Proteinase Inhibitors as Antistress Proteins in Higher Plants

Abstract

Physicochemical and functional characteristics of plant protein proteinase inhibitors as antistress biopolymers were studied to determine the mechanisms for plant resistance to phytopathogens and to obtain disease-resistant cereal and leguminous cultures. The activity of trypsin, chymotrypsin, and subtilisin inhibitors varied in monocotyledonous and dicotyledonous cultures. Study varieties of leguminous and cereal cultures were shown to contain endogenous inhibitors specific to proteinases of phytopathogenic fungi Fusarium , Colletotrichum , Helminthosporium , and Botrytis . These inhibitors were characterized by species specificity and variety specificity. Protease inhibitors from buckwheat seeds inhibited proteases of fungal pathogens and suppressed germination of spores and growth of the fungal mycelium. Our results suggest that proteinaceous inhibitors of proteinases are involved in the protective reaction of plants under stress conditions.

Cuticular defects lead to full immunity to a major plant pathogen

“…, 2000), the class III peroxidase (PER) family (At2g37130, At5g39580, At5g64120; Tognolli et al. , 2002) and the proteinase inhibitor (PI) family (At2g38870, At2g43510; Dunaevskii et al. , 2005; Figure 7).…”

“…, 2004). Proteinase inhibitors produced in many plants, including trypsin inhibitors, can inhibit B. cinerea proteases in vitro (Dunaevskii et al. , 2005), and overexpression of proteinase inhibitors from Nicotiana alata in tobacco ( Nicotiana tabacum ) was recently shown to protect against B. cinerea (Charity et al.…”

Plant pathogenesis-related (PR) proteins: A focus on PR peptides

“…As the role of specific microbial proteinases in microbial pathogenicity is not always clear, the effect of plant PIs on the activity of these enzymes has not been studied intensively. Yet, Dunaevskii et al [32] showed that buckwheat trypsin inhibitors were able to inhibit in vitro proteinases of B. cinerea, likely to be necessary for pathogenesis [99]. Also, Lorito et al [68] suggested that PIs could block the synthesis of chitin in fungal cell walls and consequently fungal growth, through inhibition of endogenous trypsin necessary for active chitin synthase [69].…”

“…Concerning their role in defense, PIs may act by reducing the ability of the attacker to (i) use its lytic enzymes necessary for pathogenicity (for fungi; e.g. [32]), (ii) complete its replication cycles (for viruses; e.g. [45]), or (iii) obtain nutrition through digestion of host proteins and thereby limit the released amount of amino acids (for nematodes, insects; e.g.…”

The cuticle

“…3 POs were proposed to reinforce cell walls most likely by crosslinking lignin monomers 4,5 and one putative role for proteinase inhibitors might be to interfere with hydrolytic fungal enzymes involved in the penetration process. 6 Tobacco overexpressing a PI gene from Nicotiana alata is better protected against B. cinerea. 7 The microarray analysis also revealed changes in gene expression of other genes.…”