Osborn T C, Kole C, Parkin I A, Sharpe A G, Kuiper M, Lydiate D J, Trick M
Department of Agronomy, University of Wisconsin, Madison 53706, USA.
Genetics. 1997 Jul;146(3):1123-9. doi: 10.1093/genetics/146.3.1123.
The major difference between annual and biennial cultivars of oilseed Brassica napus and B. rapa is conferred by genes controlling vernalization-responsive flowering time. These genes were compared between the species by aligning the map positions of flowering time quantitative trait loci (QTLs) detected in a segregating population of each species. The results suggest that two major QTLs identified in B. rapa correspond to two major QTLs identified in B. napus. Since B. rapa is one of the hypothesized diploid parents of the amphidiploid B. napus, the vernalization requirement of B. napus probably originated from B. rapa. Brassica genes also were compared to flowering time genes in Arabidopsis thaliana by mapping RFLP loci with the same probes in both B. napus and Arabidopsis. The region containing one pair of Brassica QTLs was collinear with the top of chromosome 5 in A. thaliana where flowering time genes FLC, FY and CO are located. The region containing the second pair of QTLs showed fractured collinearity with several regions of the Arabidopsis genome, including the top of chromosome 4 where FRI is located. Thus, these Brassica genes may correspond to two genes (FLC and FRI) that regulate flowering time in the latest flowering ecotypes of Arabidopsis.
甘蓝型油菜和白菜型油菜一年生和两年生栽培品种之间的主要差异是由控制春化反应开花时间的基因决定的。通过比对每个物种分离群体中检测到的开花时间数量性状基因座（QTL）的图谱位置，对这些基因在两个物种间进行了比较。结果表明，在白菜型油菜中鉴定出的两个主要QTL与在甘蓝型油菜中鉴定出的两个主要QTL相对应。由于白菜型油菜是异源四倍体甘蓝型油菜假定的二倍体亲本之一，甘蓝型油菜的春化需求可能起源于白菜型油菜。通过在甘蓝型油菜和拟南芥中使用相同探针定位RFLP基因座，还将芸苔属基因与拟南芥中的开花时间基因进行了比较。包含一对芸苔属QTL的区域与拟南芥第5号染色体顶部共线，开花时间基因FLC、FY和CO位于该区域。包含第二对QTL的区域与拟南芥基因组的几个区域呈现断裂共线性，包括FRI所在的第4号染色体顶部。因此，这些芸苔属基因可能对应于调控拟南芥最晚开花生态型开花时间的两个基因（FLC和FRI）。
