Epibrassinolide induces changes in indole-3-acetic acid, abscisic acid and polyamine concentrations and enhances antioxidant potential of radish seedlings under copper stress

Abstract

In the present study, the effects of epibrassinolide (EBL) on indole‐3‐acetic acid (IAA), abscisic acid (ABA) and polyamine (PA) tissue concentrations and antioxidant potential of 7‐day‐old Raphanus sativus L. cv. ‘Pusa chetki’ seedlings grown under Cu stress were investigated. EBL treatment alone or in combination with Cu enhanced free and bound IAA titers when compared with the metal alone. Modest increases in free and bound ABA contents were observed for EBL treatment alone. However, the combination of EBL with Cu caused major increases in both forms of ABA, over Cu alone. Among the PAs analyzed, only putrescine and cadaverine concentrations were enhanced by EBL treatment alone. By contrast, a significant decline in putrescine and spermine contents was found in seedlings treated with EBL plus Cu. EBL treatments alone or in combination with Cu enhanced activities of guaiacol peroxidase (EC1.11.1.7), catalase (EC 1.11.1.6), superoxide dismutase (EC 1.15.1.1) and glutathione reductase (EC 1.6.4.2) and protein contents in comparison with metal and control treatments. A major decrease in malondialdehyde content was also recorded for EBL treatments with or without Cu. An increase in phytochelatin content was also observed in seedlings treated with EBL alone or in combination with Cu. Major improvement in radical scavenging activities, as attested by the antioxidant activity assay using DPPH (1,1‐diphenylpicrylhydrazyl), and elevated deoxyribose and reducing powers, along with increased contents of ascorbic acid, total phenols and proline, also suggest a major influence of EBL application in mitigating copper‐induced oxidative stress in radish seedlings.

24-epibrassinolide mediated regulation of endogenous contents of auxins, abscisic acid, lipids and sugars in Brassica juncea L. under copper stress

“…There occurs crosstalk between BRs and abscisic acid which is helpful in stress alleviation. Our results are supported by the results of Choudhary et al [26]. They observed an enhancement in the endogenous content of abscisic acid in Raphanus sativus under Cu stress with the application of EpiBR.…”

“…Negative effects of Cu stress on shoot and root weight of Hordeum vulgare and Sinapis alba were observed by Gvozdenac et al [24], and on shoot weight of Phaseolus vulgaris were observed by Ashagre et al [25]. We observed an improvement in the [26] in the seedlings of Raphanus sativus. Cu adversely affects the plant growth which subsequently reduces the plant biomass in terms of reduced shoot and root weights.…”

“…Reduction in ROS reduces lipid peroxidation and the subsequent damaging effects on the biomembranes organisation. Reduction in the MDA content and so the lipid peroxidation with the coapplication of 24-EpiBR with NaCl was reported in Oryza sativa L. [42] and also with its co-appication with Cu in Raphanus sativus seedlings [26].…”

Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene

“…Therefore, it is possible that plant brassinosteroids have sufficient affinity with the rat gluco-corticoid receptor protein to be connected to their signaling chain through the recognition of molecules expressed by the constitutive CaMV promoter inserted in the transformation construct. Brassinosteroids have been shown to induce tolerance to a wide range of abiotic stresses (Kagale et al, 2007;Bajguz, 2011;Sittayat et al, 2007;Arora et al, 2010a;Koh et al, 2007) through the activation of anti-oxidative stress systems (Arora et al, 2010b), as well as the enhanced synthesis of abscisic acid (Yuan et al, 2010), ethylene, salicylic acid (Divi et al, 2010), polyamines and indole-3-acetic acid (Choudhary et al, 2010(Choudhary et al, , 2011. Responses to stress in plants, moreover, are known to be activated by increased levels of auxins, which in turn determines feedback interaction with flavonoid synthetic patterns (Peer and Murphy, 2007;Lewis et al, 2011) and crosstalk with brassinosteroid transcription process (see Depuydt and Hardtke (2011) for an extensive review).…”

Crosstalk of brassinosteroids with other phytohormones under various abiotic stresses

“…Recent advancement showed that abiotic and biotic stresses facilitate elevation in free PA content by exogenous application of BR which helps to mitigate Cu-oxidative stress [77,78]. Besides, BR treatment keeps up the ideal measure of spermidine fixation required for typical plant development and particularly enhanced the production of putrescine required for stress tolerance, however, diminishes the concentration of cadaverine which produces oxidative burst to balance substantial metal stress [79].…”