Modulating the antioxidant system by exogenous 2-(3,4-dichlorophenoxy) triethylamine in maize seedlings exposed to polyethylene glycol-simulated drought stress

Abstract

Maize (Zea mays L.), an important agricultural crop, suffers from drought stress frequently during its growth period, thus leading to a decline in yield. 2-(3,4-Dichlorophenoxy) triethylamine (DCPTA) regulates many aspects of plant development; however, its effects on crop stress tolerance are poorly understood. We pre-treated maize seedlings by adding DCPTA to a hydroponic solution and then subjected the seedlings to a drought condition [15% polyethylene glycol (PEG)-6000 treatment]. The activities of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and glutathione reductase (GR) were enhanced under drought stress and further enhanced by the DCPTA application. The activities of monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and catalase (CAT) declined continuously under drought stress; however, the activities partially recovered with DCPTA application. Up-regulation of the activities and transcript levels of APX, GR, MDHAR and DHAR in the DCPTA treatments contributed to the increases in ascorbate (AsA) and glutathione (GSH) levels and inhibited the increased generation rate of superoxide anion radicals (O2·−), the contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA), and the electrolyte leakage (EL) induced by drought. These results suggest that the enhanced antioxidant capacity induced by DCPTA application may represent an efficient mechanism for increasing the drought stress tolerance of maize seedlings.

Exogenous DCPTA Increases the Tolerance of Maize Seedlings to PEG-Simulated Drought by Regulating Nitrogen Metabolism-Related Enzymes

“…In this study, the increased contents of total amino acids, serine, glycine, valine, isoleucine, leucine, tyrosine, lysine, histidine, methionine, and arginine and the decreased contents of soluble protein in seedlings exposed to PEG-simulated drought stress may have been due to the promotion of protein degradation and the suppression of protein biosynthesis by inadequate supplies of reducing potential (in the form of NADPH and ATP) due to reduced photosynthesis (Table 4, Figure 9) [62,63]. Exogenous DCPTA weakened these effects induced by PEG-simulated drought stress, which may be attributed to the alleviation of stress-induced photosynthetic inhibition and oxidative damage, as demonstrated in our previous studies [26,27].…”

“…In our previously reported results, DCPTA was proven to increase the drought tolerance of maize seedlings under hydroponic conditions [26,27]. However, the underlying molecular mechanisms remain poorly understood.…”

“…These data show that exogenous DCPTA affected NR-involved mRNA levels and enzymatic protein synthesis rather than simply causing enzymatic activity increases, and the de novo synthesis of enzymatic proteins may be key to the increased NR activity under PEG-simulated drought conditions. Our previous study showed that exogenous DCPTA significantly decreased the accumulation of ROS by increasing their scavenging via elevation of antioxidant enzyme activities and improving the redox state of ascorbate and glutathione [27]. The increased NR activity may partly be attributed to exogenous DCPTA alleviating drought-induced oxidative damage by modulating the antioxidant system in maize seedlings.…”

“…Our previous study demonstrated that DCPTA applications could increase the drought tolerance of maize by improving the photosynthetic capability [26], modulating the antioxidant system [27], and ameliorating the soil drought effects on N metabolism in maize during the pre-female inflorescence emergence stage [28]. To further investigate the possible mechanism of the exogenous DCPTA-promoted drought tolerance of maize seedlings, this work was designed to address the following questions: (1) How do transcripts change in maize seedlings in response to drought stress and/or exogenous DCPTA?…”

Exogenous 2-(3,4-Dichlorophenoxy) triethylamine ameliorates the soil drought effect on nitrogen metabolism in maize during the pre-female inflorescence emergence stage

“…Our previous hydroponic trial found that exogenous DCPTA drastically promoted growth under non-stress conditions and mitigated the PEG-simulated drought-induced growth inhibition of maize at the seedling stage by improving photosynthetic capacity [20] and modulating antioxidant system [21]. The present study was conducted to explore whether DCPTA can alleviate soil drought injuries to maize and whether the effects are associated with the modulation of N metabolism.…”