An immunocytochemical and ultra-structural study of the extracellular matrix produced by germinating spores of Stagonospora nodorum on natural and artificial surfaces.

摘要

The temporal secretion and ultra-structure of the extracellular matrix (ECM) produced by conidia and germ-tubes of Stagonospora nodorum on wheat and other surfaces during the first 6 h post inoculation was examined. To visualize the ECM, a combination of immunological, histochemical and ultra-structural methods were employed. Lectins and two monoclonal antibodies were used. One antibody specifically recognised a conidial surface protein and the other recognised a carbohydrate epitope present on an antigen in the ECM and the germ-tube cell wall. Three major phases of ECM release on the leaf surface and two on the artificial surfaces were identified: (a) commencing less than 15 min after contact of the conidium with the host, composed of a carbohydrate core and protein halo, (b) coinciding with the emergence and growth of germ-tubes, composed of proteins and carbohydrates, (c) spreading around the conidia after germ-tube production, not seen on the artificial surfaces. Results indicated that the ECM of conidia and germ-tubes differ in thickness and composition and that the intensity of conidial ECM was affected by the surface properties of the substrata in contact. In addition, maintenance of the ECM in a hydrated state was found to be essential for study of its ultra-structure highlighting the importance of using a diversity of methods to visualize the ECM.