Differential morpho-physiological and metabolic responses of various genotypes of Andrographis paniculata to atmospheric dust stress.

The detrimental effect of airborne toxic metals is a major threat to the productivity of agricultural crops. For sustainable agriculture, it is essential to explore the tolerance of different cultivars and genotypes to atmospheric deposition. This study investigated the impact of atmospheric deposition on different genotypes of Andrographis paniculata (G1, G5, G6, and G11) at two polluted sites and one control site. The physiological and metabolic responses, as well as the subcellular localization of airborne toxic metals, were examined. Results indicated that genotypes (G11 and G5) with rough and wrinkled surfaces exhibited more epidermal cell collapse due to increased atmospheric dust deposition, leading to reduced growth and higher accumulation of toxic metals (Pb, Cd, and As) in the leaves. The subcellular distribution of toxic metals showed a lower concentration of toxic metals in organelles, and soluble fractions were observed in the G1 genotype. The variation in the activities of enzymes involved in sucrose synthase, sucrose phosphate synthase, neutral invertase, and acid invertase was associated with a trade-off between energy storage and combating oxidative stress. Multivariate analysis demonstrated that variations in carbohydrate metabolism enzymes and the total and reducing sugars among genotypes were linked to the subcellular distribution of airborne toxic metals. The nitrogen metabolism enzyme glutamate dehydrogenase increased across all genotypes at the low-polluted site and decreased at the highly polluted site. Among all genotypes, G1 showed lower metal accumulation and higher growth at both polluted sites. Overall, dust assimilation, metabolic adaptability, and subcellular metal localization are key factors influencing the resilience of each genotype against atmospheric deposition.