All for one: organ and tissue-specific responses in the hormonal modulation of plant (a)biotic interactions
[eng] Plants are not isolated organisms; instead, they constantly interact with the microorganisms in their environment, forming a holobiont that consists of the plants themselves and their entire microbiome. This holobiont must also cope with abiotic stresses, such as water deficit, for which it ha...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/212600 |
| Acceso en línea: | https://hdl.handle.net/2445/212600 http://hdl.handle.net/10803/691390 |
| Access Level: | acceso abierto |
| Palabra clave: | Fisiologia vegetal Efecte de l'estrès sobre les plantes Desenvolupament de les plantes Relacions planta-microbi Hormones vegetals Micorrizes Plant physiology Effect of stress on plants Plant development Plant-microbe relationships Plant hormones Mycorrhiza |
| Sumario: | [eng] Plants are not isolated organisms; instead, they constantly interact with the microorganisms in their environment, forming a holobiont that consists of the plants themselves and their entire microbiome. This holobiont must also cope with abiotic stresses, such as water deficit, for which it has developed specific adaptation mechanisms. These mechanisms include a wide range of modifications in the plant, like a deep restructuring of the root system and an enhancement of the plant antioxidant content. Additionally, in response to stresses like water deficit, the composition of the microbiome can change, promoting the establishment of mutualistic relationships with microorganisms like arbuscular mycorrhizal fungi that enhance the plant physiological response. These responses are regulated by phytohormones, among which abscisic acid and jasmonates are particularly relevant. Although the role of phytohormones has been studied in various developmental processes and in the regulation of (a)biotic interactions, few analyses have focused on how responses in different specific organs and tissues can collectively affect the plant hormonal regulation in front of these stresses. In this dissertation, hormonal responses in specific plant organs were studied in plants subjected to water stress in the presence or absence of arbuscular mycorrhizal fungi, paying special attention to the potential implications of tissue- specific hormonal variations in plant-microorganism interactions. To accomplish this, three different plant species were employed under different cultivation conditions. Hormone levels were analyzed in various organs and tissues, ranging from roots to leaves and fruits, including both climacteric and non-climacteric fruits, to better understand local hormonal responses and distinguish them from potential systemic responses. In the first chapter, the protective effect of the arbuscular mycorrhizal fungus Rhizoglomus irregulare on white clover (Trifolium repens L.) submitted to a progressive water stress for 20 days and a recovery period was evaluated. Emphasis was placed on hormonal responses in roots and leaves. Mycorrhization conferred greater resistance to water stress, likely due to an enhanced antioxidant protection in roots and root-to-shoot signaling mediated by lipid peroxidation derivatives, such as jasmonates. In the second chapter, the previous study was extended to a commercially important plant: tomato (Solanum lycopersicum L.). Plants were subjected to a mild water stress in the presence or absence of the arbuscular mycorrhiza R. irregulare for 14 days. Hormonal variations in roots, leaves, and fruits at different developmental stages suggested a systemic response mediated by abscisic acid, extending from roots to ripe fruits. The other hormones analyzed showed organ-dependent variations, being the root hormonal dynamics particularly intriguing, highlighting the role of the root as a central hub for hormonal regulation in response to water stress. Additionally, mycorrhization improved the plant nutritional content. Finally, in the third chapter, it was explored how hormonal changes resulting from fruit ripening could be associated with changes in the cultivable microbiome of sweet cherry (Prunus avium L.) fruits. For that purpose, hormonal and microbiological analyses by tissue were conducted. The results revealed a fundamental role of the exocarp, the fruit outermost layer, as a physical and physiological barrier against colonization by endophytic and pathogenic microorganisms, displaying interesting dynamics in jasmonic acid and salicylic acid levels. In conclusion, this doctoral thesis demonstrates the presence of differential hormonal responses among different plant organs and tissues, which could have potential implications for the entire plant. On the one hand, hormonal changes in the root resulting from mycorrhization in response to water stress could influence the hormonal responses to that stress in distant organs like leaves, as well as the nutritional and hormonal content of fruits. On the other hand, hormonal changes derived from ripening in specific fruit tissues could eventually have indirect implications for the profile of endophytic microorganisms, therefore altering the holobiont itself. |
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