Canadian Forest Service Publications
In vitro culture of western hemlock dwarf mistletoes. 1997. Deeks, S.J.; Shamoun, S.F.; Punja, Z.K. Page 74 in R.N. Sturrock, Compiler. Proceedings of the Forty-Fifth Western International Forest Disease Work Conference, September 15-19, 1997, Coast Inn of the North, Prince George, BC. Western International Forest Disease Work Conference, [S.l.].
Available from: Pacific Forestry Centre
Catalog ID: 4973
CFS Availability: Order paper copy (free)
Dwarf mistletoes (Arceuthobium spp.) are widespread and destructive parasitic flowering plants. A. tsugense (Rosend.) G.N. Jones subsp. tsugense is a parasite of western hemlock (Tsuga heterophylla (Raf.) Sarg.) on the coast from Alaska to California. A research project has been established to investigate the use of native fungi to control dwarf mistletoe. The project involves generating callus (undifferentiated tissue) from seeds placed on tissue culture medium. The callus will later be challenged with fungi to determine any inhibition of callus growth which correlates with fungal virulence. Seeds were collected from the Cowichan Lake, B.C. area and were placed on Harvey's medium with 2,4-dichlorophenoxyacetic acid (2,4-D)(.1, .5 or 1.0 mg/L) and 6-benzylaminopurine (BA)(.001, .1 or 1.0 mg/L). The seeds germinated and formed elongating radicles. There was radicle formation with all treatments but holdfasts formed only on media containing 2,4-D at .5 or 1.0 mg/L with all concentrations of BA. Radicles either split at the tip, swelled to become spherical holdfasts, or developed holdfasts at the tip. Callus arose from split radicles and split holdfasts. Light microscopy of the callus revealed undifferentiated cells that were spherical and densely stained. Future research will involve bulking up callus production via media/environmental modifications. Dual cultures can then be created involving mistletoe callus and potential biological control agents (i.e. Nectria neomacrospora and Colletotrichum gloeosporioides) to assess the ability of the fungi to inhibit callus growth.
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