基于基因芯片的甘蓝型油菜优异材料杂种优势群划分

Classifying Elite Lines in Brassica napus L.into Heterotic Groups Based on Gene Chip Tests

本研究旨在对特异油菜种质资源材料进行杂种优势群划分,提高杂交种选育效率。本研究利用新开发的甘蓝型油菜全基因组50K芯片对优异种质资源材料进行杂种优势群划分。结果表明,共检测到25 135个均匀分布于甘蓝型油菜19个染色体的SNP位点。基于这些位点数据计算的遗传距离,其变动幅度在0.012 2~0.666 2之间,平均值为0.418 1,说明这些材料的遗传多样性较好。在遗传距离阈值为0.53处,将100份材料划分为6个杂种优势群,分别为:长江中游材料后代群Ⅰ(8个品系)、黄淮流域材料群Ⅱ(5个品系)、人工合成材料群Ⅲ(7个品系)、种间杂交后代群Ⅳ(3个品系)、参考群Ⅴ(芥菜型油菜1个)、混合来源群Ⅵ,其中第Ⅵ杂种优势群包含76个来源广泛的材料,是最大的一个优势群。第Ⅵ杂种优势群在遗传距离阈值为0.45处,又划分为6个亚群,其中C亚群包含材料最多,达到40个,说明在这些特异材料中,尽管总的遗传多样性较好,但是其中部分材料遗传基础较窄。本研究还发现了4个强优势杂种模式,分别是黄淮流域材料作母本与长江中游、长江下游、种间杂交材料后代和人工合成油菜后代的杂交模式。对比聚类结果与系谱的关系,发现系谱相近的品系并不一定总是归类到同一优势群中。说明凭借系谱来确定材料的遗传关系远近,是定性的和不准确的。来自不同杂种优势群的亲本间的杂交组合,产量超对照优势高于群内亚群间的亲本组合,同一亚群内的亲本间的杂交组合的优势最低。说明杂种优势群的划分对提高选育油菜杂交种效率有帮助。

The purposes are to divide our elite germplasm into heterotic groups and increase the efficiency of rapeseed hybrid breeding.We classified 100 elite lines into heterotic groups with recently constructed 50K genomic gene chips in Brassica napus L.Results indicated that these gene chips screened 25135 valid SNP sites,which distributed evenly in 19 chromosomes of Brassica napus.Genetic distances calculated with these SNP locus among these elite lines were wide:their genetic distances ranged from 0.0122 to 0.6662 with mean genetic distance 0.4181.At genetic distance threshold value 0.53,these elite lines were divided into six heterotic groups,which were as the followings:group I(8 lines)from progenies of middle reach of Yangtze River,group II(5 lines)from progenies of Huanghuai region,group II(7 lines)from progenies of interspecific hybridization,reference group V(1 Brassica juncea line)and mixture origination group VI.The group VI was the largest,mixture origination group and included 76 lines.At genetic distance threshold value 0.45,these 76 lines in group VI were further divided into six subgroups.There were 40 lines in subgroup D,which implied that the genetic diversity in these elite line was poor.In addition,we found 4 heterotic patterns with strong heterosis,which were as the following:lines from Huanghuai region crossed with accessions from the middle and the lower reaches of the Yangtze River,interspecific hybridization progenies and artificial synthesized Brassica napus progenies.Compared with the pedigrees of the lines,the lines with similar pedigrees were not always classified into the same group,which means genetic relationships determined by pedigrees are just qualitative and are not precise.In this study,the yield heterosis of intergroup hybrids compared with the check hybrid was higher than those intra-groups and the yield heterosis of intra-subgroup hybrids.These results showed that the heterotic groups classification were helpful for improving effectiveness of rapeseed hybrid breeding.