Evaluating the potential of barley and wheat microsatellite markers for genetic analysis of Elymus trachycaulus complex species

Development and cross-species transferability of EST-SSR markers in Siberian wildrye (Elymus sibiricus L.) using Illumina sequencing

Siberian wildrye (Elymus sibiricus L.) is a perennial, self-fertilizing grass that plays an important role in animal husbandry and environmental sustenance. However, the transcriptomic and genomic information on this species is very limited, which hinders genetic and breeding studies. In the present study, 76,686,804 clean reads were generated from 11 different tissue samples of E. sibiricus by Illumina paired-end sequencing, and the reads were deposited into the NCBI SRA database (SRX574376). A total of 8,769 EST-SSRs were identified from 94,458 unigene sequences, which were obtained by de novo assembly. Moreover, 1,078 primer pairs were successfully designed, and 500 pairs were randomly selected to assess polymorphisms in 15 E. sibiricus accessions. A total of 112 primer pairs were polymorphic, and the polymorphism information content (PIC) values ranged from 0.39 to 0.81, indicating a high level of informativeness. Furthermore, these 112 polymorphic primer pairs were used to evaluate the transferability to 13 other related species, and 55 EST-SSR markers were found to be polymorphic among these 13 Elymus species. This study collected the global sequence data for E. sibiricus, and the newly developed markers will prove valuable in facilitating genetic diversity in E. sibiricus and related Elymus species.

Potential of Start Codon Targeted (SCoT) markers to estimate genetic diversity and relationships among Chinese Elymus sibiricus accessions

Elymus sibiricus as an important forage grass and gene pool for improving cereal crops, that is widely distributed in West and North China. Information on its genetic diversity and relationships is limited but necessary for germplasm collection, conservation and future breeding. Start Codon Targeted (SCoT) markers were used for studying the genetic diversity and relationships among 53 E. sibiricus accessions from its primary distribution area in China. A total of 173 bands were generated from 16 SCoT primers, 159 bands of which were polymorphic with the percentage of polymorphic bands (PPB) of 91.91%. Based upon population structure analysis five groups were formed. The cluster analysis separated the accessions into two major clusters and three sub-clusters, similar to results of principal coordinate analysis (PCoA). The molecular variance analysis (AMOVA) showed that genetic variation was greater within geographical regions (50.99%) than between them (49.01%). Furthermore, the study also suggested that collecting and evaluating E. sibiricus germplasm for major geographic regions and special environments broadens the available genetic base and illustrates the range of variation. The results of the present study showed that SCoT markers were efficient in assessing the genetic diversity among E. sibiricus accessions.

Development and annotation of perennial Triticeae ESTs and SSR markers

Triticeae contains hundreds of species of both annual and perennial types. Although substantial genomic tools are available for annual Triticeae cereals such as wheat and barley, the perennial Triticeae lack sufficient genomic resources for genetic mapping or diversity research. To increase the amount of sequence information available in the perennial Triticeae, three expressed sequence tag (EST) libraries were developed and annotated for Pseudoroegneria spicata , a mixture of both Elymus wawawaiensis and E. lanceolatus , and a Leymus cinereus  × L. triticoides interspecific hybrid. The ESTs were combined into unigene sets of 8 780 unigenes for P. spicata, 11 281 unigenes for Leymus, and 7 212 unigenes for Elymus. Unigenes were annotated based on putative orthology to genes from rice, wheat, barley, other Poaceae, Arabidopsis, and the non-redundant database of the NCBI. Simple sequence repeat (SSR) markers were developed, tested for amplification and polymorphism, and aligned to the rice genome. Leymus EST markers homologous to rice chromosome 2 genes were syntenous on Leymus homeologous groups 6a and 6b (previously 1b), demonstrating promise for in silico comparative mapping. All ESTs and SSR markers are available on an EST information management and annotation database ( http://titan.biotec.uiuc.edu/triticeae/ ).