Abstract: The objective of this study was to identify quantitative trait loci (QTL) and molecular markers associated with the contents of ash,potassium,calcium,magnesium,and phosphorus in alfalfa (Medicago sativa). To understand the genetic basis of these traits,an F₁ population that consisted of 392 individuals was developed by crossing a low-yielding precocious alfalfa genotype (male parent) with a high-yielding late-maturing alfalfa cultivar (female parent). The three-year phenotypic data were collected and QTL mapping was carried out based on the high-density genetic linkage map that had been constructed previously. The results showed that sixty-three QTLs associated with ash and four mineral elements were identified. Phenotypic variance explained by single QTL was 2.50% to 29.85%,which distributed on twenty-two linkage groups (chromosomes). Among those,eight QTLs were located at the same position repeatedly (qCa-3C-1 and qCa-3C-2,qCa-6B-1 and qCa-6B-2, qCa-6D-1 and qCa-6D-2, qAsh-8B-1 and qAsh-8B-2) and six QTLs were co-located (qP-2C and qK-2C,qP-3A and qMg-3A,qP-6D-3 and qMg-6D-2). With further validation,the markers closely linked with these QTLs may be used for marker-assisted selection in breeding new alfalfa varieties with high mineral elements.

Key words: Alfalfa quality, Traits, Mineral element, QTL analysis

摘要： 为初步鉴定与紫花苜蓿(Medicago sativa)粗灰分、钾、钙、镁、磷含量调控相关的数量性状基因座(Quantitative trait loci，QTL)和分子标记，本研究用低产早熟苜蓿和高产晚熟苜蓿杂交，构建了由392个个体组成的F₁群体，对这些性状进行3年表型数据测定，且基于前期已构建的高密度遗传连锁图谱开展QTL定位。结果表明：共检测到63个与粗灰分和4种矿质元素含量相关的QTL，分布于22个染色体上，单个QTL的贡献率为2.50%~29.85%；其中重复定位的QTL共8个(qCa-3C-1和qCa-3C-2，qCa-6B-1和qCa-6B-2，qCa-6D-1和qCa-6D-2，qAsh-8B-1和qAsh-8B-2)，共定位的QTL有6个(qP-2C和qK-2C，qP-3A和qMg-3A，qP-6D-3和qMg-6D-2)；经进一步验证，与这些QTL紧密连锁的标记可用于分子标记辅助选择育种。本研究为选育矿质营养更丰富的苜蓿新品种奠定了基础。

关键词: 紫花苜蓿, 品质性状, 矿质元素, QTL定位