proteinase inhibitor ingestion negatively impacts the growth of sorghum pest and promotes differential protease expression.

BACKGROUND

is an important insect pest infesting sorghum and maize. The larvae internalize in the stem, rendering difficulties in pest management. We investigated the effects of proteinase inhibitors (CanPIs) on larvae by and experiments.

METHODS

Recombinant CanPI-7 (with four-Inhibitory Repeat Domains, IRDs), -22 (two-IRDs) and insect proteinase activities were estimated by proteinase assays, dot blot assays and activity assays. Feeding bioassays of lab reared with CanPI-7 and -22 were performed. proteinase gene expression was done by RT-PCR. structure prediction of proteinases and CanPI IRDs was carried out, their validation and molecular docking was done for estimating the interaction strength.

RESULTS

Larval proteinases of showed higher activity at alkaline pH and expressed few proteinase isoforms. Both CanPIs showed strong inhibition of larval proteinases. Feeding bioassays of with CanPIs revealed a dose dependent retardation of larval growth, reduction of pupal mass and fecundity, while larval and pupal periods increased significantly. Ingestion of CanPIs resulted in differential up-regulation of proteinase isoforms, which were sensitive to CanPI-7 but were insensitive to CanPI-22. interaction studies indicated the strong interaction of IRD-9 (of CanPI-22) with proteinases tested.

CONCLUSIONS

Of the two PIs tested, CanPI-7 prevents induction of inhibitor insensitive proteinases in so it can be explored for developing tolerance in sorghum.

GENERAL SIGNIFICANCE

Ingestion of CanPIs, effectively retards growth; while differentially regulating the proteinases.