Effect of Brassinosteroids on Germination and Seedling Growth of Radish (Raphanus sativus L.) under PEG-6000 Induced Water Stress

Kommavarapu Mahesh, Parshavaneni Balaraju, Bellamkonda Ramakrishna, Sadhu Seeta Ram Rao

Osmania University, Hyderabad, India.

DOI: 10.4236/ajps.2013.412285                

Abstract

Effect of 24-epibrassinolide and 28-homobrassinolide on the germination and seedling growth of radish (Raphanus sativus) subjected to water stress being imposed by 15% (w/v) polyethylene glycol (equivalent to -2.95 bars of osmotic pressure) was studied. Brassinosteroids supplementation reduced the inhibitory effect of water stress on seed germination and seedling growth. The growth stimulation in radish seedlings by brassinosteroids under desiccation stress was associated with elevated levels of nucleic acids and soluble proteins and lowered activities of RNase. The mitigation of osmotic stress imposed by PEG was associated with increased scavenging of reactive oxygen species as reflected in elevated activities of superoxide dismutase, catalase and ascorbate peroxidase. Brassinosteroids also enhanced the accumulation of the osmolyte free proline in radish seedlings challenged with drought stress. The two brassinosteroids also maintained membrane integrity under water deficiency conditions as indicated by lowered lipid peroxidation reflecting in reduced MDA content. The results of present study demonstrate the protective role of brassinosteroids against PEG imposed water stress in radish seedlings.

Keywords

24-Epibrassinolide; 28-Homobrassinolide; Antioxidative System; Malondialdehyde; Polyethylene Glycol-6000; Radish; Water Stress

Conflicts of Interest

The authors declare no conflicts of interest.

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