Thaxtomin A: evidence for a plant cell wall target

Thaxtomins, are unique 4-nitroindol-3-N,l containing dioxopiperazines that cause dramatic plant cell hypertrophy and seedling stunting. This family of phytotoxins is produced by Streptomyces species that Cause diseases, of root and tuber crops; it., members are essential For patlugetncit. The symptoms produced 1) thaxtomin A suggest several potential plant cell targets including the plasma membrane, various components of the cytoskeleton and the cell wall. Dramatic increases in cell volume in onion seedling hypocotyls, radish seedling hypocotyls and tobacco suspension cultures. in response to 0.05-1.0muM 1.0 muM thaxthomin A. suggested that this phytotoxin is interacting with one or more conserved plant cell targets. Onion root tip cells treated with thaxtomin A concentrations at or below that which inhibited onion root growth were binucleate or had abnormal cell plates. Thaxtomin A {1.0-3.0 muM} inhibited normal cell elongation (if tobacco protoplasts in a manner that suggested all effect oil primary cell wall development. In summary, these data suggest that thaxtomin A alters, either directly or indirectly. the deposition or composition of monocot and dicot plant cell walls in ways that affect the wall integrity and the ability, of the cell to progress normally through cytokinesis. (C) 2002 Elsevier Science Ltd.