that Co@N-CNTs induced reactive oxygen species-mediated oxidative damage in R. solanacearum , resulting in DNA damage, cytoplasmic leakage, and membrane disruption. In pot experiments, Co@N-CNTs reduced disease severity and delayed progression, with efficacy comparable to Zhongshengmycin. Transcriptomic and biochemical analyses showed tissue-specific regulation of plant defense, reducing infection-induced SA accumulation in stems while enhancing the expression of several defense-related genes in leaves, whereas JA contents were not significantly altered. Co@N-CNTs showed no detectable adverse effects on tomato growth and exhibited low acute toxicity to Italian honeybees. Collectively, these findings demonstrate that Co@N-CNTs can control soil-borne bacterial diseases and hold promise for sustainable agriculture.