A systematic review of micro- and nanoplastics impact on plant photosynthesis

Despite rapidly growing research activity, the effects of micro- and nanoplastics (MNPs) on plant photosynthesis remain inconsistently described, with major discrepancies across species, particle types, sizes, and experimental conditions. Current literature lacks an integrated synthesis that identifies general physiological patterns and quantifies the magnitude of MNP-induced disruptions. To address this gap, this review combines a structured literature review with quantitative evaluation of extracted experimental data to assess MNP-induced changes in photosynthetic pigments, gas exchange, and chlorophyll fluorescence, as well as associated metabolic and genetic responses. Our data analysis shows that PS was the most frequently reported polymer, followed by PE, PVC, PET, PP, and PES, while plant representation was dominated by Poaceae and Cucurbitaceae. Chlorophyll declined most strongly under 0.1-1 µm particles at high concentrations and under PS exposure, with median reductions of 8 and 12%, reflecting disruptions in pigment synthesis, degradation, and thylakoid damage. Carotenoids proved even more sensitive, showing the largest decreases under > 100 µm particles, high concentrations, and PS treatments, particularly in aquatic systems, yet they also displayed occasional stimulation at low doses, consistent with their dual role in both protection and photochemistry. Gas-exchange responses pointed to biochemical limitations at high MNP levels, with PS again exerting the strongest suppression of stomatal conductance and net photosynthesis. Among fluorescence parameters, ETR emerged as the most sensitive indicator of MNP stress. The review concludes by shedding light on the possibilities that may help alleviate impact of MNPs and pointing toward the studies still needed to fully understand how MNPs alter photosynthetic function.