Enhanced nitric oxide generation in root transition zone during the early stage of cadmium stress is required for maintaining root growth in barley

Abstract

Background and Aims The objective of this study was to analyse the role of nitric oxide (NO) in relation to reactive oxygen species (ROS) production and root growth inhibition in the early response of barley root tip to cadmium. Methods We used cell-permeable NO-binding dye DAF-2DA for the NO localization and cellimpermeable dye DAR-4M for the quantification of NO in barley root apex. Results A considerable increase in NO production was detected in the transition zone of root tips already 30 min after the immersion of barley roots into 15 μM Cd. This Cd-induced NO generation further increased during the recovery period and reached its maximum level 2 h after the short-term treatment. At this stage an enhanced Cd-induced NO generation was observed in the meristematic, transition and in the beginning of elongation zone in comparison with control roots. Inhibitor of NO synthase activity markedly reduced root growth in control seedlings and had a synergistic growth inhibitory effect with Cd. On the contrary, this Cdinduced root growth inhibition was markedly alleviated by the NO donor. Exposure of roots to Cd markedly increased the production of ROS in the proximal elongation zone of root. While NO did not affect ROS generation, inhibition of its synthesis slightly decreased ROS generation in both control and Cd-treated roots. Conclusions Our results revealed that enhanced NO production is a very early response of barley root to Cd stress and it is involved in the regulation of root growth mitigating Cd-induced root growth inhibition.

Cross Talk between Nitric Oxide and Phytohormones Regulate Plant Development during Abiotic Stresses

“…Evidence obtained in Arabidopsis suggests interplay between ET and NO for upregulation of genes (AtFIT, AtbHLH39, AtFRO2, AtNAS1, AtNAS2, AtFRD3, AtMYB72) related to Fe-deiciency [82]. Although, it is well reported that enhanced NO generation helps to maintain root growth under Cd stress [83]; however, the exact role of NO under excess Fe conditions is rudimentary and demands further investigation.…”

Nitric oxide induced by polyamines involves antioxidant systems against chilling stress in tomato (Lycopersicon esculentum Mill.) seedling

“…Therefore, it still needs to be clarified whether they did encode relative genes or affect enzyme synthesis. Furthermore, we also examined the contents of NO in tomato leaves after treatment with tungstate, an inhibitor of NR, and L-NAME, an inhibitor of NOS (Besson-Bard et al, 2009;Xiong et al, 2012;Alemayehu et al, 2015;Sun et al, 2015). In this experiment, the two inhibitors (Figs.…”

Evaluation of three wheat (Triticum aestivum L.) cultivars as sensitive Cd biomarkers during the seedling stage

“…Firstly, the root elongation may have been blocked in the elongation zone due to oxidative stress. The early exposure of roots to Cd significantly increases the production of reactive oxygen species in the root's proximal elongation zone, which could be alleviated by the NO donor (Alemayehu et al, 2015). Also, the boosted NO and O 2− production is required for Cd-induced programmed cell death that is in turn induced by Cd in Lupinus luteus L. roots (Arasimowicz-Jelonek et al, 2012).…”