玉米籽粒重金属铅(Pb2+)含量的QTL定位

铅(Pb²⁺)是现存环境最大量的有毒重金属污染元素,在我国特别是西南地区种植的玉米受重金属Pb²⁺污染日益严重,已严重影响到食物安全。文章利用玉米籽粒Pb²⁺低富集自交系178和籽粒Pb²⁺高富集自交系9782杂交衍生的重组自交系群体为作图群体,利用165对SSR多态性标记,构建了总长度为1499.85 cM、标记间平均距离为9.07 cM的分子遗传图谱,对玉米籽粒Pb²⁺含量性状进行了QTL定位分析,以期为选育籽粒低富集Pb²⁺的玉米新品种提供参考。结果表明,在Pb²⁺浓度为333.32 mg/kg胁迫下,共检测到2个与籽粒Pb²⁺含量相关的QTL,分别位于玉米第1、第4号染色体,其中qPC1位于标记区间umc1661~phi002h之间,表型贡献率为11.13%,加性效应为0.062;qPC4位于umc1117~nc005之间,表型贡献率为5.55%,加性效应为-0.044。性状相关分析结果表明,籽粒中Pb²⁺含量与穗长、穗粗、行粒数、穗重和百粒重等产量性状间均未达到显著水平,表明选育玉米籽粒Pb²⁺低富集的新自交系或杂交种不一定会影响到产量性状,而且籽粒Pb²⁺含量是一个相对独立的遗传性状。

Mapping of QTLs controlling Pb2+ content in maize kernels under Pb2+stress

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.