Research Physiological Response And Antioxidative Mechanism Of Wheat (Triticum Aestivum L.) Seedings Under Copper Or Cadmium Stress

Heavy metal is a very important environmental pollutants, if the cultivation media is thought to be contaminated by heavy metals, it will not be easyly eliminate in short time. So, in load cultivating conditions of heavy metal research that the mechanism of migration, enrichment, toxicity, detoxification and resistance in wheat plant, the measures of insured security of producting area and avoided the soils were polluted and adopted cleanly producting technology were key about carrying out the safe wheat production, were also important research task. This study selected the half-winter wheat of Ai-kang 58 as research subject, through the hydroponic experiment, imitate to study the effect of accumulation regularity of Cu, Cd, the distribution of intracellular content, the change of chemical form, and the wheat seeding growth under Cu²⁺,Cd²⁺ stress, as well as the mineral elements absorption. Methods the Real-time fluorescent quantitative PCR (Real-time Q-PCR) was employed to analysis that the discrepancy of antioxidant enzymes and genes expression during the stress process of wheat roots. The main research results are as follows:1. The wheat growth and development was directly influenced under Cu²⁺, Cd²⁺ stress. The high concentrations of Cu²⁺, Cd²⁺ inhibit the growth of root and leaf, dry matter accumulation and root elongation. In the same concentration, the inhibitory effect of Cd²⁺ was relatively more intense than that of Cu²⁺.2. Supplied from the exogenous of Cu²⁺, there was a positive correlativity of the content of Cu, Cd or accumulation and treatment of concentration in the roots and leaves. And the content of Cu²⁺, Cd²⁺ in roots was higher than in leaves.3. Cu²⁺,Cd²⁺ showed a disparity to the different of metal and concentrations and treatment times in the distribution of cellular elements in wheat seeding. Cell walls are the major storage tank of Cu²⁺ stress, while cytosine took second place. Just the reverse, cytosine was the major storage tank of Cd²⁺ stress, while cell walls took second place. And that including mitochondria, chloroplast, nucleus, and other important components in the cytoplasm of organelles heavy metal content were the lowest. Thus it can be seen that the important measures was took advantage and eliminated disadvantage as well as protected their own tissues in order to avoiding the accumulation of Cu and Cd in major functional organs.4. Chemical form of Cu, Cd in wheat plants is correlates closely to the content of exogenous of Cu, Cd and treatment time. The advantage lay with inorganic slat and amion acids with significant activity extracted by 80% alcohol of Cu(NO₃)₂ and CuCl₂ in wheat plants under Cu²⁺ stress. Extractable concentrations in the shape of Nacl had the highest content under Cd²⁺ stress, including the pectin, protein combination and adsorption states and other forms, can decrease the toxicity aroused by the activity of plant growth metabolism.5. To analysis the relationship of exogenous Cu²⁺, Cd²⁺ and other mineral elements for K, Ca, Mg, Na, Fe, Mn, Zn and B in wheat seeding, found that the antagonism to the absorb of K, Ca, Mg, Mn, Zn and B under Cu²⁺ stress in wheat seeding. Cd²⁺ stress had the effects of inhibiting the absorb K, Zn, Mg, Na, Fe Mn and B. And the restrain absorb of nutritive element to the Cd²⁺ was higher than the Cu²⁺.6. Compared with between the activity change and gene expression of antioxidative enzymes in the roots of triticum aestivum L. in response to the stress of Cu²⁺ and Cd²⁺, results showed that times, concentrations and the interaction of them had significant differences. Moreover, the enzyme activity of the three antioxidants under Cu²⁺ stress was significantly lower than that under Cd²⁺ stress to the same conditions, the changes of enzymes activity showed that SOD was higher than the POD and GST. But, at mRNA level had an obviously adverse effect on Cu²⁺ stress, three antioxidative enzyme genes also showed that the GST gene expression was higher than POD and Cu/ZnSOD under the stress of Cu²⁺. Analyzed the different types of heavy metal stress, there was a disagreement between activity change and gene expression of antioxidative enzymes, it was speculated that at the level of regulation on transcription and translation exists space and time treated unequally, also because there are different transcription slicing and post translation modification.