The Physiological Differentiation Of Cercospora Zeae-maydis And Varieties Resistance Research

Gray Leaf Spot(GLS)is also known as caulispora leaf spot of maize,which is mainly caused by Cercospora zeae-maydis,and it has gradually gone up a major disease in the northeast corn region of China causing seriously damage to corn production.This paper is based on the identification of the pathogen of GLS,spoted in Northeast of China in 2016,which studied the pathogenicity differentiation;On one hand,by using the ISSR molecular marker technology,studying on the genetic diversity of Cercospora zeae-maydis;On the other hand,artificial inoculation method was used to identify the disease resistance of Maize Varieties in Liaoning Province,which identified the main varieties roundly.The main results are as follows:1.The isolation of GLS in Northeast China from 2016 was carried out,using the conventional single spore isolation technique,which showed that it obtained 72 strains.The molecular and morphological identification of the 72 strains of pathogenic bacteria were C.zeae-maydis,proofing the GLS pathogen in northest of China only C.zeae-maydis,no C.zeina and C.Sorghi.A systematic study of 24 of these advantages was studied to further study the basis of the pathogenicity differentiation of GLS in northeast China.2.This paper probes into the pathogenicity differentiation of GLS bacteria in northeast China,by selecting 20 strains of C.zeae-maydis carried out with 8 common key maize self-interbreeding,and the initial period of the plaque,the characteristics of plaque and the type of response had been detailed.It can be divided into 20 types of pathogenic bacteria from the three main maize producing areas in Northeast China,which are divided into 5 pathogenic types:Strong pathogenic type(group A),Moderately pathogenic type(group B),Moderately pathogenic type(group C),Weakly pathogenic type(group D)and Weakly pathogenic type(group E).3.Analyzed genetic diversity of 24 strains of C.zeae-maydis in Northeast China,by ISSR markers,it turned out that the similarity coefficient between the 24 tested strains was between 0.72-1.00,and the similarity between different strains was significantly different.This shows that there was no significant correlation between genetic diversity and geographical origin.4.Through artificial simulation of natural onset of gray leaf spot,testing some of the main maize varieties in Liaoning province of their simple resistance in recent years,the results showed that 73 of the tested varieties were resistant to disease and accounted for about 86.30%,susceptible varieties accounted for 13.70%,proving the varieties produced in Liaoning have certain resistance to gray leaf spot now,while most of them were moderately resistant,less high resistance.