Study On Toxin Production And Gene For Fumonisin Biosynthesis In Fusarium Monliforme Isolated From Corn In Sichuan Province

maize ear rot has been the most important disease of the world,which is caused by Fusarium graminearu and other fungis.But the main fungi is Fusarium moliforme.It reduces corn grain yield,makes poor quality,and the grains which were infected contain mycotoxin can lead poisoning cases and influence humans' health.To carry out the research of the toxin-producing strains has important significance both in theory and practice,we collected eggplant samples showing symptoms of Fusarium monliform from 6 sample -collecting spots in Sichuan.In this study,by performing culture isolateion and single- spore isolation,48 isolates of Fusarium monliform were got in 2007 and 2008.The experiment had studied on the toxin-producing conditions and abilities of Fusarium monliform isolates from different districts and determined of fumonisin biosynthesis gene from molecular's degree.The results of the research showed as follow:1.Toxin-producing condition and mycelium growth of Fusarium monliform:We choosed three strains which from different districts for test.The effects of media,Temperature, initial PH and time on production by Fusarium monliform were studied.The result showed that the best media for toxin production was Richard in the four medias and the maximum toxin production occurred 10 days after cultivation,at PH5 and 25℃temperature,three strains growed best in PS or PD media,and the maximum mycelium growth occurred 20 days after cultivation,at PH3 and 20℃-30℃temperature.It indicated that the conditions were inconsistent beween toxin-producing condition and mycelium growth.2.toxin-producing ability of Fusarium monliform strains from Sichuan: We selected Richard media and conditons which were fit for producing toxin.We cultured 48 strains which were from six cities and countries and took bioassry method which was showed by inhibition rate of maize's radicel and measured the relative amount of toxin - producing and compared toxin- producing ability.However,The study found that.the different was existed among strains.The strongest toxin-producing strain was CHB-18 which was from Ya'an.The weakest toxin- producing strain was LZ-4 which was from Luzhou.There were unrelation bewwen Geographical origin and toxin-producing ability,that was toxin-producing ability of the same Geographical origin of strains existed different.It also indicated that choosing right toxin-producing conditions and applying bioassry method could determine toxin- producing ability of isolates strong or weak,which were simple and accurate and economical ways.3.Detect fumonisin biosynthesis gene of Fusarium monliform strains from Sichuan: We used specific primer Fum5F/Fum5R to amplify DNA of 48 Fusarium monliform strains which were from Sichuan,determined that whether the strains had the key gene (fum1 gene) or not,The result showed that 41 strains had toxin-producing gene of the 48 strains,accout for 85.42%of the isolates.It also showed that strains of Sichuan had toxin-producing gene universal.Many strains of Sichuan had ability of producing fumonisin,which provided basis for safety detection of food.