Abstract:

Lead (Pb²⁺) is one of the most abundant heavy-metal elements in the environment. Pb²⁺ 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 Pb²⁺ in the kernels) and 9782 (a Pb²⁺-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 Pb²⁺ content in maize kernels were then analyzed to provide the basis for breeding elite maize varieties with low Pb²⁺in the kernels. Two QTLs, qPC1 and qPC4, related to Pb²⁺ 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 Pb²⁺ 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-Pb²⁺maize breeding. This suggested that the Pb²⁺content in maize kernel under Pb²⁺stress was an independent genetic trait.

Key words: maize ( L.), Pb2+ stress, Pb2+ content in maize kernels, QTLs mapping