European Journal of Biotechnology and Bioscience

Authors
Deepak Singh Bagri, Deepak Kumar, Devanshi Chandel Upadhyay, Ram Prasad and Chandrama Prakash Upadhyay

Abstract
Brass inosteroids (BRs) are a group of plant growth steroidal hormones present in very low concentrations in seeds, pollen and young plant tissues, reported to be involved in plant development as well as protection of plants against various biotic and abiotic stresses. In this study, we report the amelioration of salt, drought and heavy metal stress by the application of of 24-epibrassinolide (EBR) on in vitro and ex vitro grown tomato (Lycopersicon esculentum L. cv. Pusa Ruby). A reduction in seed germination and growth parameters such as shoot length, total leaf area and plant dry weight was observed seen under these stresses. However, these parameters showed enhanced values with the application of EBR showing either in vitro or ex-vitro conditions. Significant increases in total chlorophyll, proline contents and nitrate reductase (EC 1.6.6.1) activities were observed in tomato treated with EBR when compared to their respective stress controls. The activities of antioxidant enzymes ascorbate peroxidase (EC 1.11.1.11), catalase (EC 1.11.1.6), dehydroascorbate reductase (EC 1.8.5.1), glutathione reductase (EC 1.6.4.2) and superoxide dismutase (EC 1.15.1.1) enhanced in tomato under NaCl, drought or heavy metal stresses and their activities further enhanced with the application of EBR. The endogenous levels of indole-3-acetic acid (IAA) and abscisic acid (ABA) elevated significantly in the leaves of tomato seedlings and plants treated with EBR compared to stress controls. This is the first comprehensive report confirming the protective role of EBR in imparting plant tolerance to major abiotic stresses under both in vitro and ex vitro conditions.