Identification Of Pathogen And Genetic Diversity Of Curvularia Leaf Spot In Heilongjiang Province

Maize curvularia leaf spot was a serious disease affecting yield and quality of corn in Heilongjiang Province,from minor disease had become the main disease.In order to clarify the distribution,pathogen types,virulence differentiation and genetic diversity of Curvularia leaf spot in Heilongjiang Province,the pathogens were collected and identified from Harbin,Suihua,Daqing,Qiqihaer,Jiamusi,Mudanjiang,Jixi,Qitaihe,Heihe and Yichun,and the virulence differentiation and SSR analysis of Curvularia were also studied,the results were as follows:(1)156 pathogenic were isolated from the diseased leaves,and identified by morphological and rDNA-ITS sequence analysis.All the isolates were divided into 4 species:C.lunata(87 strains,55.8%),C.inaequalis(23 strains,14.7%),C.clavata(26 strains,16.8%)and C.pallescen(20 strains,12.8%).C.pallescens is the dominant species in Heilongjiang provience.(2)Xianyu 335,Pengcheng 9,Kennian,Huangzao 4 and Demeiya 2 were selected out of 10 different maize varieties as the differential hosts.C.lunata was divided into 15 races(CL1-CL15),and CL 12 was the dominant race;C.inaequalis was divided into 12 races(CC1-CC12)with the dominant races CC2 and CC11;C.clavata was divided into 11 races(C11-C111)with the dominant races C12 and C19;and C.pallescen was divided into 8 races(CP1-CP8)with the dominant races CP6 and CP7.(3)The SSR reaction system was optimized,and the best reaction system was determined as follows:0.2 mmol/L dNTP 2.0μL,2.0 μmol/L primer 1.0 μL,30 ng/gL template DNA,2.5 U/μL Taq DNA polymerase 0.5 μL,10 × Buffer 3.0 μL,ddH2O 11.5 p.L,annealing temperature with 53.4℃.(4)A total of 43 loci were amplified from 156 isolates of Curvularia,including 30 polymorphic loci and 69.8%of polymorphic loci.The polymorphism loci were mainly distributed between 450 bp and 650 bp,and the frequencies of the genes were between 1.9318 and 1.9434 in the range of 550 bp to 600 bp.The expected heterozygosity was between 0.4831 and 0.4845,Shannon information index between 0.6703～0.6751.Cluster analysis showed that the different strains come from the same area were not attributed to one group,and the different strains belong to the same physiological race were not attributed to one group.There were no correlation between the geographical origin and the virulance.