| Dwarf mistletoes (Arceuthobium spp.) are parasitic flowering plants that attack commercially valuable conifers. The biology of this genus along with 22 other genera of parasitic flowering plants that have been cultured in vitro is reviewed in detail with respect to distribution, host range, and tissue culture procedures. A procedure for in vitro culture of western hemlock dwarf mistletoe (A. tsugense Rosend. G. N. Jones subsp. tsugense) is described. A factorial experiment evaluated the effects of media, temperatures, presence or absence of light, and plant growth regulators on the production of radicles, holdfasts, and callus. The tissue culture procedure was used for in vitro screening of calli and germinated seeds of A. tsugense subsp. tsugense with potential fungal biological control agents (Cylindrocarpon cylindroides and Colletotrichum gloeosporioides). Mistletoe tissues were prepared for light microscopy 1, 2, 3, 7 and 14 days post-contact with fungi. The process of pathogenesis was investigated, and specimens were rated for extent of colonization. (Abstract shortened by UMI.). |
