Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2004
Publication Date: 7/29/2004
Citation: Pechan, T., Williams, W.P., Mohan, S., Ozkah, S., Bassford, E., Shivaji, R., Luthe, D. 2004. Irritable bowel syndrome in insects: Plant defenses that disrupt the peritrophic matrix [abstract]. Proceedings International Entomology Congress.
Technical Abstract: We have demonstrated that a unique 33-kD cysteine protease (Mirl-CP) accumulates in the whorls of caterpillar-resistant corn genotypes in response to feeding by fall armyworm (Spodoptera frugiperda) larvae and other lepidopterans. The growth of fall armyworm larvae reared on transgenic Black Mexican Sweet (BMS) cells that ectopically expressed Mir-CP was retarded approximately 70%. Physiological indices suggested that this was due to impaired nutrient utilization. Scanning electron microscopy (SEM) of midguts from fall armyworm larvae reared on resistant plants or transgenic BMS indicated that peritrophic matrix (PM) was severely damaged. Because Mirl-CP binds chitin, we speculate that it might be tethered to the PM where it digests PM proteins. Proteomic analysis of PM proteins isolated from larvae reared on resistant and susceptible corn genotypes indicated that approximately three proteins were absent from the PM of larvae reared on resistant plants. This suggests that the protease may affect the integrity of the PM by attacking specific PM proteins. To test this, Mirl-CP has been expressed in a heterologous expression system using a recombinant baculovirus vector and Trichoplusia ni larvae as hosts. Mirl-CP has been purified to homogeneity from the hemolymph and its affects on PM structure will be tested in vivo and in vitro.