Viscin Cells in the Dwarf Mistletoe Arceuthobium ... - Davidsonia

More documents

Recommendations

Info

74 principle that high publication rate is a diagnostic sign of competence, and is to be rewarded by substantial research funding. Given the reality of limited research funding, the slower projects are poorly funded, indeed such slow-progressing scholars may be deemed unsuitable for a tenured position. The result is that long-term study on life-history or resolution of several physical forms in a single life history (larva-adult invertebrates; anamorph-teleomorph fungi) has become ‘side project’ research and even when the work is done, the necessary taxonomic expertise and herbarium facilities are limited or in some cases no longer available. The question remains, “Where are we to find future generations of scientific naturalists” As the biodiversity loss and climate change alarm bells ring louder, students will certainly see the need and the opportunity to strengthen and even reconstruct the foundation of natural history scholarship upon which we have relied up to now. How many species remain to be discovered, catalogued and systematically assessed The estimates vary widely but the numbers are very large, particularly in nonvascular plant, microbial and invertebrate biology. Clearly, we must meet the need for competent expert observation and understanding of the principles of taxonomy, regardless of whose taxonomic philosophy one may prefer. But fieldwork requires substantial funding to cover travel costs to and from research sites; costs of personal living on site; and preparation of herbarium and museum material, data processing, and continuing costs associated with ensuring the research specimens are stored properly and space can expand to contain the vital new materials. The field station, usually funded from charitable trusts or endowments, has itself become an endangered institution, especially if funding has come from an institution’s main budget allocation. Botanical gardens may already have picked up some of the natural history obligations, but those who are lucky enough to do research at these places have an increasing obligation to take a much more proactive role in leading the resurrection of scientific natural history. Many of my generation (students in the 1950s) link their decision to become field biologists directly to a well organized, albeit short, excursion to study plants in their natural setting.
Davidsonia 17:3 75 Viscin Cells in the Dwarf Mistletoe Arceuthobium americanum — “Green Springs” with Potential Roles in Explosive Seed Discharge and Seed Adhesion Abstract The genus Arceuthobium comprises angiosperms that are aerial parasites on Pinaceae and Cupressaceae. These parasites are serious forest pests in North America, where they damage timber trees. Arceuthobium spreads by explosive discharge, which is facilitated by a sticky fruit tissue called “viscin” that remains on the dispersed seed and enables its adhesion to the next host. Viscin tissue is comprised of mucilaginous, elongated viscin cells. The purpose of this study was to further characterize the viscin cells. Arceuthobium americanum (the lodgepole pine dwarf mistletoe) has viscin cells that have spirally-arranged cell wall fibrils. These cellular “springs” are shorter within the fruit than when outside and hydrated, which suggests that their expansion results from a pressure release that aids in propulsion. Following drying, viscin cells again coil and shorten, securing the seed to the host. Discharged viscin cells contain green chloroplasts and show a positive reaction for operation of oxidation-reduction biochemistry when stained with tetrazolium chloride, indicative of viability. Introduction The genus Arceuthobium (the dwarf mistletoes; family Viscaceae) is a group of new and old world dioecious angiosperms that are aerial parasites on Pinaceae and Cupressaceae (Hawksworth and Wiens 1996). These parasites are economically important in Canada, especially in British Columbia (BC) and Alberta, where they are destructive pathogens of commercially valuable coniferous timber trees (Hawksworth 1983). Arceuthobium infection causes annual economic losses amounting to an estimated 3.8 x 10 6 m 3 of lumber in western Cynthia M. Ross, Assistant Professor, Department of Biological Sciences, Thompson Rivers University, P.O. Box 3010, 900 McGill Rd., Kamloops, BC, Canada, V2C 5N3. cross@tru.ca
Page 1 and 2: Volume 17, Number 3 July 2006 David
Page 3: Davidsonia 17:3 73 Editorial This i
Page 7 and 8: Davidsonia 17:3 77 xylose and gluco
Page 9 and 10: Davidsonia 17:3 79 Image: Cynthia M
Page 11 and 12: Davidsonia 17:3 81 Image: Cynthia M
Page 13 and 14: Davidsonia 17:3 83 cell mucilage ca
Page 15 and 16: Davidsonia 17:3 85 such activity in
Page 17 and 18: Davidsonia 17:3 87 Comparison of Tw
Page 19 and 20: Davidsonia 17:3 89 Photo: Esson et
Page 21 and 22: Davidsonia 17:3 91 Photo: Esson et
Page 23 and 24: Davidsonia 17:3 93 Based on purely
Page 25 and 26: Davidsonia 17:3 95 Figure 5: Scatte
Page 27 and 28: Davidsonia 17:3 97 REFERENCES Allen
Page 29 and 30: Davidsonia 17:3 99 The next step, t
Page 31 and 32: Davidsonia 17:3 101 plant cuticles
Page 33 and 34: Davidsonia 17:3 103 Gleanings Notes
Page 35 and 36: Table of Contents Editorial Taylor

Viscin Cells in the Dwarf Mistletoe Arceuthobium ... - Davidsonia

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?