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Molecular Mechanisms Regulating Mycorrhizal Associations in Woody Plants
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Molecular Mechanisms Regulating Mycorrhizal Associations in Woody Plants. |
| 개인저자 | Cope, Kevin Richard. |
| 단체저자명 | The University of Wisconsin - Madison. Cellular & Molecular Bio - AG. |
| 발행사항 | [S.l.]: The University of Wisconsin - Madison., 2018. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2018. |
| 형태사항 | 145 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781687973221 |
| 학위논문주기 | Thesis (Ph.D.)--The University of Wisconsin - Madison, 2018. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Ane, Jean-Michel. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | The application of fertilizers in agronomic systems is necessary to meet the nutrient demands of crop production. However, this practice often results in the pollution of the environment. More sustainable practices are needed to prevent the continued degradation of natural systems. In nature, the roots of plants have forged alliances with beneficial microbes in the soil to help alleviate nutrient deficiencies. Understanding how symbiotic plant-microbe interactions form is crucial for developing more sustainable agronomic practices that limit our dependence on fertilizers and minimize negative impacts of crop production on the environment.Mycorrhizal fungi are one class of filamentous microorganisms that form a mutualistic association with the roots of most land plant species. They provide the roots of their host plants with increased access to limited mineral nutrients in the soil in exchange for carbon derived from photosynthesis. Two major types of mycorrhizal associations include arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM). The molecular mechanisms regulating how both types of mycorrhizal associations form has been a major research topic for decades, although more attention has been given to AM fungi. As a result, an entire molecular signaling pathway has been identified that is necessary for the development of the AM symbiosis. It is known as the "common symbiosis pathway" (CSP) because it is also required for both the rhizobia-legume and actinorhizal symbioses.The CSP is activated by lipochitooligosaccharides (LCOs), which are symbiotic signaling molecules that are also produced by rhizobia. At the core of the CSP are three genes: CASTOR, POLLUX, and CCaMK. CASTOR and POLLUX regulate a cellular phenomenon known as nuclear calcium spiking which is then decoded by CCaMK leading to changes in gene expression necessary for the development of both the AM and rhizobia-legume symbioses.Ectomycorrhizal symbioses are one of the most widespread associations between roots of woody plants and soil fungi in forest ecosystems. These associations contribute significantly to the sustainability and sustainagility of these ecosystems through nutrient cycling and carbon sequestration. Unfortunately, the molecular mechanisms controlling the mutual recognition between both partners are still poorly understood. Given the role of the CSP in diverse symbiotic associations, we hypothesized that the CSP might also play a role in ECM associations.Genomic data suggests that ECM fungi possess all of the genetic components necessary for the biosynthesis of LCOs. Furthermore, the genomes of some ECM-host plants possess all of the genes associated with the CSP (e.g., Populus). Using mass spectrometry, we showed that multiple ECM fungi produce an array of LCOs and demonstrated that they can trigger both root hair branching in legumes and, most importantly, calcium spiking in the ECM-host plant Populus. For one ECM fungal species, Laccaria bicolor, we demonstrated that calcium spiking in Populus occurred in a CASTOR/POLLUX-dependent manner. Purified non-sulfated LCOs enhanced lateral root development in Populus in a CCaMK-dependent manner and sulfated LCOs enhanced the colonization of Populus by L. bicolor. The colonization of Populus roots by L. bicolor was reduced in both CASTOR/POLLUX and CCaMK RNA interference lines and the expression of a mycorrhiza-induced phosphate transporter, PT12, was reduced in the CCaMK-RNA interference line compared to wild-type. Altogether, our work demonstrates that L. bicolor uses the CSP for full establishment of its mutualistic association with Populus.Future work should focus on determining if the CSP is required for the establishment of other ECM associations using stable gene knock-outs. Furthermore, the role of nutrient transporters in the maintenance of ECM associations should be evaluated. Investigating these areas of research will allow for better utilization of ECM associations in the sustainable production of woody plants and/or management of forest ecosystems. |
| 일반주제명 | Plant sciences. Microbiology. Molecular biology. |
| 언어 | 영어 |
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