Genotoxicity Of Heavy Metals And Their Accumulation And Transfer In Hordeum Vulgare

The heavy metal cadmium (Cd), lead(Pb), copper(Cu), chromium(Cr) is a kind of environmental pollutant with stronger toxicity in agricultural ecosystems,which greatly influences the growth and development, physiological and genetic metabolic of the plant. In this paper Hordeum vulgare is selected as the material in the experiment. Indoor foster method is applied to study the effects of Cd²⁺, Pb²⁺, Cu²⁺, Cr⁶⁺ in different concentrations (5 mg·L^-1, 10 mg·L^-1, 20 mg·L^-1, 40mg·L^-1, 80 mg·L^-1) on Hordeum vulgare from the aspects of accumulation and migration, some physiological and biochemical indicators of molecular and genomic DNA damage. The results are as follows:The dynamic changing rule of Cd²⁺,Pb²⁺,Cu²⁺,Cr⁶⁺ of different concentrations on absorbing,accumulating and distributing in barley seedling. The results shows that with the increasing of the treatment concentrations, the content of four heavy metals in barley seedling increased; with the time increasing, the content of heavy metal in roots of the barley seedling presents the trend of reducing after rising, while the content of heavy mental in the stems and leaves is like this: first rising, then falling, then rising. By comparing the content of four heavy metals in the barley seedling its accumulating order in the roots is Pb²⁺>Cu²⁺>Cd²⁺>Cr⁶⁺; in the stems and leaves is Cu²⁺>Cd²⁺>Pb²⁺>Cr⁶⁺ ;the ability of transferring from roots to stems and leaves is Cu²⁺>Cd²⁺>Cr⁶⁺>Pb²⁺. The content of heavy metals in the roots was more than in the stems and leaves.Effects of Cd²⁺,Pb²⁺,Cu²⁺,Cr⁶⁺ in different concentrations on the soluble sugar, soluble protein and ATPase activity in leaves of barley seedling are studied. The results indicated that under the poisoning of Cd ,Pb ,Cu ,Cr , (1) the soluble sugar content in barley seedling leaves gradually reduces with the concentration and processing time increasing. (2) the soluble protein content of barley seedling leaves rapidly declining with Cd²⁺,Cr⁶⁺, Pb²⁺concentration increased, whereas with Cu²⁺ dealing with the barley, the formation of the soluble protein content in the leaves is promoted under the low density, and is inhibited and formatted under the high density. (3) Cd²⁺,Cr⁶⁺ on barley seedlings can inhibit the ATPase activity, for with the performance of the Cd²⁺,Cr⁶⁺ concentration increasing and processing time extending, ATPase activity of barley seedling leaves gradually declines. Cu ,Pb on the activity of ATPase presents the trend of promoting in the low concentrations and inhibiting in the high concentration, for the performance of the activity of the ATPase increases first, then declines with the Cu²⁺,Pb²⁺ concentration. The influence of Cd , Pb , Cu , Cr stress upon the content of DNA of the barely seedling and its damaging effect of the DNA in the root of seedlings. The results indicated that (1) the content of DNA in the roots and leaves of barely seedling decreases with the treatment of Cd²⁺,Pb²⁺,Cu²⁺,Cr⁶⁺ and the content of DNA in the roots decreases greatly than that in the leaves. (2) Different kind of heavy mental treatment causes different DNA damaging form to the barley seedling. With the treatment of Cu the DNA hyperchromic effects higher than the compared ones shows that Cu²⁺ treatment in the trialed intensity causes DNA fragmentation of the barley seedlings. With the treatment of Pb²⁺ the DNA hyperchromic effects lower than the compared ones shows that Pb²⁺ treatment in the trialed intensity causes DNA cross-linking of the barley seedlings. The treatment of Cd²⁺,Cr⁶⁺ the DNA hyperchromic effects has the trend of increasing first, then decreasing, which shows that low concentration of Cd²⁺,Cr⁶⁺ causes DNA fragmentation the barley seedlings, the high concentration of them leads to DNA cross-linking. (3) The changes occurring in random amplified polymorphic DNA(RAPD) profiles of barley seedling following Cr⁶⁺ treatment includes appearance of new bands and loss of normal bands and variation in band intensity compared with the normal seedlings. These changes of DNA polymorphisms are positive correlation with the Cr⁶⁺ concentration.