Differential responses of phenolic compounds of Brassica napus under drought stress.

This work evaluated the effect of drought stress on seedling growth, protein, soluble sugars, and phenolic compounds of two cultivars of canola (RGS003 and Sarigol). Drought stress was induced with polyethylene glycol (PEG) at 0, 5, 10, and 15%. Drought stress increased root fresh weight in both cultivars and the effect of drought was more pronounced in RGS003. Shoot fresh weight reduced in Sarigol at 10 and 15% of PEG. Drought stress significantly increased seedling fresh weight in RGS003. Sarigol accumulated higher amounts of protein as compared to RGS003. At all PEG concentrations, the soluble sugars contentwas higher in Sarigol as compared to control. Total phenol content was enhanced at higher drought level (15%) while flavonol content increased at lower level (5%) in both cultivars. Phenylalanine ammonia-lyase (PAL) activity and its relative expression were increasedin RGS003 at 10% of PEG. Overall, RGS003 cultivar had more capacity to tolerate drought stress than Sarigol cultivar.     .