Abstract
Cadmium (Cd) is an important industrial agent and environmental pollutant that is a major cause of plants disease. This study was conducted to investigate the impact of Cd on the physiological and molecular traits of garlic growth and active constituent. The garlic cloves were irrigated with different concentrations of Cd. The obtained results show that the measured pigments and total soluble sugars decreased with increased Cd concentration in growth medium. Meanwhile protein and proline content increases due the important role of proline as osmoregulation of plants, stabilization the protein synthesis machinery and an effective singlet oxygen quencher. Cd supports the activity of antioxidant enzymes (catalase, peroxidase, polyphenol oxidase and superoxide dismutase) as a defense system ROS detoxification during normal metabolism and particularly during stress. Alliinase gene expression in the green leaves of garlic plants was negative correlated with Cd stress. The maximum expression were observed at low concentration of Cd (5 and 10 mM). Higher doses of Cd cause a great reduction in allicin production in garlic leaves.