Long-term copper (Cu2+) exposure impacts on auxin, nitric oxide (NO) metabolism and morphology of Arabidopsis thaliana L.

Abstract

Plants are able to dynamically adapt to their environment by reprogramming of their growth and development. Copper (Cu 2?) excess modifies shoot and root architecture of plants by a lesser known mechanism, therefore the involvement of a major hormone component (auxin) and a signal molecule (nitric oxide) in Cu 2?induced morphological responses were studied in Arabidopsis using microscopic methods. Auxin-inducible gene expression was visualized in DR5::GUS Arabidopsis and nitric oxide (NO) levels were detected by DAF-FM fluorophore in the stem and root system. Copper excess caused the inhibition of stem and root growth of Arabidopsis, during which cell elongation, division and expansion were also affected. The symptoms of stress-induced morphogenic response were found in the root system of 25 lM Cu 2?-treated plants. In both organs, the decrease of auxindependent gene expression was found, which can partly explain the growth inhibitions. Besides hormonal system, nitric oxide metabolism was also affected by Cu 2?. In root tips, copper excess induced NO generation, while NO content in lateral roots was not affected by the treatments. Using nia1nia2 mutants, nitrate reductase enzyme as a putative source of Cu 2?-induced NO was identified in Arabidopsis primary roots.

Modulation of CuO nanoparticles toxicity to green pea (Pisum sativum Fabaceae) by the phytohormone indole-3-acetic acid

“…Moreover, Katekar and Geissler (1982), reported that under chloride presence, pea plants form chlorinated indole acetic acid that has higher affinity than IAA for auxin receptors; thus, reducing the IAA activity in plants. In addition, Kolbert et al (2012), reported that in Arabidopsis thaliana, Cu stress decreased the auxin-dependent gene expression, resulting in a reduction of root growth. Fig.…”

24-epibrassinolide mediated regulation of endogenous contents of auxins, abscisic acid, lipids and sugars in Brassica juncea L. under copper stress

“…Cu at high concentrations affects the auxin content in the cotyledons and apices of primary roots of Arabidopsis [29]. Cu led decline in the auxins levels was reported by Kolbert et al [30] in Arabidopsis thaliana L. plants, which was responsible for the decrease in the growth of plants. IAA application enhanced the total FW of Musa sp.…”

Regulatory Role of Nitric Oxide in Alterations of Morphological Features of Plants Under Abiotic Stress

“…Interestingly, there was no difference between wild-type (WT) and a NO-overproducing mutant A. thaliana seedlings in response to exposure to Cu 2+ in excess (Peto et al 2011), suggesting a very minor role, if any, for NO being an endogenous signal in the morphological response to heavy metal stress. However, this interpretation might be complicated by the auxin homeostasis in the same tissue under the same stress (Peto et al 2011;Kolbert et al 2012).…”

“…It would also seem that NO might play a minor role in the morphological response of cotyledons under abiotic stress. However, other parallel experiments studying auxin metabolism and transport in the wild-type, NO-overproducing, and NO-deficient A. thaliana seedlings in response to Cu 2+ treatments revealed a more complex network of antagonistic relationships between NO levels and auxin homeostasis (Peto et al 2011;Kolbert et al 2012). This has added implications to the conceptual framework that there are cross talks among ROS, auxin, and ethylene, which have already been considered as the important signals in the SIMRs (Potters et al 2009).…”