title: General up regulation of Spodoptera frugiperda trypsins and chymotrypsins allows its adaptation to soybean proteinase inhibitor.
abstract: The existence of a diverse serine proteinase gene family in lepidopteran insects suggests they play a significant role in the insect adaptation to plant proteinase inhibitors. These proteinases have been shown to be involved in the process of proteolytic digestion in insect larvae. We carried out a selective transcriptome study of midguts from Spodoptera frugiperda larvae fed on a diet supplemented with soybean proteinase inhibitor (SPI). Using subtracted cDNA libraries made of gut-expressed transcripts, a total of 2100 partial sequences were obtained, of those 38% were related to digestive process. Two large and diverse groups of chymotrypsins and trypsins were obtained, and some of these proteinase-encoding genes were further characterized by quantitative RT-PCR. The transcription analyses revealed two groups: one group of genes constitutively expressed in the control larvae that is up regulated by introducing SPI to the diet, and a second group that is absent in the control but is induced by the SPI-rich diet. This observation suggests that adaptation of S. frugiperda to SPI involves de novo synthesis and also up regulation of existing enzymes. Proteases from intestines of larvae reared on a diet with SPI showed insensitivity to the inhibitor. The proteases were also insensitive to a broad-spectrum potato proteinase inhibitor preparation. We propose that adaptation of S. frugiperda to SPI follows a "shotgun" approach, based on a general up regulation of a large set of endoproteinases.
authors.affiliation: Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Caixa Postal 83, 13400-970 Piracicaba, SP, Brazil.
authors.forename: Daniela
authors.initials: D
authors.lastname: Brioschi
authors.forename: Larissa D
authors.initials: LD
authors.lastname: Nadalini
authors.forename: Mario H
authors.initials: MH
authors.lastname: Bengtson
authors.forename: Mari Cleide
authors.initials: MC
authors.lastname: Sogayar
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Moura
authors.forename: Marcio C
authors.initials: MC
authors.lastname: Silva-Filho
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002918:Chymotrypsin / Q000032:analysis / Q000235:genetics; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000201:enzymology; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011480:Protease Inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D013025:Glycine max / Q000737:chemistry; D018411:Spodoptera / Q000201:enzymology* / Q000235:genetics; D014357:Trypsin / Q000032:analysis / Q000235:genetics; D015854:Up-Regulation
chemical_list: D011480:Protease Inhibitors; D010450:Endopeptidases; D002918:Chymotrypsin; D014357:Trypsin