Abstract
The present study examined the interactive effects of fluoride and phthalates on their uptake, generation of reactive oxygen species and activation of antioxidative defence responses in Spirodela polyrhiza L. Schleiden. A hydroponic study was conducted in which S. polyrhiza cultured in Hoagland’s nutrient medium, was exposed to fluoride (50 ppm) and different concentrations viz., 75, 150 300 ppm of diethyl phthalate (DEP) and diallyl phthalate (DAP) individually as well as in combination for the time period of 24, 72, 120 and 168 h respectively. A significant decline in fresh weight, dry to fresh weight ratio, total chlorophyll, carotenoid content and increased anthocyanin content was observed. Fluoride and phthalates was found to be readily accumulated by S. polyrhiza in all the exposure periods. Interestingly, when binary treatments were given in nutrient medium, uptake of both fluoride and phthalate was found to be influenced by each other. In combined treatments, DEP stimulated fluoride uptake, while its own uptake was restricted by fluoride. In contrary to this, fluoride stimulated DAP uptake. Moreover, combined stress further caused significant decrement in carbohydrate, protein content and increment in MDA levels, phenolic content and electrolyte leakage. Nevertheless, phthalates showed more pronounced oxidative stress and growth inhibition compared to fluoride. To cope up with the oxidative damage, enhanced level of antioxidant enzymatic activities was observed in S. polyrhiza under both fluoride and phthalate stress as compared to control. Scanning electron microscope imaging of leaf stomata revealed that combined stress of fluoride with phthalates caused distortion in the shape of guard cells. Confocal micrographs confirmed the generation of reactive oxygen species, cell damage, disruption in membrane integrity, and enhanced levels of glutathione in plant cells. This study focussed on ecotoxicological and interactive significance of fluoride led phthalate uptake or vice versa which was also assumed to confer tolerance attributes.
Highlights
In today’s modern world, the widespread use of inorganic and organic compounds for agricultural and industrial purposes has induced dramatic influence on physical, chemical and biological characteristics of environment
Plant stimulate the activation of various antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), peroxidases like ascorbate peroxidase (APX) and guaiacol peroxidase (GPOX) as well as glutathione reductase (GR)
Chromatographic separation of mixed sample containing diethyl phthalate (DEP) and diallyl phthalate (DAP) was shown in (Supplementary Fig. 1) where two peaks were obtained separated from baseline and without any interference peak
Summary
In today’s modern world, the widespread use of inorganic and organic compounds for agricultural and industrial purposes has induced dramatic influence on physical, chemical and biological characteristics of environment. It is necessary to unravel the ecotoxicological and combined effects of stressors on specific living organisms which act as an early warning bioindicators[1,3,4,5] In this present investigation, we analysed the individual and joint toxic effects of fluoride and two phthalates, namely DEP and DAP on physiological and biochemical attributes of S. polyrhiza. PEs are unable to bind covalently to the plastic which force them to leach out into the environment and deteriorate the environmental health Their tendency to bioaccumulate in living organisms induced endocrine disruption, malformations and reproductive disorders which is a matter of serious concern[10]. This study is a dedicated attempt in this perspective to investigate tolerance and defense strategies of S. polyrhiza to combined effect of fluoride and phthalates on growth parameters, accumulation of fluoride and phthalates content, pigments (chl a, chl b, total, carotenoids and anthocyanins), carbohydrate, protein, lipid peroxidation, proline, electrolyte leakage, phenols, antioxidant enzymatic activities (SOD, CAT, APX, GPOX and GR), stomatal movements and cell viability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
