marker-assisted selection in wheat - ictsd

260Marker-assisted selection – Current status and future perspectives in crops, livestock, forestry and fishFigure 3Selection and clonal propagation of elite trees by the minicutting technology(A) Elite trees are selected, juvenile sprouts are induced by partial bark stripping while keeping the tree alive. (B) Operationalmother plants in hydroponic sand beds from where apical minicuttings are harvested for propagation. (C) Minicuttings arerooted without any use of growth regulators in controlled environment greenhouses. (D) High productivity clonal foreststands that reach over 60 m 3 /ha/year.ment. Although isozyme markers wereinitially used for these purposes (Moranand Bell, 1983), DNA polymorphismsprovide an enhanced level of resolutionboth at the locus level with much higherexpected heterozygosity values and at thegenome level with greater coverage. DNAmarkers provide a powerful tool to quantifyexisting levels of genetic variation inbreeding and production populations offorest trees. Molecular markers can be usedto estimate the extent of genetic divergencebetween individuals selected to composesuch populations and resolve several issuesof individual identity even at high levels ofrelatedness, including varietal protectionand the verification of alleged parentage inopen pollinated breeding systems. Someoperational applications of molecularmarkers for management of genetic variationin Eucalyptus are outlined below.Identification of elite clonesThe correct identification of clones iscurrently the most common application ofmolecular markers in Eucalyptus operational