Interactions Between Paecilomyces Lilacinus,Fusarium Oxyspor Umand Root-Knot Nematode In Straw Reactor

Cucumber is one of the crops that have been harmed by the continuous planting, the nematode and wilt diseases are increased by the continuous planting. Paecilomyces lilacinus is one of the most important fungal bio-control agents, it can prevent cucumber from root-knot nematode and from Fusarium oxysporum that causes cucumber wilt. Applying straw reactor on the greenhouse plants can change the soil microbial ecology, and improve it develop toward the favorable direction for the growth of plants. But the population changes of beneficial microorganisms and relationship with pathogens in the straw reactor have not been clarified. In this study, the relationship between beneficial microorganism (Paecilomyces lilacinus) and pathogens (root-knot nematode and Fusarium oxysporum) in the straw reactor was clarified, and it provided a theoretical basis for the research on ecological regulation mechanism of beneficial microorganisms and the evaluation of the bio-control efficacy.The results of the research are as follows:1. Specific primers of Paecilomyces lilacinus were designed throuth RAPD technology. Polymorphism in genomic DNA of Paecilomyces lilacinus strains as well as closely related strains was analyzed with random primer by RAPD. Sequence-specific fragments with203bp could be obtained from Paecilomyces lilacinus strains, respectively, which were absent in other Paecilomyces strains. Primers were designed on the base of the nucleotide sequence information of RAPDs. One pair of primers was selected and the amplification product with195bp was transformed into more-specific SCAR marker. The specificity of the primer was further tested, only Paecilomyces lilacinus strains could be amplified to the corresponding SCAR by the pair of primers. This PCR-based method is useful to track Paecilomyces lilacinus in soil samples rapidly and efficiently.2. Real-time PCR system for detecting Paecilomyces lilacinus was developed. Standard curve developed by using the RAPD clone plasmid of Paecilomyces lilacinus strain YES-2-14gave rise to0.955as linear correlation coefficient between DNA concentrations and Ct values. By testing soil samples, the relative standard curve developed to give rise to0.9977as linear correlation coefficient, it indicated that the system of Real-time PCR for Paecilomyces lilacinus was useful for accurate quantification of Paecilomyces lilacinus in soil.3. Real-time PCR system for detecting Fusarium oxysporum was developed. Standard curve developed by using clone plasmid of Fusarium oxysporum gave rise to0.995as linear correlation coefficient between DNA concentrations and Ct values. By testing soil samples, the relative standard curve developed to give rise to0.9873as linear correlation coefficient.4. The straw reactor was established, and the interaction relationships between Paecilomyces lilacinus with root-knot nematode and Fusarium oxysporum in the straw reactor were investigated. The straw reactor could increase the inhabitation of Paecilomyces lilacinus toward nematode. After processed by the straw reactor, the quantities of Paecilomyces lilacinus in the soil around the root in the composite nursery and root-knot nematode nursery were significantly less than in the soil only treated with biocontral bacteria(p=0.05), it certificated that the straw reactor could increase the quantity of Paecilomyces lilacinus; after processed by the straw reactor, the quantities of Fusarium oxysporum in the soil of the composite nursery and nematode nursery were not significantly different with in the soil only treated with biocontral bacteria(p=0.05), it indicated that the straw reactor could not increase the inhibition of Paecilomyces lilacinus against Fusarium oxysporum.