Biology subjects

Schueler, S.

Publications and source records attributed to Schueler, S..

5 recordsLinked to original sources

bioRxiv2025

Unravelling the intraspecific variation in drought responses in seedlings of European black pine (Pinus nigra J.F. Arnold)

O_LIUnderstanding intraspecific variation in drought tolerance is essential for predicting the adaptive capacity of forest species under climate change. Yet, the molecular basis of this variation remains poorly understood in ecologically and economically important conifers. C_LIO_LIWe integrated high-throughput phenotyping with metabolomics and transcriptomics under standardized soil drying to investigate drought responses across nine climatically distinct provenances of the conifer Pinus nigra. We tested whether drought tolerance--measured as decline in maximum quantum yield of the photosystem II (Fv/Fm)--varies among provenances, follows a climatic cline, and involves trade-off with growth. To identify the underlying molecular basis, we performed metabolomics and transcriptomics in four provenances representing contrasting drought tolerance. C_LIO_LIDrought tolerance varied significantly among provenances and was decoupled from growth, yet showed no differentiation along the climatic cline. Drought tolerant provenances differed from sensitive ones in both constitutive and drought-induced levels of flavonoid and diterpene metabolites. Transcriptomic profiles further highlighted provenance-specific differences in gene expression related to flavonoids. C_LIO_LIOur results demonstrate the utility of integrating automated phenotyping with molecular profiling to uncover the metabolic basis of drought adaptation, laying the groundwork for targeted studies on metabolite function and tolerance strategies in non-model conifers. C_LI

plant biology↗

bioRxiv2025

Fast barcode calling based on k-mer distances

DNA barcodes, which are short DNA strings, are regularly used as tags in pooled sequencing experiments to enable the identification of reads originating from the same sample. A crucial task in the subsequent analysis of pooled sequences is barcode calling, where one must identify the corresponding barcode for each read. This task is computationally challenging when the probability of synthesis and sequencing errors is high, like in photolithographic microarray synthesis. Identifying the most similar barcode for each read is a theoretically attractive solution for barcode calling. However, an all-to-all exact similarity calculation is practically infeasible for applications with millions of barcodes and billions of reads. Hence, several computational approaches for barcode calling have been proposed, but the challenge of developing an efficient and precise computational approach remains. Here, we propose a simple, yet highly effective new barcode calling approach that uses a filtering technique based on precomputed k-mer lists. We find that this approach has a slightly higher accuracy than the state-of-the-art approach, is more than 500 times faster than that, and allows barcode calling for one million barcodes and one billion reads per day on a server GPU.

bioinformatics↗

bioRxiv2024

Limitations of ad hoc genotyping in detecting ash dieback tolerance in Fraxinus excelsior

Ash dieback (ADB), caused by the invasive alien fungal pathogen Hymenoscyphus fraxineus, is an emerging disease that poses major threats to the survival of common ash (Fraxinus excelsior) in Europe. Here, we report on a field trial aiming at the identification of ADB tolerant genotypes while encompassing the genetic diversity of common ash in Austria. Over 35,000 progenies from more than 600 putative tolerant mother trees were assessed for ADB symptoms over a period of three years. One tolerant and one susceptible progeny from a subset of the mother tree range (570 trees) were genotyped using the 4TREE array, a genotyping tool developed specifically to screen common ash provenances for their tolerance to ash dieback. We aimed to (1) better characterize the genetic structure of common ash in Austria, (2) identify hybrids between common ash and F. angustifolia (narrow-leaved ash), (3) detect genetic loci associated with tolerance to ADB, and (4) identify genetic variation associated with abiotic factors such as temperature and precipitation influencing the severity of ADB. We identify ash individuals from Eastern Austria matching putative hybrids with F. angustifolia showing varying degrees of F. angustifolia ancestry in structure analyses. The non-hybrid gene pool is characterized by shallow genetic structure following a west to east geographic pattern. In contrast to our expectations, genotype-damage association analyses overall fail to detect SNPs associated with tolerance to ADB. Our findings underscore that the polygenic architecture governing tolerance and the rapid decay of genomic linkage disequilibrium (LD) (within approximately 10 kb) significantly limit the ability to identify association outliers using the 4TREE SNP array. This highlights the constrained utility of chip genotyping approaches for this specific purpose. In contrast, the array proves successful in detecting hybrids between common ash and narrow-leaved ash, as well as outlier SNPs associated with abiotic predictors (such as annual precipitation and temperature) known to influence the severity of ADB damage.

genetics↗

bioRxiv2023

The Arabidopsis U1 snRNP regulates mRNA 3'-end processing

The removal of introns by the spliceosome is a key gene regulatory mechanism in eukaryotes, with the U1 snRNP subunit of the spliceosome playing a crucial role in the early stages of splicing. Studies in metazoans show that the U1 snRNP also conducts splicing-independent functions, but the lack of genetic tools and knowledge about U1 snRNP-associated proteins have limited the study of such splicing-independent functions in plants. Here, we describe an RNA-centric approach that identified more than 200 proteins associated with the Arabidopsis U1 snRNP, among them mRNA cleavage and polyadenylation factors. The loss of U1 core components is linked to premature cleavage and polyadenylation within gene bodies and alternative polyadenylation site selection in 3-UTRs. Overall, our work provides a comprehensive view of U1 snRNP interactors and reveals novel functions in regulating mRNA 3-end processing in Arabidopsis, thus establishing the groundwork for a better understanding of non-canonical functions of plant U1 snRNPs.

plant biology↗

bioRxiv2020

Looking for the needle in a downsized haystack: Whole-exome sequencing unravels how selection and gene flow have shaped climatic adaptation in Douglas-fir (Pseudotsuga menziesii)

The widespread Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) occurs along a steep gradient of diverse climates throughout its natural range, which is expected to result in spatially varying selection to local climate conditions. However, phenotypic signals of climatic adaptation can often be confounded, because unraveled clines covary with signals caused by neutral evolutionary processes such as gene flow and genetic drift. Here, we present phenotypic and genotypic data from a common garden experiment showing a putative signal of adaptation to climate after trees have been growing for 40 years in a common environment. Sixteen Douglas-fir provenances originating from a North-to-South gradient of approx. 1,000 km were analyzed and genomic information was obtained from exome capture, which resulted in an initial genomic dataset of >90,000 single nucleotide polymorphisms. We used a restrictive and conservative filtering approach which permitted us to include only SNPs and individuals in environmental association analysis (EAA) that were free of potentially confounding effects (LD, relatedness among trees, heterozygosity deficiency and deviations from Hardy-Weinberg proportions). We used four conceptually different genome scan methods based on FST outlier detection and gene-environment association in order to disentangle truly adaptive SNPs from neutral SNPs and found that a relatively small proportion of the exome showed a truely adaptive signal (0.01-0.17%) when population substructuring and multiple testing was accounted for. Nevertheless, the unraveled SNP candidates showed significant relationship with climate at provenance origins which strongly suggests that they have most likely featured adaption in Douglas-fir across a steep climatic gradient. Two SNPs were independently found by three of the employed algorithms and one could be assigned with high probability to a Picea abies homolog gene involved in circadian clock control as was also found in Populus balsamifera.

evolutionary biology↗