Abiotic stress–induced inhibition of root growth and ascorbic acid oxidase activity in barley root tip is associated with enhanced generation of hydrogen peroxide

Abstract

Using short-term treatments, the aim of this study was to analyze the role of hydrogen peroxide in the regulation of AAO activity during Cd, Cu or IAA treatments in barley root tips. For analysis individual barley root segments were obtained by the gradual cutting of each root from the tip to the base 1, 2, 3 or 6 h after short-term treatments. Already a short 30 min exposure of barley roots to Cd induced significant root growth inhibition in a Cd concentration dependent manner, which was accompanied by a marked reduction of AAO activity. At Cu concentration which had no effect on the root growth a significant increase in AAO activity was observed. This increased AAO activity was detected only in ionically-bound CW fraction. In contrast, Cu at higher concentration and IAA inhibited both ionically-bound CWAAO isozymes. Prompt inhibition of AAO activity immediately after short-term treatment was observed only in the case of H 2 O 2 treatment suggesting that H 2 O 2 may act as an inhibitor of AAO. This was further supported by the observation that all Cd-, Cu-or IAA-induced root growth and AAO activity inhibition in barley roots was connected with an elevated production of H 2 O 2 .

Cadmium-induced reactive oxygen species generation, changes in morphogenic responses and activity of some enzymes in barley root tip are regulated by auxin

“…In Arabidopsis root apex, a marked IAA accumulation was observed afBrought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 6/13/15 3:15 PM ter Cu exposure, which was probably responsible for the reorganization of root system architecture such as root hair and lateral root formation (Lequeux et al 2010). In addition to morphogenic changes, it has been previously reported that exposure of roots to either Cd or IAA evoked similar changes in enzyme activities such as inhibition of AAO or stimulation of LOX activity (Zelinová et al 2011;Alemayehu et al 2013). Taken together, the results of this study and previous observations strongly indicate that Cd-induced morphogenic responses and some changes in enzyme activities are induced by changes in IAA redistribution and accumulation.…”

“…In addition, abiotic stress-induced growth inhibition is often accompanied by a marked reduction in AAO activity (Pignocchi et al 2003;Zelinová et al 2011). In the present work we have shown that despite a significant alleviation of Cd-induced root growth inhibition by the pre-treatment of Cd-treated seedlings with 1-NOA or PCIB, AAO activity decreased in comparison with only Cd-treated seedlings, suggesting that the inhibition of AAO activity is probably not directly involved in the Cd-induced reduction of root growth.…”

“…Our previous studies have revealed that Cd-induced H 2 O 2 generation reaches its maximum 3 h, while changes in enzymes activity and root morphology fully developed only 6 h after the short-term treatment with Cd (Zelinová et al 2011;Tamás et al 2012;Alemayehu et al 2013;Zelinová et al 2013). Therefore, in this study we analysed the effect of TIBA, 1-NOA or PCIB on the Cdinduced alteration in IAA content and ROS production in barley root tip 3 h after the short-term treatments.…”

“…On the other hand, its marked inhibition was observed after the exposure of seedlings to Cd, Cu, hydrogen peroxide or IAA accompanied by a marked root growth inhibition (Zelinová et al 2011).…”

Hydrazine Hydrate and Dissolved Oxygen-Triggered Near-Infrared Chemiluminescence from CuInS2@ZnS Nanocrystals for Bioassays

“…The recovery in human serum was 97.4–102% with the RSD smaller than 5% ( n = 3) (Table ). Importantly, as the CL of the proposed signal-off NIR CL sensor could be completely quenched with 800 μM AA, a signal-on NIR CL biosensor was further proposed to detect AAO by catalyzing the oxidation of 800 μM AA with AAO . The linear range for determining AAO was 1–75 mU/mL, and the linear equation was I / I 0 = 0.04 [AAO] + 0.98 ( R 2 = 0.9992, Figure S6 and Table S3).…”