Can lysozymes mediate antibacterial resistance in plants?

Lysozymes are defined as enzymes with a specific hydrolytic activity directed against the bacterial cell wall component peptidoglycan (murein). The bacteriolytic in vitro activity of different lysozymes from various organisms is well known for a long time. Also in several plant species the presence of lysozymes has been detected in recent years (1, 2, 8, 19, 21, 27, 43, 44). Yet, an involvement of endogenous plant lysozymes in plant-bacteria interactions has not been demonstrated until now. Because of their enzymatic activity a participation in plant defence responses seems conceivable. In comparison to the analysis of plant chitinases and beta -1,3-glucanases, plant lysozymes have been characterized to a limited extent only. Most of the known plant lysozymes are bifunctional enzymes also displaying a chitinase activity. Following, the analysis of plant chitinases and glucanases allows insight into some aspects of plant lysozyme function.