利用回交法与Wx基因分子标记辅助选择培育糯性小麦

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BC5 F2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。

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

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 co-dominant 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 I_2-KI dying method was used to select full waxy genotype individual from F_2 seeds.The full waxy genotype individual was crossed with recurrent parent "Chuanyu 12".After 5 generations of self-cross and backcross,BC_5F_2 segregating population was obtained.Using the markers above,8 Wx genotypes were developed from the BC_5F_2 population,which follows Mendelian segregation.Among them,there were 2 aabbdd waxy plants whose amylose content in the BC_5 F_3 seeds were 1.81% and 0.82%,respectively.In addition,there were partial waxy plants(AAbbdd and aabbDD) whose amylose content in the BC_5F_3 seeds were 15.24 % and 17.57%,respectively.Most agricultural traits of the BC_5F_2 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.