Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Defense Is a Key Factor

Relative tolerance of different species of Brassica to cadmium toxicity: Coordinated role of antioxidant defense and glyoxalase systems

“…A similar result was obtained by Nouairi et al, (2006), in which the total chl content reduction of B. juncea was significantly lower than B. napus. Abiotic stresses at the molecular level accelerate the production of ROS such as 1 O 2 , O 2 •− , H 2 O 2 , and OH • (Hasanuzzaman et al, 2012a). In our study, excessive production of H 2 O 2 and O 2…”

“…An increased level of GSSG may be due to the oxidation of GSH to GSSG during the scavenging process of ROS . Toxic metals increase GSH content, which scavenges ROS with the help of GPX and GST (Hasanuzzaman et al, 2012a;Szalai et al, 2009). In the present study, GPX increased significantly compared with the control plants in all the Brassica species tested.…”

“…Glutathione is often considered an important intracellular antioxidant of the AsA-GSH cycle, and the GSH/GSSG ratio in particular has a vital function in the redox status and stress signaling processes. Therefore, higher GSH/GSSG is considered to support improved abiotic stress tolerance including toxic metal stress (Gill and Tuteja, 2010;Hasanuzzaman et al, 2012a). Cd stress significantly increased the GSH levels in all three Brassica species, compared with the control seedlings, and the highest increase was observed in B. juncea.…”

“…In plant cells, SOD constitutes the frontline defense against ROS and it catalyzes and converts O 2 •− to H 2 O 2 (Hasanuzzaman et al, 2012a). Previous research findings showed that Cd stress increases SOD activity Rahman et al, 2016).…”

“…Plants can also work against Cd stress through metal chelation, exclusion, active excretion or compartmentalization (Gratão et al, 2005). Moreover, to minimize oxidative stress plant cells are equipped with antioxidant defense system composed of nonenzymatic antioxidants (ascorbic acid, AsA; glutathione, GSH; phenolic compounds; alkaloids; nonprotein amino acids and α-tocopherols) and enzymatic antioxidants (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; and glutathione S-transferase, GST) (Pang and Wang, 2008;Gill and Tuteja, 2010;Hasanuzzaman et al, 2012a). Plants also have an MG detoxification system including two vital enzymes, glyoxalase I (Gly I) and glyoxalase II (Gly II), where GSH acts as co-factor.…”