Analysis On The Physiological Races Of Setosphaeria Turcica And The Pathogenic Gene StGlu1 Of Race 1

Northern corn leaf blight is a fungal disease caused by Setosphearia turcica,which can infect maize crops.Large-scale outbreaks are very likely to occur with the low ambient temperature and the high air humidity,especially in the corn-growing areas of North China,the spring corn-growing areas of the Northeast,and the corn-growing areas of the high-altitude and cool areas of the Southwest.In addition,the occurrence of northern corn leaf blight is also closely related to the physiological differentiation of the pathogen S.turcica,that is,the variation of physiological races.In this experiment,the physiological differentiation of125 purified strains of S.turcica from Northeaster China was identified,and the transcriptome data of race 0 and race 1 after interacting with the host for 48 h were used to analyze and compare the differentially expressed genes of the two were screened,and a specific pathogenic gene St Glu1 was screened from the up-regulated differential genes of physiological race 1,and cloned,bioinformatically analyzed,expressed by HEK293 and pathogenicity analyzed.The specific research results are as follows:1.Identified and analyzed the population structure of the physiological race of S.turcica in Northeast ChinaPhysiological differentiation of 125 isolated and purified strains was identified by identifying hosts containing different monoresistance genes Ht1,Ht2,Ht3 and Ht N,and a total of 10 types of physiological races were identified,including 0,1,2,3,N,23,1N,3N,12 N and 123 N.In terms of regional distribution,7 races were identified in Liaoning,Heilongjiang and Jilin,and 5 races were identified in Inner Mongolia.In terms of frequency of occurrence,the dominant race was race 0,accounting for 49.6%,followed by race 1 with19.2%.The virulence frequency of strains to Ht1 was the highest,reaching 30.98%;the frequency of Ht2 was the lowest,which was 14.54%.2.Clarified the similarities and differences in the transcriptomes of the physiological races 0and 1 of S.turcica in the interaction with the hostThe results of race 0 transcriptome data showed that the differentially up-regulated genes were 1711 and the down-regulateds were 1443.The differentially up-regulated genes of race 1were 1081 and the down-regulateds were 1763.The differential genes of race 0 were significantly enriched in GO terms such as catalytic activity,ribosome,and hydrolase activity,etc.The ones of race 1 were enriched in GO terms such as membrane composition,hydrolase activity,carbohydrate metabolism process,etc.There are differences in the number and types of KEGG pathways between race 0 and race 1,and the enriched metabolic pathways are 52 and 33,respectively.Pathogenic metabolic pathways,such as pentose phosphate pathway,glutathione metabolism were enriched in race 0,while starch and sucrose metabolism,peroxisome were enriched in race 1.3.Cloned St Glu1 gene of physiological race 1 of S.turcica.and analyzed its bioinformaticsSequencing results showed that the full length of St Glu1 gene was 1464 bp,and there were two introns with sizes of 49 bp and 53 bp,respectively.Analysis of the basic properties of the protein sequence encoded by the St Glu1 gene showed that the St Glu1 protein had a relatively stable structure,including 453 amino acids,more hydrophilic sites,no transmembrane helical structure,analyzed as a secreted protein.There are only α-helix,β-sheet and random coil in the secondary structure types,and these three structures can also be found in the tertiary structure model.By constructing a phylogenetic tree of St Glu1 protein,it was found that it was 100% identical to Exserohilum turcicum Et28 A.4.Optimized St Glu1 gene and analyzed its eukaryotic expression and pathogenicityThe p TT5-sy-St Glu1 eukaryotic expression vector was constructed,and the recombinant protein with a size of 47.8 k Da was obtained after transfection and culture.When the temperature of was 50 °C,the p H was 5,and the reaction time was 20 min,the enzyme activity was the highest.After the protease solution was inoculated into the treated maize leaves,the leaves appeared chlorotic at 12 h,and the lesions expanded and withered aggravated at 48 h,but there was no significant change in the control group.The St Glu1 gene is involved in regulating the secretion of related proteins,which helps for race 1 infect the host.