Studies On Biological Activity Of Bromo-1,2, 3-thiadiazole Derivatives

Because of successful commercialization of 1,2,3- thiadiazole based plant elicitors, acibenzolar-S-methyl (BTH) and tiadinil (TDL), biological activity of 1,2,3-thiadiazoles attracted more and more attentions. On the basis of successful discovery of methiadinil as a candidate elicitor, succeeding studies discovered that bromo substituted 1,2,3-thiadiazoles (experimental codes:ZHH-1, ZHH-4, ZHH-5) also had good biological activity, In order to provide more basis for novel elicitor development, this thesis conducted futher studies on the biological activities and preliminary mode of action.The biological activities determination of ZHH-1, ZHH-4 and ZHH-5 at 50μg/mL indicated that, ZHH-1, ZHH-4 and ZHH-5 had good and wide specitium of antimicrobial activity against 18 species of typical plant pathogenic fungi including Ascomycetes, Deuteromycetes and Basidiomycetes which occurred regularly in Chinse fields.To provide theoretical guidelines for the application and development of plant elicitors and their mode of action, BTH, TDL, azoxystrobin, tricyclazole, virazole and ningnanmycin were selected as controls, comparative studies on the mode of action against Magnaporthe grisea, Botrytis cinerea, and tobacco mosaic virus were conducted. In vitro studies indicated that, ZHH-1, ZHH-4 and ZHH-5 had good significant inhibition to the mycelium growth spore germination, germ tube elongation of Magnaporthe grisea. appressorium penetration, they had no inhibition to appressorium formation, and however, they could significantly inhibit the invasion of the fungi. In addition, microscopic examination revealed these compounds attributed a series of distinct morphological and structural changes including serious distortion, wavy growth of the hyphae, there appeared naked protoplasm on the top of the hyphae. In vivo studies indicated that, ZHH-1, ZHH-4 and ZHH-5 had good fungicide against Magnaporthe grisea, Botrytis cinerea, TMV.Green fluorescence protein (GFP) was used as a reporter gene to trace the invasion of TMV for studies on the mode of action.,The TMV expression vector, p35S:30B:GFP containing Agrobacterium EHA105, was injected into leaves of Nicotiana benthamiana., inactivation and protection effects were determinated. The results indicated that,3 compounds had good antivirus activity.All studies showed that,3 bromo substituted 1,2,3-thiadiazoles:ZHH-1, ZHH-4 and ZHH-5 had good fungicide activity and antivirus activity.