Cadmium toxicity promotes hormonal imbalance and induces systemic resistances in barley

Abstract

Cadmium (Cd) is a widely distributed pollutant that adversely affects plants’ metabolism and productivity. Phytohormones play a vital role in the acclimation of plants to metal stress. On the other hand, phytohormones trigger systemic resistances, including systemic acquired resistance (SAR) and induced systemic resistance (ISR), in plants in response to biotic interactions. The present study aimed to investigate the possible induction of SAR and ISR pathways in relation to the hormonal alteration of barley seedlings in response to Cd stress. Barley seedlings were exposed to 1.5 mg. g− 1 Cd in the soil for three days. Cd accumulation resulted in a reduction in the nutrient content of barley seedlings. The specific activity of superoxide dismutase and the content of hydrogen peroxide significantly increased in response to Cd toxicity. The content of abscisic acid, jasmonic acid, and ethylene increased under Cd exposure. Cd treatment resulted in the upregulation of NPR1, PR3, and PR13 genes in SAR pathways. The transcripts of PAL1 and LOX2.2 genes in the ISR pathway were also significantly increased in response to Cd treatment. These findings suggest that hormonal-activated systemic resistances are involved in the tolerance of barley to Cd stress.