Mapping Of One Major QTL For Maize (Zea Mays L.) Kernel Row Number And Construction Of Its Near Isogenic Lines (NILs)

Maize (Zea mays L.) is an important crop for global food security and energy production. The grain yield is determined by kernel number per ear (KNE) and 100-kernel weight. KNE is an important yield component, which could be subdivided into kernel row number (KRN) and kernel number per row (KNPR). Then, the KRN is one of the most important traits that affect maize yield and the identification and cloning of QTL/gene associated with KRN is very useful for genetic improvement of grain yield.In previous studies one major QTL (qKRN8) related to kernel row number and accounting for 15.13% of the phenotypic variation was identified on chromosome 8 (bin8.03-bin8.04) with a F2 mapping population derived from V54 (8-10 rows, donor) and L87 (14-16 rows, receptors). Based on the previous study, in this work, QTL qKRN8-NTL (near inbred line) have been constructed via molecular assisted selection (MAS) and remapping of qKRN8 was done using an advance backcross population. The main results of this experiment are as follows:1. Construction of QTL qKRN8-NILUsing V54 as donor parent and L87 as recurrent parent and 82 pairs of polymorphic SSR markers evenly distributed, we constructed the QTL-NIL of qKRN8. The two plants S905 and S604 had higher recovering ratio of genetic background,95% and 94% in BC2F1 generation, respectively. These two plants were selected to produce BC3F1.2. Remapping of qKRN8The qKRN8 was mapped to the umc1904 and umc1202 interval region on chromosome 8, using the BC3F1 population. The mapping result was consisted to that of F2populations. In the umc1904 and umc1202 interval region, seven SSR or Indel markers were developed and the distance between any two neighboring markers was about two million base pairs.3. Construction of Chromosomes substitution linesIn 2014, a BC4F1 population containing 4106 individuals was developed. Five individuals containing recombination breakpoints in the QTL interval were selected, self-pollinate and used for the progeny test. According to the progeny test result, the qKRN8 was narrowed down to umc1904-SD51 interval corresponding.