AsNAC Genes: Response to High Mercury Concentrations in Allium sativum Seed Clove

Heavy metal contamination in soils is a growing concern due to anthropogenic activities, and <i>Allium sativum</i> (garlic) has shown tolerance to mercury pollution. We analyzed the physiological and molecular responses of garlic cloves exposed to HgCl₂ at 0, 5000, 23,000, and 46,000 mg/kg for 2, 3, and 4 h. The germination percentage was lower than 46,000 mg/kg Hg for 4 h. We also analyzed the expression levels of <i>NAC</i> transcription factors and found that <i>AsNAC11</i> had higher expression at 46,000 mg/kg at 2 h; <i>AsNAC17</i> was underexpressed and the maximum was at 2 h at 23,000 mg/kg. <i>AsNAC20</i> had the highest expression (30 times more than the control) at 3 and 4 h with 23,000 mg/Kg. <i>AsNAC27</i> showed the highest expression at 3 h with 23,000 mg/kg. The tissues exhibited a maximum Hg bioconcentration factor of 0.037 at 23,000 mg/kg, indicating moderate mercury absorption. However, at a concentration of 46,000 mg/kg, the BCF decreased to 0.023. Our in-silico analysis revealed that the analyzed <i>AsNACs</i> are associated with various abiotic stress responses. This study provides valuable insights into genes that could be utilized for genetic improvement to enhance crop resistance to mercury soil contamination.