Different effects of calcium and penconazole on primary and secondary metabolites of Brassica napus under drought.

The effects of penconazole (PEN) and calcium (Ca2+) on physiological and biochemical parameters were investigated in two canola cultivars (RGS003 and Sarigol) under water stress. Drought increased protein content in RGS003, but PEN, Ca2+ and PEN-Ca2+ treatment induced protein content in Sarigol. PEN, Ca2+ and PEN-Ca2+ treatment enhanced soluble sugar content in RGS003. In contrast to Sarigol, drought and PEN treatment induced total phenol content in RGS003. Flavonoid content increased by drought, but Ca2+ and PEN-Ca2+ treatment decreased it in both cultivars. Ca2+ and PEN-Ca2+ treatment enhanced tocopherol content in both cultivars under drought stress. Drought stress increased Phenylalanine ammonia-lyase (PAL) activity in Sarigol. PEN-Ca2+ treatment increased relative expression of PAL and its activity in RGS003. Fatty acid composition was modified by drought, PEN and Ca2+. Saturated fatty acid (stearic acid) content declined but unsaturated fatty acid (oleic acid) content enhanced in both cultivars under drought. The application of PEN and Ca2+ decreased unsaturated fatty acids (linoleic and linolenic acid) in RGS003 under drought. According to our results, PEN and Ca2+ changed physiological and biochemical parameters and therefore these compounds are suggested for reduction of the negative effects of drought stress in canola.