Biomechanics of Rhizomorph Development in <i>Armillaria mellea</i>
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Miami University / OhioLINK
2008
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ndltd-OhioLink-oai-etd.ohiolink.edu-miami12179488842021-08-03T05:40:30Z Biomechanics of Rhizomorph Development in <i>Armillaria mellea</i> Yafetto, Levi Botany basidiomycota biomechanics fungi hyphae invasive growth osmotic pressure osmolyte rhizomorph spectroscopy turgor pressure Fungal rhizomorphs are complex, multicellular, root-like organs formed through the aggregation, interlacing, and adhesion of millions of tip-growing hyphae. There has been very little research on the invasive mechanism utilized by rhizomorphs to penetrate compacted soils and woody substrates. Initial studies with <i>Meruliporia incrassata</i>, a wood-decay fungus that decomposes wooden components of buildings with an annual value of destruction estimated in millions of dollars, was aimed at inducing rhizomorphs <i>in vitro</i>. This attempt was not very successful, as only mycelial cords were produced. The pathogen <i>Armillaria mellea</i> was therefore chosen because it readily forms rhizomorphs in culture and serves as an excellent model for developmental studies. This dissertation presents findings from experiments designed to study (i) comparative features of rhizomorph anatomy in <i>M. incrassata</i> and <i>A. mellea</i> that support its invasive behavior; (ii) the adaptive growth response of rhizomorphs subjected to mechanical stress; (iii) the biochemical basis of turgor generation within rhizomorphs, and (iv) novel measurements of the forces exerted by growing rhizomorphs. Anatomical studies of rhizomorphs of <i>A. mellea</i> cultured in potato dextrose agar (PDA) revealed zones of hyphal tissues namely, an outer layer of peripheral hyphae, radial hyphae, longitudinal hyphae, and a central cavity. <i>A. mellea</i> rhizomorphs were observed to have faster growth than mycelia in PDA. We determined that increasing concentration of agar stimulated the production of more rhizomorphs, with those in media having higher concentration of agar extending faster with tapered tips. Turgor generation within <i>A. mellea</i> rhizomorphs was shown to be partially due to the accumulation of osmolytes. Erythritol and mannitol were identified using Gas Chromatography/Mass Spectrometry (GC/MS) and quantitatively determined to be the most dominant osmolytes that contribute to turgor generation. Osmometric studies revealed that substantial portion of turgor generated was used to exert pressure at the tip of the rhizomorphs during invasive growth. The varying amounts of force that these <i>A. mellea</i> rhizomorph tips exert were measured, using a sensitive strain gauge. Our experiments provide the first clear picture of the mechanical processes that allow rhizomorphs to function as migratory, exploratory and invasive organs in low-moisture and nutrient-poor environments that present substantial obstacles to fungal colonization. 2008-08-11 English text Miami University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=miami1217948884 http://rave.ohiolink.edu/etdc/view?acc_num=miami1217948884 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Botany basidiomycota biomechanics fungi hyphae invasive growth osmotic pressure osmolyte rhizomorph spectroscopy turgor pressure |
| spellingShingle |
Botany basidiomycota biomechanics fungi hyphae invasive growth osmotic pressure osmolyte rhizomorph spectroscopy turgor pressure Yafetto, Levi Biomechanics of Rhizomorph Development in <i>Armillaria mellea</i> |
| author |
Yafetto, Levi |
| author_facet |
Yafetto, Levi |
| author_sort |
Yafetto, Levi |
| title |
Biomechanics of Rhizomorph Development in <i>Armillaria mellea</i> |
| title_short |
Biomechanics of Rhizomorph Development in <i>Armillaria mellea</i> |
| title_full |
Biomechanics of Rhizomorph Development in <i>Armillaria mellea</i> |
| title_fullStr |
Biomechanics of Rhizomorph Development in <i>Armillaria mellea</i> |
| title_full_unstemmed |
Biomechanics of Rhizomorph Development in <i>Armillaria mellea</i> |
| title_sort |
biomechanics of rhizomorph development in <i>armillaria mellea</i> |
| publisher |
Miami University / OhioLINK |
| publishDate |
2008 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=miami1217948884 |
| work_keys_str_mv |
AT yafettolevi biomechanicsofrhizomorphdevelopmentiniarmillariamelleai |
| _version_ |
1719423393339539456 |