Sim Sung-Chur, Yu Ju-Kyung, Jo Young-ki, Sorrells Mark E, Jung Geunhwa
Department of Horticulture and Crop Science, Ohio State University, Ohio Agricultural Research and Development Center, Wooster, OH 44691, USA.
Genome. 2009 May;52(5):431-7. doi: 10.1139/g09-019.
A large number of expressed sequence tags (ESTs) in public databases have provided an opportunity for the systematic development of simple sequence repeat (SSR) markers. EST-SSRs derived from conserved coding sequences show considerable cross-species transferability in related species. In the present study, we assessed the utility of cereal EST-SSRs in ryegrass (Lolium spp.). A total of 165 cereal EST-SSRs were tested; a high rate of transferability (57%) and polymorphism (67% of functional EST-SSRs) was demonstrated between cereals and ryegrass. A total of 46 segregating loci derived from 37 EST-SSRs were mapped on an existing ryegrass genetic map. The mapped loci were uniformly distributed across all seven linkage groups without significant clustering at the distal regions of linkage groups. Sequences of ryegrass amplicons generated by randomly selected 16 EST-SSRs were aligned with reference sequences of cereal EST-SSRs. The SSR motifs and repeat lengths of the cereal EST-SSR markers were different from the majority of ryegrass amplicons. Furthermore, a majority of EST-SSRs amplified different flanking sequences of SSRs in ryegrass than the original cereal sequences. Our results suggest that the high degree of cereal EST-SSR transferability to ryegrass can be a useful enhancement to the molecular database of PCR-based markers but sequence analysis is essential before transferring genetic information using comparative mapping.
公共数据库中的大量表达序列标签（EST）为简单序列重复（SSR）标记的系统开发提供了契机。源自保守编码序列的EST-SSR在相关物种中显示出相当高的跨物种转移性。在本研究中，我们评估了禾本科EST-SSR在黑麦草（黑麦草属）中的实用性。共测试了165个禾本科EST-SSR；结果表明，禾本科植物与黑麦草之间具有较高的转移性（57%）和多态性（功能性EST-SSR的67%）。从37个EST-SSR中获得的46个分离位点被定位到现有的黑麦草遗传图谱上。定位的位点均匀分布在所有七个连锁群中，在连锁群的远端区域没有明显的聚集。随机选择16个EST-SSR产生的黑麦草扩增子序列与禾本科EST-SSR的参考序列进行比对。禾本科EST-SSR标记的SSR基序和重复长度与大多数黑麦草扩增子不同。此外，与原始禾本科序列相比，大多数EST-SSR在黑麦草中扩增出不同的SSR侧翼序列。我们的结果表明，禾本科EST-SSR对黑麦草的高度转移性可以有效地扩充基于PCR的分子标记数据库，但在利用比较图谱转移遗传信息之前，进行序列分析至关重要。
