Low temperature tolerance is depressed in wild-type and abscisic acid-deficient mutant barley grown in Cd-contaminated soil

The accumulation of heavy metals in soil, especially cadmium (Cd), may influence the tolerance of crops to other abiotic stress, such as low temperature. In this study, the low temperature tolerance of abscisic acid (ABA)-deficient mutant (Az34) barley and its wild-type (WT) irrigated with Cd solution (1 g L−1) was tested. It was found that Cd aggravated the destruction of chloroplast ultrastructure and disturbed the ion homeostasis under low temperature. The presence of Cd increased the reactive oxygen species (ROS) accumulation, along with the depressed antioxidant enzyme activities, and limited the plant growth. Compared with WT, Az34 plants had lower ROS scavenging ability and decreased maximum quantum efficiency of PS II (Fv/Fm) under Cd and low temperature. In addition, the C-repeat binding factor and cold response (CBF-COR) signaling pathway was negatively affected by Cd treatment under low temperature, which also reduced the low temperature tolerance in barley. Therefore, it was indicated that the Cd reduced the low temperature tolerance in barley, that highlighted the potential risks of depressed low temperature tolerance caused by Cd pollution in barley.