Arabidopsis Thaliana as a Model System for Studying Plant- Pathogen Interactions

Although plants are continuously exposed to a variety of potentially pathogenic microorganisms, successful infections are rare. Plants utilize a diverse array of defense mechanisms to prevent microbial infections. Some of these defense strategies involve constitutively expressed physical and chemical barriers that provide a first line of defense against potential pathogens (Mansfield 1983). Other defense mechanisms are specifically induced upon attempted infection. These induced defense responses include the synthesis of polyphenolic lignins and hydroxyproline-rich glycoproteins which are incorporated into plant cell walls, causing the walls to be more resistant to microbial invasion? the synthesis of the hydrolases (β-1,3- glucanase and chitinase, which may inhibit fungi by degrading their cell walls; and the synthesis and accumulation of antimicrobial compounds called phytoalexins (Bell 1981, Collinge and Slusarenko 1987, Darvill and Albersheim 1984, Hahlbrock and Scheel 1987).