Growth and physiological alterations related to root-specific gene function of LrERF061-OE in Glycyrrhiza uralensis Fisch. hairy root clones under cadmium stress

Abiotic stresses, particularly heavy metals, are a threat to living organisms, including plants. Heavy metals activate ethylene biosynthesis and ultimately stimulate reactive oxygen species (ROS)-related gene expression to enhance stress tolerance. The identification and functional analysis of such stress-related genes is very important to increase the stress tolerance of valuable plants to heavy metals. Ethylene responsive factor ERF061 belongs to the ERF transcription factor family, controls plant growth and ontogenesis and regulates abiotic stress in model plant species. Therefore, in this study, we examined the tolerance function of LrERF061 via an overexpression vector in the growth and physiology of G. uralensis hairy roots under cadmium (Cd) stress. The effect of different Cd concentrations (0, 25, 50, 75, 100 mg/L) on the growth and physiology of LrERF061-OE hairy roots (LrE-HR) and control hairy roots (LrC-HR) of G. uralensis was measured. Initially, at low cadmium concentrations, there was a stimulating effect of Cd on G. uralensis LrE-HR and LrC-HR. However, at high cadmium doses, the growth of LrC-HR was retarded compared to that of LrE-HR. Intriguingly, a significant increase was observed in the relative expression level of LrERF061-OE in LrE-HR at 100 mg/L Cd. According to the results, compared to LrC-HR (11 mg/g), LrE-HR showed maximum Cd uptake (81 mg/g) at high Cd concentrations. The antioxidant enzyme activities (SOD, CAT and POD) in LrE-HR were enhanced at high Cd concentrations compared to those in LrC-HR. This work first highlighted the effect of LrERF061-OE, which is upregulated under Cd stress in G. uralensis hairy root clones, on heavy metal tolerance. Current study for the first time aimed to evaluate effect of ethylene responsive transcription factor (LrERF061) under Cd stress on growth and physiological properties of Glycyrrhiza uralensis hairy root clones.