Transcriptome analysis of ultrasonic pretreatment enhancing cadmium tolerance through defense-growth coordination and photosynthetic-nutrient optimization in maize

Cadmium (Cd) soil contamination poses a serious threat to maize production. We demonstrate that ultrasonic pretreatment (500 W, 5 min) enhances maize Cd tolerance by systemically adjusting the balance between defense and growth processes. Pretreatment altered the plant’s defense system, mitigating Cd-induced growth inhibition by attenuating the overactivation of the antioxidant system while sustaining photosynthesis and improving nutrient (notably Fe and Ni) homeostasis. Integrated transcriptomic and gene co-expression network analyses showed this coordinated adjustment was orchestrated by key transcription factors that modulate gene networks central to photosynthesis and redox balance. Partial least squares path modeling quantified the strategy, identifying enhanced photosynthesis (path coefficient: 0.44) and optimized nutrient acquisition (0.76) as the primary drivers of pretreatment-induced biomass gain. This study establishes a systemic mechanistic framework for ultrasonic pretreatment under laboratory conditions, demonstrating how it enhances maize resilience by reducing the metabolic burden of antioxidant overactivation and redirecting resources toward growth-sustaining processes. However, its practical efficacy under field conditions warrants further validation. • Ultrasonic pretreatment rebalances defense and growth to alleviate Cd toxicity in maize. • Enhanced photosynthesis and nutrient uptake drive pretreatment-induced biomass gain. • Ultrasonic pretreatment presents a green strategy for crop resilience under Cd stress.