MSA - Cell and molecular biology/Physiology & Genetics
Yafetto, L. , Money, N.P. , Davis, D.J. , Dumais, Jacques .
New information on the mechanics of rhizomorph extension in Armillaria gallica.
Armillaria species and other fungal plant pathogens and wood-decay basidiomycetes produce rhizomorphs that facilitate their spread through soil and plant tissues. Rhizomorphs are complex, multicellular, root-like organs formed through the aggregation, interlacing, and adhesion of millions of hyphae. Although the importance of rhizomorphs in fungal ecology and plant disease has been studied for many years, very little is known about the mechanics of rhizomorph extension. Time-lapse recordings of cultured rhizomorphs of Armillaria gallica reveal a number of crucial features of their growth mechanism. While rhizomorphs exhibit polarized growth, hyphal elongation is spread over an extended region subtending the tip. In addition, the hyphae that cover the tip of the organ act like the root cap of vascular plant and are driven through the substrate by the elongation of cells within the center of the rhizomorph. This presentation will highlight (i) features of rhizomorph anatomy in this fungus that support its invasive behavior; (ii) the adaptive growth response of rhizomorphs subjected to mechanical stress; (iii) novel measurements of the forces exerted by growing rhizomorphs; and (iv) zones of extension that thrust rhizomorphs through their surroundings. These studies provide new information on mechanical processes that allow rhizomorphs to function as migratory organs in low-moisture and nutrient-poor soils that otherwise serve as substantial obstacles to fungal movement.
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1 - Harvard University, Department of Organismic and Evolutionary Biology, 1102 Biological Laboratories, 16 Divinity Avenue, Cambridge, MA, 02138, USA
2 - Miami University, Botany, 700 East High Street, 316 Pearson Hall, Oxford, OH, 45056, USA
3 - College of Mount St. Joseph, Department of Chemistry and Physical Science, 5701 Delhi Road, Cincinnati, OH, 45233, USA
4 - Harvard University, Department of Organismic and Evolutionary Biology, 16 Divinity Ave, Cambridge, MA, 02138, USA
Presentation Type: Oral Paper:Papers for Topics
Location: White Pine/Cliff Lodge - Level C
Date: Monday, July 27th, 2009
Time: 10:30 AM