小麦千粒重主效QTL QTKW.caas-6A的精细定位和物理图谱构建

Fine mapping and physical map construction for thousand kernel weight (TKW) genes in wheat are of great importance for molecular marker-assisted selection and gene cloning. Previously, we identified a major QTL QTKW.caas-6A for TKW in the Zhou 8425B/Chinese Spring RIL population using the wheat 90K SNP assay. Based on the flanking markers of QTKW.caas-6A and linked markers of its, the F2, F2:3, F3:4 and F4:5 secondary populations from two crosses ZB6242×ZB6185 and ZB6242×ZB6218 were used for fine mapping of QTKW.caas-6A (ZB6242 has an allele at QTKW.caas-6A locus for higher TKW, whereas ZB6185 and ZB6218 have an allele for lower TKW; the parents showed only allelic variations at QTKW.caas-6A locus). The BSR-Seq and genomic sequence and physical map information of chromosome 6A are employed to develop molecular markers tightly linked (with genetic distances less than 0.1 cM) or co-segregated with QTKW.caas-6A for a high-resolution genetic mapping. In addition, a physical map covering QTKW.caas-6A will be constructed and candidate genes will be detected. These will provide an important basis for marker-assisted selection and map-based cloning of QTKW.caas-6A.

小麦千粒重基因的精细定位和物理图谱构建是分子标记辅助育种和基因克隆的基础。项目申请人前期在周8425B/中国春群体中发现一个千粒重主效QTL QTKW.caas-6A，根据90K SNP芯片分型结果，以目标QTL侧翼标记及其连锁标记为参考，用携带QTKW.caas-6A位点纯合高千粒重等位基因家系ZB6242和纯合低千粒重等位基因家系ZB6185、ZB6218的两个组合（双亲间只在QTKW.caas-6A位点有差异）的F2、F2:3、F3:4和F4:5群体为研究材料，通过三个世代的混池RNA测序（BSR-Seq），并结合6A染色体基因组序列信息，发掘与QTKW.caas-6A紧密连锁（连锁距离0.1 cM以内）或共分离的分子标记，构建覆盖QTKW.caas-6A位点的高精度遗传图谱和物理图谱，精细定位QTKW.caas-6A，并发掘其候选基因，为分子标记辅助育种及该基因的图位克隆奠定基础。

小麦千粒重基因的精细定位和物理图谱构建是分子标记辅助育种和基因克隆的基础。本研究以携带QTKW.caas-6A位点纯合高千粒重等位基因家系ZB6094和纯合低千粒重等位基因家系ZB6120及父本中国春的两个组合的F2、F2:3、F3:4和F4:5群体为研究材料，利用周8425B 20x重测序结果，共开发8个多态性KASP标记，针对目标区段筛选出8种交换单株；使用QTKW.caas-6A区域的3个KASP标记检测BC1F4每个杂合交换单株衍生后代的基因型，得到8个交换单株，并在收获后考察所有衍生后代的千粒重。根据基因型和表型进行成组法t测验，结果显示：4个交换单株的杂合区段衍生出的两种纯合基因型的平均千粒重差异显著（P＜0.05）；另外4个交换单株杂合区段衍生出的两种纯合基因型的平均千粒重差异不显著（P＞0.05）。两部分的结果表明QTKW.caas-6A的候选基因标记区间不明确，还需要进一步验证。撰写SCI论文1篇，申请国家发明专利1项。