Differential response of antioxidative systems of maize (Zea mays L.) roots cell walls to osmotic and heavy metal stress

Abstract

An analysis of peroxidase and ascorbate oxidase activity, phenolic content and antioxidant capacity of isolated maize root cell walls was performed in controls and plants stressed with polyethylene glycol (PEG) or heavy metals, zinc or copper. Peroxidase activity (oxidative and peroxidative) was more pronounced in the ionic than in the covalent cell wall fraction. PEG induced an increase and Zn(2+) a decrease of both ionically bound peroxidase activities. In the covalent fraction, Cu(2+) decreased oxidative and increased peroxidative activity of peroxidase. Isoelectric focusing of ionically bound proteins and activity staining for peroxidase demonstrated increased intensities and appearance of new acidic isoforms, especially in Zn(2+) and PEG treatments. Most pronounced basic isoforms (pI ~ 7.5) in controls, decreased in intensity or completely disappeared in stressed plants. Ascorbate oxidase activity was significantly increased by PEG and decreased by Zn(2+) treatments, and highly correlated with peroxidase activity. Antioxidant capacity and total phenolics content increased in heavy metal-treated and decreased in PEG-treated plants. Analysis of individual phenolic components revealed p-coumaric and ferulic acids, as the most abundant, as well as ferulic acid dimers, trimers and tetramers in the cell walls; their quantity increased under stress conditions. Results presented demonstrate the existence of diverse mechanisms of plant response to different stresses.

Water Stress Effect on Cell Wall Components of Maize (<i>Zea mays</i>) Bran

“…Alvarez et al (2008) analysed xylem sap of ʽFR697ʼ maize cultivar after 12 days of drought treatment and they observed the same pattern of hydroxycinnamic acids composition of the present study, reporting that t-ferulic acid was the predominant with a decreasing of 46% of this compound after drought treatment and this result was higher than the current experiment, in addition p-coumaric acid increased 286% which is a different behaviour comparing with the current results. Vuletić et al (2014), analysed the effect of osmotic stress in root cell walls of the maize inbred line ʽVA35ʼ and they found that content of total phenols diminished 30%, which is in agree with this results, but they also found a different behaviour in the analysis of hydroxycinnamic acids since they observed an increase of 49 and 18% in t-ferulic acid and p-coumaric respectively.…”

Growth Stimulatory Effects and Genome-Wide Transcriptional Changes Produced by Protein Hydrolysates in Maize Seedlings

“…Moreover, ROS, such as H 2 O 2 and ${\text{O}}_2^{-}$ are known secondary messages in several pathways associated with responses to biotic and abiotic stresses in plants (Apel and Hirt, 2004). Aside from their anti-oxidative activity, peroxidases are the most abundant enzymes in the cell wall where they display a multifunctional activity, also related to growth regulation (Vuletic et al, 2014). Peroxidases exist in multiple forms exhibiting different cellular localization and playing numerous biological functions.…”

Modification of antioxidant systems in cell walls of maize roots by different nitrogen sources

“…The most abundant phenolic constituents of maize root cell walls are ferulic and p-coumaric acids (Vuletić et al, 2014) esterified with arabinoxylan (Hatfield et al, 1999) and lignin (Hatfield & Chaptman, 2009), respectively. Much greater increase in DPPH scavenging activity than in reducing power in the same cell wall isolates could be ascribed to the presence of ferulic acid esters, being extremely potent as DPPH radical scavengers and possessing weaker reducing power than free ferulic acid (Szwajgier et al, 2005).…”

“…In both cell wall fractions, mixed N induced the increase of MDH activities (>40%) in lateral roots only, while in primary roots the activity was decreased (Table 5). Ascorbate oxidase activity was found to be predominantly covalently bound (~ 95% of total activity) to the cell walls (Vuletić et al, 2014), and thus the effects of N forms were analyzed in NaCl-washed cell wall suspension. The activity was higher in nitrategrown plants (Table 6), in both lateral (27% increase) and primary roots (24% increase).…”