The effect of salinity stress on activity of some antioxidant enzymes and expression of genes coding calcium-dependent protein kinase as the key determinants of salt tolerance in canola

Salinity stress is one of the most important abiotic stresses affecting the yield of oilseed rape. To study the physiological and biochemical changes, and expression BnaCDPK6, BnaCDPK 10 genes in rapeseed (Brassica napus L.). Two tolerant cultivars (Slm046 and Zarfam) and two susceptible cultivars (Okapi and Sarigol) were planted in a growth chamber and were irrigated by 100 and 200 mM NaCl and normal water. Studied parameters include relative water content, malondialdehyde, the enzyme activity of antioxidant enzymes (Superoxide dismutase and Catalase) and the expression of calcium-dependent protein kinase 6 and 10 coding genes (BnaCDPK6, 10).  The result indicated the relative water content and malondialdehyde with a high level of salt (200 mM NaCl) decreased and increased under stress respectively. The antioxidant enzymes Superoxide dismutase and Catalase content and BnaCDPK6 and BnaCDPK10 expression increased by high severity salinity stress that tolerant cultivars showing more increase. These results indicated that increasing the reactive oxygen species due to salt stress plays an important role in damaging cell membrane in canola, and the plant increases its protective mechanisms against the production of reactive oxygen species by increasing the activity of antioxidant enzymes and an increase in the expression of calcium-dependent protein kinase genes expression.