Integration of EST-CAPS markers into genetic maps of Eucalyptus urophylla and E. tereticornis and their alignment with E. grandis genome sequence

A suite of 91 expressed sequence tag (EST) derived cleaved amplified polymorphic sequence (CAPS) markers were developed and used for enriching the genetic maps of Eucalyptus urophylla and E. tereticornis built previously based on random amplified polymorphic DNA (RAPD) markers. The EST-CAPS markers were highly similar to original ESTs, with sequence identity ranging from 92.5% to 100.0%. In linkage analysis, 48 and 42 EST-CAPSs were integrated into the genetic maps of E. urophylla and E. tereticornis, respectively, including 13 shared by both maps, while 14 were unmapped. For E. urophylla, the final map had a total length of 1789.5 cM and a mean interval between markers of 9.7 cM, being 284.9 cM larger and 1.3 cM less than those of the prior RAPD map, respectively. For E. tereticornis, the final map had a length of 1488.1 cM and a mean interval of 10.3 cM, being 452.4 and 0.2 cM more than the prior map, respectively. All the 77 newly mapped EST-CAPSs found each at least one homologue in the E. grandis genome sequence released recently, and conserved synteny and colinearity were observed between E. grandis genome and our linkage groups. The enriched maps would provide a set of useful markers for genome analysis, comparative mapping and fine-mapping of important genes located in conserved regions for the important tree genus Eucalyptus.