Genetic evidence for host specificity in the hemi-parasitic Viscum album L. (Viscaceae)

Nuclear ribosomal DNA (nrDNA) ITS sequences and partial sequences of three non-coding chloroplast DNA (cpDNA) introns and spacers were used to assess genetic variation within and among three presumed host races of the hemi-pa rasite Viscum album L. Currently, identification of host races occurs via t he host trees, and morphological differences are minute at best, cpDNA and nrDNA ITS sequences revealed little sequence variation, but the variation f ound consistently supported the distinction of three host races. cpDNA and ITS sequences were not incongruent, as assessed by the incongruence length difference test. A combined analysis supported the sister group relationshi p between mistletoes from deciduous trees and fir.