Comprehensive Analysis of Heavy Metal-Associated Domain Containing Genes Using Nitric Oxide-Mediated Transcriptomic Analysis in Arabidopsis

Metal ions play important roles in cellular and subcellular processes in both animals and plants. Heavy metal associated domain (HMA) containing genes encode small identical proteins of 69 to 73 amino acid in length mostly associated with transport of metal ions in and out of the cell. They are very important for spatio-temporal transportation of metal ions for binding with various enzymes and co-factors. We identified 16 different Arabidopsis HMA genes differentially expressed in response to nitrosative stress induced by infiltrating 1 mM CysNO (S-nitrocysteine) into the leaf apoplast. Out of the 14 genes, expression of 8 HMA genes was increased, whereas, the expression of 6 genes was reduced. Computational characterization of HMA genes from Arabidopsis revealed the presence of a highly conserved Cys-XX-Cys motif within the HMA domain which may be target for S-nitrosylation and trans-nitrosylation. Promoter analysis also revealed the presence of important Cis-regulatory elements within a region 1.5 kb upstream of the transcriptional initiation site such as TCA element, CAAT, TATA-box. Further characterization of HMA gene through functional genomics showed that at1g51090 plants were resistant to the bacterial pathogen Pseudomonas syringae(DC3000). Additionally, this gene positively regulates shoot development while negatively regulates root development under oxidative stress (induced by H₂O₂ and Methyl Vilogen) and nitrosative stress conditions induced by (CysNO and GSNO). Overall, these results imply that HMA domain containing genes may play important role in plant development and immunity.