玉米是世界上最大的栽培作物，在全球粮食安全保障体系中起着关键的作用。玉米粗缩病是由灰飞虱传播的病毒性病害，在南美、欧州、亚州和非洲等地均有发生。近十年来，在我国尤其是黄淮海地区粗缩病迅速蔓延，年发病面积达千万亩以上，对玉米生产构成严重威胁。由于缺少高抗品种，生产上通过推迟播期的方法来躲避灰飞虱的入侵，但是，这种消极的防治措施效果有限，而且存在着巨大的隐患。当务之急是要收集抗性资源，克隆抗病基因，阐明抗病机理，从遗传上解决玉米抗粗缩病问题。本项目利用关联和连锁分析相结合剖析玉米抗粗缩病遗传模式，发掘抗病基因/QTL新位点；在前期定位的基础上克隆隐性抗病主效QTL，观察其在病毒接种前后的时空表达特征，明确其识别病毒的功能位点；采用转录组、酵母双杂交等综合手段，搜索参与抗性反应的基因，推测抗性的代谢途径，阐述玉米抗粗缩病的分子机制。最终，我们将发展分子标记，开展分子育种，改良玉米对粗缩病的抗性。

Maize is the largest cultivated crop worldwide and plays key role towards food security around the world. Maize rough dwarf virus (MRDV) disease, a viral disease transmitted by small brown planthopper, has rapidly spread across South America, Europe, Asia, and Africa. In China, MRDV has become one of major maize diseases during the last 10 years, especially in the Yellow-huai-hai river plain. The disease area reaches up to 10 million Mu per year, and this poses a grave threat to this strategic maize production region of China. Owing to the lack of resistant hybrids, the current protection measure is to delay sowing time to avoid planthopper infestation. However, this conservative measure has proved to be less effective and potentially a high risk. Therefore, it is extremely urgent to identify host resistance to control MRDV through the identification of resistant germplasm, isolation and characterization of resistance genes, and molecular breeding of resistant cultivars. In the current project, we will conduct joint linkage-association mapping to reveal the inheritance mode of maize resistance to MRDV and to identify more resistance loci. We plan to clone the gene for a key recessive resistance QTL revealed in our previous study, followed by analysis of its temporal and spatial expression profiles. We plan to identify the host target protein and its viral recognition sites. We will take the transcriptome and proteome approaches, together with yeast two-hybrid method, to search for those genes involved in the MRDV resistance pathways. Taken all these data together, we can decipher the genetic mechanism of maize resistance to MRDV. Finally, we will develop markers and conduct marker-assisted selection to improve maize resistance to MRDV.