Elucidating the molecular mechanisms underlying grassland species in response to more persistent precipitation regimes
One aspect of climate change is the increased persistence of precipitation regimes (PRs), characterized by alternated longer dry and wet periods. While the ecological impacts of singular extreme events like drought and flood have been extensively studied, the immediate and legacy effects of the evolving more persistent PR, particularly at the molecular level in plants, remain underexplored. This doctoral thesis aims to bridge this knowledge gap by conducting a large-scale outdoor experiment, applying a range of PR from short to long dry/wet cycles to grassland mesocosms. Ecometabolomics analysis revealed that the metabolome of a relatively sensitive species, Centaurea jacea, shifted under mild PR (10-day dry/wet cycle), while the metabolome of other less sensitive species changed only from a 20-day PR onwards. Accumulation of amino acids, lignin, and decreased non-structural sugar levels are universal responses across several species to increasing PR extremity, while changes in other metabolite classes are exhibited in a more species-specific manner. The sensitive species are less capable of inducing sufficient changes in important molecules such as lignin and phenylalanine, which may partly explain its sensitivity in PR responses. Beyond immediate effects, my research found that previous exposure to more persistent PR resulted in acclimated grassland communities in the following year. These communities showed increased aboveground productivity and structural sugar content, reduced molecular stress responses and reduced diversity. Furthermore, soil inoculum from more persistent PR promoted the upregulation of several pathways, such as hormone synthesis (e.g., jasmonic acid, abscisic acid, salicylic acid, ethylene), oxidative stress, cell wall modification (e.g., lignin deposition, callose synthesis, cell wall thickening, pectin metabolic process), and chitin catabolic processes, which may provide potential beneficial effects for plants. In conclusion, this thesis demonstrates that more persistent PR induces significant changes in plant biochemical and transcriptional levels. While these changes may enhance the acclimation of grassland species, they may also decrease nutritive value, potentially altering their role in the feeding of organisms. Species or individuals unable to induce sufficient protective changes may be excluded from the community, leading to a loss of diversity in the ecosystem.
Antwerp : University of Antwerp, Faculty of Science, Department of Biology , 2024
267 p.
Supervisor: Asard, Han [Supervisor]
Supervisor: Abd Elgawad, Hamada [Supervisor]
Supervisor: Laukens, Kris [Supervisor]
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Creation 11.01.2024
Last edited 04.03.2024
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