Goodwillie Carol, Ritland Carol, Ritland Kermit
Department of Biology, East Carolina University, Greenville, North Carolina 27858, USA.
Evolution. 2006 Mar;60(3):491-504.
Mapping of quantitative trait loci (QTL) was used to investigate the genetic architecture of divergence in floral characters associated with the mating system, an important adaptive trait in angiosperms. Two species of Leptosiphon (Polemoniaceae), one strongly self-fertilizing (L. bicolor) and the other partially outcrossing (L. jepsonii), were crossed to produce F2 and both backcross progenies. For each crossing population, a linkage map was created using amplified fragment length polymorphism markers, and QTL were identified for several dimensions of floral size. For each of the five traits examined, three to seven QTL were detected, with independent datasets yielding congruent results in some but not all cases. The phenotypic effect of individual QTL was generally moderate. We estimated that many of the QTL were additive or showed dominance toward L. bicolor, whereas comparison of mean trait values for parental and cross progenies showed apparent overall dominance of L. jepsonii traits. Colocalization of QTL for different dimensions of floral size was consistent with high phenotypic correlations between floral traits. Substantial segregation distortion was observed in marker loci, the majority favoring alleles from the large-flowered parent. A low frequency of male sterility in the F2 population is consistent with the Dobzhansky-Muller model for the evolution of reproductive isolation.
数量性状位点（QTL）定位被用于研究与交配系统相关的花部性状差异的遗传结构，交配系统是被子植物中一种重要的适应性性状。两种薄果草属（花荵科）植物，一种是高度自交的（双色薄果草），另一种是部分异交的（杰氏薄果草），进行杂交产生F2代以及两个回交后代群体。对于每个杂交群体，使用扩增片段长度多态性标记构建连锁图谱，并鉴定出花大小几个维度的QTL。在所检测的五个性状中，每个性状检测到3至7个QTL，在一些但并非所有情况下，独立数据集产生了一致的结果。单个QTL的表型效应通常中等。我们估计许多QTL是加性的，或者对双色薄果草表现出显性，而亲本和杂交后代平均性状值的比较表明杰氏薄果草性状明显总体占优。花大小不同维度的QTL共定位与花部性状之间的高表型相关性一致。在标记位点观察到大量的分离畸变，大多数偏向于来自大花亲本的等位基因。F2群体中雄性不育的低频率与生殖隔离进化的多布赞斯基-穆勒模型一致。
