Construction of a linkage map and mapping loci controlling flowering time in Brassica oleracea

在甘蓝中克隆了4个控制春化反应开花时间的FLC基因。Schranz（2002）报道了4个克隆的FLC同源物中的3个是FLC 1、FLC 3和FLC 5。另一个是在甘蓝中发现的一个新的FLC同源基因，由于与芜菁的BrFLC具有较高的同源性，因此命名为BoFLC 2。利用限制性片段长度多态性（RFLP）、序列相关扩增多态性（SRAP）、切割扩增多态性序列（CAPS）和扩增片段多态性（AFLP）基因座构建了甘蓝遗传连锁图谱。157个标记覆盖了1196 cM，确定了9个主要连锁群，与该物种的单倍体染色体数目相当。43个结构基因，包括4个FLC同源物和一个常数（CO），控制春化和日长响应开花时间，分别进行了定位。在该图上检测到6个控制开花时间的数量性状基因座。3个甘蓝FLC直向同源基因FLC 1、FLC 3和FLC 5在图谱中与控制开花时间的QTL无关，而其中1个QTL位于FLC 2的定位区域，表明FLC 2可能控制甘蓝的开花时间。该连锁图谱包含4个FIC同源基因，可为甘蓝育种提供参考。

Four FLC genes controlling vernalization-responsive flowering time were cloned in Brassica oleracea. Three out of the four cloned FLC homologues were FLC1,FLC3 and FLC5 reported by Schranz(2002). The other one was a new FLC homologue in Brassica oleracea and was named as BoFLC2, because it showed high sequence homology to BrFLC of Brassica rapa. A detailed linkage map of Brassica oleracea was constructed based on segregation of Restriction Fragment Length Polymorphism (RFLP) loci, Sequence Related Amplified Polymorphism(SRAP) loci, Cleaved Amplified Polymorphic Sequences(CAPS) loci and Amplified Fragment Polymorphism(AFLP) loci. One hundred and fifty-seven markers covered 1196 cM and defined 9 major linkage groups, which were equals to the haploid chromosome number of this species. Forty-three structural genes including four FLC homologues and one constans(CO), which control vernalization-and day length-responsive flowering time, respectively, were mapped. Six quantitative trait loci(QTLs) controlling flowering time were detected in the map. Three FLC orthologues of Brassica oleracea, FLC1,FLC3 and FLC5 were not related to QTLs controlling flowering time in the map, whereas one of the QTLs was located on the region where FLC2 was mapped, indicating that FLC2 may control flowering time in Brassica oleracea. The linkage map including four FIC homologues will be useful for breedling programs of Brassica oleracea.