Adhesion of conidia and germlings of the plant pathogenic fungus Bipolarissorokiniana to solid surfaces

Soon after coming in contact with its host, the plant pathogenic fungus Bip olaris sorokiniana produces an extracellular material that appears to be im portant for adhering conidia arid germlings to the host surface. To further understand this step of the infection, the adhesion of B. sorokiniana to a rtificial solid surfaces was examined. On a hydrophobic (polystyrene) surfa ce adhesion occurred in two stages, the first by conidia and the second by germlings. Conidial adhesion occurred shortly (0-1 h) after hydration. The conidia were easily detached by increasing the shear force and including de tergents in the washing buffer. As conidia were hydrophobic, these observat ions indicate that conidial adhesion to polystyrene is due to weak, hydroph obic interaction. The second stage of adhesion was accompanied by conidial germination and occurred 1-2 h after hydration and contact with the surface . Concomitant with the delayed adhesion, the fungus produced an extracellul ar matrix (ECM). The adhesion of germlings was firm and surface-unspecific since they adhered to both hydrophobic and hydrophilic (glass) surfaces, Ex cept for strong bases, hydrochloric acid and broad-specificity proteases (i ncluding Pronase E), none of the hydrolytic enzymes, electrolyte solutions, ionic and hydrophobic detergents and organic solvents removed germlings fr om the solid surfaces. The adhesion of germlings incubated in the presence of the protein glycosylation inhibitor tunicamycin or the lectins Con A (Co ncanavalin A) and GNA (from Galanthus nivalis) was significantly reduced, w hich indicates the involvement of surface glycoproteins in this process. Th e surface proteins of germlings were labelled with I-125, extracted and ana lysed by two-dimensional gel electrophoresis. This revealed about 40 surfac e proteins over a wide pH range (4-10) with molecular masses between 10 and 100 kDa.