Plant proteinase inhibitors

Farmer EE, Ryan CA, Octadecanoid precursors of jasmonic acid activate the synthesis of wound-inducible proteinase inhibitors, Plant G //4 129—134,1992. 

The seeds and vegetative part of plants contain several sorts of inhibitors of insect, fungal, mammalian, and endogenous proteinases. These inhibitors may be involved in plant defense mechanisms against predators and participate in the development of the plant itself. Peptidic proteinase inhibitors are well studied in the families Fabaceae, Poaceae, Asteraceae, and Solanaceae (37). Non-proteinaceous inhibitors of serine... 

Table 3 Proteinase inhibitor families found in plants...

In the Andes, nearly all of the about 160 varieties of wild potatoes, and two of the eight cultivated species are toxic. Some frost-resistant species that grow above 3600 m have high levels of alkaloids, which are bitter and potentially toxic. These are hybrids between Solanum stenotonum and wild potatoes such as Solanum megistacrolohum and Solanum acaulc. Other secondary plant compounds in potatoes are saponins, phytohemagglutinin, proteinase inhibitors, sesquiterpene phytoalexins, and phenols. 

Regulation of Synthesis and Accumulation of Proteinase Inhibitors in Leaves of Wounded Tomato Plants... 

Two proteinase inhibitors, Inhibitors I and II, accumulate in leaves of tomato plants when attacked by chewing Insects or mechanically wounded. The accumulation of these two antinutrient proteins is apparently a defense response and is initiated by the release of a putative wound hormone called the proteinase Inhibitor inducing factor (PIIF). The direction of flow of PIIF out of wounded leaves is primarily towards the apex and transport occurs maximally about 120 min following wounding. After a single severe wound, the vitro translatable tomato leaf mRNA specific for Inhibitors I and II Increases to a maximum within four hours and remains constant for about five hours when it decreases rapidly to about 50% of the maximum. 

A severe mechanical wound on a single leaf of tomato plants initiates a complex series of extracellular and intracellular reactions which result in the synthesis and accumulation of two proteinase Inhibitors, Inhibitors I and II, in leaf cells (J, 2. A second wounding, within a few hours, results in a 2-3 fold Increase in the rates of accumulation initiated by the... 

The wound-induced synthesis and accumulation of proteinase Inhibitors I and II in tomato leaves has provided a model system to study the regulation of proteinase inhibitor genes in plants. The simplicity of the phenomenon has made it possible to Isolate the wound-factor, or hormone, and to study its release, direction and rate of transport in tomato plants. Messenger RNA has been isolated from leaves of wounded plants and contains translatable mRNAs for the two proteinase inhibitors. Studies with these mRNAs have provided a basis for the initiation of a program to clone inhibitor cDNAs for studies of the molecular basis of the wound-Induced process of inhibitor synthesis. 

Broadway, R. M., Duffey, S. S., Pearce, G. and Ryan, C. A. (1986). Plant proteinase-inhibitors a defense against herbivorous insects. Entomologia Experimentalis etApplicata 41 33-38. 

Peng, J.H. Black, L.L. (1976) Increased Proteinase Inhibitor Activity in Response to Infection of Resistant Tomato Plants by Phytophthora infestans. Phytopathology 66, 958-963. 

Wildron, D.C., Thain, J.F., et al. (1992) Electrical signaling and systematic proteinase inhibitor induction in the wounded plant. Nature 360 62-65... 

M. Sasaki, H. Yamamoto, H. Yamamoto, and 5. lida. Interaction of human serum proteinase inhibitors with proteolytic enzymes of animal, plant, and bacterial origin. J. Biochem. 75 171 119741. 

Plants express a variety of typically very stable proteinase inhibitors in a range of tissues, from seeds to leaves to flowers, which are toxic to microbes and predatory insects. These peptide-based inhibitors come in a range of sizes, from the smallest gene-encoded cyclic peptide known to date, sunflower trypsin inhibitor 1 (SFTI-1),1/92 a 14-residue cyclic peptide with a single disulphide bond, to squash inhibitors93 that are approximately 30 residues in size and feature a cystine-knot motif, to 50-residue proteinase inhibitors found in the stigmas of the ornamental... 

FARMER, E.E., RYAN, C.A., Interplant communication airborne methyl jasmonate induces synthesis of proteinase inhibitors in plant leaves, Proc. Natl. Acad. Sci. USA, 1990, 87, 7713-7716. 

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