Instituto de Agricultura Sostenible, IAS-CSIC, Apdo 4084, Córdoba E-14080, Spain.
BMC Plant Biol. 2013 Jun 3;13:87. doi: 10.1186/1471-2229-13-87.
Hordeum chilense, a native South American diploid wild barley, is one of the species of the genus Hordeum with a high potential for cereal breeding purposes, given its high crossability with other members of the Triticeae tribe. Hexaploid tritordeum (×Tritordeum Ascherson et Graebner, 2n=6×=42, AABBH(ch)H(ch)) is the fertile amphiploid obtained after chromosome doubling of hybrids between Hordeum chilense and durum wheat. Approaches used in the improvement of this crop have included crosses with hexaploid wheat to promote D/H(ch) chromosome substitutions. While this approach has been successful as was the case with triticale, it has also complicated the genetic composition of the breeding materials. Until now tritordeum lines were analyzed based on molecular cytogenetic techniques and screening with a small set of DNA markers. However, the recent development of DArT markers in H. chilense offers new possibilities to screen large number of accessions more efficiently.
Here, we have applied DArT markers to genotype composition in forty-six accessions of hexaploid tritordeum originating from different stages of tritordeum breeding program and to H. chilense-wheat chromosome addition lines to allow their physical mapping. Diversity analyses were conducted including dendrogram construction, principal component analysis and structure inference. Euploid and substituted tritordeums were clearly discriminated independently of the method used. However, dendrogram and Structure analyses allowed the clearest discrimination among substituted tritordeums. The physically mapped markers allowed identifying these groups as substituted tritordeums carrying the following disomic substitutions (DS): DS1D (1H(ch)), DS2D (2H(ch)), DS5D (5H(ch)), DS6D (6H(ch)) and the double substitution DS2D (2H(ch)), DS5D (5H(ch)). These results were validated using chromosome specific EST and SSR markers and GISH analysis.
In conclusion, DArT markers have proved to be very useful to detect chromosome substitutions in the tritordeum breeding program and thus they are expected to be equally useful to detect translocations both in the tritordeum breeding program and in the transference of H. chilense genetic material in wheat breeding programs.
智利野生二倍体大麦是一种南美原生的大麦，是具有高谷类作物育种潜力的大麦属物种之一，因为它与黑麦族的其他成员具有很高的可杂交性。六倍体tritordeum（×Tritordeum Ascherson et Graebner，2n=6×=42，AABBH（ch）H（ch））是通过智利野生大麦与硬粒小麦杂种加倍染色体获得的可育双二倍体。用于改良这种作物的方法包括与六倍体小麦杂交，以促进 D/H（ch）染色体取代。虽然这种方法与黑小麦一样成功，但也使育种材料的遗传组成复杂化。到目前为止，tritordeum 品系是基于分子细胞遗传学技术和使用一小组 DNA 标记进行筛选来分析的。然而，H. chilense 中 DArT 标记的最新发展为更有效地筛选大量品系提供了新的可能性。
在这里，我们应用 DArT 标记对来自不同 tritordeum 育种阶段的 46 个六倍体 tritordeum 品系的基因型组成进行了分析，并对 H. chilense-小麦染色体添加系进行了分析，以允许它们进行物理作图。进行了多样性分析，包括构建系统发育树、主成分分析和结构推断。独立于使用的方法，可清楚地区分整倍体和取代的 tritordeum。然而，系统发育树和结构分析允许最清楚地分辨取代的 tritordeum。物理作图标记允许将这些组鉴定为携带以下单价体取代的取代 tritordeum：DS1D（1H（ch））、DS2D（2H（ch））、DS5D（5H（ch））、DS6D（6H（ch））和双取代 DS2D（2H（ch））、DS5D（5H（ch））。这些结果使用染色体特异性 EST 和 SSR 标记和 GISH 分析进行了验证。
总之，DArT 标记已被证明对检测 tritordeum 育种计划中的染色体取代非常有用，因此预计它们在 tritordeum 育种计划中以及在将 H. chilense 遗传物质转移到小麦育种计划中检测易位时同样有用。
