A Study Of Sesame Fusarium Wilt Pathogens Toxin And Its Toxic Effects On Sesame

Sesame(Sesamum indicum L.,2n=26)which belongs to the Sesamum genus in Pedaliaceae family,is one of the most important oilseed crops.SFW is caused by Fusarium oxysporum f.sp.sesame(FOS),Sesame Fusarium Wilt and charcoal rot are two major fungal diseases in sesame.Sesame wilt disease have occurred in many countries,such as:China,India,Sudan,Egypt and Pakistan.it gives significant impact on the prevention and control of wilt disease.Therefore,we must explore the mechanism of sesame wilt promptly,Studies have shown that the toxin has an important role in the pathogenic process,However,till now there are no reports about sesame Fusarium wilt toxin and it's toxicity on sesame.So,we explored the method to extrac FOS toxin and analysis it's composition.After that,we evaluated it's toxicity on sesame seedlings.The above work is for seting up the foundation for the further studies about FOS pathogenesis and it's interaction with sesame.Main results are shown below.1.The toxicity test of the FOS metabolitesUsing the FOS metabolites deal with sesame seed to test toxicity.rusults proved that HSF009100(strong pathogenicity),HSF008005(medium pathogenicity)and HSF007021(weak pathogenicity)all could produce FOS toxins after cultivating 15d in PD.And,we can extract brown paste crude toxin from three strains.Both resistance varieties(Yu zhi 11 and ZHENGZHI 98N09)and cultivars(rong xian black sesame and ji 9014)could be harmed by those toxin.2.Analysis of the crude toxin componentUsing HPLC and HPLC-MS to analyze the crude toxin composition that producted by HSF009100,HSF008005 and HSF007021 under the PD condition.HPLC results showed that the result of degree of elution separation was not very good,the result of gradient elution is better.HPLC-MS results showed that crude toxin composition may include seven types of toxin which are shown below:(1).fusaric acid/FA.(2).FA+O.(3).Crotonolactone.(4).Diacetoxyscirpenol,DAS(5).Sterigmatocystin ST.(6).Aflatoxin B1.(7).DON/Deoxynivalenol.3..Analysis of the FOS toxin componentIn order to get more clear component of FOS toxin.Experiment made some adjustments:(1).increase the types of culture,In addition to PD and Czapek Dox,Richard.low carbon Richard;(2).Optimized HPLC conditions;(3).Substituted FOS bacterium fluid filtrate for crude toxin as the analysis object;(4).Using the standard sample HPLC results to account for mass spectrometry,liquid chromatography.Ultimately ensured the FOS toxin contains fusaric acid/FA,molecular formula:C10H13NO2,structured:5-butyl picolinate(5-butylpicolinic acid),which is one of the fusarium NHST mycotoxins,and for the first time found three FA intermediates:C10H13NO4 + O2(FA),C10H13NO3 + O(FA),C10H11NO2(FA-H2),three kinds of intermediate's toxicity on sesame is still unknown.4.Research the production regulation of FOS FAUsing PD,Czapek,Richard,and low carbon Richard respectively culture HSF009100 and HSFO0021,analysis content of FOS FA within 1?60d,at the same time,detecting bacteria liquid 's spores concentration,dry weight of hyphae,and pH value,analysis of the correlation between them and FA production.Results show that the two strains in four kinds of medium all can produce FOS FA.In Czapek medium,FA which was producted by HSF007021 is the highest(4133 ug/ml).Correlation analysis results showed that there is no significant correlation between content of FOS FA and pathogenicity,pH value,spores concentration,dry weight of hyphae.But it has a close relationship with nutrition conditions.5.The toxicity test of the FOS FA on sesame seedlingsTo ascertain the toxic effect of FOS FA on the sesame seedlings,Separately mix MS medium and sterile water with different concentrations FA which produce by HSF009100 and HSF007021.FA concentrations are:1?5?10?g/ml.Then dealing with four sesame varieties(YuZhi 11,ZHENG ZHI 98N09,Rong Xian black sesame and Ji 9014),the results show that the FA which produce by the two FOS strains can inhibit all these seedlings'growth or make the seedling die away.And as the increasing of concentration and time,the hurts of sesame seedlings would also increased.