根系遗传改良对于实现作物高产高效有着重要意义。有效气生根在玉米生长中后期的养分、水分吸收及抗倒伏中起着关键作用，但其发育的分子遗传调控机制并不清楚。课题组前期在染色体臂2.04处定位到一个控制有效气生根数量主效QTL-qEBRN2，利用其近等基因系测交种验证了该位点在不同遗传背景下具有显著的遗传效应，并具有节肥增产的潜力。通过精细定位，将该位点锚定到物理距离在61.4Kb的基因组区间内，进一步结合全基因组关联分析确定了候选基因。本项目拟在此基础上，通过基因沉默和功能互补等转基因材料证明目标基因功能，并分析其在器官、组织中的时空表达特征及蛋白的生化特性；利用关联群体进行遗传多样性分析，挖掘优良等位基因；利用转录组、蛋白质组分析，推测其作用途径；期望系统阐明控制有效气生根数QTL-qEBNR2的分子遗传调控途径。在田间和盆栽条件下，利用同位素示踪技术定量化该基因在提高氮效率中的实际贡献。

Genetic improvement of root traits is able to contribute greatly to high yield and resource use efficiency in crops. In maize the effective brace roots play a dominant role in nutrient and water uptake and anti-lodging during the later growth stage. However, the genetic control of maize brace root development remains unclear. We previously identified a QTL (QTL-qEBRN2) at chromosomal region bin 2.04. This QTL was found to control the number of effective brace roots and contribute to yield increase at low nitrogen input when it was crossed into different genetic background. QTL-qEBRN2 has been fine mapped to a interval with 61.4 Kb physical distance and the candidate gene is further targeted by genome-association analysis. In this project, we aim to clone the candidate gene and elucidate its biological function in controlling brace root growth via the tools of gene silencing, genetic complementation by maize transformation, in situ hybridization etc. The regulatory network of the candidate gene will be dissected using transcriptomic, and proteomic analysis. This work aims to discover the genetic regulatory pathway of QTL-qEBNR2 in controlling effective brace root development. Additionally, the contribution of qEBNR2-based effective brace root growth in efficient nitrogen uptake will be evaluated using 15N isotope tracing technique.