Analysis Of Resistance Gene To Northern Corn Leaf Blight In Maize Germplasm

Northern corn leaf blight (NCLB), caused by Exserohilum turcicum, is one of the mostdestructive diseases in maize productions and is worldwide distribution including China. The useof resistant cultivars is the most economical and effective strategy to control the disease. E.turcicum-maize interaction is a typical model of gene-for-gene relationship, so the resistance genesin maize can be postulated based on the model. Many disease resistance genes including someNCLB resistance genes have been mapped using molecular marker. Using tightly linked markersto detect resistant genotype in germplasm has been becoming a rapid and effective way. Theobjectives of this study were to determine resistant genotypes in maize gemplasm screened asphenotype of resistantce to NCLB during 1986 to 2004.1. Using spray inoculation technique, 100 resistant germplasms were identified for theinteraction types with different virulent races. The results showed that Ht1 gene was in 49germplasms, account for 49%; Ht2 gene in 24 germplasms, account for 24%; Ht3 gene in 29germplasms, account for 29%; HtN gene in 13 germplasms, account for 13%.2. Five pairs of primers, umc1202, bnlg1152, umc1149 and SD-06₆₃₃ linked to Ht2 gene andbnlg1666 linked to HtN gene, were retested for the practicability in resistant gene markingusing NIL Huangzaosi. The results showed that no any specific or polymorphic fragmentswere amplyfied in all of the primers.3. 29 SSR primers were amplified for identifying the linkage with resistant genes. The resultsshowed that only one pair of primers (umc1684), located on chromosome 7.04, producedpolymorphic fragments between Huangzaosi and Huangzaosi Ht3. It means that umc1684should be linked to Ht3 gene.4. 30 RAPD primers were used to analyze the linkege with resistance genes in NIL Huangzaosi.Five of them (S1004,S1008,S1009,S1012,S1013) were specific amplify. The specificfragments were converted to be sequenced characterized amplified region (SCAR) markers.One SCAR marker (SC-S09₆₅₆) was identified to be linked to Ht3 and another SCAR marker(SC-S13₃₁₄) was identified to be linked to HtN. SC-S09₆₅₆ and SC-S13₃₁₄ were used to identify100 resistant germplasms, and Ht3 gene was found in 20 germplasms and HtN gene in 10germplasms. This result was same with the result tested with different races.