ISSN:
1572-9788
Keywords:
proteinase inhibitor
;
giant taro
;
host plant resistance
;
Helicoverpa armigera
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract A giant taro proteinase inhibitor (GTPI) cDNA was expressed in transgenic tobacco using three different gene constructs. The highest expression level obtained was ca. 0.3% of total soluble protein when the cDNA was driven by the Arabidopsis rbcS ats1 promoter. Repeated feeding trials with Helicoverpa armigera larvae fed on clonally derived T0 and T1 plants expressing GTPI demonstrated that, relative to those fed on control plants, some growth inhibition (22–40%) occurs, but there was no increase in larval mortality. Proteinase activities of larvae fed on GTPI-expressing tobacco or GTPI-containing diet were examined to monitor the spectrum of digestive proteinases in the midgut. Total proteinase activity was reduced by 13%, but GTPI-insensitive proteinase activity was increased by up to 17%. Trypsin was inhibited by 58%, but chymotrypsin and elastase were increased by 26% and 16% respectively. These results point to an adaptive mechanism in this insect that elevates the levels of other classes of proteinases to compensate for the trypsin activity inhibited by dietary proteinase inhibitors.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1009681323131
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