Analysis On The Community Diversity Of Root Rot Pathogenic Fungi In Continuous Cropping Soybean Rhizosphere Soil

Nowadays,The demand of soybean in China is growing rapidly and the shortage of soybean will relate to national food security directly.Now the rominent contradiction between supply and demand market are increased.For a long time,domestic soybean acreage had been exhibited continuous cropping and the acreage had accounted for 20%in our country.The phenomenon about soybean continuous cropping was especially serious in Heilongjiang province,and the acreage had been up to 50%~ 70%in recent years.In order to solve the problem of soybean continuous cropping obstacle and improve the production.This study in order to research the diversity of high incidence stage of root rot pathogenic fungi,their periodic variation characteristics in continuous cropping soybean rhizosphere soil and selected the advantages of root rot fungi in the different growth stage in the meantime,which provid theoretical basis for revealing the diversity of high incidence stage of root rot pathogenic fungi in continuous cropping soybean rhizosphere soil,lay the foundation of targeting measures against the law of soybean root rot,provide vital significance to improve the yield and quality of the northeast spring soybean production.Three representative soybean varieties,Ken Feng 16(KF16),Hei Nong 44(HN44)and Hei Nong 48(HN48),with a larger promoting planting area in Heilongjiang province were selected in this study and planted in soil of contrast,continuous one year and two year.Take samples in seedling stage and branching and extract total genome with roots and rhizosphere soil respectively.V1 and V2 fragments of 18S rRNA of fungi were obtained by PCR and then analyzed by denaturing gradient gel electrophoresis(DGGE).The characteristic bands and common bands were sent for sequencing.Then the results of sequencing were submitted for blast in GenBank of NCBI in order to obtain the information of sequences.At the same time,the abundance,dominance,diversity of DGGE profiles were analyzed.The results showed that the continuous cropping years,soybean varieties and different growth period are all affected the DGGE profiles about the soybean root rot pathogen fungi,which is significant difference.Samples of dominant population and dominance of the lowest population have changed in the map.It showed that the different continuous year to soybean root rot pathogen fungi flora of different varieties soybean has significant influence.It was showed that the thirteen bands are Pythium ultimum,Fusarium sp.,Ascomycete sp.,Pleosporales sp.9 Alicorhagia sp,.Rhizoctonia solani,Mucor sp.and Penicillium sp.,five of them were uncultured fungi.In this experiment,13 DGGE bands had been sequenced.The dominant of soybean root rot pathogenic fungi in the experimental filed could be divided into Pythium ultimum and Fusarium sp..Phylogenetic analysis also showed that these unkown fungi had close relationship with the two main fungi.