Effects of fungicide triadimefon on development of Curvularia lunata in vitro

The effects of triadimefon[1-(4-chlorophenoxy)-3,3-dimetyol-1-(1,2,4-triazol-l-yl)butan-2-one],a systemic fungicide from the triazol group were examined on morphology,structure,cell wall components of Curvularia lunata by means of electron microscopy and cytochemical labelling techniques.The studies revealed that triadimefon not only inhibited the hyphal growth but also caused a series of marked morphological and structural alterations of hyphae.These changes included irregular swelling,excessive branching,tumorous protuberance on the surface of hyphae,and considerable thickening of the hyphal cell walls,particularly at the hyphal tip region.The septum development of the hyphae was inhibited and became malformed.Dense electronic opaque material secreted by fungicide-treated hyphal cells was observed by TEM.Using cytochemical techniques,the labelling densities of chitin andβ-1,3-glucan on the cell wall of the fungicide-treated hyphae were decreased dramatically comparing with those of the control hyphae,indicating that the detrimental effects of the fungicide on structure and function of the hyphal membranes,and composition changes of the cell walls.The possible mechanism involved in mode of action of triadimefon against Curvularia lunata was discussed.