Ht Gene Marker Development And Identification Of Races Of Exserohilum Turcicum In Shanxi Province

Northern corn leaf blight (NCLB), caused by Exserohilum turcicum, is one of the most destructive diseases in maize production and is worldwide distribution including China.It's an economical and effective way to to control the disease by using resistant cultivars. E. turcicum-maize interaction is a typical model of gene-for-gene relationship, so the physiological races in Exserohilum turcicum can be postulated based on the model. With the development and application of the molecular markers, many resistance genes in the plants, which control the qualitative traits and the quantitative characters, have been mapped. Using linked molecular markers has been a rapid and effective way to study the resistant gene. Anyhow, the improper utilization of the resitant gene will always be a most reason for the"lost"of the cultivars'resistance in the filed. So, it will be of importance to the rational distribution and safety product if we sduty on the variation in the races in the field.1. 300 RAPD primers were used to analyze the linkege with resistance genes in the mixed NILs, and there were 20 primers that showed specific polymorphic amplification. Two stable markers SBSP-14,SBSU-14, may relate with the Ht3 and HtN, by analysis the sequence we got.2. 19 RGA primers were amplified for identifying the linkage with Ht resistant genes. ZmRppl (3) showed a polymorphic amplification in the mixed NIL pools with Ht and no polymorphic fragments in the mixed NILs pools without Ht gene. Through the blast in the NCBI, we found that there were high Identities between this sequence and Oryza sativa LRK1 protein (LRK1) mRNA. What's more, the sequence was also proved to contain a LRR in it and it was also receptor-like protein kinase in many other plants. ZmRppl (3) may relate to the resistance of Ht gene.3. 22 SSR primers, 25cM from the Ht gene, were amplified for identifying the linkage with resistant genes. But there were no polymorphic fragments in the mixed NILs pools. The results showed that no any specific or polymorphic fragments were amplyfied in all of the primers.4. Twenty-eight isolates of Exserohilun turcicum,the causal agent of northern corn leaf blight (NCLB), in Shanxi Province in 2007,were identified in races by using the differential hosts with different Ht genes. The result suggested that there were 8 physiological races including 0,1,2,12,13,12N,123,and123N.The The frequency of virulence of E. turcicum isolates to Ht genes was: Ht1(64.3%); Ht2(71.4%); Ht3(35.7%); HtN(28.6%).