QTL mapping of flowering related traits of maize with and without nitrogen application

Objectives The purpose of this study was to dissect variation of maize flowering-related traits under two conditions of nitrogen applied normally or none, and to map the related QTLs.

Methods One panel included 160 Single Segment Substitution Lines (SSSLs) was constructed by using foundation parental lines of Zong3 and Xu178 as donor and receptor parents, respectively. The panel was treated with two conditions of nitrogen applied normally or none by using the split-plot experiment design, and the nitrogen treatment was set as the main plot and genotypes were set as the sub-plots under three environments, including Guiyang, Dejiang in Guizhou Province and Luoping in Yunnan Province. Three flowering-related traits, including day to pollen (DTP), day to silk (DTS) and anthesis-silking interval (ASI), were investigated in one treatment.

Results The results showed that across the whole genome, about 54 flowering-related traits QTLs were identified under the two N treatments, which were mainly located on the chromosome 1, 3, 6, 9 and 10, among them, 3 QTLs were common under three environments. Under N⁺ treatment, QTLqDTS9a controlling day to silling (DTS) was found which was located on chromosome 9, and could explain 3.05% genetic variation; another QTLqASI10a controlling the ASI was also found, which located on chromosome 10, and could explain 30.74% genetic variation. Under N– conditions, QTLqDTP9 was identified, which could explain 3.43% genetic variation of DTP;qDTS9a related withDTS was found, which located on chromosome 9, and could explain 4.08% genetic variation; QTLqASI10 was also identified, which located on chromosome 10, and could explain 50.28% genetic variation. Comparing between N+ and N– conditions showed that, the QTLs identified under N– was much more than those under N+ treatment.

Conclusions Two commonly QTLs are existed in the two nitrogen treatments, one isqDTS9a, which is located on Bin9.02, with flank markers of umc1170-umc1636-bnlg1401-umc1271, and the other isqASI10a, which is located on Bin 10.04, with flank markers of umc1077-umc1053-umc2350. These loci may play important role in nitrogen absorbing, transporting, and utilization during maize development, and served as candidate loci in further map-based cloning of maize flowering-related traits.