| Rice blast which is caused by Magnaporthe oryzae is one of the most serious diseases in the world.Rice blast,rice sheath Blight and rice bacterial leaf blight are listed as rice three diseases.According to the research,the plants resistances to tric-yclazole which is protective fungicide and five systemic fungicides of isoprothio- lane, iprobenfos, carbendazim, fenoxanil, kasumin of the 50 strains of Magnaporthegrisea (Herbert) Barr gathered from rice of plants in Hunan province,Hubei province,Guangxi probince in the south of China in 2008 were determined by the mean of bacterial colonial growth-rate.By analyzi-ng the frequence, the baselines-sensitivity to above six fungicides of Magnaporthe grisea(Herbert)Barr were established. And the low and high resistam-metalaxy 1 strains of Magnaporthe grisea (Herbert) Barr have been gained with the method of isoprothiolane inducement, as well as the hereditary stabilities of all the resistant-isoprothiolane strains and the resistance levels of all the resistant- isoprothiolane strains. Besides, in the research of the colonial growth-rate,a lot of sporangium, the pathogenigity with comformity of the high and low resistant-isoprothiolane strains and the sensitive strain were compared with the path of colonial diameter,The method of count, the method of inoculation in vivo and the mean of computation, respectively. The conformity of the low and high resistant-isoprothiolane strains and the sensitive strain and the conductivity changing of isoprothiolane solution by dealing with different concentrations were analysed. As well as the polyacrylamide gel electrophoretical patterns of the esterases and the soluble proteins of the low and high resistant- isoprothiolane strains and the sensitive strain and the interactive resistances of the five systemic fungicides of resistant-isoprothiolane strains in Magnaporthe grisea (Herbert) Barr.The test results were as below:l.The EC50 values of isoprothiolane,tricyclazole,iprobenfos,carbendazim,fenoxanil and kasumin to the 40 strains of Magnaporthe grisea (Herbert) Barr ranged from 1.08μg/mL to 22.54μg/mL,0.68μg/mL to 11.53μg/mL,10.67μg/mL to 92.74μg/mL, 50.34μg/mL to 96.55μg/mL,2.12μg/mL to 7.09μg/mL and 2.29μg/mL to 178.77μg/ mL.The average values of EC50 to the 40 strains of above six fungicides were 7.9 6μg/mL,3.51μg/mL,43.10μg/mL,116.93μg/mL,4.91μg/mL and 43.38μg/mL.2.The mean EC50 values of isoprothiolane, tricyclazole,iprobenfos,carbendazim, fenoxanil and kasumin to the 40 strains,which were all from sensitive colony and composed the continuous and approximately normal distributions-resistance, respec-ti vely were 0.7487μg/mL,0.4259μg/mL,6.5729μg/mL,3.4521μg/mL,0.8532μg/mL and 1. 8532μg/mL.They could be used as the baselines-sensitivity of Magnapor the grisea (Herbert) Barr.3.10 lower resistance strains with 1 higher resistance strains were engendered by isoprothiolane experiment. when isoprothiolane focus increased within the range of from 0μg/mL to 400μg/mL, The occurrence frequency of resistant strains increased. The mutation frequency of resistant strains and the logarithm of isoprothiolane concentration is highly positive correlation.4. Resistance mutations of resistance can genetic down. Rice blast strains in F2, F4, F6 generation is stable and genetic down gradually.5. Ten low resistant strains’ EC50 of isoprothiolane ranged from 16.02μg/mL to 56.02μg/mL, and the average EC50 was 36.00μg/mL; the resistance levels of 10 low resistance strain ranged from 4.26 to 14.90 and the average resistance level were about 9.57.The EC50 of isoprothiolane of mutations 200M-008 EC50 value (1832.10μg/mL) is the largest, its resistance level (487.26) highest; Did not appear of resistant mutations. Resistant-isoprothiolane could belong to quality traits mutations.6. The vitro,vivo and compound fitness indexes of the sensitive strain,LX003 were higher than the tested resistant strains,and the highest index specie was high resistant strain,200M-008. But the three fitness indexes had no any correlationship with resistances of Magnaporthe grisea.7.The membrane of Magnaporthe grisea (Herbert) Barr could be damaged by Isoprothiolane.During the sensitive strain,LX003, the low resistant strain,200M-005and the high resistant strain,200M-008,The membrane permeability of first two st rains has increased after isoprothiolane treatment. While the high resistant strain, 200M-008 had stronger ability to resist to isoprothiolane. And this ability has the inverse ratio with the concentration of isoprothiolane.8. Some Magnaporthe grisea hot the spirit of rice LX003, low antibacterial strains of the sensitive plant 200M-005 and 200M-008 strains resistant to the esterase on electrophoresis there exist obvious differences between the specificity,LX003,the low resistant-isoprothiolane strain,200M-005,and the high resistant-isoprothiolane strain,200M-008, in Magnaporthe grisea (Herbert) Barr. Besides the sensitive strain,LX003, had the esterase-gonos of Rf0.716 and Rf0.835 while the highresistant strain 200M-008 only had the esterase-zone of Rf0.452. The quantity of the esterasezone of Rf 0.033 in the high resistant strain,200M-008, and in the low resistant strain, 200M-005,was higher than that in the sensitive strain,LX003.9.These are little significant differences in the polyacrylamide gel electrophoretical patterns of the soluble proteins between the spirit of rice LX003 strains resistant strains sensitive,200M-008and low antibacterial strains of 200-M005 3 strains in Magnaporthe grisea(Herbert)Barr.But the expression on the picture of resistant-isoprothiolane strains were higher than sensitives.10. The resistant-isoprothiolane strains in Magnaporthe grisea (Herbert) Barr had negative cross-resistance to iprobenfos,which belongs to the systemic fungicide and had no cross-resistance to tricyclazole,which belongs to the unsystemic fungicide,to carbendazim, which belongs to the systemic fungicide,to fenoxanil,which belongs to the systemic fungicide,and to kasumin, which belongs to the systemic fungicide. |
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