Plant protease inhibitors: Biological roles and applications in plant stress tolerance

Abstract

Plants have evolved a plethora of defense mechanisms to protect themselves against various biotic and abiotic stresses. Plants are in a constant evolutionary arms race with their attacking insect herbivores and pathogens over a long period of time. Plants when attacked by insects or pathogens use different defense mechanism that involves calcium-signaling, production of reactive oxygen species, phytohormones, miRNAs, secondary metabolites, and defense proteins. The production of protease inhibitors is one such mechanism that contributes to plant defense by severely reducing the growth and development of phytopathogens. Proteases are proteolytic proteins that are necessary for plants to carry out important functions, and the proteolytic activity of proteases needs to be regulated in a controlled manner. Plant protease inhibitors are a family of small protein/peptide/amino acid derivatives that are involved in important biological processes of plants including growth, development, and defense against pests and pathogens (Polya, 2003; Van Der Hoorn, 2008).