小麦Wx基因近等基因系的创制及其对直链淀粉含量、面条感官品质的影响

为明确不同Wx基因对小麦直链淀粉含量的影响以及筛选面条品质优异的基因型，以糯小麦品系Caiwx (aabbdd)为3个Wx基因隐性突变供体亲本，以扬麦01-2 (AABBDD)为轮回亲本，利用连续回交结合花粉碘染、STS标记和同工酶标记检测方法，创制了8种Wx基因纯合基因型的近等基因系，其基因型分别为AABBDD、AABBdd、AAbbDD、AAbbdd、aaBBDD、aaBBdd、aabbDD和aabbdd。利用这些基因型探讨了不同Wx基因对直链淀粉含量及面条感官品质的影响。结果表明，各系的直链淀粉含量为0.9%~24.8%，系间差异显著；糯小麦型(aabbdd)直链淀粉含量最低，双缺失型和单缺失型其次，双缺失型中aaBBdd型含量最高，单缺失型中AAbbDD型含量最低，表明Wx-B1对直链淀粉的合成作用最大。糯小麦型面条的色泽、表观、软硬度、黏性、韧性得分以及总分显著低于其他类型及轮回亲本扬麦01-2；单缺失型面条的色泽、表观得分、总分显著高于轮回亲本扬麦01-2，其中aaBBDD型面条品质表现突出，与市售优质面条粉“雪花粉”制作的面条得分相当，而其他7种基因型及轮回亲本扬麦01-2的面条评分均显著低于雪花粉。说明可以通过遗传操作Wx基因培育优质面条小麦品种。

Development of Near-isogenic Lines with Different Wheat Wx Genes and Their Effects on Amylose Content and Noodle Quality

Granule bound starch synthase (GBSS), controlled by Wx gene, is a key enzyme for amylose synthesis. Wheat has three homologous Wx genes located on 7BS, 4AL, and 7DS. The purpose of this study was to understand the effects of wheat Wx genes on amylose content and noodle sensory quality. A waxy wheat line, Caiwx (aabbdd), was used as a donor parent for Wx null al-leles, and a high yield cultivar, Yangmai 01-2 (AABBDD), was used as a recurrent parent. A BC9F2 population was constructed through successive backcrossing assisted by pollen staining with I2-KI solution. Eight homozygous near isogenic lines (NILs) with different Wx gene combinations (AABBDD, AABBdd, AAbbDD, AAbbdd, aaBBDD, aaBBdd, aabbDD, and aabbdd) were then identified by STS markers of Wx genes and GBSS isoenzyme markers in the BC9F4 generation. The amylose contents and noodle sensory quality of these NILs were evaluated. The amylose contents of the NILs ranged from 0.9% to 24.8% with signifi-cant difference among lines. There was a regularly descending trend of amylose content in genotypes as normal wheat (AABBDD) > single null allele genotypes (aaBBDD, AAbbDD, and AABBdd) > double-null-allele genotypes (aabbDD, aaBBdd, and AAbbdd) > waxy wheat (aabbdd). Genotype aaBBdd had the highest amylose content in the double-null-allele group, and genotype AAbbDD had the lowest amylose content in the single-null-allele group. This indicated that Wx-B1 allele plays the most important role in amylose synthesis. It was also found that the amylose content reduction did not follow a directly linear relationship when the null allele number increased. Thus, we inferred that there exits gene interaction among different Wx alleles. The result of noo-dle sensory quality evaluation showed that there were significant differences among the eight NILs. All the noodle sensory scores of waxy wheat (aabbdd) on color, appearance, firmness, stickiness, as well as the total score, were the lowest among the eight NILs. The single null genotypes performed better noodle sensory quality than the other genotypes and the recurrent parent Yang-mai 01-2. In the single-null-allele group, the aaBBDD genotype showed the best noodle sensory quality (scored 87.4). Noodles made of flour of aaBBDD genotype were as good as those made of Xuehua flour, a kind of high-quality flour for noodle-making. However, the other seven genotypes and Yangmai 01-2 had significantly lower noodle scores than Xuehua flour. Therefore, it is feasible to develop wheat cultivars with high noodle quality through genetic manipulation on Wx gene.