Study On Improving Northern Corn Leaf Blight Based On Recycling Breeding Strategy In Maize

In view of the Backbone of maize germplasm in northeast China is easily affected by northen corn leaf blight,the study applies recycling breeding strategies,form SS group and NSS group.and 8 excellent inbred lines were screened by a high density identification,using test species to evaluate its yield combining ability,combine with identification of northern leaf blight and phenotypic characterization,screening a new inbred lines of breeding application potential,at the same time using SNP marker analysis its genetic basis.The main results are as follows:1.After two years of identification of Northen corn leaf blight of the new materials by recycle improvement,the overall resistance level was above,which indicated that the strategy based on recycling strategy could effectively improve the characteristics of northern leaf blight.2.By two sites field experiments,the eight recycling breeding have been taken yield combining ability and agronomic traits identification,screening out four excellent inbred lines with high combining ability,respectively,A6(J106 * LH214 / J106),A4(J106 * T99 / J106),A3(J106*T99/J106)and A1(X21/4 * 4-144-144),the general combining ability values respectively were7.45,6.77,6.10,3.94.A3 / X21,A6 / X21,new combination has great potential to increase production.3.Cluster analysis and principal component analysis showed that the 20 inbred lines could be divided into SS group and NSS group.The modified Si-144 lines(A1 and A2)were divided into SS group,and the genetic distance between the modified Si-144 and X21 was 0.223 and0.281,respectively.The modified lines of J106(A3,A4,A5,A6,A7,A8)were divided into NSS group,and the genetic distance between the modified lines was relatively close,which was consistent with the genealogy.4.The genomic genetic structure of A6(J106*LH214/J106),donor(LH214)and recipient(J106)was analyzed.The genetic similarity coefficient between A6 and LH214 was higher than0.757,and the imported fragments from LH214 on chromosome 10,5 and 2 were all more than85%.The genetic similarity coefficient between A6 and J106 was 0.536,and the imported fragments from J106 on chromosome 8 and 1 were more than 40%,with an average value of42.57%.