Fine Mapping Of The Major QTL Qhkw5-3 For Hundred Kernel Weight In Maize

Kernel weight is one of the most important traits in maize yield traits and researching the genetic mechanisms of kernel weight is the key to further improve maize yield.In this study,46 inbred lines of maize inbred lines,Zheng 58,and Chang 7-2were used as donors.by means of cross breeding,multiple backcross and molecular marker assisted selection,were constructed as non repeated homozygote single segment substitution line.One of the homozygote single segment substitution lines SSSL-Z22(substitution fragment was bnlg278..umc1680..bnlg1306),which hundred kernel weight of SSSL-Z22 was steadily detected two years,and there was a very significant difference between the hundred kernel weight with Zheng 58.Using SSSL-Z22 as the basic material,the F2:3 population of SSSL-Z22 * Zheng 58 was constructed.The hundred kernel weight of major QTL qhkw5-3 was identified in the chromosome fifth between SSR markers SYM033 and SYM108 of Bin5.06,the genetic distance was 8.8 c M,the physical distance is 4.44 Mb,accounting for 11.2%of phenotypic variation.This study,based on the previous research progress,F1 was obtained by using maize single segment substitution line homozygote SSSL-Z22 and inbred line Zheng58,and then BC1F1 was obtained by F1 and SSSL-Z22.According to the results of the preliminary location,the recombinant individual plants in BC1F1 were screened out,and the recombinant individual plants were all inbred BC1F2.BC1F2 segregation populations were used for fine mapping of the major QTL qhkw5-3 for hundred kernel weight in maize.In order to further fine mapping of the major QTL qhkw5-3 for hundred kernel weight in maize,molecular markers were used to screen BC1F3 populations,and the secondary single segment substitution line homozygote of different length was constructed.The main conclusions are as follows:1.In order to fine location of the hundred kernel weight QTL qhkw5-3,the BC1F1 populations constructed by(SSSL-Z22 * Z58)*SSSL-Z22 was used screened recombinant single plants.In the spring of 2015,1849 recombinant seeds were screened from 14759 seeds of BC1F1,using the SSR molecular markers SYM033 and SYM108 at both ends of the target interval,based on the results of preliminary mapping.In the summer of 2015,all recombinant grains were planted and 21 pairs of SSR markers were detected in the target zone.37 recombinant genotypes were obtained and BC1F2 were obtained by inbred.2.In the winter of 2015 years,BC1F2 populations and parents were planted in Hainan breeding base of Henan Agricultural University.In combination with genotype and phenotype of BC1F2 segregating populations,the major QTL qhkw5-3,which controls hundred kernel weight of maize,was localized between SSR molecular marker SYM077 and SYM084,and its physical distance was 442.6kb.In the same year,37 genotypes BC1F1 inbred progeny BC1F2 were planted separately and BC1F3 were selected by means of molecular marker assisted selection.3.In the summer of 2016,BC1F3 populations were planted altogether,to combine with of all the 34 pairs of SSR molecular markers of primary mapping constructed the genetic linkage map,using molecular marker assisted selection method to the screening of secondary homozygote single segment substitution lines,24 different length of the secondary homozygote SSSLs were obtained,which provided the basis for further fine mapping.The results laid the foundation for narrow the interval and the further fine mapping of the major QTL qhkw5-3 of hundred kernel weight in maize,also provided a reference for molecular breeding of maize.