Archivio Journal of Plant Pathology

Abstract:

Effects of the fungicide tebuconazole, applied as a leaf spray after inoculation of wheat leaves with stripe rust were examined by means of electron microscopy and immunogold labelling Tebuconazole strongly inhibited the development of Puccinia striiformis in host leaf tissues, and also markedly altered the structures of the hyphae and haustorium. These changes included increased vacuolation, irregular thickening of cell walls, necrosis or degeneration of cytoplasm, and collapse of the hypha and haustorium. Large differences were detected in P. striiformis-infected wheat leaves treated with fungicide compared with the untreated control. A very thick layer of wall appositions and large encasements were usually formed in the infected fungicide-treated leaves whereas such structures were never observed in the infected wheat leaves without fungicide treatment. In addition, chitinase, ß-1,3-glucanase and lignin were detected in wheat leaf tissues by immunogold labelling. Accumulation of the two enzymes and lignin increased slightly in infected leaves compared with uninoculated healthy leaves, while a much higher accumulation of the two enzymes and lignin was detected in infected wheat leaves after fungicide treatment. Our results suggest that tebuconazole not only inhibited development of P. striiformis in wheat leaves, but also enhanced structural and biochemical host defense reactions in the infected host.