Metabolomic Studies For Wheat, Fusarium Graminearum And Their Interactions

Fusarium head blight(FHB) is an important wheat disease which has not only caused huge losses to wheat production,but also the mycotoxin contamination brought by the pathogen-Fusarium graminearum is poisonous to both human and the livestock. what's more,crucial food security problems produced have been more and more concerned.Using the metabolomic approach can give new insights to understand the related mechanisms of wheat-Fusarium graminearum interaction system,and provide Chemical data and theoretical foundation for elucidating resistant response and promoting the ability of FHB controlling.In this thesis,NMR-based metabolomic analytical methods combined with pattern recognition techniques such as PCA and OPLS-DA were used to study the below aspects:(1) the possible physiological mechanism of FHB resistance obtained in two transgenic wheat lines,which expressing AG gene and AG-D2 fusion gene, respectively;(2) the common and different responses between Sumai 3(resistant) and Annnong 8455(susceptible) after FHB pathogen infection;(3) the influences of metabolic fluxes when Tri5,Tps1 and Tps2 gene were singularly knocked out in Fusarium graminearum,and the changes of metabolomic profiling in host-pathogen interaction system caused by these genes single mutation;(4) the metabolic variation of wheat induced by DON in a time-series experiment.Our results showed that,(1) the two transgenic events did affect the wheat metabolomic profiling,and such effect was greater in TG AG than TG AG-D2.Without pathogen infection stress,it appeared that TG AG had obtained the resistant physiological basis.However,after FHB pathogen infection 48 h the two transgenic lines displayed more similar metabolomic profiling, involving highlighted enhancement of N flux metabolism and phenylpropanoids pathway,inhibition of GB synthesis,which were believed to be related with FHB resistance;(2) In Sumai 3 and Annong 8455 inoculated by Fusarium graminearum, there were some common changes in amino acid synthesis and TCA cycle,but Sumai 3 could accumulate more 5-Hydroxyferuloyl malate.In addition,GABA,glutamine, valine,leucine etc.showed different variation among Sumai 3 and Annong 8455.The common and different response against FHB pathogen laid metabolic foundation for interpreting defend response and resistant mechanism;(3) Tri5 and Tps genes mutation could significantly change metabolomic profiling of Fusarium graminearum,and the different effect was also found in the same class gene-types.?Tri5 had higher trehalose level than wild-type,and showed lower content in GABA,alanine,choline etc.;Tps gene mutation not only inhibited trehalose systhesis pathway,but also affected the abundance of glucose,glycine betaine,succinate etc.;what's more important,these genes mutation could affect metabolomic profiling of wheat-FHB pathogen system,and such effect displayed difference in resistant and susceptible wheat cultivar,which indicated these genes played important roles in fungi and host-pathogen interaction system;(4) the metabolomic profiling of wheat was induced to significantly change after DON inoculation 24 h,involving the increasing of aromatic amino acids and inhibition of glycine betaine,which offered very valuable metabolic data to understand the pathogenic mechanism of DON.All of these results above-mentioned demonstrated that NMR-based metabolomics is undoubtedly a powerful and remarkable tool for studying wheat-FHB pathogen interaction- the complex biological system,and give biochemical insights to recognize the interacting mechanism,in addition,act as a potentially important platform for studying transgenic crop,gene function,pathology and toxicology etc..