Synteny between bulb onion and bunching onion based on linkage maps.

以洋葱（AlliumcepaL.）和洋葱串（A. fistulosum L.）。这两个种都属于Cepa组，染色体数目相同（2n=16），因此认为它们之间存在着高水平的大同线性。然而，没有进行详细的比较，因为两个物种的地图上几乎没有共同的标记。本研究的目的是在全基因组水平上评估洋葱和洋葱鳞茎的同线性。首先，我们在F_2群体中构建了黄鳞茎洋葱和红葱的基本连锁图谱。连锁图谱由11个连锁群组成，共有164个标记，覆盖1040 cM。用65个标记将10个连锁群划分到8条染色体上。虽然两个SNP标记（F3' H和DFR）都位于第7染色体上，但两个性状标记（Pg和Ant1）与DFR紧密连锁。在第7染色体上也检测到一个控制鳞茎色素沉着的QTL。在F_2和F_2：3代，DFR位点上的胡葱等位基因被替换后，红色素沉着程度显著变深。因此，DFR基因是影响该群体鳞茎颜色的关键基因之一。

Linkage maps have been developed for bulb onion(Allium cepa L.) and bunching onion(A. fistulosum L.). It is considered that a high level of macrosynteny exists between these 2 species since they belong to the section Cepa and have the same chromosome number(2n=16). However, a detail comparison has not evaluated because there are few common markers onto the maps of both species. The objective of this study was to evaluate synteny at the genome-wide level between bunching onion and bulb onion. As a first step, we developed a basal linkage map in F_2 population between yellow bulb onion and red shallot. Linkage map consists of 11 linkage groups with 164 markers covering 1, 040 cM. Ten linkage groups were assigned to eight chromosomes with 65 markers. Although both SNP markers(F3' H and DFR) were located on the Chr. 7, two trait markers, Pg and Ant1, were closely linked to DFR. A QTL for bulb pigmentation was also detected on the Chr. 7.All individuals homozygous for onion allele at DFR loci showed no pigmentation in F_2 individuals. The degree of red pigmentation became significantly darkened by replacing shallot allele at DFR in both F_2 and F_<2 : 3>. Therefore, DFR is one of key genes involved in bulb color in this population.