Construction of Microsatellite Linkage Maps for Corymbia

Abstract

The genus Corymbia is closely related to the genus Eucalyptus, and like Eucalyptus contains tree species that are important for sub-tropical forestry. Corymbia’s close relationship with Eucalyptus suggests genetic studies in Corymbia should benefit from transfer of genetic information from its more intensively studied relatives. Here we report a genetic map for Corymbia spp. based on microsatellite markers identified de novo in Corymbia sp or transferred from Eucalyptus. A framework consensus map was generated from an outbred F2 population (n = 90) created by crossing two unrelated Corymbia torelliana × C. citriodora subsp. variegata F1 trees. The map had a total length of 367 cM (Kosambi) and was composed of 46 microsatellite markers distributed across 13 linkage groups (LOD 3). A high proportion of Eucalyptus microsatellites (90%) transferred to Corymbia. Comparative analysis between the Corymbia map and a published Eucalyptus map identified eight homeologous linkage groups in Corymbia with 13 markers mapping on one or both maps. Further comparative analysis was limited by low power to detect linkage due to low genome coverage in Corymbia, however, there was no convincing evidence for chromosomal structural differences because instances of non-synteny were associated with large distances on the Eucalyptus map. Segregation distortion was primarily restricted to a single linkage group and due to a deficit of hybrid genotypes, suggesting that hybrid inviability was one factor shaping the genetic composition of the F2 population in this inter-subgeneric hybrid. The conservation of microsatellite loci and synteny between Corymbia and Eucalyptus suggests there will be substantial value in exchanging information between the two groups.

Progress in Myrtaceae genetics and genomics: Eucalyptus as the pivotal genus

“…A catalog of the current resource of microsatellite markers by genera is given in the Electronic supplementary material. A resource of 366 microsatellite markers has been published for Eucalyptus (Brondani et al 1998(Brondani et al , 2006Byrne et al 1996;Ottewell et al 2005;Steane et al 2001;Thamarus et al 2002) and a set of 28 for the related genus Corymbia (Jones et al 2001;Shepherd et al 2006). In the non-eucalypt Myrtaceae, 113 microsatellite markers have been developed from Melaleuca (Miwa et al 2000;Rossetto et al 1999a), 24 for Metrosideros Kaneko et al 2007), nine for Eugenia (Ferreira-Ramos et al 2008), 14 for Myrtus (Albaladejo et al 2010), ten for Calothamnus (Elliott and Byrne 2005), eight for Syzygium (Hillyer et al 2007), and 13 for Acca .…”

“…Transfer among the sister genera Corymbia and Eucalyptus ranges between 25 and 50%, with higher rates possibly achieved where methodological strategies designed to maximize transfer rates were adopted (Kirst et al 1997;Shepherd et al 2006). Transfer among the major Eucalyptus subgenera has been variable and ranged between 40 and 96%, but transfer within a subgenus (Symphyomyrtus) has been significantly higher (80-100%).…”

Microsatellites retain phylogenetic signals across genera in eucalypts (Myrtaceae)

“…Eight polymorphic SSRs used in this study have been published previously: EMCRC26, EMCRC32, EMCRC39 (Jones et al, 2001); EMCRC46, EMCRC51, EMCRC54, EMCRC93 (Shepherd et al, 2006); Eg126 (Thamarus et al, 2002). For each primer pair, the forward primer was fluorescently labelled with a dye.…”

“…Where the problems of range constraints, high mutation rates and size homoplasy are addressed, SSRs may be utilised in phylogenetic studies, even among divergent taxa, so long as SSR primers amplify across such taxa. In eucalypts, cross-genera SSRs transferability has recently been reported to be high (Shepherd et al, 2006). We used 8 polymorphic SSRs isolated from Corymbia variegata (F. Muell.…”

Population genetic analysis and phylogeny reconstruction in Eucalyptus (Myrtaceae) using high-throughput, genome-wide genotyping

“…The development of microsatellite primers for eucalypt taxa (Brondani et al 1998(Brondani et al , 2006Byrne et al 1996;Glaubitz et al 2001;Jones et al 2001;Ottewell et al 2005;Shepherd et al 2006;Steane et al 2001;Thamarus et al 2002) opened the door for reliable genome-wide genotyping of a relatively large number of samples. Microsatellite markers gave researchers the power to examine genetic relationships within and among populations of one (e.g., Butcher et al 2009;Elliott and Byrne 2003;Jones et al 2007;Payn et al 2008;Rathbone et al 2007;Walker et al 2009; see also Byrne 2008 and references therein) or a few closely related species (e.g., Holman et al 2003, Le et al 2009, Shepherd et al 2008.…”