玉米雄穗分枝数主效QTL定位及qTBN5近等基因系构建

立足于发掘玉米雄穗分枝数优异基因资源,利用郑单958骨干亲本郑58和昌7-2构建的188个重组自交系(recombinant inbred line,RIL)家系群体,结合288个多态性分子标记构建的连锁图谱和2年玉米雄穗分枝数表型数据,运用完备复合区间作图法进行QTL定位,共检测到5个控制玉米雄穗分枝数的一致性主效QTL,分别位于玉米5条染色体上。通过连续回交及分子标记辅助选择构建了位于bin 5.05的控制雄穗分枝数主效QTL-qTBN5近等基因系(near isogenic line,NIL),对基因遗传效应进行了验证,并将qTBN5进一步定位在13.2 Mb区间之内,为玉米雄穗分枝数主效基因的精细定位及分子育种奠定基础。

Major Quantitative Trait Loci Mapping for Tassel Branch Number and Construction of qTBN5 Near-isogenic Lines in Maize (Zea mays L.)

Tassel branch number (TBN) is a principal component of maize tassel-related traits important for modern maize breeding and production. To understand the genetic basis of tassel branch number, we adopted 288 markers exhibiting polymorphisms between Zheng 58 and Chang 7-2 to construct the genetic linkage map, and conduct quantitative trait loci (QTLs) analysis using sets of 188 recombinant inbred line (RIL) families derived from the elite maize inbred lines vz. Zheng 58 × Chang 7-2. Five major QTLs controlling tassel branch number within five different chromosomes respectively were validated by using the inclusive composite interval mapping method (ICIM) based on phenotypic data collected in two years. Because qTBN5 located on chromosome bin 5.05 was found to be an important QTL, qTBN5 near-isogenic lines (qTBN5-NILs) were developed by backcrossing and marker-assisted selection, and qTBN5 was further mapped in 13.2 Mb intervals. These findings will advance our understanding of the inheritance basis of TBN, and also facilitate the fine mapping and molecular breeding programs in maize.