Biology subjects

Stahl, C.

Publications and source records attributed to Stahl, C..

4 recordsLinked to original sources

bioRxiv2026

Longer projected droughts will impair the recovery of tropical seedlings and their leaf microbiota

The increasingly severe droughts in the Amazon Basin make it urgent to understand the resilience of tropical tree species and their microbiota. Plant-associated fungi and bacteria (i.e. extended phenotype) modulate drought stress for their hosts, but their role in recovery dynamics remains poorly understood. To test the impact of different drought durations on the recovery of both physiology and microbiota of tropical trees, we followed the responses of nearly 1,000 seedlings belonging to seven tropical tree species of seasonally flooded (SF) forests in a greenhouse experiment. Seedlings were subjected to different droughts, reflecting a current, a projected and an extreme drought scenario of the French Guiana climate. Plant responses were monitored after the drought and after rewetting. Plant performance was estimated through leaf gas exchange, photochemical functioning, leaf water potentials and water-related traits as well as morphological traits. Bacterial and fungal leaf communities were characterized with respectively 16S and ITS2 markers using high-throughput sequencing. Increasing the duration of the drought reduced the ability of plants to recover physiological functions, with differences among species which were only partially predicted by their drought tolerance strategies. Bacterial diversity increased in most plant host species after mild drought but not under the most severe stress. Bacterial dispersion and turnover responses were strongly host species-specific, without a general directional pattern across species. Fungal communities showed greater compositional stability, but exhibited consistently higher turnover compared to bacterial communities during both drought and recovery, with no convergence toward control composition. Finally, none of the recovery networks mirrored the architecture of the control network, regardless of prior drought duration, demonstrating that the integrated extended phenotype does not recover even when individual traits show signs of recovery. Our results reveal that both physiological recovery and microbial community recovery are strongly shaped by the plant host species identity and drought duration This study widens knowledge of SF tropical forests, vulnerable habitats in the context of climate change, through the lens of the associated microbial communities and functional traits. Beyond the effects of an increasingly uncertain climate combined with a rise in the frequency of extreme events, our study places emphasis on including tree species extended phenotypes in considering their recovery dynamics.

ecology↗

bioRxiv2024

Cell type and locus-specific epigenetic editing of memory expression

Epigenetic modifications parallel multiple memory processes, but evidence that the epigenetic makeup of a single site can guide learnt behaviors has so far been lacking. Here, we developed CRISPR-based epigenetic editing tools to address this question in a cell type-specific, locus-restricted and temporally controllable manner in the adult mouse brain. Focusing on learning-induced neuronal populations, we provide a proof-of-principle that site-specific epigenetic dynamics are causally implicated in memory expression.

neuroscience↗

bioRxiv2018

Low functional but large soil-related variations in growth trajectories characterise the widespread Neotropical tree Cecropia obtusa Trecul (Urticaceae)

AO_SCPLOWBSTRACTC_SCPLOWO_LITrait-environment relationships have been described at the community level across tree species. However, whether interspecific trait-environment relationships are consistent at the intraspecific level is yet unknown. Moreover, we do not know how consistent is the response between organ vs. whole-tree level. C_LIO_LIWe examined phenotypic variability for 16 functional leaf (dimensions, nutrient, chlorophyll) and wood traits (density) across two soil types, Ferralitic Soil (FS) vs. White Sands (WS), on two sites for 70 adult trees of Cecropia obtusa Trecul (Urticaceae) in French Guiana. Cecropia is a widespread pioneer Neotropical genus that generally dominates early successional forest stages. To understand how soil types impact resource-use through the processes of growth and branching, we examined the architectural development with a retrospective analysis of growth trajectories. We expect soil types to affect both, functional traits in relation to resource acquisition strategy as already described at the interspecific level, and growth strategies due to resource limitations with reduced growth on poor soils. C_LIO_LIFunctional traits were not involved in the soil response, as only two traits-leaf residual water content and K content-showed significant differences across soil types. Soil effects were stronger on growth trajectories, with WS trees having the slowest growth trajectories and less numerous branches across their lifespan. C_LIO_LIThe analysis of growth trajectories based on architectural analysis improved our ability to characterise the response of trees with soil types. The intraspecific variability is higher for growth trajectories than functional traits for C. obtusa, revealing the complementarity of the architectural approach with the functional approach to gain insights on the way trees manage their resources over their lifetime. Soil-related responses of Cecropia functional traits are not the same as those at the interspecific level, suggesting that the effects of the acting ecological processes are different between the two levels. Apart from soil differences, much variation was found across sites, which calls for further investigation of the factors shaping growth trajectories in tropical forests. C_LI

ecology↗

bioRxiv2018

Sent to the Corner: xylem vessel anatomy not surface area determines megaphyll hydraulics in Cecropia obtusa Trecul (Urticaceae)

Corners rule predicts a positive correlation between leaf dimensions and the cross-sectional area of the primary stem. Although this relationship is usually explained by hydraulic and mechanical requirements, these hypotheses have never been tested empirically. However, Corners rule is tricky to investigate since rapid secondary growth of the stem prevents a rigorous link being established between a given leaf and the supporting stem. We chose a twig-like leaf model since petiole anatomy is only linked to the attached lamina. We tested the hypothesis that anatomical adjustments to hydraulic requirements related to vessel size enable reduced investment in tissue in the framework of Corners rule. We conducted a functional, mechanistic and intraspecific investigation of Cecropia obtusa Trecul, a Neotropical pioneer tree, by integrating morphological, anatomical and theoretical hydraulic traits around the lamina-petiole size relationship. The twig-like structure of the leaf and the strong lamina-petiole correlation of this model tree species made it possible to use the leaf-level model for a rigorous investigation of the functional implications of Corners rule. We found a positive correlation between petiole size, lamina size, the ratio of mean vessel area to vessel frequency in the petiole xylem and theoretical specific conductivity in the petiole xylem. Hydraulic function supports Corners rule to a lesser extent than previously thought. Variations in vessel dimensions mainly drive xylem hydraulic performances and avoid disproportionate petiole cross-sections to answer to hydraulic requirements associated with lamina size.

plant biology↗