Wounding of the leaves of potato or tomato plants by adult Colorado potato beetles, or their larvae, induces a rapid accumulation of a proteinase inhibitor throughout the plants' tissues that are exposed to air. This effect of insect damage can be simulated by mechanically wounding the leaves. The transport of a factor out of damaged leaves takes place rapidly after the wound is inflicted and the levels of proteinase inhibitor, in both damaged and adjacent leaves, rises strikingly within a few hours. The rapid accumulation of a powerful inhibitor of major intestinal proteinases of animals in response to wounding of the leaves is probably a defense mechanism.

http://science.sciencemag.org/content/sci/175/4023/776.full.pdf

Wound-Induced Proteinase Inhibitor in Plant Leaves: A Possible Defense Mechanism against Insects.

http://www.ejbiotechnology.info/index.php/ejbiotechnology/article/viewFile/v5n1-3/948

Plant protease inhibitors in control of phytophagous insects

Protein proteinase inhibitor genes in combat against insects, pests, and pathogens: natural and engineered phytoprotection.

Proteases, though essentially indispensable to the maintenance and survival of their host organisms, can be potentially damaging when overexpressed or present in higher concentrations, and their activities need to be correctly regulated. An important means of regulation involves modulation of their activities through interaction with substances, mostly proteins, called protease inhibitors. Some insects and many of the phytopathogenic microorganisms secrete extracellular enzymes and, in particular, enzymes causing proteolytic digestion of proteins, which play important roles in pathogenesis. Plants, however, have also developed mechanisms to fight these pathogenic organisms. One important line of defense that plants have to fight these pathogens is through various inhibitors that act against these proteolytic enzymes. These inhibitors are thus active in endogenous as well as exogenous defense systems. Protease inhibitors active against different mechanistic classes of proteases have been classified into different families on the basis of significant sequence similarities and structural relationships. Specific protease inhibitors are currently being overexpressed in certain transgenic plants to protect them against invaders. The current knowledge about plant protease inhibitors, their structure and their role in plant defense is briefly reviewed.

	 

	Key words: Proteases, enzymes, protease inhibitors, serpins, cystatins, pathogens, defense.

/pdf/plant-protease-inhibitors-a-defense-strategy-in-plants-43ik3ns4vr.pdf

John M. Rancour

Papers

Isolation of a carboxypeptidase B inhibitor from potatoes