Resource allocation in the legume-rhizobia symbiosis: an integration of modelling and experimental approaches
<p>The symbiosis between plants of the legume family and nitrogen-fixing rhizobia underpins global food security. Legume crops are a major source of protein in human diets, either directly or indirectly as feed for livestock. Application of inoculant rhizobial strains is common practice in man...
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| Materiálatiipa: | Oahppočájánas |
| Giella: | English |
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2017
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| _version_ | 1826276527331868672 |
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| author | Westhoek, A |
| author2 | Turnbull, L |
| author_facet | Turnbull, L Westhoek, A |
| author_sort | Westhoek, A |
| collection | OXFORD |
| description | <p>The symbiosis between plants of the legume family and nitrogen-fixing rhizobia underpins global food security. Legume crops are a major source of protein in human diets, either directly or indirectly as feed for livestock. Application of inoculant rhizobial strains is common practice in many areas, as plant growth is often nitrogen limited and the symbiosis can significantly enhance yields. However, rhizobial strains and outcomes of the symbiosis vary widely. This variation has also been studied by evolutionary biologists interested in the stability of mutualisms. They proposed that plants may prevent establishing symbioses with ineffective strains (partner choice), or provide them with fewer resources (sanctioning). I studied both mechanisms, combining modelling and experimental approaches.</p> <p>Mathematical modelling was used to predict how plants should allocate resources to maximise growth rates, depending on rhizobial nitrogen provision and carbon requirements and on soil nitrogen conditions. The use of marked mutant strains – easily distinguishable and differing in a single rhizobial characteristic – overcame previous experimental difficulties. It was found that pea (<em>Pisum sativum</em> L.) plants are not able to exert partner choice, but do sanction in a more complex way than was previously established. In line with model predictions, resources were preferentially allocated to the single – best available – strain, so that resources allocated to an intermediate-fixing strain depended on whether or not a strain providing more nitrogen was available. Contrary to model predictions, there was no indication of discrimination based on rhizobial carbon requirements.</p> <p>The results cannot be explained by resource allocation in proportion to nitrogen received, and indicate systemic integration of information from different nodules. I formulate a hypothesis about the underlying plant regulatory mechanisms, and discuss implications of the results for selecting inoculant strains and enhancing yields in the field. Future work will rely on further integration of theoretical and applied methods and perspectives.</p> |
| first_indexed | 2024-03-06T23:15:18Z |
| format | Thesis |
| id | oxford-uuid:66ed2e7d-85d3-4090-a822-28609ea866c7 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T23:15:18Z |
| publishDate | 2017 |
| record_format | dspace |
| spelling | oxford-uuid:66ed2e7d-85d3-4090-a822-28609ea866c72022-03-26T18:34:56ZResource allocation in the legume-rhizobia symbiosis: an integration of modelling and experimental approachesThesishttp://purl.org/coar/resource_type/c_db06uuid:66ed2e7d-85d3-4090-a822-28609ea866c7Plant biologyBiologyMicrobiologyEnglishORA Deposit2017Westhoek, ATurnbull, LPoole, PPreston, G<p>The symbiosis between plants of the legume family and nitrogen-fixing rhizobia underpins global food security. Legume crops are a major source of protein in human diets, either directly or indirectly as feed for livestock. Application of inoculant rhizobial strains is common practice in many areas, as plant growth is often nitrogen limited and the symbiosis can significantly enhance yields. However, rhizobial strains and outcomes of the symbiosis vary widely. This variation has also been studied by evolutionary biologists interested in the stability of mutualisms. They proposed that plants may prevent establishing symbioses with ineffective strains (partner choice), or provide them with fewer resources (sanctioning). I studied both mechanisms, combining modelling and experimental approaches.</p> <p>Mathematical modelling was used to predict how plants should allocate resources to maximise growth rates, depending on rhizobial nitrogen provision and carbon requirements and on soil nitrogen conditions. The use of marked mutant strains – easily distinguishable and differing in a single rhizobial characteristic – overcame previous experimental difficulties. It was found that pea (<em>Pisum sativum</em> L.) plants are not able to exert partner choice, but do sanction in a more complex way than was previously established. In line with model predictions, resources were preferentially allocated to the single – best available – strain, so that resources allocated to an intermediate-fixing strain depended on whether or not a strain providing more nitrogen was available. Contrary to model predictions, there was no indication of discrimination based on rhizobial carbon requirements.</p> <p>The results cannot be explained by resource allocation in proportion to nitrogen received, and indicate systemic integration of information from different nodules. I formulate a hypothesis about the underlying plant regulatory mechanisms, and discuss implications of the results for selecting inoculant strains and enhancing yields in the field. Future work will rely on further integration of theoretical and applied methods and perspectives.</p> |
| spellingShingle | Plant biology Biology Microbiology Westhoek, A Resource allocation in the legume-rhizobia symbiosis: an integration of modelling and experimental approaches |
| title | Resource allocation in the legume-rhizobia symbiosis: an integration of modelling and experimental approaches |
| title_full | Resource allocation in the legume-rhizobia symbiosis: an integration of modelling and experimental approaches |
| title_fullStr | Resource allocation in the legume-rhizobia symbiosis: an integration of modelling and experimental approaches |
| title_full_unstemmed | Resource allocation in the legume-rhizobia symbiosis: an integration of modelling and experimental approaches |
| title_short | Resource allocation in the legume-rhizobia symbiosis: an integration of modelling and experimental approaches |
| title_sort | resource allocation in the legume rhizobia symbiosis an integration of modelling and experimental approaches |
| topic | Plant biology Biology Microbiology |
| work_keys_str_mv | AT westhoeka resourceallocationinthelegumerhizobiasymbiosisanintegrationofmodellingandexperimentalapproaches |