Role of Pathogen related protein families in defence mechanism with potential role in applied biotechnology

Plants are threatened by various pathogen attacks from a wide range of pathogenic organisms like fungi, oomycetes, bacteria, viruses and insect which causes various devastating diseases resulting in reduced crop production. In this response plants have evolved various diverse mechanisms to defend themselves against various pathogenic speices attack. The plant response to pathogen attack activates various host plant signal transduction pathways and accumulates pathogenesis-related (PR) proteins. Therefore, PR proteins are usually induced upon attack of various pathogens and stress such as drought, osmotic, cold, salinity, metal stress, UV light. In plants, PR proteins plays a diverse multiple functions like plant defense, disease resistace, cell wall rigidification, development, antifungal activity, enzymatic functions (?-1,3-glucanase, chitinase, defensins) and adaption to stress. Currently PR proteins are categorized into seventeen families (PR 1-17) according to their biochemical functions and properties. The antimicrobial activity of pathogenesis-related proteins provides valuable tools for engineering resistance in plants with ecomomic improtance. Future exploitation of these proteins reflects their potential role in various agribiotechnological applications. This review discusses about the comprehensive function of PR proteins in plant development, classification, disease resistance and their utility in genetic engineering for enhancing disease resistance in crop plants with essential measures in disease controlling strategies.