Selenite-induced hormonal and signalling mechanisms during root growth of Arabidopsis thaliana L.

Abstract

Selenium excess can cause toxicity symptoms, e.g. root growth inhibition in non-hyperaccumulator plants such as Arabidopsis. Selenite-induced hormonal and signalling mechanisms in the course of development are poorly understood; therefore this study set out to investigate the possible hormonal and signalling processes using transgenic and mutant Arabidopsis plants. Significant alterations were observed in the root architecture of the selenite-treated plants, due to the loss of cell viability in the root apex. During mild selenite excess, the plants showed symptoms of the morphogenic response: primary root (PR) shortening and increased initiation of laterals, ensuring better nutrient and water uptake and stress acclimation. As well as lower meristem cell activity, the second reason for the Se-induced growth hindrance is the hormonal imbalance, since the in situ expression of the auxin-responsive DR5::GUS, and consequently the auxin levels, significantly decreased, while that of the cytokinin-inducible ARR5::GUS and the ethylene biosynthetic ACS8::GUS increased. It is assumed that auxin and ethylene might positively regulate selenium tolerance, since reduced levels of them resulted in sensitivity. Moreover, high cytokinin levels caused notable selenite tolerance. During early seedling development, nitric oxide (NO) contents decreased but hydrogen peroxide levels increased reflecting the antagonism between the two signal molecules during Se excess. High levels of NO in gsnor1-3, lead to selenite tolerance, while low NO production in nia1nia2 resulted in selenite sensitivity. Consequently, NO derived from the root nitrate reductase activity is responsible for the large-scale selenite tolerance in Arabidopsis.

Nitric oxide enhances selenium concentration by promoting selenite uptake by rice roots

“…Furthermore, the role of NO to promote Se concentration of rice seedling roots under Se IV supply was confirmed. Our data are consistent with the results of Lehotai et al () in the model plant Arabidopsis thaliana , but differ from those in Brassica rapa , in which Se itself triggered NR and NOS dependent generation of endogenous NO ( Chen et al, ).…”

Characterization, expression, and functional analysis of polyamine oxidases and their role in selenium‐induced hydrogen peroxide production in Brassica rapa

“…Beside plant hormones, nitric oxide has been reported to be a regulator of PAOs in plants . Se stress can modulate endogenous nitric oxide level through positive or negative pathways in plants . Therefore, further studies are needed to reveal the complicated role of nitric oxide in the regulation of PAOs in plants in response to Se stress.…”

An Overview of Selenium Uptake, Metabolism, and Toxicity in Plants

“…In another study, Se generated ROS initiated defense mechanism against Se stress (De Pinto et al, 2012). Previous studies reported that ROS accumulation under Se stress increased lipid peroxidation, cell mortality in Arabidopsis and Vicia faba (Lehotai et al, 2012; Mroczek-Zdyrska and Wójcik, 2012). Apart from plant cells, Wallenberg et al (2010) reported generation of mitochondrial superoxide in human cells under Se stress.…”