Acesulfame K, not as sweet as you think: Insights into its physiological and biochemical side-effects on rice growth and development

Acesulfame potassium (ACE), an artificial sweetener, is extensively used worldwide and is ubiquitous in aquatic environments in several countries. As an emerging contaminant, ACE may pose a risk to aquatic and water-dependent plant species. This study investigated the physiological and biochemical responses of rice ( Oryza sativa L.) to constant ACE exposure during its key growth stages. The results revealed that ACE exposure had no significant inhibitory effect on the final seed germination rate but significantly impeded early seedling growth, particularly radicle elongation. Biochemical analyses indicated that ACE induced oxidative stress, as evidenced by the altered activities of key antioxidant enzymes and a marked, dose- and time-dependent increase in malondialdehyde (MDA) content, which indicates lipid peroxidation. Specifically, low concentrations of ACE (2.5 μM) enhanced chlorophyll a ( Chla ) synthesis in leaves during specific growth stages, whereas higher concentrations (50 and 100 μM) ultimately inhibited it, leading to the disruption of the photosynthetic apparatus. Furthermore, rice exhibited a significant capacity for ACE uptake and translocation, with accumulation in the following order: roots > stems > leaves. Uptake efficiency increased with plant development and peaked during the booting stage of plant growth. Crucially, sustained exposure led to a progressive decline in soluble protein content, particularly during later growth stages. Collectively, these novel findings demonstrate that ACE imposes substantial physiological stress on rice, primarily through the induction of oxidative damage, disruption of key metabolic pathways, and previously uncharacterized pollutant bioaccumulation and translocation, highlighting the potential risk to rice productivity and underscoring the urgent need for field validation studies.