Abstract:Thymol is a famous plant-derived compound that has been widely used in pharmacy due to its antioxidant and antimicrobial properties. However, the modulation of intrinsic plant physiology by thymol remains unclear. It is a significant challenge to confer plant tolerance to Cd (cadmium) stress. In the present study physiological, histochemical, and biochemical methods were applied to investigate thymol-induced Cd tolerance in tobacco (Nicotiana tabacum) seedlings. Thymol was able to alleviate Cd-induced growth inhibition of tobacco seedlings in both dose-and time-dependent manners. Both histochemical detection and in-tube assays suggested that thymol treatment blocked Cd-induced over-generation of reactive oxygen species (ROS), lipid peroxidation, and loss of membrane integrity in both leaves and roots. Thymol decreased Cd-induced cell death that was indicated in vivo by propidium iodide (PI) and trypan blue, respectively. Thymol stimulated glutathione (GSH) biosynthesis by upregulating the expression of γ-glutamylcysteine synthetase 1 (GSH1) in Cd-treated seedlings, which may contribute to the alleviation of Cd-induced oxidative injury. In situ fluorescent detection of intracellular Cd 2+ revealed that thymol significantly decreased free Cd 2+ in roots, which could be explained by the thymol-stimulated GSH biosynthesis and upregulation of the expression of phyochelatin synthase 1 (PCS1). Taken together, these results suggested that thymol has great potential to trigger plant resistant responses to combat heavy metal toxicity, which may help our understanding of the mechanism for thymol-modulated cell metabolic pathways in response to environmental stimuli.

No abstract

No abstract

No abstract

BACKGROUND Selenium (Se)‐induced phytotoxicity has been linked to oxidative injury triggered by the accumulation of reactive oxygen species (ROS) due to the disturbance of anti‐oxidative systems. However, the way Se stress induces hydrogen peroxide (H2O2) production in plants is a long‐standing question. Here we identified the role of polyamine oxidase (PAO) in H2O2 production in the root of Brassica rapa upon Se stress. RESULTS Studying Se‐induced growth inhibition, H2O2 accumulation, and oxidative injury in the root of Brassica rapa, we found that excessive Se exposure resulted in a remarkable increase in PAO activity. Inhibition of PAO activity led to decreased H2O2 content and alleviated oxidative injury in the Se‐treated root. These results indicated that Se stress induced PAO‐dependent H2O2 production. A total of six BrPAO family members were discovered in the genome of B. rapa by in silico analysis. Se stress pronouncedly upregulated the expression of most BrPAOs and further transient expression analysis proved that it could lead to H2O2 production. CONCLUSION These results suggest that Se stress upregulates the expression of a set of BrPAOs which further enhances PAO activity, contributing to H2O2 generation in roots. © 2019 Society of Chemical Industry