title: Identification of a bioactive Bowman-Birk inhibitor from an insect-resistant early maize inbred.
abstract: Breeding of maize, Zea mays, has improved insect resistance, but the genetic and biochemical basis of many of these improvements is unknown. Maize oligonucleotide microarrays were utilized to identify differentially expressed genes in leaves of three maize inbreds, parents Oh40B and W8 and progeny Oh43, developed in the 1940s. Oh43 had enhanced leaf resistance to corn earworm larvae, Helicoverpa zea, and fall armyworm larvae, Spodoptera frugiperda, compared to one or both parents. Among ca. 100 significantly differentially expressed genes, expression of a Bowman-Birk trypsin inhibitor (BBI) gene was at least ca. 8-fold higher in Oh43 than in either parent. The Oh43 BBI gene was expressed as a recombinant protein. Purified BBI inhibited trypsin and the growth of fall armyworm larvae when added to insect diet. These experiments indicate that comparative gene expression analysis combined with insect resistance measurements of early inbreds can identify previously unrecognized resistance genes.
authors.affiliation: Crop Bioprotection Research Unit and ‡Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture , 1815 North University Street, Peoria, Illinois 61604, United States.
authors.forename: Eric T
authors.initials: ET
authors.lastname: Johnson
authors.forename: Christopher
authors.initials: C
authors.lastname: Skory
authors.forename: Patrick F
authors.initials: PF
authors.lastname: Dowd
mesh_terms: D000818:Animals; D060434:Herbivory; D007814:Larva / Q000254:growth & development; D010572:Pest Control, Biological / Q000379:methods*; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D018411:Spodoptera / Q000254:growth & development; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000737:chemistry*; D003313:Zea mays / Q000737:chemistry / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D014361:Trypsin Inhibitors; D014357:Trypsin