The release of the first tree genome sequence for Populus tricocarpa, along with continuing rapid development of Populus EST, microarray and metabolomic technologies, promises to advance forest tree genomics. High throughput transformation by knockout or other gene manipulation strategies to generate large numbers of transgenic Populus for functional elucidation of the estimated 36 000 genes will soon follow. The efficacy of large-scale transformation approaches for advancing Populus genomics will ultimately depend on the availability of properly maintained transgenic germ lines for distribution. The Arabidopsis community has already demonstrated the value of shared genetic resources, especially mutant and transgenic seed stocks, in functional genomics research. Seed bank will not work for the Populus research community. Instead, a stock distribution center for transgenic Populus research will have to be based on long-term preservation of clonal germplasm. This review presents recent progress in applying cryogenic techniques for clonal preservation of long-lived trees and discusses the challenges facing Populus molecular geneticists in germplasm preservation.