The differences in the nitrogen isotope composition between a maize hybrid and its parents

Understanding of nitrogen stable isotope variation in maize hybrids might help obtaining information on nitrogen absorption and distribution in different maize hybrids. In this study, we examined the nitrogen isotopic composition of different parts of maize hybrids under a laboratory culture experiment. The results showed that the δ15N values of different parts of the maize hybrid and its parents were ordered as follows: δ15Nstem>δ15Nleaf>δ15Nroot. The variation pattern of δ15N between the roots and leaves(Δδ15Nroot-leaf) of the maize hybrid was the same as that of δ15N between the roots and stems (Δδ15Nroot-stem). Therefore, the order of Δδ15Nroot-leaf as well as Δδ15Nroot-stem was as follows: Δδ15Nroot-leaf of the maize hybrid>Δδ15Nroot-leaf of the female parent (T4)>Δδ15Nroot-leaf of the male parent (803) and Δδ15Nroot-stem of the maize hybrid>Δδ15Nroot-stem of the female parent (T4)>Δδ15Nroot-stem of the male parent (803). This order is consistent with heterosis, indicating that differences in δ15N reflect the phenomenon of heterosis. The present study provides data in support of using the isotope technique to determine nitrogen distributions inside a plant and guide crossbreeding.

解析玉米杂交种的氮稳定同位素（nitrogen stable isotope）变异特征，有助于获取不同玉米杂交种的氮素吸收与分配相关信息。本研究通过实验室培养试验，测定了玉米杂交种及其亲本不同器官的氮同位素组成（δ15N）。结果表明，玉米杂交种及其亲本的各器官δ15N值排序为：茎秆δ15N > 叶片δ15N > 根系δ15N。玉米杂交种的根系与叶片间δ15N差值（Δδ15Nroot-leaf）的变化模式，与其根系与茎秆间δ15N差值（Δδ15Nroot-stem）的变化模式一致。因此，Δδ15Nroot-leaf与Δδ15Nroot-stem的排序均如下：玉米杂交种的Δδ15Nroot-leaf > 母本T4的Δδ15Nroot-leaf > 父本803的Δδ15Nroot-leaf；玉米杂交种的Δδ15Nroot-stem > 母本T4的Δδ15Nroot-stem > 父本803的Δδ15Nroot-stem。该排序与杂种优势的表现规律一致，表明δ15N值差异可反映杂种优势现象。本研究可为利用同位素技术解析植物体内氮素分布、指导作物杂交育种提供数据支撑。