QTL Identification Of Main Agronomic Characters Based On Advanced Backcross Population In Maize

Most of important agronomic traits in maize are quantitative in nature and are controlled by polygene, which are called quantitative trait loci(QTL). Identification and mapping of QTL are important for maize breeding. A series of backcross introgression lines derived from the recipient parent Zheng58 and donor parent Chang 7-2 were developed based on SSR marker assisted selection. The donor genome contents in the backcross generation were analysied. QTL mapping of several agrinomic trait were carried out by Windows QTL IciMapping v2.0 software.The main results are as follows:1.The genome contents were analyzed in the developing process of backcross The donor segment number (DSN)ranged from 3 to20 in BC2F1 ,with an average of 9.76;The donor segment length (DSL)ranged from 2.5 cM(centiMorgen) to 633.6cM, with an average of 110.2 cM; The donor genome size(DGS) ranged from 269.6cM to 3057.9Cm, with an average of 762.6cM. In BC3F1, The least DSN is 1 and the most one is 11. The average number is 5.02.The shortest DSL is 2.5cM and the longest one is 348.4cM. The average length is 82.5 cM. The smallest DGS is 54.4cM and the largest one is 1114.2 cM. The average length is 414.2cM .2. In this study, the three genomic parameters were directly analyzed using a set of single sequence repeat SSR markers covering the entire maize genome.from BC2F1 to BC3F1. The results demonstrated that DSN,DSL and DGS reduced 52.1%, 9.4%, 47.4% respectively.3. Based on 69 advanced populations, 76 QTL for ten agronomic traits were detected by windows QTL IciMapping(ICIM)2.0 software,including plant height, ear height, number of tassel branches, tassel length, leaves top length,the leave length, the leave wideth, the leave angle,the leave oriein and the area of leave.. LOD threshold values for all traits were purposed for three. 12,11,12,4,8,5,5,9,2 and 8 QTL were detected for these traits, respectively. Among these QTL,13,13,17,3,2 and 4 were located on chromosome7,8,9, 1,4 and 10, respectively.4. They were distributed unevenly on chromosomes and trended to be in clusters. 5 QTL linking to the microsatellite marker of mmc0241 were detected in chrosome 6,which are revelant to the traits such as PH,TBN,LF,LL,LFA,respectively. 8 QTL linking to the SSR marker of umc1671 were detected in chrosome 7 ,which are revelant to the traits such as PH,EH,TBL,LF,LFA,LL,LA,LOV,respectively. 9 QTL linking to the microsatellite marker of bnlg1067 were detected in chrosome 8 ,which are revelant to the traits such as PH,EH,TBL,TBN,LF,LL,LA,LOV,LFA,respectively. 7 QTL linking to the microsatellite marker of umc1492 were detected in chrosome 9 ,which are revelant to the traits such as PH,EH,LF,LL,LFA,LA,LOV,respectively. 5 QTL linking to the SSR marker of umc1492 were detected in chrosome 9,which are revelant to the trait such as TBN,LF,LFA,LA,LOV,respectively. The identify for QTL was used to study inheritance , fine map and clone of QTL.