Genetic Diversity And Pathogenicity Differentiation Of Ustilaginoidea Viren

Rice false smut,caused by Ustilaginoidea virens(Cooke)Takahashi,is a kind of Rice Panicle disease.Because of Ustilaginoidea virens is a polyetic epidemic disease,the occurrence of the disease is related to the year,region,and host material.Therefore,the research on rice false smut focused on the same year,the same region,and the same rice plant and genetic diversity in the same host species separation of ustilaginoidea virens,pathogenic differentiation ability and biological characteristics and the correlation between the three,make a theoretical basis for the infection characteristics of rice false smut and resistance breeding.This experiment will be chiamydospore 2016 from Ya'an Caoba village Guanghua acquisition high sense of rice false smut Pujiang No.6 on the acquisition,through the method of tissue isolation,obtain single spore strains,and analyzed the genetic diversity,differentiation of pathogenicity determination and biological characteristics observation.The main experimental results are as follows:1)Analysis of genetic diversity of false smutThe isolated and purified strains of the single spores were subjected to MLST analysis by PCR amplification of the DNA identified as false smut.The 97 strains that were amplified by mark1 established a genetic evolution tree and were divided into 9 genetic groups I,II,III,IV,V,VI,VII,VIII,and IX.Among them,group I is the dominant group,34 in total,accounting for 35.1% of the total;II,III,IV,V,VI,VII,VIII,and IX groups were 2,2,10,11,4,1,8,25 respectively,this accounted for 2.1%,2.1%,10.3%,11.3%,4.1%,1%,8.2%,and 25.8% of the total bacterial strains.The 94 strains amplified by maker 2 were divided into 2 genetic groups I and II.Class I contained 93 strains,accounting for 98.9% of the total population;Class II contained one strain,which accounted for 1.1% of the total population.The experimental results show that the genetic diversity existed between the separated host material the same year,the same region,the genetic background of ustilaginoidea virens,even there are genetic differences between the same rice bran balls,,but similar to the genetic background of most strains.By comparing the genetic diversity of the strains isolated in 2013 and 2014,it was found that there wasgenetic diversity among the rice cultivars isolated from different years,the same region,and the same host material,and the genetic variation of population was more obvious and the evolutionary potential was stronger.In recent years,the distribution of small species has changed and new groups are produced.The dominant population of pathogenic bacteria may be gradually changing or the gene frequency of the pathogen may have changed due to the cultivation of resistant varieties or the pressure of the environment.In this paper,the sporulation,colony color,and colony morphology of 50 single spore strains were observed.It was found that most of the spores produced from the same strain of the same spike had no significant difference in sporulation.There was no significant difference between single spore strains isolated from different chiamydospore with a spike,only the difference between a few strains;and between sporulation isolated from different rice between ustilaginoidea virens some significant,some exist without significant differences.The color of colony was divided into 5 categories: white,yellow,yellow green,ink green and yellow brown,which accounted for 18%,18%,28%,28% and 8% of the tested strains respectively.The colony morphology was divided into flat and uplifting colonies,which accounted for 70% and 30% of the tested strains respectively.There is no corresponding relationship between the genetic diversity of Rice False Smut and the characters of culture and sporulation.2)Determination pathogenicity differentiation of false smut17 strains selected from the genetic group of maker1 were inoculated to 6 rice materials to determine their pathogenicity differentiation.The results showed that the inoculation difference of the inoculated strains was different on 6 different rice materials,but the pathogenicity differentiation of 08R2394 between 92-548 and Pujiang 6 was not obvious.There was a clear pathogenicity differentiation among the strains of false smut,different strains showed different pathogenicity in rice of different materials,different strains showed pathogenic differences on the same rice material,and pathogenic differences existed between the strains isolated from the same spike and those isolated from the same strain of rice balls,such as: the disease spike rate and disease index of strain127-2-8 pair material R13149-19-1 were 50% and 21.33.The spike rate and disease index of 127-2-10 to R13149-19-1 were 13.33% and 6 respectively.Each strain withdifferent genetic clustering was inoculated on the rice material,.each cluster contained different pathogenic conditions,there was no one-to-one correspondence between the variation of disease index and spike rate and genetic clustering.