Analysis About Genetic Diversity Of Soil Bacteria In Replant And Fertility Apple Orchard In Bohai Apple-planting Area

In this study, we used T-RFLP and DGGE to study and compare soil bacterial diversity and community structure of three samples which had serious replant problem. With relevant environmental data, we used the PCA, CCA and other statistical method to evaluating the changes in soil bacterial communities associated with replant problem. Though analysised the culturable bacteria in soil sample which from nine sampling points in apple-producing areas around the Bohai area. We got a strain of antagonistic bacteria which had good resistance to the apple common soil-borne diseases, and a stain of bacteria which had effective degradation of phloridzin(the main autotoxic agents of apple).The result of diversity analysis pointed that the community structure of soil sample from apple orchard which had replant problem was significant different from that which orchard was fertility. The bacterial diversity index and evenness index of soil in fertility orchard is higher than which in replant problem orchard, and the dominance index is opposite. The result of CCA pointed that the content of Cu in soil leaded the difference of soil bacteria community structure between apple replant problem and fertility orchard. The result of T-RFLP pointed that, the main bacteria in apple orchard soil in Bohai area is belong to Firmicutes,γ-Proteobacteria, Actinobacteria,α-proteobacteria,β-proteobacteria, Bacteroidetes, Tenericutes. The proportion ofγ-Proteobacteria and Actinobacteria in soil which gathered from replant problem orchard is bigger than which from fertility orchard. Tenericutes was only found in fertility orchard soil, and the T-RF 489bp only found in replant problem orchard which belong toγ-Proteobacteria.The result of DGGE pointed that, the main bacteria in apple orchard soil in Bohai area is belong to Firmicutes,γ-Proteobacteria, Actinobacteria,α-proteobacteria.We had separated a stain of bacteria which had significant resistance to Fusarium prolifertum and Fusarium moniliforme, and this two pathogenic bacteria is common occurred in the soil that planted apple tree. And we also had separated a stain of bacteria which could degrading the phlorhizin that in soil. The effectiveness of the bacteria which could degrading the phlorhizin had been validated in pot experiment, and the effectiveness of the bacteria which had resistance to Fusarium prolifertum and Fusarium moniliforme was being validated in pot experiment.The experimental result pointed that, the difference of bactetial community structure in soil between replant problem and fertility apple orchard was significant. The change about quantity and proportion of Tenericutes, Actinobacteria,γ-Proteobacteria was one reason which caused the difference. And the change of quantity of Tenericutes,γ-Proteobacteria was related to the quantity of Cu in soil. The bacteria which could degrading the phlorhizin could effectively reduce the apple autotoxicity which caused by phlorhizin.