Zhang L Y, Bernard M, Leroy P, Feuillet C, Sourdille P
UMR INRA-UBP Amélioration et Santé des Plantes, 234 Avenue du Brézet, 63100 Domaine de Crouël, Clermont-Ferrand Cedex 2, France.
Theor Appl Genet. 2005 Aug;111(4):677-87. doi: 10.1007/s00122-005-2041-5. Epub 2005 Jul 21.
The increasing availability of expressed sequence tags (ESTs) in wheat (Triticum aestivum) and related cereals provides a valuable resource of non-anonymous DNA molecular markers. In this study, 300 primer pairs were designed from 265 wheat ESTs that contain microsatellites in order to develop new markers for wheat. Their level of transferability in eight related species [Triticum durum, T. monococcum, Aegilops speltoides, Ae. tauschii, rye (Secale cereale), barley (Hordeum vulgare), Agropyron elongatum and rice (Oryza sativa)] was assessed. In total, 240 primer pairs (80%) gave an amplification product on wheat, and 177 were assigned to wheat chromosomes using aneuploid lines. Transferability to closely related Triticeae species ranged from 76.7% for Ae. tauschii to 90.4% for T. durum and was lower for more distant relatives such as barley (50.4%) or rice (28.3%). No clear putative function could be assigned to the genes from which the simple sequence repeats (SSRs) were developed, even though most of them were located inside ORFs. BLAST: analysis of the EST sequences against the 12 rice pseudo-molecules showed that the EST-SSRs are mainly located in the telomeric regions and that the wheat ESTs have the highest similarity to genes on rice chromosomes 2, 3 and 5. Interestingly, most of the SSRs giving an amplification product on barley or rice had a repeated motif similar to the one found in wheat, suggesting a common ancestral origin. Our results indicate that wheat EST-SSRs show a high level of transferability across distantly related species, thereby providing additional markers for comparative mapping and for following gene introgressions from wild species and carrying out evolutionary studies.
小麦（普通小麦）及相关谷类作物中表达序列标签（EST）的可得性不断增加，为非匿名DNA分子标记提供了宝贵资源。在本研究中，从265个含有微卫星的小麦EST中设计了300对引物，以便开发小麦新标记。评估了它们在8个相关物种[硬粒小麦、一粒小麦、斯卑尔脱山羊草、节节麦、黑麦（黑麦草）、大麦（大麦）、长穗偃麦草和水稻（水稻）]中的可转移性。总体而言，240对引物（80%）在小麦上产生了扩增产物，其中177对利用非整倍体系定位到了小麦染色体上。向密切相关的小麦族物种的可转移性范围从节节麦的76.7%到硬粒小麦的90.4%，而对于亲缘关系较远的物种如大麦（50.4%）或水稻（28.3%）则较低。即使大多数简单序列重复（SSR）来自位于开放阅读框（ORF）内的基因，也无法明确赋予其假定功能。BLAST：将EST序列与12条水稻假分子进行比对分析表明，EST-SSR主要位于端粒区域，且小麦EST与水稻染色体2、3和5上的基因具有最高的相似性。有趣的是，大多数在大麦或水稻上产生扩增产物的SSR具有与小麦中发现的重复基序相似的重复基序，这表明它们有共同的祖先起源。我们的结果表明，小麦EST-SSR在远缘物种间表现出高度的可转移性，从而为比较作图以及追踪野生物种的基因渗入和进行进化研究提供了额外的标记。
