Protective Effect of Exogenous Quercetin Against Salt Stress in Triticum aestivum and Triticum durum

Abstract

Various stress factors lead to increased reactive oxygen species (ROS) formation and increased damage to various plant tissues. Data obtained using fluorescence microscopy show that under abiotic stress, the most intense ROS staining is observed in the epidermal and cortical cells of the root cap and division zones. Increased ROS formation under abiotic stress activates the antioxidant system in wheat. The expression level of the MnSOD and Cu/ZnSOD genes in the Orenburgskaya 22 wheat variety (Triticum aestivum) is more than twice that in the Zolotaya variety (Triticum durum). An amount of 150 mM NaCl activates MnSOD and Cu/ZnSOD gene expression in the Orenburgskaya 22 wheat variety, increases glutathione (GSH) content, and activates GSH-associated enzymes. Therefore, different wheat genotypes have different mechanisms for neutralizing ROS. The antioxidant quercetin reduces ROS formation and also promotes antioxidant system activation in the Orenburgskaya 22 variety and has virtually no effect on the Zolotaya variety. However, it does reduce ROS before and after NaCl treatment in both wheat genotypes. Salt stress causes an increase in the number of small and large autophagosomes in root cells of Triticum durum wheat, while, in Triticum aestivum, large vacuoles not marked by ATG8 and small autophagosomes near the nucleus form in root cortex cells. Treatment of control plants with quercetin does not increase the number of autophagosomes. Treatment with quercetin after salt stress does not increase the number of ATG8-marked autophagosomes in cells of either genotype. Treatment with quercetin before salt exposure leads to an increase in the number of autophagosomes in durum wheat cells. PCR analysis of autophagy genes revealed features of the initiation of autophagosome formation. Thus, quercetin exerts a protective effect against salt stress. However, its use is limited to plants with high flavonoid content. Quercetin may have promising applications in agriculture.