| The element Pb2+and Cu2+are two important environmental pollutants, which long-trems existence in our soil-ecological system with the characteristic of easy to accumulation and difficult to be degraded. Excess of Pb2+and Cu2+in siol environment will decline the fertility of soil, reduce the quality of agricultural products, meanwhile, can be harmful to human health through the food chain. Four genotypes foxtail millet from Shanxi, China were selected in this paper as the material in the experiment. The pot culturing method is applied to foster the foxtail millet seedlings. This study examined the uptake, accumulation and the distribution characteristics of Pb2+, Cu2+in four genotypes foxtail millet seedlings and the eco-physiological charateristics of foxtail millet response to Pb, Cu stress, meanwhile, random amplified polymorphic (RAPD) technology were used to study the diffences on the DNA damage effect of foxtail millet. The main results are as follows:The accumulation amount of Pb2+, Cu2+in foxtail millet seedlings had a dose-response relationship with the treatment concentration, the accumulation of roots were significantly higher than that of leave and stems. From the absorption and transportation capacity, we can indicated that the absorption capacity of Pb2+was higher than Cu2+, but the transpotation ability was Cu2+much higher than that of Pb2+. The transportation ability of D2-8and An06from roots to stems and leaves was much better than that of Zhaogu and Huangmi.Pb2-and Cu2+had different degrees inbition on the root length, the shoot length and the biomass of four foxtail millet seedlings. The shoot length, root length and biomass all decreased under Pb2+pollution, but Cu2+showed stimulation under low concentrations and inhibition of higher concentrations. Four genotypes of foxtail millet seedlings response to Pb2+, Cu2+stress had a significant interspecific difference. The inhibit effects of Pb2+on the root length, the shoot length and the biomass was greater than that of Cu2+of four foxtail millet seedlings.The influence of Pb2+, Cu2+on the content of chlorophyll, soluble protein, soluble suger, malondialdehyde (MDA) and proline were differences.(1) Different concentrations of Pb2+inhibited the synthesis of chlorophyll of four foxtail millet seedlings, but Cu2+stimulated the chlorophyll synthesis at low concentrations (less than100mg·kg-1), but inhibite at high concentrations (more than200mg·kg-1).(2) The soluble protein content of foxtail millet seedlings were gradually decreased with the rising of Pb2+concentrations, which had significant differences compared with the control(P<0.05).(3)Pb2+induced a significant inhibited effect on the synthesis of soluble suger of four foxtail millet seedlings, while Cu2+pollution make the soluble suger content firstly declined, and then increased with increasing of Cu2+concentrations.(4) Within the Pb2+, Cu2+concentration range, the content of MDA of four foxtail millet seedlings were gradually increased with the rising of treatment concentrations, expose to400mg·kg-1reach the maximum value, all the treatment group had significant differences with the control(P<0.05).(5) The proline content of four foxtail millet seedlings was increased at first and decreased subsequently with the increasing of Pb2+, Cu2+concentration. From the effects on the growth indexes and physiological indices, it was found that the ecophysiological-and geno-toxicities of Pb2+on foxtail millet seedlings was higher than Cu. The tolerance order of Pb2+was An06>D2-8>Huangmi>Zhaogu, and the tolerance of Cu2+was D2-8> An06> Zhaogu>Huangmi.Pb2+and Cu2+stress can make signicant damage effect to genomic DNA of foxtail millet seedlings.(1) The content of DNA in foxtail millet seedlings decreased with the concentration of Pb2+, the treatment of Cu2+showed that low concentrations promote the synthesis of DNA, high concentrations gradually decread the synthesis.(2)DNA hyperchromic effects with the intend of initial increased followed by decline in four foxtail millet seedlings in response to the rising Pb2+, Cu2+concentration, whichi showed that low concentrations of Pb2+and Cu2+cause DNA fragmentation, the high concentrations of them lead to DNA cross-linking.(3)The changes in the RAPD fingerprints under Pb2+, Cu2+stress included the variation of band intensity, loss of normal bands and appearance of new band, in comparison with the control. The genomic DNA of foxtail millet was significantly affected by Pb2+than that of Cu2+.The result indicated that the damage effect of Pb2+on the primary strecture of foxtail millet seedlings was stronger than that of Cu2+. |
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