[Mapping of QTLs controlling Pb(2+) content in maize kernels under Pb(2+)stress]

Lead (Pb(2+)) is one of the most abundant heavy-metal elements in the environment. Pb(2+) pollution has become increasingly serious in maize planting areas, especially in the southwest of China, which even threatens food security. In the present study, a RILpopulation derived from 178 (an inbred line with low accumulation of Pb(2+) in the kernels) and 9782 (a Pb(2+)-hyperaccumulator in the kernels) was used for QTL mapping. A molecular genetic map with the length of 1499.85 cM and an average inter-marker distance of 9.07 cM was constructed with 165 pairs of SSR markers. QTLs controlling Pb(2+) content in maize kernels were then analyzed to provide the basis for breeding elite maize varieties with low Pb(2+)in the kernels. Two QTLs, qPC1 and qPC4, related to Pb(2+) content in maize kernels were identified on chromosome 1 and 4, respectively. qPC1 was located between markers umc1661 and phi002, accounting for 11.13% of phenotypic variance with an additive effect value of 0.062. While qPC4 was located between markers umc1117 and nc005, explaining 5.55% of the phenotypic variance with an additive effect value of -0.044. However, there was no significant correlation observed between Pb(2+) content in the kernels and any of yield-related traits including ear length, ear diameter, kernel row number and weight of per-hundred kernels, indicating that yield-related traits would not be changed in the process of low-Pb(2+)maize breeding. This suggested that the Pb(2+)content in maize kernel under Pb(2+)stress was an independent genetic trait.