ABSTRACT Acid rain (AR) has been reported to induce stress in plants affecting its productivity, growth, flowering and physiology. The molecular changes induced in plants due to the effect of acid rain or acid induced orientation or chloroplast streaming remains largely unknown. Therefore, in the current study we report for the first time the static and permanent changes in the cell of the medicinal plant Bacopa monnieri L. due to sulphur-simulated acid rain (S-SiAR). AR induced effects witnessed by the reduction of the size of starch granules and chloroplast, amount of the granules per unit area, dissolving cell walls, breaking the normal fiber, salt-induced strain in the various components of the cell. Effect of starch granule and chloroplast due to S-SiAR was analyzed using light, confocal and scanning electron microscopic techniques. The elements viz. potassium and magnesium present in the chloroplasts reveal acidic pH due to effect of S-SiAR observed by the ionization of Mg and K (to Mg2+ and K+), in which K+ induced by the effects of S-SiAR revealed a net negative Nernst potential of about -87.55 mV. Calcium is mainly present on the cell walls and responsible for binding of starch granules become ionized to Ca2+ on interacting with AR indicated by the altered Nernst potential of +137.04 mV. A net potential difference may cause the above streaming of chloroplast towards the large starch granules. From this study, we report AR-induced physiological changes in medicinal plant Bacopa monnieri L. for the first time.
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