Exogenous Application of 28-Homobrassinolide Modulates the Dynamics of Salt and Pesticides Induced Stress Responses in an Elite Rice Variety Pusa Basmati-1

Abstract

Brassinosteroids play an essential role in regulating various aspects of plant growth and development as well as adaptation to various environmental stresses. The present work provides an analysis of the response of various stress markers upon exogenous application of 28-homobrassinolide (HBL) on Pusa Basmati-1, a commercially important rice variety, under salt and pesticide (Chlorpyrifos and Imidacloprid) stress. Rice seeds treated with HBL were analyzed for various growth parameters, protein, proline and malondialdehyde content (MDA), antioxidant enzyme activities, and their gene expression analysis (Cu/Zn-SOD, Fe-SOD, Mn-SOD, APX, CAT, and GR) in the presence or absence of salt and pesticide stress. Stress-induced reduction in growth, protein, and chlorophyll content and enhancement of proline and MDA content of seedlings was observed. The exogenous application of HBL resulted in the improvement of growth parameters as well as protein and proline content. MDA content decreased significantly under the effect of HBL treatment both under stress and control conditions. HBL treatment also enhanced the activity of various antioxidant enzymes which corroborated with the reduced accumulation of O 2 ⋅- and H2O2 under the effect of salt and pesticides. The differential response of various isoforms of SOD under the effect of HBL and stress treatments was observed under salt and among different pesticide treatments. From this study, the potent activity of HBL in stress mitigation in response to salt and pesticide treatment in rice is established.