A 1,000-loci transcript map of the barley genome: new anchoring points for integrative grass genomics

An integrated barley transcript map (consensus map) comprising 1,032 expressed sequence tag (EST)-based markers (total 1,055 loci: 607 RFLP, 190 SSR, and 258 SNP), and 200 anchor markers from previously published data, has been generated by mapping in three doubled haploid (DH) populations. Between 107 and 179 EST-based markers were allocated to the seven individual barley linkage groups. The map covers 1118.3 cM with individual linkage groups ranging from 130 cM (chromosome 4H) to 199 cM (chromosome 3H), yielding an average marker interval distance of 0.9 cM. 475 EST-based markers showed a syntenic organisation to known colinear linkage groups of the rice genome, providing an extended insight into the status of barley/rice genome colinearity as well as ancient genome duplications predating the divergence of rice and barley. The presented barley transcript map is a valuable resource for targeted marker saturation and identification of candidate genes at agronomically important loci. It provides new anchor points for detailed studies in comparative grass genomics and will support future attempts towards the integration of genetic and physical mapping information.