Intergeneric hybridization between Menziesia and Rhododendron based on molecular phylogenetic data

Recently, DNA sequence analyses of the plastid (pt) matK gene and the nuclear (nr) internal transcribed spacer (ITS) region revealed that the genus Menziesia is nested in the genus Rhododendron. It means that Menziesia has a potential to make new hybrids with Rhododendron species. Thus, to obtain intergeneric hybrids, M. multiflora was cross-pollinated with 7 Rhododendron species: R. kaempferi, R. kiusianum, R. tashiroi, R. wadanum, R. pentaphyllum, R. quinquefolium, and R. ovatum. These Rhododendron species were placed in the same clade of Menziesia by molecular phylogenetic analyses. Hybrid seedlings were obtained from reciprocal crosses between M. multiflora and R. kiusianum and between M. multiflora. as a maternal parent, and R. tashiroi and R. kaempferi. The frequency of vigorous green progenies was about 10%; most progenies were pale-green or albino. The hybridity of the seedlings was verified by PCR-RFLP analysis of nr ITS region, thereby demonstrates that members of the genus Menziesia can be useful in the breeding program of Rhododendron.