陆地棉因其适应性广、产量高而被广泛种植。然而，我国不是棉花的起源地，我国培育的品种血缘非常狭窄。长期的定向选择使得我国陆地棉品种遗传基础很狭窄，品种性状进一步提升的空间非常有限，DNA标记的研究结果也验证了这一现象。陆地棉性状遗传基础的解析对于陆地棉的改良具有重要意义。然而，目前的研究多采用两亲本的作图群体。多态性低和等位基因少限制了陆地棉性状遗传基础的解析。为了更好的解析陆地棉性状的遗传基础，本项目组成员通过多年的努力，创造了12亲本的MAGIC群体。这些亲本包括高产、优质、抗枯萎病、耐黄萎病及抗虫性状优良的材料。本研究拟以该群体为研究对象，开展以下研究：（1）借助本课题组构建的高密度图谱和RAD-seq测序，研究该群体的基因型构成；（2）结合多环境的表型鉴定，剖析优良性状形成的遗传基础，着重解析不同等位基因的效应；（3）筛选公共多态性标记和综合性状好的优良品系，应用于育种研究。

Cotton is one of the important economic crops in China. Among the four cultivated species, upland cotton cultivars are widely cultivated because of its wide adaptability and high yield production. However, our country is not the origin place of cotton, the upland cotton cultivars are mainly derived from some basic cultivars introduced from the United States, which resulted in the narrow genetic diversity. Long-term directional selection makes genetic basis of upland cotton cultivars in our country very narrow; the further promotion space of cultivar traits is very limited. DNA marker research results on the genetic diversity also confirmed this phenomenon. Upland cotton breeding are now facing with serious "bottleneck effect" in China. The genetic dissection of important traits in upland cotton cultivars is very important to genetic improvement of this crop. However, the recent studies are mainly focused on populations derivred from biparents or few parents. The low polymorphism and the few alleles restrict the studies of genetic dissection of upland cotton. In order to better understand the genetic basis of important traits in upland cotton, our project team members developed a MAGIC (Multi-parent Advanced Generation Inter-Cross) population with 12 parents through several years of efforts. These parents include varieties with high yield, good fiber quality, resistance to fusarium wilt and verticillium wilt, and resistance to insects, which is an ideal population of study quantative traits in cotton. Based on this MAGIC population, our researches will focus the following contents: (1) with the aid of the high-density cotton genetic map constructed in our lab, and the RAD-seq sequencing, the genotype composition of the MAGIC population will be studied to understand the different parent's chromosome distribution; (2) combined with phenotype identified in multi enviroments, the genetic basis of different trait architecture will be analyzed; the effect of different alleles will be especially studied; (3) polymorphic molecular markers that can be directly used by other researchers will be provided; elite verities with many good trait characters will be identified through the field test and molecular marker assisted selection, which will be applied to breeding research.