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

作者：Nóra Lehotai, Zsuzsanna Kolbert, Andrea Pető, Gábor Feigl, A. Ordog, Devanand Kumar, Irma Tari, László Erdei · 发表于：Journal of Experimental Botany · 年份：2012 · DOI：10.1093/jxb/ers222 · 被引用次数：149 · 研究领域：Selenium in Biological Systems、Plant Stress Responses and Tolerance、Plant Micronutrient Interactions and Effects

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,...