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News from Elsewhere

White pine blister rust research

by Dr. Charles Michler, Project leader

Over the past five years, scientists of the Forest Biotechnology Unit (RWU-4155) of the North Central Research Station in Rhinelander, Wisconsin have developed a set of tools for the study of white pine and the associated white pine blister rust pathogen.

 Dr. Craig Echt and colleagues developed a set of molecular DNA markers, for differentiating among individual white pines.  Such ?DNA fingerprinting? markers are useful in paternity analyses and in measuring genetic diversity.  Dr. Paul Zambino has been developing methods for early screening of white pine genotypes for white pine blister rust susceptibility.  These protocols will aid tree breeders and nursery managers in selecting at an early age, genetic families of white pine that are blister rust resistant before those families are produced in large quantities and deployed in the field where the costs of seedling mortality are much greater.  Dr. Charles Michler continues investigations into methods for producing white pine genetically transformed to be blister rust resistant.

The Unit is entering a new stage of research in which tools such as DNA marker analysis and blister rust screening developed in the laboratory are being employed in field studies to answer questions of local and regional importance to resource managers and policy makers.  DNA markers have recently been used locally to demonstrate that various harvest regimes employed by the Menominee Tribal Enterprises had little impact on the genetic diversity of the residual white pine stands.  These DNA markers are now being applied, under the coordination of Dr. Paul Anderson, to address a regional question of genetic diversity in remnant white pine across northern Minnesota.  Within-stand and among-stand diversity are being determined from a sampling of white pine 80 years of age and older from throughout the species range in Minnesota.  These measures of genetic variation will be used to validate hypotheses about post-glacial migration of white pine into Minnesota to (1) determine whether white pine genotypes are sorted across the Minnesota landscape based on adaptation to physiography or climate, and (2) establish baseline estimates of genetic diversity that can be geographically referenced by resource managers to assess potential impacts of management activities and natural disturbances on white pine diversity.

Dr. Paul Zambino is establishing several test plantations of white pine in Minnesota with genetic families that have displayed a range of blister rust sensitivity in his laboratory screening tests.  Seedling performance in these field plantings will be used to validate the usefulness of early screening criteria developed in the laboratory.  Further, a selected number of white pine families ranging in known blister rust susceptibility will be incorporated as bio-indicators of rust pressure into a white pine outplanting test being established by Dr.
Anderson to determine the degree of specificity with which white pine families are adapted to their geographic origin.  Within five years, this test will generate data for the establishment of preliminary seed zones to guide white pine reforestation and restoration efforts in Minnesota.

Thus, the combined efforts of several North Central Station Scientists are being actively applied to the restoration and maintenance of a genetically diverse and productive white pine component in Minnesota forests.