Ecotype-specific responses of Typha domingensis to microplastics: Antioxidant defense and biochemical adaptations in wetland ecosystems

The inherent ability of plants to withstand microplastic (MP) stress is primarily governed by complex structural and physio-biochemical adaptations. In this study, the MP tolerance mechanisms of six naturally occurring ecotypes of Typha domingensis Pers. were assessed by examining plant pigments, ionic homeostasis, secondary metabolites, and antioxidant defense responses in MP-contaminated wetlands. Data were analyzed using one-way ANOVA and PCA ( n = 6), with significance at P ≤ 0.05. Significant variations were observed among ecotypes in plant growth, physiology, and biochemical responses. Marala Headworks (Eco-6) and River Jhelum (Eco-1) ecotypes displayed the maximum shoot and root biomass, indicating greater tolerance to MPs. Conversely, ecotypes i.e., Aik Drain (Eco-3) and River Ravi (Eco-5) exhibited the lowest biomass, suggesting heightened sensitivity to MP toxicity. Chlorophyll a and b contents varied significantly, with Eco-1 showing the highest and Eco-5 the lowest concentrations. Antioxidant enzyme (SOD, POD, and CAT) activities were significantly elevated in Eco-6, while Eco-5 showed the lowest activity. MP exposure led to increased malondialdehyde (MDA) levels, particularly in Eco-3 and Eco-5, highlighting damages due to oxidative stress. Influence of different MPs in all ecotypes was evident in terms of total soluble sugars and total free amino acids. Mineral ion contents, including sodium, potassium, and nitrogen, also varied significantly among ecotypes after exposure to MP. Heavy metals (Cr, Pb, As, Ni, Cd) and oxidative stress markers correlated positively with MP concentration. Analysis revealed distinct MP polymer compositions and shape distributions among ecotypes. The findings underscore the complex interplay between MPs, heavy metals, and plant physiology, necessitating further research on mitigation strategies for wetland ecosystems. • Ecotype-specific responses of Typha to MP contaminated wetlands were delineated. • Pigment loss and biomass drop differ among Typha ecotypes. • Eco-6 and Eco-1 showed high adaptability under MP toxicity by sustaining elevated biomass. • Superior tolerance of Eco-6 was linked to elevated antioxidant capacity. • PS and PVC types as well as fragments and film shapes remained the most abundant MPs.