Proteomic Analysis Of Insecticide Resistance Of The White-Backed Planthopper, Sogatella Furcifera (Horvath) (Homoptera: Delphacidae)

In this paper, the resistance mechanism of white-backed planthopper (WBPH), Sogatella furcifera Horvath to malathion and the stress response of WBPH treated with the LD₂₅ dose of malathion are studied, using a proteomic approach. And a cDNA library of WBPH is constructed. The results are shown as follows:1 The proteomic base of the resistance mechanism to malathion of WBPHUsing sequence extracting to prepare the samples, protein solution 1 (S1) and 2 (S2) in resistant and susceptible strain are separated respectively by two dimensional-polyacrylamide gel electrophoresis (2D-PAGE). There are 172 different proteins (specific expression or different in quantity) between resistant strain S1 and susceptible strain S1 while 97 different proteins between two S2. It represents that the profiles of proteins in two strains are significantly distinctive. 10 spots different in expression are selected to be analyzed utilizing LTQ-MS. Sequence analysis revealed that the expression of enolase, prophenol oxidase, phosphoenolpyruvate carboxykinase, troponin and cytochrome oxidase is different between two strains, which are related to insect resistance. Searching in the protein databases, there is no homology to be found with spot No.4. Analysis of the MS result provides primary insight about the proteins' function, which are different in expression between two strains. And we hypothesize that these proteins reflects the overall changes after insecticide treatment.2 Proteomic analysis of the stress response in WBPH treated with the LD₂5 dose of malathionWhile primary studying of the protein differential expression in resistant and susceptible strain treated with the LD25 dose of malathion (Ck with acetone), there are 131 spots to be detected in all member gels. 90 spots perhaps relate to the susceptibility or stress response to malathion in both WBPH strains. 4 spots out of 90 relate to both the susceptibility and stress response. Comparing with both Ck of two strains, there are 48 different proteins (specific expression or different in quantity).After treating with the LD25 dose malathion, there are 41 and 49 differential expression proteins in resistant and susceptible strain respectively, comparing with their Ck. Also there are 40 different proteins between two strains, which are both treated with the LD25 dose malathion. We suggest that the protein expression of WBPH will to be changed after malathion treatment. 3 cDNA Library Construction and ESTs Analysis of WBPHTo analyze the nucleotide constitution and sequence homology of the expressed sequence tags (ESTs) from the insecticide-resistant strain of the whitebacked planthopper, Sogatella furcifera for cloning new resistance-related genes and understanding the molecular mechanism of insecticide resistance. A directional cDNA library constructed from the poly(A) RNA of malathion-resistant Sogatella furcifera adults is used to generate ESTs. The sequences are queried for BLAST homology searches against GenBank databases including dbEST by BLASTn and BLASTx. A total of 364 ESTs with an average length of 457.2bp are obtained. The GC contents of the 5' terminus sequences is about 38.1%, and 35.3% for the 3' terminus sequences without poly(A) tails. 45.6% of the ESTs show significant matches with known peptides, mainly consisting of protein with housekeeping functions such as metabolism and energy transfer. These identified sequences represent housekeeping proteins, i.e. cytochrome b, NADH dehydrogenase, elongation factor, ATP synthase, actin and tubulin are reported to involve in insect resistance to insecticides. Analysis of partial ESTs provides primary insights about the genes expressed during the adult stage of malathion-resistant Sogatella furcifera strain.