RESUMEN
Light emitting diodes (LEDs) as an alternative light source for plants had shown to enhance the plant material quality. Indian borage or Plectranthus amboinicus (Lour.) Spreng, a medicinal herb produces carvacrol as the major volatile organic compound (VOC). Histolocalization of VOCs and expression pattern of the terpenoid biosynthesis genes after spectral light treatment is not yet reported in P. amboinicus. This work investigated the morpho-physiological, biochemical and transcriptional responses towards red, green, blue, warm white and red-blue (RB, 1:1) LEDs treatment at 40 ± 5 µmol m-2 s-1 light intensity after 40 days. Maximal growth index (GI), leaf fresh weight and dry weight were obtained in RB (1:1) treated plants. There was one-fold increase in phenolics content and 2.5-fold increase in antioxidant activity in comparison to warm white. High quantity of terpenes and phenolics deposition were observed in the glandular trichomes of RB (1:1). Maximum carvacrol accumulation (14.45 µmol g-1 FW) was also detected in RB (1:1). The transcript levels of early terpene biosynthesis genes PaDXS, PaDXR, PaHMGR and cytochrome P450 monooxygenase genes, PaCYP1 and PaCYP9 were highly upregulated in RB (1:1) and green. The overall results suggest RB (1:1) as the better lighting option amongst the studied spectral lights for obtaining maximum phytochemicals in P. amboinicus. Work is being continued with different spectral ratios of red and blue LED lights to maximize phytochemical accumulation, the outcome of which will be reported elsewhere in near future. Supplementary Information: The online version contains supplementary material available at 10.1007/s00344-023-11028-6.
RESUMEN
The present study focuses on the emitted and endogenous scent profiles of Uvaria hamiltonii flowers. Among the 34 compounds identified, sesquiterpenoids were found to dominate the floral volatiles composition. Profiles from endogenous scent volatiles showed higher number of compounds than the emitted ones. The anthocyanin pigment responsible for the flower colour was also explored. It was found that a single anthocyanin compound, cyanidin-3-O-glucoside, was principally responsible for petal colour. Total phenolic content was evaluated and antioxidant capacities were studied with the help of DPPH, FRAP and ABTS assays. The total phenolic content and the antioxidant capacity were higher in methanolic extract as compared to aqueous, petroleum ether and ethyl acetate extracts of U. hamiltonii flowers.
