Isolation And Analysis Of CDNA Clones For Genes Related To Wing Differentiation In Rhopalosiphum Padi

Researches on wing polymophism of aphids have been widely conducted since 1960's. These researches have concentrated on the induction of environmental factors and the regulation of hormone on aphids' wing development. Many research indicated that there are many difference on gene expression in different environment. So it is very important that investigating the difference on gene expression between alate and apterous using molecular biology technique.The difference on gene expression between alate and apterous aphids in 3rd larval stages of Rhopalosiphum padi was investigated, using suppression subtract hybridization (SSH) technique. 200 of differentially expressed cDNA fragments were cloned. 11 Expresed Sequence Tags(ESTs) expressed exclusively in alate larval were screened by the method of Reverse Northern. The result of 11 ESTs DNA sequence analysis showed that, one EST named GD4 fragment shared 83% homology with the gene of Rho-family, GJ18 fragment was with 98% homology to the gene of commensal bacterium of aphid, Buchnera aphidicola, and the other 9 ESTs were unknown genes fragments. GD4 with poly A (namely with a complete 3'-end sequence) was cloned by 5' -RACE technique, and then jointed to obtain the full length cDNA. Results of sequencing and characteristic analysis showed that the full length cDNA of D4 was 986bp, the open reading frame of D4 was 576bp, encoding 191 amino acids. The results of alignment with database in GenBank and TIGR, showed that GD4 had 76.74% homology to cDNA of cell division cycle 42(cdc42) in Xenopus laevis, 70.05% to cdc42 in Drosophila melanogaster. cdc42 is a gene of Rho-family belonged to little G protein superfamilies, with GTPase activity, which plays important roles in cell signal transduction, including cytoskeletal reorganization, pheromone response, cell proliferation, cytokinesis. In addition , many researching about commensal bacterium of aphid indicated that commensal bacterium maybe plays important roles in develop of aphids .It suggest that GD4 and GJ18 may be some key related genes mediating the wing differentiation of larval aphid in Rhopalosiphum padi. Furthermore, other 9 unknown genes were supposed which maybe play some important roles in wing differentiation of larval aphid in Rhopalosiphum padi. We'll do more experiment for them.