The Detection Techniques And Pest Risk Analysis For Sudden Death Syndrome Pathogens Of Soybean

Sudden Death Syndrome of Soybean (SDS) caused by Fusarium virguliforme and Fusarium tucumaniae respectively is a relatively new and severe soybean disease distributed in United States and some other main soybean produce countries. Because SDS is a typical soil-borne disease, SDS pathogens can survive in soil for many years and exist the great possibility to be introduced to a new place along with soybean trade. Since China has been importing a big mount of soybean from United States etc. and lacking the knowledge of SDS, the aim of this study is to establish SDS pathogens detection method for quarantine and identification and to define the risk level of SDS pathogens to be introduced by imported soybean, in order to prevent the SDS to be introduced into China and to protect soybean industry of China further.In this study, a modified selective culture medium named PCNB can enumerate and enrich SDS pathogens from soil was found. A method of inoculation is established and some Chinese soybean varieties are proved sensitive to SDS pathogens. The two pairs of supposed specific primers to SDS pathogens, Fsg1/Fsg2 and FsgEFl/FsgEF2 have been tested to SDS pathogens and their similar pathogens by the PCR amplification. The experimental results showed that both pairs of primers were not specific to SDS pathogens. In Southern blot hybridization, total DNA of the different strains of SDS pathogens and their similar pathogens digested with either EcoRl or Hindâ…¢, were hybridized with mtDNA probes of 2u18 and 4u40. The result of pattern of RFLP with EcoRI digested showed that F. virguliforme, F. tucumaniae and their similar species F. phaseoli had their own specific bands respectively. Therefore, the detection techniques for SDS pathogens can be established, e.g. isolating SDS pathogens from the soil carried by imported soybean with the selective culture medium PCNB, then identifying the pathogen with Southern blot hybridization.The results of the pest risk analysis showed that SDS is a destructive soybean disease with significant economic impact to China and satisfies the quarantine pest definition in geographical, management and economic criterions. SDS pathogens should be listed as quarantine pests of China. The risk level of SDS pathogens is high due to the high probability of establishment, distribution and high probability of transmission from imported soybean to local hosts. Basing on results of risk assessment, three quarantine management options are proposed. Applying anyone of the three quarantine management options can reduce the risk of SDS pathogens to acceptable level.