General up regulation of Spodoptera frugiperda trypsins and chymotrypsins allows its adaptation to soybean proteinase inhibitor

Insect Biochem Mol Biol. 2007 Dec;37(12):1283-90. doi: 10.1016/j.ibmb.2007.07.016. Epub 2007 Aug 6.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Chymotrypsin / analysis
  • Chymotrypsin / genetics
  • Endopeptidases / genetics
  • Endopeptidases / metabolism*
  • Larva / enzymology
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • Protease Inhibitors / isolation & purification
  • Protease Inhibitors / metabolism*
  • Soybeans / chemistry
  • Spodoptera / enzymology*
  • Spodoptera / genetics
  • Trypsin / analysis
  • Trypsin / genetics
  • Up-Regulation

Substances

  • Protease Inhibitors
  • Endopeptidases
  • Chymotrypsin
  • Trypsin