Abstract: Helicoverpa armigera (Hübner) saliva play important roles in insecthost plant interactions. In this study we constructed a cDNA library of salivary glands of H. armigera larvae where saliva is secreted. We randomly sequenced 1 501 expressed sequence tags (ESTs), and clustering resulted in a total of 821 unigenes. Blast2 GO program was used to do BLASTx, functional annotation and metabolism analysis. Finally, we classified mRNAs in salivary glands of H. armigera larvae. By annotation of these ESTs, genes encoding 17 enzymes for digestion of fat, 5 enzymes for digestion of carbohydrates, and 20 serine proteases (of which 16 are newly reported) were identified, suggesting that the function of salivary glands is secreting saliva for predigestion. The cuticle protein, odorantbinding protein and chemosensory protein genes were identified in salivary glands of H. armigera larvae for the first time. The results will lay a foundation for studying predigestion system in H. armigera.

Key words: Helicoverpa armigera, salivary glands, cDNA library, digestive enzymes, expression profile, EST analysis