二倍体杂种优势马铃薯育种的展望

Prospects of Diploid Hybrid Breeding in Potato

马铃薯育种进程缓慢主要是由马铃薯四倍体遗传特性决定的。高度杂合的四倍体马铃薯中隐性基因表现频率低,使得很多有害的等位基因被隐藏在四倍体中,而有利等位基因很难重组到一个四倍体品种中,这是造成马铃薯杂交育种周期长的一个重要原因。马铃薯无性繁殖有利于保持原品种的优良性,生育期短;但储运成本高、容易退化。实生籽利用的优点是储运简便、基本不传播病虫害,且有利于知识产权保护。与四倍体实生种相比,二倍体F1育种可以通过不断自交将有害基因剔除掉,从而获得优良自交系用于F1实生籽生产。随着马铃薯研究的不断发展和马铃薯全基因组测序的基本完成,近几年二倍体F1实生籽育种成为了国际马铃薯研究的热点。然而,要实现二倍体实生籽生产,自交不亲和及其自交衰退是培育自交系的绊脚石。我们正在克隆自交不亲和抑制基因Sli,并且通过杂交将该基因整合到优良栽培品种中,为下一步培育出优良二倍体自交系奠定基础。同时我们也正在全基因组水平上挖掘马铃薯自交衰退相关基因区域,希望能进一步了解自交衰退的遗传机理,探索一条快速克服自交衰退的分子育种路径。这些工作将有助于建立马铃薯二倍体F1育种体系,带动马铃薯产业进入新的"绿色革命"。

Potato breeding process is slow, mainly due to its tetraploid genetic characteristics. It takes large selection programmes on progeny plants derived from crosses between tetraploid potato cultivars to select a clone that has the right balance between unfavourable alleles and compensating alleles at the same or at other loci. The clonal propagation of potato offers important agronomic and genetic advantages. However, clonal propagation has more drawbacks, where true potato seed production can make up for these deficiencies. In order to achieve continuous progress in potato breeding, an alternative system should be developed that is based on the structural removal of unfavourable alleles. Diploid breeding can ＂purge＂ the detrimental alleles by constantly selfing to elite inbred lines for F1 seed production. The availability of genome sequence and re-sequencing leads diploid FI breeding to be the hot topic. However, the hurdle in the development of diploid potato inbred lines is self-incompatibility and inbreeding depression. We are working on fine-mapping of an S locus inhibitor gene, and transferring the gene to elite cultivars. In addition, we focus on dissecting the inbreeding depression by re-sequencing doubled haploid popualtion, which would be essential for further genetic study of inbreeding loads in potato. The research will facilitate the setup of the diploid F1 breeding system in potato that will give birth to the Green Revolution of the potato industry.