Abstract: Quantitative trait loci (QTLs) of the lamina length of Lolium perenne have been studied to better understand the genetic control of growth in grasses and to help the fixation of favorable alleles. Thus, a mapping population was built by crossing a‘long-leave' genotype and a‘short-leaf' one. Genetic maps were constructed at LOD=5.5 by the mean of 178 molecular markers, including 167 AFLP, 6 RAPD and 5 iso-enzyme loci. Lamina length was measured first in the greenhouse at the early germination stage, and later in the field at the late germination stage. Over all, 10 markers significantly associated with lamina length were found, its mean single genetic effect ranging from 6 mm to 19.1 mm. Only 3 markers appeared to be QTLs of lamina length at the early stage, the other 7 were related to the lamina length measured in the field. To avoid redundancy of QTLs found in each parent, a multiple regression analysis with all significant markers (ANOVA, P<0.005) from both parents was then carried out on the average lamina length in the field. Three markers closely related to the lamina length explained 50.9% (r²) of the total phenotypic variance of which a marker is expected to respond. The interaction of the most favorable combination of these markers could extend or shorten the lamina length by 26 mm. As the realized heritability over the 3 cycles of mass selection for lamina length was estimated to be 0.32, it is suggested that selection of even only 2 markers could be more efficient than phenotypic selection.

Key words: Lolium perenne, Lamina length, Quantitative trait loci, Genetic mapping, Molecular markers

摘要： 选择固定有益等位基因,研究多年生黑麦草叶片长度数量性状位点,结果表明:与叶长最为相关的3个标记所表达的变异占表型总变异的50.9%(r²);在选择中如能将这3个标记最优化地组合在一起,其综合共同作用有望使叶片长度延长和缩短2mm;鉴于供试材料在最初3个世代的群体选择中所估测到叶片长度的遗传力为0.32,这样在今后的选择工作中,即使只使用现有的两个标记,其效果亦优于传统的表型选择法.

关键词: 多年生黑麦草, 叶片长度, 数量性状位点(QTLs), 遗传图, 分子标记