Studies On Genetic Diversity And Pathogenicity Of The Dominant Pathogens Of Maize Ear Rot In Summer-Sown Maize Of China

Corn is one of the most important food and feed crops in the world.Summer corn is an important corn producing area in China,with 16.65 million hectares,accounting for 39.87% of the country’s total and more than 60% of China’s livestock feed.Corn ear rot is a worldwide fungal disease that occurs in maize ear,which can not only harm the yield and quality of corn,but also produce a variety of mycotoxins,endangering the health and safety of human and animals.At present,there are few studies on the genetic diversity,pathogenicity and toxin production of Fusarium in the whole summer maize planting area,and no complete theoretical system has been formed.In this experiment,Fusarium is the dominant pathogen of maize ear rot,was taken as the research object to explore the genetic structure and diversity,pathogenicity and toxin production of the dominant Fusarium population in summer corn planting area.to provide a theoretical basis for the prediction and control of corn ear rot disease in summer corn planting area.Seven pathogens of Fusarium verticillioides,Fusarium proliferatum,Fusarium graminearum,Fusarium oxysporum,Aspergillus,Penicillium and Rhizopus were identified by translational elongation factor l α(EF-l α)and specific primers.The genetic diversity of dominant Fusarium species in summer maize planting area was analyzed by ISSR molecular marker technology,and the pathogenicity difference and toxin production ability of F.verticillioides and F.proliferatum isolates were analyzed.The results show that:1.ISSR analysis showed that the population diversity of 472 strains of Fusarium verticillioides were the highest in Henan,the second in Shandong and the lowest in Shanxi.The genotypes in Henan were the most unique,and there was frequent gene communication(Nm=6.7497)among populations.ISSR analysis showed that the population diversity 279 of Fusarium proliferatum were the highest in Anhui,the second in Jiangsu and the lowest in Hebei.Cluster analysis shows that the genetic distance between Henan and Shanxi is the closest,and that between Jiangsu and Hubei is the farthest.There was frequent gene exchange(Nm=3.0875)among the pathogen populations,and the ISSR analysis of 77 strains of Fusarium graminearum showed that the population diversity of Fusarium graminearum was the highest in Henan,the second in Anhui and the lowest in Jiangsu.Cluster analysis showed that the genetic distance of Shandong and Jiangsu was the closest.AMOVA analysis showed that the variation sources of the three Fusarium populations were mainly from within the population.According to STRUCTURE structure analysis,the three pathogens populations were mainly divided into three clusters in summer maize region.2.Different polymorphic strains were selected for indoor and field pathogenicity analysis,and the difference of pathogenicity in the field was similar to that in the laboratory.The difference analysis of indoor pathogenicity of Fusarium verticillioides showed that the average disease severity index(DSI)in Henan was the highest,the average DSI in Shandong was the second,and the average DSI in Hubei was the lowest.The difference analysis of field pathogenicity of Fusarium verticillioides inoculated in Hefei showed that the average DSI of Anhui was the highest,the average DSI of Henan was the second,and the average DSI of Hubei was the lowest,and the average DSI of Fusarium proliferatum in Anhui was the highest,the average DSI of Shandong was the second,and the average DSI of Hubei was the lowest.The influence of precipitation on pathogenicity is higher than that of temperature and humidity.The isolates of different genetic similarity groups showed different degrees of invasiveness,and some isolates of the same genetic similarity group also showed different degrees of invasiveness,so the isolates in the province were analyzed separately.There were significant differences in pathogenicity.Based on the analysis of pathogenicity and polymorphic loci,the results showed that the correlation coefficient between pathogenicity and genetic diversity was not high.3.Different strains of Fusarium verticillioides and Fusarium proliferatum were selected to analyze their ability of producing Fumonisin.the results showed that all the isolates had Fumonisin gene.The strongest population of Fusarium verticillioides in Henan,the second was the strain population in Anhui and the lowest in Jiangsu.Among Fusarium proliferatum,the ability of producing Fumonisin B1 was the strongest in Henan,followed by Anhui,and the lowest in Hubei,and the strongest in Henan,followed by Anhui,and the lowest in Jiangsu.The isolates of different genetic similarity groups showed different degrees of invasiveness,and some isolates of the same genetic similarity group also showed different degrees of invasiveness,so the isolates in the province were analyzed separately.There were significant differences in the ability of producing Fumonisin.Based on the analysis of pathogenicity and Fumonisin production,the results showed that there was a significant positive correlation between pathogenicity and Fumonisin production.4.54 maize materials were artificially inoculated with Fusarium verticillioides for resistance analysis,of which 2% were identified as high resistance,65% as disease resistance,31% as moderately resistant and 2% as susceptible.