Margaret Pooler

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Genetics, Genetic Resource Evaluation, and
Genetic ImprovementofLandscape Trees and Shrubs

• Margaret Pooler
• USDA/ARSU.S. National Arboretum
• Washington, D.C.

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Overall Objective

• Evaluate, breed, and release improved landscape
  trees and shrubs that are disease and pest
  resistant, tolerant of environmental stresses,
  and are of superior ornamental value.

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Specific Initiative Objective

• Use biotechnology to improve woody
  ornamental landscape plants by
• Establishing regeneration and transformation
  systems in redbud and flowering cherry.
• Investigating and adapting molecular marker
  technologies for use in woody ornamental plant
  breeding.

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Funding from Initiative used to hire postdocs or
support scientists to conduct transgenic/molecular
work

• Karen Hokanson
• EunJu Cheong
• John Cordts
• Hongmei Ma

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Research Approach Tissue Culture

• Establish in-vitro cultures of several species of
  Cercis (redbud) and Prunus (flowering cherry)
• Test for ability to regenerate (organogenesis or
  embryogenesis).
• Focus transformation efforts on those taxa that
  regenerate well.

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Research Approach Molecular Markers

• Use markers for which genomic information is not
  necessary (e.g. AFLPs).
• Use markers which have been developed for other
  species in the genus (e.g. SSRs in Prunus).

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Results Tissue Culture

• Regeneration of Prunus taxa from cotyledons of
  mature stored seed.
• Somatic embryogenesis and GFP transformation of
  Prunus incisa from root explants.

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Results Tissue Culture

• Regeneration of Cercis yunnanensis from leaf
  pieces.

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Results Molecular Markers

• Preservation and DNA fingerprinting of the
  historic Tidal Basin cherries
• SSR markers from sweet and sour cherry are being
  used to characterize ornamental cherry germplasm

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Results Molecular Markers

• Characterization of genetic diversity of
  Lagerstroemia fauriei
• Identification of interspecific hemlock progeny
• Genetic identity of the African Firebush

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Future Prospects

• Identify and obtain genes and gene constructs
  for transformation of Cercis and Prunus
  germplasm
• Viral resistance
• Fungal resistance
• Sterility

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Future Prospects

• Continue to develop molecular markers to
  determine
• Genetic identity of hybrids or accessions,
  including introgressive hybridization in
  populations.
• Genetic distances among individuals in a breeding
  population or among species in a genus.
• Conservation strategies
• Taxonomic and evolutionary relationships