CYTOLOGY AND IMMUNO-CYTOCHEMISTRY STUDIES OF EFFECTS OF TEBUCONAZOLE ON WHEAT HEAD BLIGHT PATHOGEN IN VITRO
戊唑醇对赤霉病菌生长发育影响的细胞学和免疫细胞化学研究

The effects of tebuconazole, a triazol group fungicide, were examined on morphology, structure, cell wall components and toxin production of Fusarium graminearum in vitro by means of electron microscopy and cytochemical labeling techniques. The results revealed that tebuconazole not only inhibited hyphal growth of F. graminearum, but also caused a series of marked morphological and structural alterations of hyphae. These changes included irregular swelling and excessive branching of the hyphae, considerable thickening of the hyphal cell walls, particularly at the hyphal tip region, increasing vacuoles and lipoids, very frequent septation with malformed septa and necrosis or degeneration of the hyphal cytoplasm. The formations of new structures like non-membraneous inclusion bodies and new hyphae (daughter hyphae) inside of the collapsed hyphal cells were often detected in the cytoplasm of fungicide-treated hyphae. However, the daughter hyphae also showed abnormal alterations such as irregular thickenings of the cell walls, necrosis of the cytoplasm and formation of new daughter hyphae. Furthermore, immunocytochemical labeling revealed that the labeling density for the toxin in the fungicide-treated hyphae was markedly lower as compared to the control hyphae. but the labeling densities of the chitin and -l, 3-glucan were higher in the cell walls of the fungicide-treated hyphae than in the control hyphae, indicating an excessive accumulation of chitin and ?l, 3-glucan in the cell walls of the fungicide-treated hyphae due to the detrimental effects of the fungicide on structure and functions of the hyphal membranes.