利用回交法与Wx基因分子标记辅助选择培育糯性小麦

Developing Waxy Wheat with Backcrossing Approach and Molecular Markers-Assisted Selection

以中国春糯性位点全套近等基因系为研究材料,对小麦Wx基因的6个STS标记和1个CAPS标记进行了筛选。改良PCR扩增条件以及产物检测方式后,从这些标记中筛选出3个标记,包括鉴定Wx-A1、Wx-D1位点的2个共显性STS标记和Wx-B1位点的1个显性STS标记,用于本研究中糯性小麦的分子标记辅助育种。在育种过程中,首先配制全糯材料“98Y1441”与推广品种“川育12”的杂交组合,采用籽粒碘染法从其F2种子中选择全糯基因型个体与回交亲本川育12杂交,如此反复自交、回交,历经数代异地加代繁殖得到BC5F2代回交改良群体。利用上述3个分子标记从该群体中筛选出了8种Wx基因型,经卡方检验,其分离比符合3对基因的分离比例,其中基因型为aabbdd的植株有2株,直链淀粉含量分别为1.81%和0.82%,为全糯小麦;基因型为AAbbdd,aabbDD的部分糯性植株各有1株,直链淀粉含量分别为15.24%和17.57%。研究中获得的BC5F2代群体的农艺性状接近回交亲本,并明显优于全糯材料“98Y1441”,表明采用回交法与Wx基因分子标记辅助选择相结合,有助于培育高产、优质的全糯和部分糯小麦。

A series of Chinese Spring Wx loci near-isogenic lines were used to identify the specific bands of 6 STS markers and 1 CAPS marker of Wx genes. After optimizing PCR amplification and separation of PCR products, 3 codominant and dominant STS-markers were identified at the Wx-A1, Wx-D1 loci and Wx-B1 loci, respectively, which were used in molecular markers-assisted selection of waxy wheat in our breeding program. A cross between waxy wheat ＂98Y1441＂ and variety ＂Chuanyu 12＂ was made, and I2-KI dying method was used to select full waxy genotype individual from F2 seeds. The full waxy genotype individual was crossed with recurrent parent ＂Chuanyu 12＂. After 5 generations of self-cross and backcross, BCsF2 segregating population was obtained. Using the markers above, 8 Wx genotypes were developed from the BC5F2 population, which follows Mendelian segregation. Among them, there were 2 aabbdd waxy plants whose amylose content in the BCs F3 seeds were 1.81% and 0.82%, respectively. In addition, there were partial waxy plants （AAbbdd and aobbDD） whose amylose content in the BC5F3 seeds were 15.24 % and 17.57%, respectively. Most agricultural traits of the BC5F2 segregating population resembled those of the recurrent parent ＂Chuanyu 12＂, and superior to waxy wheat parent ＂98Y1441 ＂. This shows that backcross approach in combination with molecular markers-assisted selection of waxy genes is helpful to develop partial and full waxy wheat with good traits in the waxy wheat breeding program.