Modulation of Exogenous Glutathione in Ultrastructure and Photosynthetic Performance Against Cd Stress in the Two Barley Genotypes Differing in Cd Tolerance

Abstract

Greenhouse hydroponic experiments were conducted using Cd-sensitive (Dong 17) and tolerant (Weisuobuzhi) barley genotypes to evaluate genotypic differences in response of photosynthesis and ultrastructure to Cd toxicity in the presence of exogenous glutathione (GSH). Addition of 20 mg L(-1) GSH in 5 μM Cd culture medium (Cd + GSH) significantly alleviated Cd-induced growth inhibition and reduced Cd concentration in leaves and roots especially in the sensitive genotype Dong 17. Exogenous GSH greatly ameliorated Cd-induced damages on leaf/root ultrastructure, e.g., compared with Cd alone treatment, chloroplasts in plants treated with Cd + GSH become better or in relatively normal shape with well-structured thylakoid membranes and parallel pattern of lamellae and unfolded more starch grains but less osmiophilic plastoglobuli; nuclei of root cells were better formed and chromatin distributed more uniformly in both genotypes, and number of plastids and mitochondria cristae in Dong 17 resumed to control level. The examination of photosynthetic performance revealed GSH dramatically increased net photosynthetic rate (P(n)), stomatal conductance (G(s)), and transpiration rate (T(r)) in the both genotypes and strongly stimulated Cd-induced decrease in the maximal photochemical efficiency (F(v)/F(m)) especially in the sensitive genotype.

Alleviation of cadmium toxicity in cucumber (Cucumis sativus) seedlings by the application of selenium

“…In the present experiment, considerable increased Fo and reduced Fv/Fm were observed in cucumber under Cd stress. Similar results were observed in rice, soybean, tobacco and barley (Kao et al, 2003;Cai et al, 2011;Wang et al, 2011;Liu et al, 2015), however, there was no significant different in Y(NO) under Cd stress in comparison with control (Fig. 4).…”

Glutathione in plants: biosynthesis and physiological role in environmental stress tolerance

“…Exogenous GSH resulted in the increase of plant dry weight in the following two barley varieties: Weisuobuzhi (by 42.3%) and Dong 17 (by 70.6%). The reduced shoot/root Cd concentrations of 33.8/42.2% in Weisuobuzhi and 59.4/66.3% in Dong 17 relative to the Cd alone treatment reflects that GSH can suppress plant Cd uptake (Wang et al 2011). …”

“…Bergmann and Rennenberg (1993) also demonstrated a time-dependent increase in GSHS activity in same species upon exposure to Cd. Wang et al (2011) reported some injury symptoms, such as leaf chlorosis, necrosis and stunting in barley seedlings when subjected to Cd (5 lM). However, the addition of GSH (20 mg L -1 ) in the Cd culture medium can alleviate the Cd-induced growth inhibition and leaf injury symptoms significantly.…”

“…The improved membrane and anatomical structures were due to the antioxidant functions of GSH. The mechanisms underlying the improvement in physiological processes under stress indicates various others roles for GSH which deserve further research (Wang et al 2011). Chen et al (2010) studied the antioxidant functions of GSH that enhanced Cd stress tolerance in rice.…”

“…Exogenously applied GSH can improve abiotic stress tolerances in plants (Kattab 2007;Salama and AlMutawa 2009;Wang et al 2011;Wu et al 2011;Chen et al 2012;Nahar et al 2015a, b, c). In this review, we concentrate on the biosynthesis and metabolism of GSH and its roles in plants under environmental stress conditions, focusing on recent research findings on GSH and abiotic stress tolerance.…”