Application of genetic markers in the domestication, conservation and utilisation of genetic resources of Australasian tree species

Domestication programs are currently being developed for a number of Australasian tropical tree species for plantations largely outside Australia. An assessment of the genetic resources of several species has been made on the basis of levels and patterns of genetic diversity at molecular marker loci. On the basis of growth performance and other quantitatively inherited commercial traits, populations from only limited regions of the geographic range were included in baseline selections of breeding programs for species such as Acacia mangium, A. auriculiformis, A. aulacocarpa and Eucalyptus pellita. For A. mangium, this domestication strategy resulted in a high proportion of the genetic resources of the species being included in breeding programs, but for other species such as A. aulacocarpa a significant fraction of the genetic resources were not incorporated into the baseline populations. The same molecular marker data sets enabled the formulation of conservation strategies both in situ and ex situ for these important commercial species. Within Australia many tree species are utilised directly from native forests in the absence of domestication efforts. Preliminary results from a study on genetic impacts of silvicultural regeneration practices in native forests indicate that there is very limited loss in genetic diversity in E. sieberi, a locally abundant species, under either clearfelling with aerial resowing or the seed tree system. Questions remain concerning the impact of silvicultural regeneration practices on species that are more locally rare.