Biology subjects

Pietzenuk, B.

Publications and source records attributed to Pietzenuk, B..

4 recordsLinked to original sources

bioRxiv2025

Interlocus gene conversion causes mosaic divergence in tandem paralogues - simulating HMA4 evolution in Arabidopsis halleri

Following gene duplication, the evolutionary trajectories of gene copies can be shaped by various processes including mutation, selection, recombination and interlocus gene conversion (IGC). To explore their dynamics and consequences, we developed a mathematical model that simulates the early evolution of recently duplicated, tandemly arrayed gene families with positive selection on the new gene copy. We compared the results of our model to sequence variation of the three tandemly arrayed HEAVY METAL ATPase 4 (HMA4) gene copies of Arabidopsis halleri, which are known to undergo IGC. However, rate and efficacy of IGC vary within genes, resulting in a mosaic pattern of divergence. Informed by empirical data, our model captures the impact of IGC and unequal crossing-over on the diversity within each gene copy and the divergence among them. By tailoring the model to the HMA4 gene copies, we demonstrate the models flexibility and its potential to provide insights into the evolutionary dynamics driving the evolution of tandemly arrayed paralogues. This study enhances our understanding of the balance between homogenization and divergence of gene family evolution.

evolutionary biology↗

bioRxiv2024

Diverging Arabidopsis populations quickly accumulate pollen-acting genetic incompatibilities

The process by which species diverge from one another, gradually accumulate genetic incompatibilities and eventually reach full-fledged reproductive isolation is a key question in evolutionary biology. However, the nature of reproductive barriers, the pace at which they accumulate and their genomic distribution remain poorly documented. The disruption of co-adapted epistatic interactions in hybrids and the accumulation of selfish genetic elements are proposed contributors to this process, and can lead to the distortion of the mendelian segregation of the affected loci across the genome. In this study we detect and quantify segregation distortion across the genomes of crosses produced from a diverse sampling of Arabidopsis lyrata and A. halleri populations, two species at the early stages of speciation and that can still interbreed. We show that both the frequency of occurrence and the magnitude of distortion loci increase as the parents genetic distance from one another increases. We also observe that distorter loci evolve rapidly, as they occur not only within interspecific hybrids, but also in intraspecific hybrids produced from isolated population crosses. Finally, we identify both genome-wide non-independence and two specific genomic regions on different chromosomes where opposite distortion effects are repeatedly observed across multiple F1 individuals, suggesting negative epistasis is a major contributor to the evolution of hybrid segregation distortion. Our study demonstrates that pollen-acting segregation distortion is ubiquitous, and contributes not only to the ongoing reproductive isolation between A. halleri and A. lyrata, but also between very recently diverged populations of the same species.

genomics↗

bioRxiv2021

Energy status-promoted growth and development of Arabidopsis require copper deficiency response transcriptional regulator SPL7

Copper (Cu) is a cofactor of around 300 Arabidopsis proteins including photosynthetic and mitochondrial electron transfer chain enzymes critical for ATP production and carbon fixation. Plant acclimation to Cu deficiency requires the transcription factor SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE7 (SPL7). We report that in the wild type and in the spl7-1 mutant, respiratory electron flux via Cu-dependent cytochrome c oxidase remained unaffected under both normal and low-Cu cultivation conditions. Contrary to the wild type, supplementing Cu-deficient media with exogenous sugar failed to stimulate growth of spl7-1. The spl7-1 mutant accumulated carbohydrates including the signaling sugar trehalose 6-phosphate, as well as ATP and NADH, also under normal Cu supply and without sugar supplementation. Late flowering of spl7-1 was in agreement with its attenuated sugar responsiveness. Functional TOR and SnRK1 kinase signaling in spl7-1 suggested against fundamental defects in these energy-signaling hubs. Sequencing of chromatin immunoprecipitates combined with transcriptomics identified direct targets of SPL7-mediated positive regulation, including FE SUPEROXIDE DISMUTASE1 (FSD1), COPPER-DEFICIENCY-INDUCED TRANSCRIPTION FACTOR1 (CITF1) and uncharacterized bHLH23 (CITF2), as well as an enriched upstream GTACTRC motif. In summary, transducing energy availability into growth and reproductive development requires the function of SPL7. Our results could help to increase crop yields, especially on Cu-deficient soils.

plant biology↗

bioRxiv2019

Enhanced genome integrity maintenance and few large stress-mitigating changes in Arabidopsis halleri extreme-habitat local adaptation

Heavy metal-rich toxic soils and ordinary soils are both natural habitats of Arabidopsis halleri. The molecular divergence underlying survival in sharply contrasting environments is unknown. Here we comparatively address metal physiology and transcriptomes of A. halleri originating from the most highly heavy metal-contaminated soil in Europe, Ponte Nossa (Noss/IT), and from non-metalliferous (NM) soil. Noss exhibits enhanced hypertolerance and attenuated accumulation of cadmium (Cd), and transcriptomic Cd responsiveness is decreased, compared to plants of NM soil origin. Among the condition-independent transcriptome characteristics of Noss, the most highly overrepresented functional class of "meiotic cell cycle" comprises 21 transcripts with elevated abundance in vegetative tissues, in particular Argonaute 9 (AGO9) and the synaptonemal complex transverse filament protein-encoding ZYP1a/b. Increased AGO9 transcript levels in Noss are accompanied by decreased long terminal repeat retrotransposon expression, and are shared by plants from milder metalliferous sites in Poland and Germany. Expression of Iron-regulated Transporter (IRT1) is very low and of Heavy Metal ATPase 2 (HMA2) strongly elevated in Noss, which can account for its specific Cd handling. In plants adapted to the most extreme abiotic stress, broadly enhanced functions comprise genes with likely roles in somatic genome integrity maintenance, accompanied by few alterations in stress-specific functional networks.

plant biology↗