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EUROPEAN CENTRAL FORAGES DATABASES 17
Standards for regeneration
The following background information was presented by R. Sackville Hamilton together with draft
standards for the regeneration of perennial forage species. It was agreed that a subgroup composed of
R. Sackville Hamilton, P. Marum and L. Maggioni would revise this draft further and circulate it to
the Group before publication in the present report.
Guidelines for the regeneration of accessions in seed collections of the
main perennial forage grasses and legumes of temperate grasslands
The main protocol is presented as Appendix III. This section is a summary of the paper
presenting further background details (full text, page 103).
Decisions for regeneration protocols represent a compromise between maximizing the
number of accessions that can be regenerated each year within available resources, and
maximizing the genetic integrity of accessions. An important element of the regeneration
protocol is based on the interaction between base and active collections as recommended in
the Genebank Standards (FAO/IPGRI 1994). The impact of loss of genetic integrity on the
distinctness of accessions was a second major consideration in developing the protocol.
There are three primary causes of loss of genetic integrity: drift, selection (natural and
artificial, conscious and unconscious), and contamination with alien genes (through alien
pollen, alien seed, alien plants, or even through incorrectly identifying and labelling
accessions). Most perennial forage grasses and legumes are obligate outbreeders, and so
display high genetic variance within populations, high potential for genetic changes by drift
and selection during regeneration, and present a high risk for cross-pollination between
regeneration plots if they are not adequately isolated. There is also a high risk for
contamination with alien plants, seed and pollen, and exceptionally high variation in
fecundity between plants in a single population, with a corresponding potential for rapid
genetic changes in response to selection pressures. The recommended conditions for
prevention of contamination with alien pollen are more stringent than currently used by
some genebanks. This reflects not only the adverse impact of contamination on genetic
integrity, but also a more cautious interpretation of the literature on pollen flow. Examples
of studies of contamination rates found in Lolium perenne and Melilotus show that insect
pollinators fly as far as they need to find a flower but no further. They express preferences
for the type of flower they visit, so the most effective barrier crop will have flowers identical
to the plot being regenerated.