Podborer (Helicoverpa armigera Hübn.) does not show specific adaptations in gut proteinases to dietary Cicer arietinum Kunitz proteinase inhibitor.
We investigated the response of Helicoverpa armigera larvae towards ingestion of Cicer arietinum Kunitz proteinase inhibitor (CaKPI), which caused antagonistic effects on developing H. armigera larvae. CaKPI-degrading proteinases were not detectable in either control or sensitized larvae. There were negligible increases in total proteinase activity, as well as in trypsin-like and chymotrypsin-like activities of H. armigera gut proteinases (HGPs). Decrease in sensitivity of HGPs to inhibition by CaKPI was not observed when the inhibitor was fed suggesting that the insect had not shown a specific adaptive response to dietary CaKPI. Semi-quantitative reverse transcriptase polymerase chain reaction (Q RT-PCR) analysis showed a general up-regulation of proteases in larvae that ingested CaKPI and a specific regulation of individual transcripts was not observed. CaKPI had maximum inhibitory activity against HGP derived from fourth instar larvae. CaKPI was equally potent in inhibition of HGPs derived from larvae fed on different host plants, as well as various proteinase inhibitors (PIs) to which larval adaptation was previously reported. The lack of larval response to CaKPI was attributable to the atypical active site sequence and inhibitory activity of CaKPI and/or to the pre-adaptation of H. armigera larvae due to the constant exposure to basal levels of CaKPI in chickpea seeds or a chickpea seed-based diet.
Srinivasan
Ajay
A
Plant Molecular Biology Group, Division of Biochemical Sciences, National Chemical Laboratory, Pune 411008, India.
Chougule
Nanasaheb P
NP
Giri
Ashok P
AP
Gatehouse
John A
JA
Gupta
Vidya S
VS
D000222:Adaptation, Physiological; D000818:Animals; D029863:Cicer / Q000737:chemistry*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology; D004064:Digestive System / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D007814:Larva / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D007915:Lepidoptera / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D010940:Plant Proteins / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D004044:Dietary Proteins; C053865:Kunitz-type protease inhibitor, plant; D010455:Peptides; D010940:Plant Proteins; D011994:Recombinant Proteins; D010447:Peptide Hydrolases