Cd-induced cytotoxicity and its HO-1 and ROS quenching enzyme-mediated regulation in 2–3 leaf stage seedlings of Sorghum bicolor: An important millet crop of the arid & semi-arid regions

Cadmium is a non-essential trace metal element with no known biological function. Cd is toxic to both plants and human beings; hence, it is of prime concern to the scientific community. The objective of this research is to find out the effect of heme oxygenase 1 on Cd toxicity in Sorghum bicolor seedlings. Hydroponically adapted seedlings were treated to various concentrations of Cd within the range of 10 to 200 μM. Seedlings were harvested after 120 h of Cd stress. The cellular homeostasis and metal tolerance mechanisms were conducted to evaluate growth parameters, stress parameters (MDA and H₂O₂ content), non-enzymatic and enzymatic parameters (CAT, APX and GPX) including HO 1. The results showed that HO 1 activity was measured to be highest in leaves at 150 μM CdCl₂, which was 29.61 %.The HO 1 activity was correlated with the MDA content and antioxidant enzymes activity at this Cd concentration. The highest activity of HO 1 was revealed through the decrease of GPX and CAT activities. Consequently, HO 1 works within a cohort that helps the development of the plant's defense mechanisms by scavenging ROS, which is confirmed by the time-dependent study. Accordingly, our research highlighted that HO 1 might increase the efficiency of stress tolerance by enhancing antioxidant defence mechanisms against Cd toxicity in S. bicolor.