A PCR Marker for a Populus deltoides Allele and its use in Studying Introgression with Native European Populus nigra

1997

S. 123-130

23 Lit. Ang.

Serie

400087521

Populus nigra L. is a native European tree species, once widespread, but now under threat of gradual extinction, at least in parts of its distribution range. Conversion of natural flood plain forests is the greatest problem in Central Europe. Riverside forests are often planted with hybrid poplars, mainly Populus deltoides Marsh. x Populus nigra clones. This practice introduces genes of a foreign species, the American black cottonwood (Populus deltoides), within the gene pool of Populus nigra as there are no apparent crossing barriers between hybrids and native poplars. Effective gene conservation requires reliable genetic markers for introgression. Based on a genetic marker in an American hybrid poplar (Populus deltoides x Populus trichocarpa Torr. and Gray) F2-pedigree linkage map (Bradshaw et al. 1994), a simple assay was developed that detects a Populus deltoides- specific allele in hybrids with Populus nigra. The patterns of inter- and intra-specific polymorphism were investigated by analysing controlled-cross and open-pollinated seed, and Populus nigra trees from native stands. Evidence for the presence of the Populus deltoides allele was found in seeds collected in a hybrid plantation, however surprisingly low levels of this allele were detected in areas with native Populus nigra trees, though hybrid plantations occur at some distance.