Aryadeep Roychoudhury

Melatonin is a known pleiotropic antioxidant and signaling molecule, found in both plants and animals. Although melatonin was found to translocate via the human glucose transporter 1 (GLUT1), any mechanism of transporter‐mediated uptake of melatonin has remained unknown in plants. In the present manuscript, we found an orthologue of GLUT1 in tobacco and established its role as a functional phytomelatonin transporter (MelT) using fluorescence tracking, via melatonin‐conjugated quantum dot nanoparticles. Overexpression of NtMelT in the model plant Nicotiana benthamiana showed increased uptake of the conjugated nanofluorophores to a maximum of 5.4‐fold in roots and 2.1‐fold in leaves, while application of N ‐ethylmaleimide (inhibitor of glucose transporter) suppressed their translocation. This ensured the specificity of NtMelT for transporting melatonin. Due to increased uptake and distribution, the transgenic lines maintained a maximum of 4.6‐fold more endogenous melatonin. The transgenics were tolerant against arsenic, copper, lead, nickel, and fluoride toxicity. Increased activity of the enzymatic antioxidants detoxified excess reactive oxygen species and alleviated the associated physiological injuries. Translocation of melatonin significantly reduced bioaccumulation of the toxic pollutants and ensured normal flowering and seed setting in the transgenic plants. Overall, the present research provides a solution for safe rice cultivation under polluted environment.

The present manuscript represents the identification and predictive structural characterization of novel human GLUT1-orthologue, melatonin transporter (Mel

The aim of this study was to decipher the reprogramming of protective machineries and sulfur metabolism, as responses to time-dependent effect of fluoride stress for 10 and 20 days in two indica rice (Oryza sativa) varieties. Unregulated accumulation of fluoride via chloride channels (CLC1 and CLC2) in 10-day-old (cv. Khitish) and 20-day-old (cv. MTU1010) seedlings caused higher accumulation of H2O2 and superoxide anion that eventually incited chlorophyll loss and electrolyte leakage, along with the formation of malondialdehyde and methylglyoxal. Higher fluoride accumulation also enhanced lipoxygenase and NADPH oxidase activities, which further aggravated the oxidative damages. However, for stressed 20-day-old Khitish and 10 day-old MTU1010 seedlings, plant growth was maintained with lesser oxidative damages due to upregulated expression of H+-ATPase and FEX along with the elevated level of cysteine and H2S, which could be linked with higher activity of ATP-S, OASTL, and DES. The activity of the enzymatic antioxidants (superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, and glutathione peroxidase) and level of non-enzymatic antioxidants (anthocyanins and flavonoids) were also enhanced that strengthened the antioxidative potential of the seedlings. Our work demonstrated that differential reprogramming of the protective metabolites and sulfur assimilation pathways is responsible for the differential pattern of adaptive strategies against fluoride stress in the two indica rice varieties, with Khitish exhibiting tolerance against long-term fluoride stress, whilst MTU1010 showing high susceptibility to the same.