利用未减数配子基因创制小麦加倍单倍体的效率及技术体系研究

The union of unreduced female and male gametes leads to spontaneous chromosome doubling, which is not only the important way of the origin of polyploid species but also an important tool for enhancing crop doubled haploid breeding efficiency. A major quantitative trait locus QTug.sau-3B responsible for unreduced gametes formation was discovered in tetraploid Triticum turgidum wheat and was further transferred to elite common wheat lines using synthetic hexaploid wheat as the bridge. This project is to make wheat/wheat F1 hybrids between the elite lines with this gene region and commercial cultivars. Wheat/wheat F1 hybrids and their parents will be then pollinated with the fresh pollen of Imperata cylindrica in order to produce wheat haploid through chromosome elimination of I. cylindrica. Doubled haploid (DH) may be then developed by spontaneous chromosome doubling in haploids because of the union of unreduced female and male gametes. This project is to evaluate the efficiency of QTug.sau-3B gene leading to spontaneous chromosome doubling and to establish wheat DH breeding technology system by combining chromosome elimination resulted from wheat-I. cylindrica hybrids and spontaneous chromosome doubling resulted from the union of unreduced female and male gametes. It is expected that this study will help to resolve technical bottlenecks of artificial chromosome doubling and enhance the efficiency of DH application in wheat genetics and breeding.

未减数配子的结合实现染色体自动加倍，是多倍体物种起源的重要途径，也是提高作物加倍单倍体（DH）育种效率的重要手段。我们前期从四倍体小麦发掘出控制未减数配子形成的强效QTL位点QTug.sau-3B，并通过人工合成小麦为“桥梁”，将其导入到综合农艺性状优良的小麦新品系中。本项目拟利用这样的优良新品系与小麦推广品种形成F1杂种，杂种及其亲本然后与白茅（Imperata cylindrica）远缘杂交，通过远缘杂种白茅染色体削除诱导产生小麦单倍体，利用未减数配子基因实现单倍体的染色体自动加倍。通过该研究，验证QTug.sau-3B基因实现染色体自然加倍的有效性及效率，并探索建立“基于小麦-白茅杂交实现染色体削除和未减数配子基因实现染色体自动加倍”的小麦DH育种技术。期待该研究有助于解决人工染色体加倍存在的技术瓶颈，从而大大提高加倍单倍体在小麦遗传育种中的应用效率。

四倍体小麦含有控制未减数配子形成的强效QTL位点QTug.sau-3B，但是QTug.sau-3B基因在小麦加倍单倍体育种中的应用研究缺乏。本项目利用已导入四倍体小麦QTug.sau-3B基因的优良小麦新品系与小麦推广品种的杂种F1做母本，用白茅（Imperata cylindrica）进行授粉，通过远缘杂种白茅染色体削除诱导产生了小麦单倍体，利用未减数配子基因实现单倍体染色体自动加倍。4个小麦（QTug.sau-3B）/小麦F1与11份白茅进行杂交，共授粉8396朵小花，获得了5034粒种子。通过幼胚拯救获得了732个单倍体胚，50个单倍体植株。其中，35个单倍体植株含有QTug.sau-3B紧密连锁SSR标记Xgpw1146分子标记等位位点，编号为H31-3小麦单倍体植株在25/18℃（16/8h）和25/10℃（16/8h）条件下均能自交结实，自交结实率分别为4.35%和2.41%，成功获得了加倍单倍体。通过该研究，筛选到了小麦单倍体诱导效率较高的白茅基因型BMZ1801和BMZ1616，初步建立了“基于小麦-白茅杂交实现染色体削除和未减数配子基因实现染色体自动加倍”的小麦DH育种技术。本研究结果将为未减数配子基因在小麦加倍单倍体育种中的应用奠定理论基础。