Biology subjects

Gawronski, P.

Publications and source records attributed to Gawronski, P..

7 recordsLinked to original sources

bioRxiv2025

Transpiration, Photoinhibition and Non-photochemical Quenching Reciprocally Control Foliar Heat Emission

Global warming intensifies heat waves and drought, causing energy absorption in excess (EAE) in plants, thereby inhibiting transpiration and photosynthesis. Non-photochemical quenching (NPQ) contributes significantly to EAE dissipation as heat, with leaves emitting ca. 107 W m-2 while absorbing ca. 417 W m-2. Foliar temperature is further elevated when transpiration is inhibited, but NPQ is not increased. Surprisingly, during generic photosynthetic electron transport and NPQ partial inhibition, foliar temperature under EAE was reduced considerably. Our findings emphasize the importance of mutual co-regulation of photosynthetic electron transport, NPQ, and transpiration in foliar temperature regulation and suggest that overall heat emission from forest ecosystems may conditionally vary on a terawatt (TW) scale per 1,000,000 km-2. Global warming models do not take into account this putative phenomenon. One Sentence SummaryPhotosynthesis and Foliar Thermoregulation

plant biology↗

bioRxiv2024

The new role of carbonic anhydrases and bicarbonate in acclimatization and hypoxia stress responses in Arabidopsis thaliana

Plant growth and stress responses largely depend on the chloroplast retrograde signaling. Stoichiometry of carbon dioxide assimilation and transpiration, efficiency of photosynthesis, and absorbed energy fate in photosystems between photochemistry, fluorescence and heat channels impact on the chloroplast retrograde signaling. Recent studies revealed that 22 kDa photosystem II protein (PsbS) and plant {beta} carbonic anhydrases ({beta}CAs), except their obvious functions, are also involved in regulation of plant stress responses. Obtained results suggest that simultaneous overexpression of {beta}CA1 and/or {beta}CA2 with PsbS genes leads to improved photoprotection, acclimation to variable light conditions, and water use efficiency. However, this was achieved on the costs of lower biomass gain in double and triple (oePsbSoe{beta}CA1 and oePsbSoe{beta}CA1{beta}CA2, respectively) transgenic lines in comparison to Col-0, and npq4-1 mutant. After bicarbonate fertilization we observed significant increase in biomass production in triple transgenic lines compared to oePsbS and npq4-1 plants, but not to Col-0. Transcriptomic analysis revealed that bicarbonate treatment of double and triple transgenic lines specifically induced expression of genes and transcription factors related to hypoxia, freezing, drought, high light, and pathogen attack stress responses, contrary to other genotypes. Interestingly, expression of two of these transcription factors, DREB - CBF2 subfamily (A-1 of ERF/AP2), and BT2 were reduced in oePsbS transgenic line. Our results suggest a novel regulatory role of {beta}CAs and bicarbonate in the regulation of stress responses and plant productivity.

plant biology↗

bioRxiv2024

Deciphering the RNA Modification Landscape in Arabidopsis Chloroplast tRNAs and rRNAs Reveals a Blend of Ancestral and Acquired Characteristics

Chloroplasts in plant leaves are essential for protein synthesis, relying on transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs) encoded by the chloroplast genome. Although post-transcriptional modifications of these non-coding RNAs are common in many systems, chloroplast tRNA and rRNA modifications are not well characterised. In this study, we investigated the post-transcriptional modifications in chloroplast tRNAs and rRNAs of Arabidopsis thaliana using tRNA sequencing, liquid chromatography-mass spectrometry, targeted rRNA sequencing, and analysis of public data. Our results revealed similarities between chloroplast non-coding RNAs and bacterial systems (e.g., Escherichia coli), such as modification patterns at the anticodon-adjacent position and the variable loop of tRNAs, along with conserved modifications in the small subunit rRNA. Additionally, we identified features shared with eukaryotic systems that likely contribute to the correct three-dimensional structure of chloroplast tRNAs. Unique modifications were also discovered, including a potential novel modification at wobble position in tRNA-IleCAU, which may be crucial for distinguishing isoleucine codons from methionine codons, and chloroplast-specific rRNA modifications that likely compensate for altered ribosome structure. These findings suggest that the chloroplast translation machinery, through co-evolution with its eukaryotic host, has adopted features beyond those typically found in bacteria, reflecting a blend of ancestral and acquired characteristics.

plant biology↗

bioRxiv2023

Selective sweeps identification in distinct groups of cultivated rye (Secale cereale L.) germplasm provides potential candidates for crop improvement

BackgroundDuring domestication and subsequent improvement plants were subjected to intensive positive selection for desirable traits. Identification of selection targets is important with respect to the future targeted broadening of diversity in breeding programmes. Rye (Secale cereale L.) is a cereal that is closely related to wheat, and it is an important crop in Central, Eastern and Northern Europe. The aim of the study was (i) to identify diverse groups of rye accessions based on high-density, genome-wide analysis of genetic diversity within a set of 478 rye accessions, covering a full spectrum of diversity within the genus, from wild accession to inbred lines used in hybrid breeding, and (ii) to identify selective sweeps in the established groups of cultivated rye germplasm and putative candidate genes targeted by selection. ResultsPopulation structure and genetic diversity analyses based on high-quality SNP (DArTseq) markers revealed the presence of three complexes in the Secale genus: S. sylvestre, S. strictum and S. cereale/vavilovii, a relatively narrow diversity of S. sylvestre, very high diversity of S. strictum, and signatures of strong positive selection in S. vavilovii. Within cultivated ryes we detected the presence of genetic clusters and the influence of improvement status on the clustering. Rye landraces represent a reservoir of variation for breeding, and especially a distinct group of landraces from Turkey should be of special interest as a source of untapped variation. Selective sweep detection in cultivated accessions identified 133 outlier positions within 13 sweep regions and 170 putative candidate genes related, among others, to response to various environmental stimuli (such as pathogens, drought, cold), plant fertility and reproduction (pollen sperm cell differentiation, pollen maturation, pollen tube growth),and plant growth and biomass production. ConclusionsOur study provides valuable information for efficient management of rye germplasm collections, which can help to ensure proper safeguarding of their genetic potential and provides numerous novel candidate genes targeted by selection in cultivated rye for further functional characterisation and allelic diversity studies.

plant biology↗

bioRxiv2020

Light-dependent translation change of Arabidopsis psbA correlates with RNA structure alterations at the translation initiation region

mRNA secondary structure influences translation. Proteins that modulate the mRNA secondary structure around the translation initiation region may regulate translation in plastids. To test this hypothesis, we exposed Arabidopsis thaliana to high light, which induces translation of psbA mRNA encoding the D1 subunit of photosystem II. We assayed translation by ribosome profiling and applied two complementary methods to analyze in vivo RNA secondary structure: DMS-MaPseq and SHAPE-seq. We detected increased accessibility of the translation initiation region of psbA after high light treatment, likely contributing to the observed increase in translation by facilitating translation initiation. Furthermore, we identified the footprint of a putative regulatory protein in the 5 UTR of psbA at a position where occlusion of the nucleotide sequence would cause the structure of the translation initiation region to open up, thereby facilitating ribosome access. Moreover, we show that other plastid genes with weak Shine-Dalgarno sequences (SD) are likely to exhibit psbA-like regulation, while those with strong SDs do not. This supports the idea that changes in mRNA secondary structure might represent a general mechanism for translational regulation of psbA and other plastid genes. SIGNIFICANCERNA structure changes in the translation initiation region, most likely as a result of protein binding, affect the translation of psbA and possibly other plastid genes with weak Shine-Dalgarno sequences.

plant biology↗

bioRxiv2020

Deep sampling and pooled amplicon sequencing reveals hidden genic variation in heterogeneous rye accessions

Loss of genetic variation negatively impacts breeding efforts and food security. Genebanks house over 7 million accessions representing vast allelic diversity that is a resource for sustainable breeding. Discovery of DNA variations is an important step in the efficient use of these resources. While technologies have improved and costs dropped, it remains impractical to consider resequencing millions of accessions. Candidate genes are known for most agronomic traits, providing a list of high priority targets. Heterogeneity in seed stocks means that multiple samples from an accession need to be evaluated to recover available alleles. To address this we developed a pooled amplicon sequencing approach and applied it to the out-crossing cereal rye (Secale cereale). Ninety-five rye accessions of different improvement status and worldwide origin, each represented by a pooled sample comprising DNA of 96 individual plants, were evaluated for sequence variation in six target genes involved in seed quality, biotic and abiotic stress resistance. Seventy-four predicted deleterious variants were identified using multiple algorithms. Rare variants were recovered including those found only in a low percentage of seed. A large extent of within-population heterogeneity was revealed, providing an important point for consideration during rye germplasm conservation and utilization efforts. We conclude that this approach provides a rapid and flexible method for evaluating stock heterogeneity, probing allele diversity, and recovering previously hidden variation.

genomics↗

bioRxiv2019

Dual-targeted transcription factors are required for optimal photosynthesis and stress responses in Arabidopsis thaliana

Chloroplast to nucleus retrograde signaling is essential for cell function, acclimation to fluctuating environmental conditions, plant growth and development. The vast majority of chloroplast proteins are nuclear-encoded and must be imported into the organelle after synthesis in the cytoplasm. This import is essential for the development of fully functional chloroplasts. On the other hand, functional chloroplasts act as sensors of environmental changes and can trigger acclimatory responses that influence nuclear gene expression. Signaling via mobile transcription factors (TFs) has been recently recognized as a way of communication between organelles and the nucleus. In this study, we performed a targeted reverse genetic screen to identify novel dual-localized TFs involved in chloroplast retrograde signaling during stress responses. We found that CHLOROPLAST IMPORT APPARATUS 2 (CIA2), a TF with putative plastid transit peptide can be detected in chloroplasts and the nucleus. Further, we found that CIA2, along with its homolog CIA2-like (CIL) act in an unequally redundant manner and are involved in the regulation of Arabidopsis responses to UV-AB, high light, and heat shock. Finally, our results suggest that both CIA2 and CIL are crucial for chloroplast translation. Our results contribute to a deeper understanding of signaling events in the chloroplast-nucleus cross-talk.\n\nSignificanceWe found that a transcription factor CIA2 can be located in chloroplasts and nucleus. CIA2 and is close homolog CIL are involved in protein translation and abiotic stress responses, and we suggest that they play an essential role in retrograde signaling between these organelles.

plant biology↗