Maize-mediated Interaction Between Fusarium Graminearum And Antagonistic Bacteria

Fusarium graminearum is a common fungal pathogen,which causes crop diseases,such as corn root rot,resulting in serious economic losses to the agricultural economy.Furthermore,Fusarium graminearum produces biological toxins during the infection process,which causes a major threat in human and animal health,as well as food safety.The prevention and control of Fusarium graminearum has gradually become a research hotspot.Therefore,it is critical to screen and identify the antagonistic bacteria for Fusarium graminearum and analyze its antagonistic mechanism.In order to understand the antagonistic mechanism of antagonistic bacteria,this paper isolated and screened the antagonistic strains of Fusarium graminearum in the rhizosphere soil of the diseased maize,and antagonized the screening of the bacteria and identification of strains.Corn was used as a mediator to perform transcriptome analysis on the antagonistic mechanism of antagonistic bacteria,to clarify the expression of antifungal genes in antagonistic bacteria,and to clarify the signal transduction between the two by gene expression.The results showed that 35 strains of bacterial colonies were isolated from the maize rhizosphere soil in the heavily infected maize field of Litangzhuang,Xinzheng City.Ten strains with obvious antagonistic effects were screened for rescreening,and the strain was screened according to the radius of the inhibition zone.The antagonistic effect was best the T14,T20,and T29 strains.Physiological and biochemical indicators,16 S rDNA sequence analysis and phylogenetic tree construction were performed on the above three strains,confirming that T14 is Pseudomonas migulae,T29 is Bacillus amyloliquefaciens,and T20 The species is Pseudomonas fluorescens.After analysis of the antagonistic effects and physiological and biochemical indicators of the three strains,T20 was finally confirmed as a subsequent antagonistic strain.The antagonism test of solid medium and liquid medium showed that the growth of mycelial growth of Fusarium graminearum was slower than that of the blank control after adding the antagonistic bacteria freeze-dried bacteria powder for 3 days.In corn-mediated antagonism verification experiments,after 3 days of corn culture with the addition ofFusarium graminearum,corn leaves turned yellow,fell off,roots were corrupted and broken;After 3 days of corn culture with added Fusarium graminearum and Pseudomonas fluorescens,the growth of stems and leaves of the corn and the growth of root hairs were basically normal,and there was no phenomenon,such as yellowing of the stems,broken root hairs and so on.After antagonism verification,the root-dividing experiments mediated by corn were conducted.After repeated experiments,the same results as those described above were obtained.The strains collected from the roots of the nutrient solution were weighed after centrifugation,and were then stored at-80 ? as samples for transcriptome analysis if meeting the detection requirements.The transcriptome analysis of maize-mediated interactions between Fusarium graminearum and Pseudomonas fluorescens showed that: the value of Clean Reads Q20 is greater than 98%,and the value of Clean Reads Q30 is greater than 96%,indicating that the quality of the original sequence after filtration is high;The enrichment results of differentially expressed GO including molecular activities,cellular components,and biological processes indicated significant enrichment;The average number of Clean Reads per sample after filtration was 7758790.Totally,1959 genes were differentially expressed in genes of Pseudomonas fluorescens.Among the differential genes,1032 genes were up-regulated and927 genes were down-regulated,among which 1485 genes were significantly different.Fusarium graminearum through up-regulation of the 3-dehydroquinate dehydratase activity and the transferase activity,the biosynthesis of non-ribosomal peptides in the siderophore group is controlled,while PAHs and aromatic compounds are degraded;In the process of amino acid metabolism,the biosynthesis of phenylalanine,tyrosine and tryptophan was significantly enriched,and the metabolism of glycine,serine and threonine was also significantly down-regulated.Pseudomonas fluorescens antagonistic protein content increased,while the degradation of citric acid,thereby inhibiting the growth of Fusarium graminearum.