title: Insensitive trypsins are differentially transcribed during Spodoptera frugiperda adaptation against plant protease inhibitors.
abstract: 0The fall armyworm (Spodoptera frugiperda) is an important pest insect due to high degree of polyphagia. In order to better understand its adaptation mechanism against plant protease inhibitors, bioassays were carried supplementing diet with the Kunitz trypsin inhibitor from Entada acaciifolia seeds (EATI). In vitro assays showed an increase of proteolytic activity in EATI-fed larvae midgut. Moreover, the trypsin enzymes showed insensitivity to inhibition with EATI. In order to understand what genes were overexpressed after chronic exposition to EATI, quantitative RT-PCR analyses were performed and revealed an increase in transcription of two trypsin genes, suggesting its participation in insensitivity of midgut trypsins. Another important result was the expression of one chymotrypsin gene, which is not expressed in control fed-larvae but induced in EATI-fed larvae. New regions of higher molecular weight showing proteolytic activity were visualized in inhibitor-fed larvae by zymography gel electrophoresis, proposing that the new enzymes expressed in response of inhibitor dietary would be formatting oligomers. This is a characteristic also observed in other pest insects that adapt to feed in plant protease inhibitors diet. Additional assays revealed that trypsins from EATI-fed larvae also became insensitive against Kunitz and Bowman-Birk inhibitors from soybean. This result suggests a possible involvement of the same S. frugiperda genes in adaptation against Kunitz and Bowman-Birk inhibitors in their host plants.
authors: Department of Biochemistry, Institute of Biology, University of Campinas, Campinas 13083-970, SP, Brazil.
authors: Caio Fernando Ramalho
authors: CF
authors: de Oliveira
authors: Thaís
authors: T
authors: de Paula Souza
authors: José Roberto Postali
authors: JR
authors: Parra
authors: Sergio
authors: S
authors: Marangoni
authors: Marcio de Castro
authors: Mde C
authors: Silva-Filho
authors: Maria Ligia Rodrigues
authors: ML
authors: Macedo
mesh_terms: D000818:Animals; D007887:Fabaceae / Q000737:chemistry; D007814:Larva / Q000187:drug effects / Q000235:genetics; D011480:Protease Inhibitors / Q000494:pharmacology*; D018411:Spodoptera / Q000187:drug effects / Q000235:genetics*; D014357:Trypsin / Q000235:genetics*
chemical_list: D011480:Protease Inhibitors; D014357:Trypsin