联合GWAS和RNA-Seq技术发掘苎麻分株数显著关联位点与相关基因

Ramie (Boehmeria nivea L.) is one of the most important natural fiber crops, as well as an important forage grass in south China. Yield improvement is the vital target in ramie breeding. Ramet number, a quantitative trait controlled by multigene, is one of the important factors that affect the production of ramie. Mining significantly associated loci of ramet number and identification of relevant functional genes in ramie is fundamental for improving ramie variety. However, few reports are available. Previously, using genome-wide association study (GWAS) with a ramie natural population, we have detected 103 specific molecular markers, correlated with superior alleles that control ramet number. Thirty-four of the above markers show polymorphism in a hybrid parents whose ramet number are significantly different (the average number is 6.4 and 20.8, respectively). Then the F1 hybrid generations were reproduced via vegetative propagation. Due to the genetic heterogeneity, there is a false positive rate in GWAS results. To clear the authenticity of the ramet number significantly associated loci, single label association analysis will be conducted using the F1 segregated population with the phenotypic data of three years in two experimental bases in this study. Then the gene segments of the verified associated loci will be compared with the whole genome sequence of ramie to hunt ramet number associated genes. Transcriptome analysis and q-PCR technology will be performed to further identify ramet number associated functional genes. This study will provide gene resources and genetic basis for molecular breeding of ramet number in ramie.

苎麻是重要的天然纤维作物，也是我国南方重要饲草，提高纤维或饲用产量是苎麻育种的重要目标。分株数是影响苎麻产量的重要因素，属多基因控制的数量性状，发掘苎麻分株数显著关联位点及其相关基因对苎麻分株数分子改良具有重要意义。但是，迄今相关研究鲜见。前期，我们利用苎麻自然群体，通过全基因组关联分析（GWAS）获得103个与分株数显著关联的分子标记，发现其中34个标记在一对苎麻双亲（平均分株数分别为6.4和20.8）中存在多态性，并获得该组合F1分离群体。鉴于遗传异质性，GWAS结果存在假阳性率，本项目拟在此基础上，以该F1分离群体为材料，利用其三年两个试验点分株数数据进行单标记关联分析，检验分株数显著关联位点的真实性；继而通过分株数显著关联位点与苎麻基因组比对，寻找苎麻分株数相关基因，结合生物信息学、RNA-Seq技术和q-PCR技术鉴定分株数相关基因。本项目的实施将为苎麻分株数分子育种提供参考。

苎麻是重要的天然纤维作物，也是我国南方重要饲草，提高纤维或饲用产量是苎麻育种的重要目标。分株数是影响苎麻产量的重要因素，属多基因控制的数量性状，发掘苎麻分株数显著关联位点及其相关基因对苎麻分株数分子改良具有重要意义。但是，迄今相关研究鲜见。前期，我们利用苎麻自然群体，通过全基因组关联分析（GWAS）获得103个与分株数显著关联的分子标记，发现其中34个标记在一对苎麻双亲（平均分株数分别为6.4和20.8）中存在多态性，并获得该组合F1分离群体。鉴于遗传异质性，GWAS结果存在假阳性率，本项目在此基础上，以该F1分离群体为材料，利用其三年两个试验点分株数的数据进行单标记关联分析，检验分株数显著关联位点的真实性，共获得与苎麻分株数显著关联的有效分子标记6个；继而通过分株数显著关联位点与苎麻基因组比对，寻找苎麻分株数相关基因，结合生物信息学、RNA-Seq技术和q-PCR技术鉴定分株数相关基因，鉴定获得与苎麻分株数相关的候选基因35个。本项目的研究结果为苎麻分子育种提供参考，同时为苎麻品种分子改良提供丰富的基因资源。