Effects Of Different Heavy Metals On The Physiological Indexes And The Reaction Oxygen Scavenging System Of Arabidopsis Thaliana

As one kind of environmental pollutants,heavy metal in excess could be toxic for the growth of plant.By degenerating proteins and disrupting the membrane selectivity,heavy metals prevent the normal metabolic activities within plants.In addition,heavy metals can also lead to the accumulation of reactive oxygen species?ROS?,the oxidative damage of bio-macromolecules and even cell death.During evolution,plants have acquired a complicated system to scavenge the ROS and thus respond efficiently to heavy metal stresses.Such a system could be divided into two categories,e.g.the enzymatic system and the non-enzymatic system.The enzymatic system includes antioxidant enzymes such as superoxide dismutase?SOD?,ascorbic acid peroxidase?APX?,catalase?CAT?and glutathione reductase?GR?.The non-enzymatic system includes antioxidant agents such as ascorbic acid and glutathione.In recent years,studies on heavy metal stress and how plants respond to heavy metals have become one of research hot spots.In this study,taking one model system,Arabidopsis thaliana,as the research objective,the morphological characters and biochemical changes of plants upon various heavy metal treatments were investigated.On one hand,the contents of ROS including H₂O₂ and MDA were measured to indicate the extent of oxidative damage and on the other hand,the enzymatic activities of GSH,SOD and APX,which are related to the capacity of the reactive oxygen scavenging system,were also determined.Meanwhile,using the real-time quantitative PCR technique,the expression level of genes involved in ROS scavenging process were analyzed in order to explore the protective mechanisms of plants at the gene transcriptional level.In summary,this work studied the effects of heavy metals on plant growth through multiple analytical methods.The results showed that various heavy metals affected the vegetative and productive growth of Arabidopsis thaliana differentially and induced distinct responses in plant metabolism and gene expression related to the ROS scavenging system.