Construction Of CDNA Library And SSH Library Of Steinernema Feltiae Infective Juveniles And Genes Expression Profile Analysis

Entomopathogenic nematodes are a new type of bioinsecticide. It has broad application prospects in the pest management. Infective juveniles(IJs) are a special development stage of entomopathogenic nematodes. It is the only stage that survived in the natural environment, and its mouth, esophagus and anus close to stop the development. It has strong capacity to resist adverse environment. The genes espression profile of the IJs provided insight into the understanding of resistance mechanism as well as metabolic mechanism of the resistance, which may lay the theoretical basis for the nematodes production and application.A cDNA library from IJs of Steinernema feltiae G26 strains was constructed and the partial fragments were sequenced and analysed. A suppression subtractive hybridization (SSH) library from IJs and their 3rd developmental satge juvenile was constructed with suppression subtractive hybridization technique.1 Construction and sequence analysis of IJs of S. feltiae G26 strains cDNA libraryLD-PCR(Long-Distance PCR)method was used to construct the cDNA library successfully from the IJs of S. feltiae G26 strains total RNA, and the original titer for 3.7×10~8cuf/ml was obtained. 100 sequences were acquired from the selected 118 clones randomly by sequencing, including heat shock protein, ribosomal protein genes, translation elongation factor 1-alpha genes etc.2 Construction of IJs and their 3rd instar normal larvae of S. feltiae G26 strains SSH libraryA SSH library was constructed by suppression subtractive hybridization, using cDNA from IJs as tester and cDNA from 3rd developmental satge juvenile as driver. The SSH library was totally composed of 1628 recombinant clones, and 38 of them were sent for sequencing after Dig detection. Finally we got 20 sequences. After similarity analysis based on BLASTx and BLASTn in GenBank, the redundant cDNAs were removed, and 10 differentially expressed genes were obtained. Three genes of them were known, and one was Cysteine Protease Inhibitor family member (cpi-2) that was related to the resistance of metabolic mechanism. Seven of them were found similar to some of sequence in the database, but the functions were still not clear.This research provided theoretical foundation for revealing the resistance mechanism, development mechanism and resistance metabolic mechanism of IJs, moreover, it laid the foundation for controlling formation and development of IJs. Ultimately, costs for entomopathogenic nematodes production were reduced and the its control efficancy was enhanced.