Effects Of Planting Years On Microbial Communities’ Structure In Peony Rhizosphere Soil

Peony (Paeonia suffruticosa) belongs to small shrubs of Paeonia. It is one of thetraditional rare flowers in China, basically originate in luoyang and heze, etc. With theincrease of planting years, the pathogenic microorganism accumulated steadily, peony soilspread diseases have increased year by year. Lead to the decline of the quality of the peony.Continuous cropping obstacles phenomenon seriously affect the output of Dan skin and thequality of flower and peony industrialization.In order to explore effects of planting years on microbial communities’ structure inpeony rhizosphere soil. Four samples were collected from peony rhizosphere soil in Heze,Shandong, China, T-RFLP and DGGE technique was adopted to study the dynamic changesof bacteria and fungi community structure in the rhizosphere soil. The effect of peonycontinuous cropping on the microbial community structure in soil was exployed.T-RFLP community profiles showed bacterial community structure in rhizosphere soil ofpeony is reduced year by year after a continuous cropping. Peony rhizospheric bacterialcommunity is consisting of Firmicutes, Bacteroidetes, Firmicutes and Actinobacteria. Thediversity index of each sample was calculated by software Bio-Dap. The results showed thatthe impact of peony has caused certain effect of peony rhizosphere bacterial communitystructure; the rhizosphere bacterial communities of peony root tend to be simple.Analysis of DGGE figures showed that bacterial community structure similarities ofeach peony rhizospheric soil sample were reduced year by year. The results from DGGE aresimilar to that from T-RFLP. The changes of microbial community diversity under continuouscropping of peony might be one of the reasons causing the obstacles of continuous croppingof peony.Analysis of bands M1-M9from DGGE showed that, the similarity of M1andHalomonas magadiensis （X92150.1） was98%, M2and Pseudomonas taiwanensis （EU103629.2）was99%, M6and Flavobacterium daejeonense （DQ222427.1）was100%,the M8and Mesorhizobium metallidurans （AM930381.2）was98%, M9and Cellvibriogandavensis （AJ289162.1）was97%. Other bands were uncultured strains. The numbers ofthese strains are all decreased year by year.300strains belong to bacteria or actinomyces were isolated from peony rhizosphere soil.Based on the antagonistic analysis using the Fusarium solani as target strain,27isolates werefound resistant to this fungal pathogen. MD1, MD4, MD7, MD8, MD64, MD68, MD70havethe strongest antagonistic properties. Based on its morphological, physiological, phenotypiccharacterization and16S rDNA sequence, they were identified as Bacillus amyloliquefaciens,Bacillus malacitensis, Bacillus subtilis, Pseudomonas chlororaphis, Streptomyces albiroticuli,Bacillus tequilensis and Bacillus methylotrophicus respectively. The sequences of16S rDNAobtained in this study have been submitted to GenBank and the accession numbers areJN205338, JN205339, JN205340, JN205341, JN205342, JN205343and JN205344.The results showed that, with the increase of the years of planting, microorganismcommunity structure of peony rhizosphere have a significant change. Frist, microorganismdiversity significantly reduced, second, some pathogenicity fungi populations get enrichment,microorganism population community structure changes in peony root may be main reasonwhy the disease of soil-borne in old peony park was more serious.