Biology subjects

Galliart, M.

Publications and source records attributed to Galliart, M..

4 recordsLinked to original sources

bioRxiv2026

Taking genomics outdoors: linking local adaptation, trait variation, and gene expression in grass ecotypes across a rainfall gradient

With increasing droughts, understanding local adaptation and drought tolerance in ecologically dominant species is crucial for enhancing ecosystem resilience. We leveraged a long-term reciprocal garden to assess local adaptation and drought responses in Andropogon gerardi, a foundation grassland species in the US Great Plains. Our objectives were to identify adaptive traits, explore gene expression responses across a rainfall gradient and under experimental drought and integrate trait-based analyses with gene expression profiles to test for local adaptation. Reciprocal gardens, established a decade ago, are composed of different A. gerardi ecotypes sourced along a rainfall gradient (MAP 480-1167mm yr-1) and sown as ecological communities. Rainout shelters imposed experimental drought. We hypothesized that ecotypes should perform best in their homesite, reflecting local adaptation. The dry ecotype should perform best under rainouts and exhibit traits and expression profiles favoring drought tolerance; the wet ecotype should favor traits and gene expression enhancing growth and resource acquisition. We found ecotypes had highest biomass and cover in their homesite, confirming local adaptation. Under experimental drought, the dry ecotype demonstrated improved performance at the wet site, confirming its adaptive value under water limitation. The dry ecotype showed stress-tolerance strategies (shorter, more water-efficient, upregulated drought-response genes), while the wet ecotype emphasized growth strategies (taller, higher biomass, upregulation of growth hormone gibberellin). Using co-expression networks, gene clusters linked adaptive traits, revealing genetic mechanisms of adaptation. Results advance our understanding of adaptation by linking gene expression and trait variation to drought responses in locally-adapted ecotypes, informing ecotype climate-matching under drought.

genomics↗

bioRxiv2023

Home-field advantage affects the local adaptive interaction between Andropogon gerardii ecotypes and rhizobiome

Due to climate change, drought frequencies and severities are predicted to increase across the United States. Plant responses and adaptation to stresses depend on plant genetic and environmental factors. Understanding the effect of those factors on plant performance is required to predict the species responses to environmental change. We used reciprocal gardens planted with distinct regional Andropogon gerardii ecotypes adapted to dry, mesic, and wet environments to characterize their rhizosphere communities using 16S rRNA metabarcode sequencing. Even though the local microbial pool was the main driver of these rhizosphere communities, the significant plant ecotype effect highlighted active microbial recruitment in the rhizosphere driven by ecotype or plant genetic background. Our data also suggest that ecotypes were more successful in recruiting rhizosphere community members unique to their local homesites, supporting the "home field advantage" hypothesis. These unique homesite microbes may represent microbial specialists that are linked to plant stress responses. Further, our data support ecotypic variation in the recruitment of congeneric but distinct bacterial variants, highlighting the nuanced effects of plant ecotypes on the rhizosphere microbiome recruitment. Our results should facilitate expanded studies on understanding the complexity of plant host interactions with local soil microbes and identification of functional potential of recruited microbes. Our study has the potential to aid in predicting ecosystem responses to climate change and the impact of management on restoration practices. ImportanceIn this study, we used reciprocal gardens located across a sharp precipitation gradient to characterize rhizosphere communities of distinct dry, mesic, and wet regional Andropogon gerardii ecotypes. We used16S rRNA amplicon sequencing and focused oligotyping analysis and showed that even though the location was the main driver of the microbial communities, ecotypes could potentially recruit distinct bacterial populations. We showed that different A. gerardii ecotypes were more successful in overall community recruitment and recruitment of microbes unique to the "home" environment, when growing at their "home site". We found evidence for "home field advantage" interactions between the host and associated rhizobiomes, and the capability of ecotypes to recruit specialized microbes that were potentially linked to plant stress responses. Our study provides insights into the understanding of factors effecting the plant adaptation, improving management strategies, and predicting of the future landscape under the changing climate.

microbiology↗

bioRxiv2022

Culturomics of Andropogon gerardii rhizobiome revealed nitrogen transforming capabilities of stress-tolerant Pseudomonas under drought conditions

BackgroundClimate change will result in more frequent droughts that impact soil-inhabiting microbiomes in the agriculturally vital North American perennial grasslands. In this study, we used the combination of culturomics and high-resolution genomic sequencing of microbial consortia isolated from the rhizosphere of a tallgrass prairie foundation grass, Andropogon gerardii. We cultivated the plant host-associated microbes under artificial drought-induced conditions and identified the microbe(s) that might play a significant role in the rhizobiome of Andropogon gerardii under drought conditions. ResultsPhylogenetic analysis of the non-redundant metagenome-assembled genomes (MAGs) identified the bacterial population of interest - MAG-Pseudomonas. Further metabolic pathway and pangenome analyses detected genes and pathways related to nitrogen transformation and stress responses in MAG-Pseudomonas. ConclusionsOur data indicate that the metagenome-assembled MAG-Pseudomonas has the functional potential to contribute to the plant hosts growth during stressful conditions. This study provided insights into optimizing plant productivity under drought conditions.

microbiology↗

bioRxiv2021

Bacteria but not fungi communities differ among perennial grassland ecotypic rhizosphere under abiotic environmental stress

Environmental change, especially frequent droughts, is predicted to detrimentally impact the North American perennial grasslands. Consistent dry spells will affect plant communities as well as their associated rhizobiomes, possibly altering the plant host performance under environmental stress. Therefore, there is a need to understand the impact of drought on the rhizobiome, and how the rhizobiome may modulate host performance and ameliorate its response to drought stress. In this study, we analyzed bacterial and fungal communities in the rhizospheres of three ecotypes (dry, mesic, and wet) of a dominant prairie grass, Andropogon gerardii. The ecotypes were established in 2010 in a common garden design and grown for a decade under persistent dry conditions at the arid margin of the species range in Colby Kansas. The experiment aimed to answer whether and to what extent do the different ecotypes maintain or recruit distinct rhizobiomes after ten years in an arid climate. In order to answer this question, we screened the bacterial and fungal rhizobiome profiles of the ecotypes under the arid conditions of western KS as a surrogate for future climate environmental stress using 16S rRNA and ITS2 metabarcoding sequencing. Under these conditions, bacterial communities differed compositionally among the A. gerardii ecotypes, whereas the fungal communities did not. The ecotypes were instrumental in driving the differences among bacterial rhizobiomes, as the ecotypes maintained distinct bacterial rhizobiomes even after ten years at the edge of the host species range. This study will aid us to optimize plant productivity through the use of different ecotypes under future abiotic environmental stress, especially drought.

bioinformatics↗