Heavy metal stress-inducible early light-inducible gene CaELIP from hot pepper ( Capsicum annuum) shows broad expression patterns under various abiotic stresses and circadian rhythmicity

► Expression of CaELIP is induced in green tissues upon illumination. ► Expression of CaELIP is circadian rhythmic. ► Expression of CaELIP is induced by abiotic stresses including heavy metal stress. ► Expression of CaELIP correlates to the production of reactive oxygen species. An early light-inducible protein gene ( CaELIP) was isolated from a cDNA library of hot pepper ( Capsicum annuum) that showed heavy metal stress-inducible expressions. This gene contains an open reading frame (ORF) encoding a protein of 160 amino acids, and the protein has significant homology with reported early light-inducible proteins from other plant species. Topology analysis for CaELIP suggested three transmembrane domains. Genomic DNA blot analysis showed that CaELIP is a single copy gene in hot pepper. The treatment of seedling roots of hot pepper with Cu induced ROS generation in the root, and the level of ROS generation was paralleled to the concentration of Cu that again was matched to the increase in the CaELIP expression level. Results suggested that expression of CaELIP can be induced by the ROS generated by the excessive Cu in the plant. Exogenous SA treatment significantly alleviated Cu-induced expression of CaELIP, while exogenous JA treatment aggravated expression of CaELIP under Cu stress. CaELIP showed a transient expression when exposing the plant to light for 1 h. CaELIP also showed an endogenous circadian rhythmicity with high expression level in the morning and decreased expression level thereafter. The expression of CaELIP was also induced by high or low temperature, high salinity, drought, and stress hormone ABA. Taken together, the results suggest that CaELIP would function in responding to environmental signals and possibly regulating the response to the abiotic stresses that can be related to the abiotic stress tolerance in plants.