Cytochemistry Examination On Activity Assay And Pathogenicity Of Ustibxins

False smut is a worldwide rice disease caused by Ustilaginodea virens (cooke) Tak. It was all along ignored before 1980 because of its occasionally happening. Since 1980s', however, with the change of rice cultivar and adding of more manure into the paddyfield, false smut has become worse and worse as an important factor to influence greatly on the yield and quality of rice in some places.The false smut balls grow parasitically on panicle of rice plant, results in less yield, polluted rice and worse quality, and most important, produces toxins poisoning to human beings and domestic animals. By far, more study about ustiloxins is focused on its toxicity to human beings and domestic animals and less on the role of ustiloxins in the form of the disease, the toxicity to rice plant itself and its pathology. In order to seek for the effective means of prevention and cure of false smut and provide scientific evidences to the breeding of cultivar resisting to disease, we systematically studied the ustiloxins of false smut, including the biological activity of ustiloxins, the synthesis and secretion of ustiloxins and the role of ustiloxins in the form of the disease. The main results are as follows:1. Culturing pathogen, isolating rough ustiloxins and mensurating biological activity: Ustilaginodea virens growed slowly in the solid culture, but well in PD or PS medium. The mensuration of biological activity showed that it was better to isolate ustiloxins using culture filtrate cultured for about 20 days. More appropriate way to isolate rough ustiloxins was 100% methyl alcohol rather than 70% (NH4)2 SO1, solution because it involved the incompletely removed ions, NH4+and SO42-, which disturbed the mensuration of biological activity. The experiment of growth restrain indicated that growth restrain ratio of radicle was appropriate to be used in the mensuration of biological activity because inhibition of the rough ustiloxins to the embryo was significantly weaker than to the radicle, possibly its directly touching the ustiloxins.2. Preparing antiserum against Ustiloxin A and mensurating it with immuno-gold: The antiserum against Ustiloxin A, a main component of the toxins, was prepared by immunizing New Zealand rabbit. Elisa assay showed that the litersof the two antiserums obtained were 1:20000 and 1:6000, respectively. The specificity of the antiserum was confirmed by immuno-gold labeling and the synthesis and secretion of Ustiloxin A was examined at the cell level. We also analyzed the processes of secretion of Ustiloxin A in culture medium and in false smut ball in the field by immuno-gold labeling.3. Analysing ustiloxins inhibiting plant cell mitosis The inhibition experiment of growth of garlic radicle showed that there were more cells in the telophase stage in the garlic radicle dealed with culture filtrate of Ustilaginodea virens than those dealed with H2O. The cell volume of the former was bigger than that of the latter. So itseemed that ustiloxins could inhibit the cell mitosis, but not in the cell elongation.