**The *Populus* Genome Science Plan**

Panel on Genetic Resources

Panel Members: John Davis**,** Joerg Bohlmann, Stefan Jansson, Les
Pearson, Wan Song,

Barb Thomas, Chung-Jui Tsai, and Marc Villar

**BACKGROUND AND** **SCOPE**

A major challenge faced by any scientific research community is to
efficiently archive and distribute shared resources. The IPGC encourages
active distribution of shared genetic resources in order to minimize
unnecessary duplication of effort among research groups, thus maximizing
the rate at which new discoveries in *Populus* biology are made.

Herein we define genetic resources broadly to include: information
(*e.g.*, genome sequence, EST sequences, genetic maps, physical maps),
cloned DNA (*e.g.*, EST collections, large-insert libraries), other
molecular reagents (*e.g.*, gene expression arrays, DNA from mapping
populations), and germplasm (*e.g.*, naturally occurring or
conventionally bred genotypes, transgenic plant material generated
through functional genomics experiments).

**CURRENT STATE OF THE FIELD**

**Physical Resources**

**Financial Resources**

**SCIENTIFIC** **OBJECTIVES**

The scientific objectives being put forth here will collectively lead
the *Populus* community to develop a shared capacity and resource
development related with the following areas:

1.  Development and/or preservation of germplasm, mutant collections,
    virtual stock centers, pedigrees, cryopreserved stocks, & *in situ*
    populations and

2.  Repository and/or distribution of BAC libraries, EST libraries,
    KO/KI & gene trapping resources, etc.

**Bioinformatics.** The IPGC places high priority on establishing and/or
partnering to establish a relational database for *Populus* molecular
genetics that can be supported on a long-term basis. All activities
related to the archival and distribution of shared genetic resources
must be underpinned by a high quality, robust relational database with a
public web browser interface. The database creates a forum for
information exchange among community members, and serves as a nucleation
point for supporting other community resources including stock centers.

**DNA stocks (cDNA and genomic) and other molecular reagents.** The IPGC
aims to establish two *Populus* Biological Resource Centers, operated as
parallel collections that closely coordinate the collection, maintenance
and distribution of DNA stock resources and related molecular reagents.
The rationale for centralization is to ensure consistency in material
deposition, handling, distribution, and quality. As a general rule, it
is expected that one Center will provide services to North America and
one Center will provide services to the rest of the world. The primary
function of these Centers is to acquire, preserve and distribute DNA
stocks and molecular reagents for use by the research community. It is
anticipated that these Centers may distribute stocks on a cost-recovery
basis. It is also anticipated that at least one, or perhaps both Centers
would be housed at institutions where DNA stock resources of other
species are collected, maintained and distributed. In other words, the
IPGC recognizes the economy of scale that can be accomplished if the
Populus community can establish partnerships with existing stock
centers, or planned centers that are designed to accommodate multiple
species.

**Germplasm.** The IPGC supports a partially centralized approach to
archiving and distributing germplasm, due to practical difficulties in
centralizing all *Populus* germplasm resources. In contrast to
Arabidopsis and most annual crop plants, which are propagated and
distributed as seed representing accessions, cultivars or wild
relatives, *Populus* germplasm is usually propagated and distributed in
the form of dormant stem cuttings. Stem cuttings are placed in soil by
the recipient, after which adventitious roots and pre-formed shoots grow
and establish a new plant body that is the same genotype as (*i.e.*, a
clone of) the donor plant. Propagation of genotypes by stem cuttings
requires a good deal more space and effort than seed (which can be
stored dry and in small containers). Usually genotypes of interest are
maintained in field plots. Selected genotypes are sometimes naturally
occurring genotypes from wild stands, although progeny sets from
controlled, usually interspecific, hybridizations are often quite
valuable resources for the community. Increasingly, transgenic materials
are being produced that are valuable resources. The transcontinental
range of several *Populus* species, and the transglobal range of the
genus, creates practical difficulties in centralizing germplasm archival
and distribution. Not all species and hybrids will survive and grow in a
single location. Consequently it seems appropriate to distribute
germplasm across a series of field plots around the world. Of course,
over the long term, field sites are notoriously lost due to harvest,
land sale, etc., and it is difficult to predict with any degree of
certainty which sites would be most \"stable\" for archiving and
distributing germplasm. Ownership category options to consider might be
university, government, industry or even private lands.

The IPGC recommends that a common registry of germplasm be established
that would provide the community with a roster of available *Populus*
material that is available for research. This registry would give the
community notice of trial or plantation termination, thereby allowing
others to obtain cuttings to continue specific lines. Furthermore, the
IPGC recognizes the benefits of rapid and easy exchange of germplasm for
research purposes. To this end, the IPGC encourages the development of
blanket materials transfer agreement that is acceptable to all parties
involved in Populus research. This agreement could be used routinely to
document the current sites at which specific genotypes are being used
for research, and to accelerate the transfer of scientifically useful
germplasm among university, government, and industry research teams.

The IPGC encourages the development of cryogenic storage methods for
archiving and distributing germplasm. Cryo methods hold promise for
reducing the space and labor requirements associated with maintaining
field plantings. Cryo methods as applied to *Populus* would involve
freezing shoot tips after treatment with osmoprotectant compounds.
Subsequent revival of the shoot requires some tissue culture steps,
however when the methods are well defined for a plant species, they are
relatively simple to perform. A centralized location for developing
cryogenic storage and regeneration protocols for *Populus*, material
deposition, cryostorage and distribution would be desirable, with
potentially several other \"inactive\" storage facilities elsewhere.

**Summary**

The *Populus* community is not unique in its need to establish some
centralized entities to allow sharing of genetic resources. In
particular, archival and distribution of DNA resources could best follow
the centralized model adopted by many communities including Arabidopsis.
To be successful these Centers should be underpinned by an excellent and
robust relational database, and opportunities for partnerships with
other communities of researchers should be pursued in order to reduce
costs. The *Populus* community is somewhat unique in the challenges of
sharing germplasm, since the germplasm is propagated vegetatively. A
common registry and transfer agreement should help facilitate sharing,
albeit in a decentralized way. Finally, the development of cryostorage
methods is encouraged in order to reduce the overall costs, and increase
the overall efficiency of germplasm archival and distribution.