Hairy plant polysaccharides: a close shave with microbial esterases.

Abstract

Plants employ an impressive number of ingenious ways to protect themselves from disease. Probably the most important protection against invading micro-organisms is the erection of a tough physical barrier, the plant cell wall, which protects the delicate interior of the plant cell. Pore sizes in the plant cell wall are too small even to allow passage of viruses, and so microbes which infect by penetration must enter either through opportunistic breaks in the wall or by enzymic dissolution (Brett & Waldron, 1990). Plant-saprophytic and -pathogenic micro-organisms produce a range of enzymes to degrade plant cell walls in order to use the cell contents as nutrients or to digest and utilize the polysaccharides in the plant cell wall. This enzyme tool kit has evolved in some micro-organisms to unlock even the most recalcitrant plant cell walls, given time and suitable conditions.