Physiological Races Monitoring And Genetic Diversity Of Setosphaeria Turcica In Maize Production Areas Of Northern China

In the study, the incidence of Northern leaf blight of corn in maize production areas ofnorthern China was investigated in2011and2012, containing Hebei, Shanxi, Shan’xi,Ningxia, Gansu and Liaoning provinces. The physiological races of Setosphaeria turcicawere monitored. The mating types and genetic diversity of110strains were detected at themolecular level. The main research results were as follows:1. In2011, the Northern leaf blight of corn occurred seriously in Ningxia Guyuan,Gansu Lingtai, Shanxi Yangling, Shanxi Xinzhou and Hebei Pingquan, but slightlydamaged in Shan’xi Yulin, Liaoning Shenyang, Dandong and Tieling. Especially in HeibeiChengde, the disease occured ahead to late June. In2012, the occurrence of Northern leafblight of corn in northern maize production areas was serious generally, where the level ofpathogentic condition were5~7, and could reach9in the severely part. The diseaseincidence in the northern of Shanxi and Hebei was more serious, and the disease incidencewas earlier to late June also. The incidence of Ningxia, Shanxi and Gansu were slighter.2. The results of monitoring the physiological races in the field showed as follows.The composition of physiological races was more complex in Liaoning, Shanxi and Hebei,where exists race0, race1, race2, race3and race N. The composition of physiologicalraces was relatively simple in Shan’xi, Gansu, Ningxia. The race0was primarily and race1, race2and race N were complementary.3. The result of molecular identification on the mating type showed that101isolateswere “a” mating type, which were occupied91.82%of the total identified strains;4isolates had “A” mating type, which were occupied3.64%of the total identified strains;5isolates were “Aa”, which were occupied4.54%of the total identified strains.4. ISSR-PCR reaction system and procedures on S. turcica were established and18primers were screened in this study.5.169DNA fragments were amplified and158polymorphic loci were found in110isolates, which were occupied93.5%of DNA fragments. Based on the amplificationresults and the genetic similarity analysis by NTSYS-pc software, the cluster analysisshowed that110strains of2011and2012can be divided into fourteen groups at0.78levels. The S. turcica isolates from the northern China maize production areas displayedsignificant genetic diversity, and had relationship with the geographical position, butwhether it is associated with mating type was unconfirmed.