24-Epibrassinolide and Sodium Nitroprusside alleviate the salinity stress in Brassica juncea L. cv. Varuna through cross talk among proline, nitrogen metabolism and abscisic acid

Soil salinity is one of the major environmental obstacles that limit the crop productivity. A pot experiment was conducted with an aim to explore the ameliorative effects of exogenously applied 24-epibrassinolide (EBL) and sodium nitroprusside (SNP) in alone and/or combination against salinity stress in Brassica juncea (L.) cv. Varuna. Plants were grown in earthen pots and were exposed to 100 mM NaCl. Further, 30 days old plants were sprayed with 24-epibrassinolide (EBL, 10(-6) M) and sodium nitroprusside (SNP, 100 mu M) solutions in alone and/or combination. Plant growth indices, gas exchange parameters, chlorophyll fluorescence, nitrogen and proline metabolism, malondialdehyde, electrolytic leakage and ABA content were analyzed. Salinity stress hampered the general plant growth, affected gas exchange parameters, chlorophyll fluorescence and nitrogen metabolism, showed increase in MDA, proline and ABA content while decreased electrolytic leakage and K+/Na+ ratio. The endogenous levels of ABA revealed significant increase in salinity treatment (12.25 mu g g(-1) FW) and approaching control value (4.31 mu g g(-1) FW) in combined EBL and SNP treatment. The present findings demonstrated that EBL and SNP application could protect the plants against salinity stress suggesting the involvement of nitric oxide and brassinosteroids in salinity stress amelioration through impact on nitrogen, proline and ABA metabolism.