Biology subjects

Karpinski, S.

Publications and source records attributed to Karpinski, S..

5 recordsLinked to original sources

bioRxiv2026

CRK5 preserves antioxidant homeostasis and prevents cell death during dark-induced senescence through inhibiting the salicylic acid signaling pathway

BackgroundDark-induced senescence (DIS) is a widely used model for dissecting the regulatory mechanisms that manage leaf aging, redox imbalance, and cell death (CD) in plants. Salicylic acid (SA) is a central hormonal regulator of these processes. However, the mechanism involving upstream components, which integrate SA-dependent pathways with antioxidant homeostasis during DIS, remains unresolved. CYSTEINE-RICH RECEPTOR-LIKE KINASE 5 (CRK5) is a membrane-localized protein that plays a role in developmental and stress-responsive pathways. Its promoter contains multiple W-box cis-elements, indicating regulation by WRKY factors in SA-mediated pathways. This study investigates how CRK5 modulates SA-dependent CD and antioxidant dynamics during DIS. ResultsIn this study, SA-accumulating mutant crk5 exhibited accelerated senescence, elevated electrolyte leakage, enhanced micro-lesion formation, and markedly increased reactive oxygen species (ROS) accumulation under both control and dark conditions. These phenotypes were accompanied by a substantial reduction in carotenoid and xanthophyll pools, enhanced accumulation of phenolic compounds, and increased free radical scavenging capacity, including ascorbate peroxidase, catalase, and superoxide dismutase activities. Importantly, crk5 phenotype was fully reverted in crk5sid2 and crk5NahG double mutants, confirming that crk5 DIS phenotype is induced by activation of the SA-signaling pathway. Transcriptome profiling revealed extensive deregulation of senescence-, CD-, and redox-associated genes in crk5 during darkness, including strong induction of SAGs, metacaspases, autophagy, and antioxidant-related transcripts. The line with constitutively enhanced SA level (cpr1), used as a control, showed similar phenotypes to crk5, although transcriptional reprogramming was largely absent in cpr1 after darkness, highlighting CRK5 as a key upstream negative regulator of SA-mediated CD and positive regulator of antioxidant homeostasis. ConclusionOur work presents CRK5 as a central regulatory hub that inhibits the SA-signaling, ROS burst, and CD activation during DIS. Loss of CRK5 function is associated with the activation of SA-signaling, altered antioxidant systems, increased ROS burden, and ROS-driven CD acceleration, resulting in accelerated senescence. Conversely, suppression of SA-biosynthesis or -catabolism in a crk5 background restores the wild-type phenotype. These findings position this receptor kinase as a key mediator that coordinates hormonal, metabolic, and oxidative pathways to maintain leaf viability, providing mechanistic insight into the control of stress-induced senescence and CD in Arabidopsis.

plant biology↗

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↗

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↗

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↗