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Callose, a β-1,3-glucan plant cell wall polymer, regulates symplasmic channel size at plasmodesmata (PD) and plays a crucial role in a variety of plant processes. However, elucidating the molecular mechanism of PD callose homeostasis is limited. We screened and identified an Arabidopsis mutant plant with excessive callose deposition at PD and found that the mutated gene was α1-COP, a member of the coat protein I (COPI) coatomer complex. We report that loss of function of α1-COP elevates the callose accumulation at PD by affecting subcellular protein localization of callose degradation enzyme PdBG2. This process is linked to the functions of ERH1, an inositol phosphoryl ceramide synthase, and glucosylceramide synthase through physical interactions with the α1-COP protein. Additionally, the loss of function of α1-COP alters the subcellular localization of ERH1 and GCS proteins, resulting in a reduction of GlcCers and GlcHCers molecules, which are key sphingolipid (SL) species for lipid raft formation. Our findings suggest that α1-COP protein, together with SL modifiers controlling lipid raft compositions, regulates the subcellular localization of GPI-anchored PDBG2 proteins, and hence the callose turnover at PD and symplasmic movement of biomolecules. Our findings provide the first key clue to link the COPI-mediated intracellular trafficking pathway to the callose-mediated intercellular signaling pathway through PD., (© 2024 The Authors. Journal of Integrative Plant Biology published by John Wiley & Sons Australia, Ltd on behalf of Institute of Botany, Chinese Academy of Sciences.)

In plant species, anthocyanin accumulation is specifically regulated by light signaling. Although the CONSTITUTIVELY PHOTOMORPHOGENIC1/SUPPRESSOR OF PHYA-105 (COP1/SPA) complex is known to control anthocyanin biosynthesis in response to light, the precise mechanism underlying this process remains largely unknown. Here, we report that Increase in BONSAI Methylation 1 (IBM1), a JmjC domain-containing histone demethylase, participates in the regulation of light-induced anthocyanin biosynthesis in Arabidopsis. The expression of IBM1 was induced by high light (HL) stress, and loss-of-function mutations in IBM1 led to accelerated anthocyanin accumulation under HL conditions. We further identified that IBM1 is directly associated with SPA1/3/4 chromatin in vivo to establish a hypomethylation status on H3K9 and DNA non-CG at these loci under HL, thereby releasing their expression. Genetic analysis showed that quadruple mutants of IBM1 and SPA1/3/4 resemble spa134 mutants. Overexpression of SPA1 in ibm1 mutants complements the mutant phenotype. Our results elucidate the significance and mechanism of IBM1 histone demethylase in the epigenetic regulation of anthocyanin biosynthesis in Arabidopsis under HL conditions., (© 2024 The Authors New Phytologist © 2024 New Phytologist Foundation.)

The detection of phytohormones in real time has attracted increasing attention because of their critical roles in regulating the development and signaling of plants, especially in defense against biotic stresses. Herein, stainless steel sheet electrodes modified with carbon cement were coupled with paper-based analysis devices for direct and simultaneous detection of salicylic acid (SA) and indole-3-acetic acid (IAA) in plants. We demonstrated that the excellent conductivity of stainless steel sheet electrodes enabled us to simultaneously differentiate IAA and SA at a level of 10 nM. With our approach, the content of IAA and SA in Arabidopsis thaliana leaves infected or not infected with Pst DC3000 could be rapidly quantified at the same time. Our experimental results on differentiation of IAA and SA at different time points showed that there were antagonistic interactions between the IAA and SA after infection of Arabidopsis leaves with Pst DC3000. By offering a cost-effective approach for rapid and sensitive detection of IAA and SA, this study suggests that electrochemical detection can be used in the study and development of precision agriculture technology., (© 2022. Springer-Verlag GmbH Germany, part of Springer Nature.)

Understanding the underlying mechanisms of plant development is crucial to successfully steer or manipulate plant growth in a targeted manner. Leaves, the primary sites of photosynthesis, are vital organs for many plant species, and leaf growth is controlled by a tight temporal and spatial regulatory network. In this review, we focus on the genetic networks governing leaf cell proliferation, one major contributor to final leaf size. First, we provide an overview of six regulator families of leaf growth in Arabidopsis: DA1, PEAPODs, KLU, GRFs, the SWI/SNF complexes, and DELLAs, together with their surrounding genetic networks. Next, we discuss their evolutionary conservation to highlight similarities and differences among species, because knowledge transfer between species remains a big challenge. Finally, we focus on the increase in knowledge of the interconnectedness between these genetic pathways, the function of the cell cycle machinery as their central convergence point, and other internal and environmental cues., (© 2023 Society for Experimental Biology and John Wiley & Sons Ltd.)

β-Glucan is an eco-friendly, biodegradable, and economical biopolymer with important roles for acquiring adaptations to mitigate climate change in crop plants. β-Glucan plays a crucial role in the activation of functional plant innate immune system by triggering the downward signaling cascade/s, resulting in the accumulation of different pathogenesis-related proteins (PR-proteins), reactive oxygen species (ROS), antioxidant defense enzymes, Ca 2+ -influx as well as activation of mitogen-activated protein kinase (MAPK) pathway. Recent experimental studies have shown that β-glucan recognition is mediated by co-receptor LysMPRR (lysin motif pattern recognition receptor)-CERK1 (chitin elicitor receptor kinase 1), LYK4, and LYK5 (LysM-containing receptor-like kinase), as well as different receptor systems in plants that could be plant species-specific and/or age and/or tissue-dependent. Transgenic overexpression of β-glucanase, chitinase, and/or in combination with other PR-proteins like cationic peroxidase, AP24,thaumatin-likeprotein 1 (TLP-1) has also been achieved for improving plant disease resistance in crop plants, but the transgenic methods have some ethical and environmental concerns. In this regard, elicitation of plant immunity using biopolymer like β-glucan and chitosan offers an economical, safe, and publicly acceptable method. The β-glucan and chitosan nanocomposites have proven to be useful for the activation of plant defense pathways and to enhance plant response/systemic acquired resistance (SAR) against broad types of plant pathogens and mitigating multiple stresses under the changing climate conditions., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Main Conclusion: AtFTCD-L protein is localized on the TGN vesicles in Arabidopsis root cap cells. AtFTCD-L mutation resulted in slow root growth of Arabidopsis in high-concentration agar culture medium. Arabidopsis formiminotransferase cyclodeaminase-like protein (AtFTCD-L) in Arabidopsis is homologous to the formiminotransferase cyclodeaminase (FTCD) protein in animal cells. However, the localization and function of AtFTCD-L remain unknown in Arabidopsis. In this study, we generated and analyzed a deletion mutant of AtFTCD-L with a T-DNA insertion. We found that the growth of Arabidopsis roots with the T-DNA insertion mutation in AtFTCD-L was slower than that of wild-type roots when grown in high-concentration 1/2 MS agar culture medium. AtFTCD-L-GFP could restore the ftcd-l mutant phenotype. In addition, the AtFTCD-L protein was localized on the trans-Golgi network (TGN) vesicles in Arabidopsis root cap cells. Fluorescence recovery after photobleaching (FRAP) experiment using Arabidopsis pollen-specific receptor-like kinase-GFP (AtPRK1-GFP) stably transformed plants showed that the deficiency of AtFTCD-L protein in Arabidopsis led to slower secretion in the root cap peripheral cells. The AtFTCD-L protein deficiency also resulted in a significantly reduced monosaccharides content in the culture medium. Based on the above results, we speculate that the AtFTCD-L protein may be involved in sorting and/or transportation of TGN vesicles in root cap peripheral cells, thereby regulating the extracellular secretion of mucilage components in the root cap., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Sphingolipids, a class of bioactive lipids, play a critical role in signal transduction. Ceramides, which are central components of sphingolipid metabolism, are involved in plant development and defense. However, the mechanistic link between ceramides and downstream signaling remains unclear. Here, the mutation of alkaline ceramidase in a ceramide kinase mutant acd5 resulted in spontaneous programmed cell death early in development and was accompanied by ceramide accumulation, while other types of sphingolipids, such as long chain base, glucosylceramide, and glycosyl inositol phosphorylceramide, remained at the same level as the wild-type plants. Analysis of the transcriptome indicated that genes related to the salicylic acid (SA) pathway and oxidative stress pathway were induced dramatically in acer acd5 plants. Comparison of the level of reactive oxygen species (ROS), SA, and ceramides in the wild-type and acer acd5 plants at different developmental stages indicated that the acer acd5 mutant exhibited constitutive activation of SA and ROS signaling, which occurred simultaneously with the alteration of ceramides. Overexpressing NahG in the acer acd5 mutant could completely suppress its cell death and ceramide accumulation, while benzo-(1,2,3)-thiadiazole-7-carbothioc acid S-methyl ester treatment restored its phenotype again. Moreover, we found that the plasma membrane of acer acd5 mutant was the main site of ROS production. Ceramides accumulated in the plasma membrane of acer acd5, directly binding and activating the NADPH oxidase RbohD and promoting hydrogen peroxide generation and SA- or defense-related gene activation. Our data illustrated that ceramides play an essential role in plant defense., (© 2021 Society for Experimental Biology and John Wiley & Sons Ltd.)

In flowering plants, the interaction of pollen tubes with female tissues is important for the accomplishment of double fertilization. Little information is known about the mechanisms that underlie signalling between pollen tubes and female tissues. In this study, two Arabidopsis pollen tube-expressed CrRLK1L protein kinases, Buddha's Paper Seal 1 (BUPS1) and BUPS2, were identified as being required for normal tip growth of pollen tubes in the pistil. They are expressed prolifically in pollen and pollen tubes and are localized on the plasma membrane of the pollen tube tip region. Mutations in BUPS1 drastically reduced seed set. Most of the bups1 mutant pollen tubes growing in the pistil exhibited a swollen pollen tube tip, leading to failure of fertilization. The bups2 pollen tubes had a slightly abnormal morphology but could still accomplish double fertilization. The bups1 bups2 double mutant exhibited a slightly enhanced phenotype compared to the single bups1 mutants. The BUPS1 proteins could form homomers and heteromers with BUPS2, whereas BUPS2 could only form heteromers with BUPS1. The BUPS proteins could interact with the Arabidopsis pollen-expressed RopGEFs in the yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. The results indicated that the BUPSs may mediate normal polar growth of pollen tubes in the pistil., (© 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.)

small cysteine-rich peptides play essential roles in different stages of the plant reproductive process. Pollen germination is a prerequisite for double fertilization and is directly related to seed formation and crop yield. However, the small cysteine-rich peptides that are involved in pollen germination remain to be identified. In this study, identification and phylogenetic analysis of PCP-Bε genes in sequenced Brassicaceae show that pollen coat protein B-class protein PCP-Bε gene is widespread in Arabidopsis and its high relatives, but lost in some Brassica species. Expression analyses display that AtPCP-Bε gene is expressed in Arabidopsis pollen. Arabidopsis PCP-Bε knockout mutants are generated by CRISPR/Cas9, Phenotypic analyses show that the absence of AtPCP-Bε obviously impairs in vitro pollen germination, but has no influence on pollen tube growth, which demonstrates that AtPCP-Bε is a novel positive regulator of pollen germination. It is speculated that AtPCP-Bε should interact with the receptor from pollen to perform its function. These findings are useful for further analysis on the molecular mechanism of pollen germination., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Qiguo Gao reports financial support was provided by Natural Science Foundation Project of Chongqing. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Cadmium (Cd) represents a hazardous heavy metal, prevalent in agricultural soil due to industrial and agricultural expansion. Its propensity for being absorbed by edible plants, even at minimal concentrations, and subsequently transferred along the food chain poses significant risks to human health. Accordingly, it is imperative to investigate novel genes and mechanisms that govern Cd tolerance and detoxification in plants. Here, we discovered that the transcription factor MYC2 directly binds to the promoters of HMA2 and HMA4 to repress their expression, thereby altering the distribution of Cd in plant tissues and negatively regulating Cd stress tolerance. Additionally, molecular, biochemical, and genetic analyses revealed that MYC2 interacts and cooperates with MYB43 to negatively regulate the expression of HMA2 and HMA4 and Cd stress tolerance. Notably, under Cd stress conditions, MYC2 undergoes degradation, thereby alleviating its inhibitory effect on HMA2 and HMA4 expression and plant tolerance to Cd stress. Thus, our study highlights the dynamic regulatory role of MYC2, in concert with MYB43, in regulating the expression of HMA2 and HMA4 under both normal and Cd stress conditions. These findings present MYC2 as a promising target for directed breeding efforts aimed at mitigating Cd accumulation in edible plant roots., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

NHX5 and NHX6, Arabidopsis endosomal antiporters, play a vital role in facilitating ion and pH homeostasis in endosomal compartments. Studies have found that NHX5 and NHX6 are essential for protein trafficking, auxin homeostasis, and plant growth and development. Here, we report the role of NHX5 and NHX6 in brassinosteroid (BR) signaling. We found that hypocotyl growth was enhanced in nhx5 nhx6 under epibrassinolide (eBR) treatment. nhx5 nhx6 bri1 was insensitive to eBR treatment, indicating that NHX5 and NHX6 are downstream of the BRI1 receptor in BR signaling. Moreover, confocal observation with both hypocotyls and root tips showed that BRI1-YFP localization in the plasma membrane (PM) was reduced in nhx5 nhx6. Interestingly, brefeldin A (BFA) treatment showed that formation of the BFA bodies containing BRI1 and their disassembling were disrupted in nhx5 nhx6. Further genetic analysis showed that NHX5/NHX6 and SYP22 may act coordinately in BR signaling. NHX5 and NHX6 may regulate SYP22 function by modulating cellular K + and pH homeostasis. Importantly, NHX5 and NHX6 colocalize and interact with SYP22, but do not interact with BRI1. In summary, our findings indicate that NHX5/NHX6/SYP22 complex is essential for the regulation of BRI1 recycling and PM localization. The H + -leak facilitated by NHX5 and NHX6 offers a means of controlling BR signaling in plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

The Arabidopsis oligopeptide transporter AtOPT6 is reportedly involved in the long-distance transport of thiol compounds into sink organs. In the present study, transgenic Arabidopsis lines overexpressing AtOPT6 under the control of a phloem-specific promoter, sucrose-proton symporter 2 (pSUC2), were analyzed for thiol and cadmium (Cd) distribution during the reproductive stage, both with and without Cd exposure. Phloem specific AtOPT6-overexpressing lines did not exhibit an evident impact on bolting time. In the absence of Cd exposure, these transgenic lines showed significantly enhanced transport of endogenous glutathione into siliques, accompanied by a reduction in the glutathione content of flowers and roots during the reproductive stage. Additionally, exposure of the roots of the phloem specific AtOPT6-overexpressing lines to Cd altered the distribution of thiol compounds, resulting in an increase in the content of phytochelatins in sink organs, contributing to a significant elevation of Cd contents in reproductive sink. Our findings confirm the crucial role of AtOPT6 in unloading phytochelatin-Cd conjugates from the phloem into sink organ., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

ABA-insensitive 5 (ABI5) belongs to the basic leucine zipper class of transcription factors and is named for being the fifth identified Arabidopsis mutant unresponsive to ABA. To understand the influence of ABI5 in its active state on downstream gene expression and plant growth and development, we overexpressed the full-length ABI5 (A.t.MX-4) and the active forms of ABI5 with deleted transcriptional repression domains (A.t.MX-1, A.t.MX-2, and A.t.MX-3). Compared with the wild type, A.t.MX-1, A.t.MX-2, and A.t.MX-3 exhibited an increase in rosette leaf number and size, earlier flowering, increased thousand-seed weight, and significantly enhanced drought resistance. Thirty-five upregulated/downregulated proteins in the A.t.MX-1 were identified by proteomic analysis, and these proteins were involved in ABA biosynthesis and degradation, abiotic stress, fatty acid synthesis, and energy metabolism. These proteins participate in the regulation of plant drought resistance, flowering timing, and seed size at the levels of transcription and post-translational modification., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Plants often face high salinity as a significant environmental challenge with roots being the first responders to this stress. Maintaining K + /Na + ratio within plant cells is crucial for survival, as the intracellular K + level decreases and the intracellular Na + level increases under saline conditions. However, knowledge about the molecular regulatory mechanisms of K + loss in response to salt stress through outward-rectifying K + channels in plants is largely unknown. In this study, we found that the Arabidopsis double mutant gorkskor, in which the GORK and SKOR genes are disrupted, showed an improved primary root growth under salt stress compared to wild-type (WT) and the gork and skor single-mutant plants. No significant differences in the sensitivity to mannitol stress between the WT and gorkskor mutant were observed. Accumulation of ROS induced by salt stress was reduced in the gorkskor roots. The gorkskor mutant seedlings had significantly higher K + content, lower Na + content, and a greater resultant K + /Na + ratio than the WT under salt stress. Moreover, salt-stress-induced elevation of cytosolic free Ca 2+ concentration was reduced in the gorkskor roots. Taken together, these results suggest that Arabidopsis Shaker-type outward-rectifying K + channels GORK and SKOR may redundantly function in regulation of primary root growth under salt stress and are involved in not only the late-stage response (e.g. K + leakage) but also the early response including ROS production and [Ca 2+ ] cyt elevation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Chloroplast development underpins plant growth, by facilitating not only photosynthesis but also other essential biochemical processes. Nonetheless, the regulatory mechanisms and functional components of chloroplast development remain largely uncharacterized due to their complexity. In our study, we identified a plastid-targeted gene, ATYCO/RP8/CDB1, as a critical factor in early chloroplast development in Arabidopsis thaliana. YCO knock-out mutant (yco) exhibited a seedling-lethal, albino phenotype, resulting from dysfunctional chloroplasts lacking thylakoid membranes. Conversely, YCO knock-down mutants produced a chlorophyll-deficient cotyledon and normal leaves when supplemented with sucrose. Transcription analysis also revealed that YCO deficiency could be partially compensated by sucrose supplementation, and that YCO played different roles in the cotyledons and the true leaves. In YCO knock-down mutants, the transcript levels of plastid-encoded RNA polymerase (PEP)-dependent genes and nuclear-encoded photosynthetic genes, as well as the accumulation of photosynthetic proteins, were significantly reduced in the cotyledons. Moreover, the chlorophyll-deficient phenotype in YCO knock-down line can be effectively suppressed by inhibition of PSI cyclic electron transport activity, implying an interaction between YCO and PSI cyclic electron transport. Taken together, our findings de underscore the vital role of YCO in early chloroplast development and photosynthesis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

The autoinhibited plasma membrane calcium ATPase ACA8 from A. thaliana has an N-terminal autoinhibitory domain. Binding of calcium-loaded calmodulin at two sites located at residues 42-62 and 74-96 relieves autoinhibition of ACA8 activity. Through activity studies and a yeast complementation assay we investigated wild-type (WT) and N-terminally truncated ACA8 constructs (Δ20, Δ30, Δ35, Δ37, Δ40, Δ74 and Δ100) to explore the role of conserved motifs in the N-terminal segment preceding the calmodulin binding sites. Furthermore, we purified WT, Δ20- and Δ100-ACA8, tested activity in vitro and performed structural studies of purified Δ20-ACA8 stabilized in a lipid nanodisc to explore the mechanism of autoinhibition. We show that an N-terminal segment between residues 20 and 35 including conserved Phe32, upstream of the calmodulin binding sites, is important for autoinhibition and the activation by calmodulin. Cryo-EM structure determination at 3.3 Å resolution of a beryllium fluoride inhibited E2 form, and at low resolution for an E1 state combined with AlphaFold prediction provide a model for autoinhibition, consistent with the mutational studies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

VIP1, an Arabidopsis thaliana basic leucine zipper transcription factor, and its close homologs are imported from the cytoplasm to the nucleus when cells are exposed to mechanical stress. They bind to AGCTG (G/T) and regulate mechanical stress responses in roots. However, their role in leaves is unclear. To clarify this, mutant lines (QM1 and QM2) that lack the functions of VIP1 and its close homologs (bZIP29, bZIP30 and PosF21) were generated. Brushing more severely damaged QM1 and QM2 leaves than wild-type leaves. Genes regulating stress responses and cell wall properties were downregulated in brushed QM2 leaves and upregulated in brushed VIP1-GFP-overexpressing (VIP1-GFPox) leaves compared to wild-type leaves in a transcriptome analysis. The VIP1-binding sequence AGCTG (G/T) was enriched in the promoters of genes downregulated in brushed QM2 leaves compared to wild-type leaves and in those upregulated in brushed VIP1-GFPox leaves. Calmodulin-binding transcription activators (CAMTAs) are known regulators of mechanical stress responses, and the CAMTA-binding sequence CGCGT was enriched in the promoters of genes upregulated in the brushed QM2 leaves and in those downregulated in the brushed VIP1-GFPox leaves. These findings suggest that VIP1 and its homologs upregulate genes via AGCTG (G/T) and influence CAMTA-dependent gene expression to enhance mechanical stress tolerance in leaves., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

The normal progression of mitotic cycles and synchronized development within female reproductive organs are pivotal for sexual reproduction in plants. Nevertheless, our understanding of the genetic regulation governing mitotic cycles during the haploid phase of higher plants remains limited. In this study, we characterized RNA HELICASE 32 (RH32), which plays an essential role in female gametogenesis in Arabidopsis. The rh32 heterozygous mutant was semi-sterile, whereas the homozygous mutant was nonviable. The rh32 mutant allele could be transmitted through the male gametophyte, but not the female gametophyte. Phenotypic analysis revealed impaired mitotic progression, synchronization, and cell specification in rh32 female gametophytes, causing the arrest of embryo sacs. In the delayed pollination test, none of the retarded embryo sacs developed into functional female gametophytes, and the vast majority of rh32 female gametophytes were defective in the formation of the large central vacuole. RH32 is strongly expressed in the embryo sac. Knock-down of RH32 resulted in the accumulation of unprocessed 18 S pre-rRNA, implying that RH32 is involved in ribosome synthesis. Based on these findings, we propose that RH32 plays a role in ribosome synthesis, which is critical for multiple processes in female gametophyte development., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

RNA silencing, a conserved gene regulatory mechanism, is critical for host resistance to viruses. Liquid-liquid phase separation (LLPS) is an important mechanism in regulating various biological processes. Emerging studies suggest RNA helicases play important roles in microRNA (miRNA) production through LLPS. In this study, we investigated the functional role of RNA helicase 20 (RH20), a DDX5 homolog in Arabidopsis thaliana, in RNA silencing and plant resistance to viruses. Our findings reveal that RH20 localizes in both the cytoplasm and nucleus, with puncta formation in the cytoplasm exhibiting liquid-liquid phase separation behavior. We demonstrate that RH20 plays positive roles in plant immunity against viruses. Further study showed that RH20 interacts with Argonaute 2 (AGO2), a key component of the RNA silencing pathway. Moreover, RH20 promotes the accumulation of both endogenous and exogenous small RNAs (sRNAs). Overall, our study identifies RH20 as a novel phase separation protein that interacting with AGO2, influencing sRNAs accumulation, and enhancing plant resistance to viruses., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The unfolded protein response (UPR) is a crucial cellular mechanism for maintaining protein folding homeostasis during endoplasmic reticulum (ER) stress. In this study, the role of IRE1, a key component of the UPR, was investigated in protein translation regulation under ER stress conditions in Arabidopsis. We discovered that the loss of IRE1A and IRE1B leads to diminished protein translation, indicating a significant role for IRE1 in this process. However, this regulation was not solely dependent on the interaction with bZIP60, a key transcription factor in the UPR. Interestingly, while chemical chaperones TUDCA and PBA effectively alleviated the translation inhibition observed in ire1a ire1b mutants, this effect was more pronounced than the mitigation observed from suppressing GCN2 expression or introducing a non-phosphorylatable eIF2α variant. Additionally, the kinase and ribonuclease activities of IRE1B were demonstrated to be crucial for plant adaptation and protein synthesis regulation under ER stress conditions. Overall, this study not only highlights the complex regulatory mechanisms of IRE1 in plant ER stress responses but also provides insights into its multifaceted roles in protein translation regulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

U6 snRNA is one of the uridine-rich non-coding RNAs, abundant and stable in various cells, function as core particles in the intron-lariat spliceosome (ILS) complex. The Increased Level of Polyploidy1-1D (ILP1) and NTC-related protein 1 (NTR1), two conserved disassembly factors of the ILS complex, facilitates the disintegration of the ILS complex after completing intron splicing. The functional impairment of ILP1 and NTR1 lead to increased U6 levels, while other snRNAs comprising the ILS complex remained unaffected. We revealed that ILP1 and NTR1 had no impact on the transcription, 3' end phosphate structure or oligo(U) tail of U6 snRNA. Moreover, we uncovered that the mutation of ILP1 and NTR1 resulted in the accumulation of ILS complexes, impeding the dissociation of U6 from splicing factors, leading to an extended half-life of U6 and ultimately causing an elevation in U6 snRNA levels. Our findings broaden the understanding of the functions of ILS disassembly factors ILP1 and NTR1, and providing insights into the dynamic disassembly between U6 and ILS., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Riboflavin (RF) serves as a precursor to flavin mononucleotide and flavin adenine dinucleotide, which are crucial cofactors in various metabolic processes. Strict regulation of cellular flavin homeostasis is imperative, yet information regarding the factors governing this regulation remains largely elusive. In this study, we first examined the impact of external flavin treatment on the Arabidopsis transcriptome to identify novel regulators of cellular flavin levels. Our analysis revealed alterations in the expression of 49 putative transcription factors. Subsequent reverse genetic screening highlighted a member of the dehydration-responsive element binding (DREB) family, AtDREB2G, as a potential regulator of cellular flavin levels. Knockout mutants of AtDREB2G (dreb2g) exhibited reduced flavin levels and decreased expression of RF biosynthetic genes compared to wild-type plants. Conversely, conditional overexpression of AtDREB2G led to an increase in the expression of RF biosynthetic genes and elevated flavin levels. In wild-type plants, exposure to low temperatures and abscisic acid treatment stimulated enhanced flavin levels and upregulated the expression of RF biosynthetic genes, concomitant with the induction of AtDREB2G. Notably, these responses were significantly attenuated in dreb2g mutants. Our findings establish AtDREB2G is involved in the positive regulation of flavin biosynthesis in Arabidopsis, particularly under conditions of low temperature and abscisic acid treatment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Industrial and agricultural production processes lead to the accumulation of cadmium (Cd) in soil, resulting in crops absorb Cd from contaminated soil and then transfer it to human body through the food chain, posing a serious threat to human health. Thus, it is necessary to explore novel genes and mechanisms involved in regulating Cd tolerance and detoxification in plants. Here, we found that CDR1, a DUF946 domain containing protein, localizes to the plasma membrane and positively regulates Cd stress tolerance. The cdr1 mutants exhibited Cd sensitivity, accumulated excessive Cd in the seeds and roots, but decreased in leaves. However, CDR1-OE transgenic plants not only showed Cd tolerance but also significantly reduced Cd in seeds and roots. Additionally, both in vitro and in vivo assays demonstrated an interaction between CDR1 and OPT3. Cell free protein degradation and OPT3 protein level determination assays indicated that CDR1 could maintain the stability of OPT3 protein. Moreover, genetic phenotype analysis and Cd content determination showed that CDR1 regulates Cd stress tolerance and affect the distribution of Cd in plants by maintaining the stability of OPT3 protein. Our discoveries provide a key candidate gene for directional breeding to reduce Cd accumulation in edible seeds of crops., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Methylisothiazolinone (MIT) is a widely used preservative and biocide to prevent product degradation, yet its potential impact on plant growth remains poorly understood. In this study, we investigated MIT's toxic effects on Arabidopsis thaliana root growth. Exposure to MIT significantly inhibited Arabidopsis root growth, associated with reduced root meristem size and root meristem cell numbers. We explored the polar auxin transport pathway and stem cell regulation as key factors in root meristem function. Our findings demonstrated that MIT suppressed the expression of the auxin efflux carrier PIN1 and major root stem cell regulators (PLT1, PLT2, SHR, and SCR). Additionally, MIT hindered root regeneration by downregulating the quiescent center (QC) marker WOX5. Transcriptome analysis revealed MIT-induced alterations in gene expression related to oxidative stress, with physiological experiments confirming elevated reactive oxygen species (ROS) levels and increased cell death in root tips at concentrations exceeding 50 μM. In summary, this study provides critical insights into MIT's toxicity on plant root development and regeneration, primarily linked to modifications in polar auxin transport and downregulation of genes associated with root stem cell regulation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Soil salinity pose a significant challenge to global agriculture, threatening crop yields and food security. Understanding the salt tolerance mechanisms of plants is crucial for improving their survival under salt stress. AFP2, a negative regulator of ABA signaling, has been shown to play a crucial role in salt stress tolerance during seed germination. Mutations in AFP2 gene lead to increased sensitivity to salt stress. However, the underline mechanisms by which AFP2 regulates seed germination under salt stress remain elusive. In this study, we identified a protein interaction between AFP2 and SOS2, a Ser/Thr protein kinase known to play a critical role in salt stress response. Using a combination of genetic, biochemical, and physiological approaches, we investigated the role of the SOS2-AFP2 module in regulating seed germination under salt stress. Our findings reveal that SOS2 physically interacts with AFP2 and stabilizes it, leading to the degradation of the ABI5 protein, a negative transcription factor in seed germination under salt stress. This study sheds light on previously unknown connections within salt stress and ABA signaling, paving the way for novel strategies to enhance plant resilience against environmental challenges., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The transcriptional regulation of aluminum (Al) tolerance in plants is largely unknown, although Al toxicity restricts agricultural yields in acidic soils. Here, we identified a NAM, ATAF1/2, and cup-shaped cotyledon 2 (NAC) transcription factor that participates in Al tolerance in Arabidopsis (Arabidopsis thaliana). Al substantially induced the transcript and protein levels of ANAC070, and loss-of-function mutants showed remarkably increased Al sensitivity, implying a beneficial role of ANAC070 in plant tolerance to Al toxicity. Further investigation revealed that more Al accumulated in the roots of anac070 mutants, especially in root cell walls, accompanied by a higher hemicellulose and xyloglucan level, implying a possible interaction between ANAC070 and genes that encode proteins responsible for the modification of xyloglucan, including xyloglucan endo-transglycosylase/hydrolase (XTH) or ANAC017. Yeast 1-hybrid analysis revealed a potential interaction between ANAC070 and ANAC017, but not for other XTHs. Furthermore, dual-luciferase reporter assay, RT-qPCR, and GUS analysis revealed that ANAC070 could directly repress the transcript levels of ANAC017, and knockout of ANAC017 in the anac070 mutant partially restored its Al sensitivity phenotype, indicating that ANAC070 contributes to Al tolerance mechanisms other than suppression of ANAC017 expression. Further analysis revealed that the core transcription factor SENSITIVE TO PROTON RHIZOTOXICITY 1 (STOP1) and its target genes, which control Al tolerance in Arabidopsis, may also be involved in ANAC070-regulated Al tolerance. In summary, we identified a transcription factor, ANAC070, that represses the ANAC017-XTH31 module to regulate Al tolerance in Arabidopsis., Competing Interests: Conflict of interest statement. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The VWA domain commonly functions as a crucial component of multiprotein complexes, facilitating protein-protein interactions. However, limited studies have focused on the systemic study of VWA proteins in plants. Here, we identified 28 VWA protein genes in Arabidopsis thaliana, categorized into three clades, with one tandem duplication event and four paralogous genes within collinearity blocks. Then, we determined their expression patterns under abiotic stresses by transcriptomic analysis. All five RGLG genes were found to be responsive to at least one kind of abiotic stress, and RGLG5 was identified as a multiple stress-responsive gene, coding an E3 ubiquitin ligase with a VWA domain and a C-terminal RING domain. Subsequently, we explored tolerant function of RGLG5 by determining the crystal structure of its VWA domain. The structural comparison revealed the allosteric regulation mechanism of RGLG5-VWA, wherein the deflection of α7 led to displacement of key residue binding metal ion within MIDAS motif. Our findings provide full-scale knowledge on VWA proteins, and insights into tolerant function of RGLG5-VWA in terms of crystal structure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Masson SAS.)

The interplay between nitrogen and sulfur assimilation synergistically supports and sustains plant growth and development, operating in tandem to ensure coordinated and optimal outcomes. Previously, we characterized Arabidopsis CHLOROPHYLL A/B-BINDING (CAB) overexpression 2 (COE2) mutant, which has a mutation in the NITRIC OXIDE-ASSOCIATED (NOA1) gene and exhibits deficiency in root growth under low nitrogen (LN) stress. This study found that the growth suppression in roots and shoots in coe2 correlates with decreased sensitivity to low sulfur stress treatment compared to the wild-type. Therefore, we examined the regulatory role of COE2 in nitrogen and sulfur interaction by assessing the expression of nitrogen metabolism-related genes in coe2 seedlings under low sulfur stress. Despite the notable upregulation of nitrate reductase genes (NIA1 and NIA2), there was a considerable reduction in nitrogen uptake and utilization, resulting in a substantial growth penalty. Moreover, the elevated expression of miR396 perhaps complemented growth stunting by selectively targeting and curtailing the expression levels of GROWTH REGULATING FACTOR 2 (GRF2), GRF4, and GRF9. This study underscores the vital role of COE2-mediated nitrogen signaling in facilitating seedling growth under sulfur deficiency stress., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Arabidopsis thaliana WRKY33 is currently one of the most studied members of the Group I WRKY transcription factor family. Research has confirmed that WRKY33 is involved in the regulation of various biological and abiotic stresses and occupies a central position in the regulatory network. The functional studies of orthologous genes of WRKY33 from other species are also receiving increasing attention. In this article, we summarized thirty-eight orthologous genes of AtWKRY33 from twenty-five different species. Their phylogenetic relationship and conserved WRKY domain were analyzed and compared. Similar to AtWKRY33, the well-studied orthologous gene members from rice and tomato also have multiple functions. In addition to playing important regulatory roles in responding to their specific pathogens, they are also involved in regulating various abiotic stresses and development. AtWKRY33 exerts its multiple functions through a complex regulatory network. Upstream transcription factors or other regulatory factors activate or inhibit the expression of AtWKRY33 at the chromatin and transcriptional levels. Interacting proteins affect the transcriptional activity of AtWKRY33 through phosphorylation, ubiquitination, SUMOylation, competition, or cooperation. The downstream genes are diverse and include three major categories: transcription factors, synthesis, metabolism, and signal transduction of various hormones, and disease resistance genes. In the regulatory network of AtWRKY33 orthologs, many conserved regulatory characteristics have been discovered, such as self-activation and phosphorylation by MAP kinases. This can provide a comparative reference for further studying the functions of other orthologous genes of AtWKRY33., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Epigenetic modifications, such as histone alterations, play crucial roles in regulating the flowering process in Arabidopsis, a typical long-day model plant. Histone modifications are notably involved in the intricate regulation of FLC, a key inhibitor of flowering. Although sirtuin-like protein and NAD + -dependent deacetylases play an important role in regulating energy metabolism, plant stress responses, and hormonal signal transduction, the mechanisms underlying their developmental transitions remain unclear. Thus, this study aimed to reveal how Arabidopsis NAD  +  -dependent deacetylase AtSRT1 affects flowering by regulating the expression of flowering integrators. Genetic and molecular evidence demonstrated that AtSRT1 mediates histone deacetylation by directly binding near the transcriptional start sites (TSS) of the flowering integrator genes FT and SOC1 and negatively regulating their expression by modulating the expression of the downstream gene LFY to inhibit flowering. Additionally, AtSRT1 directly down-regulates the expression of TOR, a glucose-driven central hub of energy signaling, which controls cell metabolism and growth in response to nutritional and environmental factors. This down-regulation occurs through binding near the TSS of TOR, facilitating the addition of H3K27me3 marks on FLC via the TOR-FIE-PRC2 pathway, further repressing flowering. These results uncover a multi-pathway regulatory network involving deacetylase AtSRT1 during the flowering process, highlighting its interaction with TOR as a hub for the coordinated regulation of energy metabolism and flowering initiation. These findings significantly enhance understanding of the complexity of histone modifications in the regulation of flowering., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Ubiquitination is a pivotal type of post-translational modification, which plays a far-reaching role in plant growth and development, as well as in the response of plants to stress. Just like the two sides of a coin, de-ubiquitination also plays an important role in plant life, which has been gradually discovered in recent years. Here, we demonstrate that the UBQUITIN SPECIFIC PROTEASE 15 (UBP15), which is a UBP-type de-ubiquitinase, interacts with the SCF E3 complex adaptor ARABIDOPSIS SKP1 HOMOLOGUE 1 (ASK1) and influences its protein stability to regulate plant fertility and petal size. The UBP15 is associated with the ASK1 physically, as verified by yeast-two-hybrid (Y2H) and protein pull-down in vitro assays. Disruption of ASK1 by a T-DNA insertion generates some abnormal phenotypes, such as low fertility and small petals. Genetic analysis shows that the UBP15 mutation enhances the low-fertility and small-petal phenotypes of ask1 mutant plants. By proteomic analysis, many types of proteins were identified as potential candidate downstream genes associated with the phenotypes of ubp15 ask1 double mutant plants. Taken together, these findings reveal a molecular relationship between ASK1 and UBP15 and their interaction in the regulation of petal size and fertility, which would benefit in-depth research about the ubiquitin-related pathway in plant physiological processes in the future., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Liang Du reports financial support was provided by The National Natural Science Foundation of China. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: 6 - 4 photoproducts are the second most common UV-induced DNA lesions after cyclobutane pyrimidine dimers. In plants, they are mainly repaired by photolyases in a process called photoreactivation. While pyrimidine dimers can be deleterious, leading to mutagenesis or even cell death, 6 - 4 photoproducts can activate specific signaling pathways. Therefore, their removal is particularly important, especially for plants exposed to high UV intensities due to their sessile nature. Although photoreactivation in nuclear DNA is well-known, its role in plant organelles remains unclear. In this paper we analyzed the activity and localization of GFP-tagged AtUVR3, the 6 - 4 photoproduct specific photolyase., Results: Using transgenic Arabidopsis with different expression levels of AtUVR3, we confirmed a positive trend between these levels and the rate of 6 - 4 photoproduct removal under blue light. Measurements of 6 - 4 photoproduct levels in chloroplast and nuclear DNA of wild type, photolyase mutants, and transgenic plants overexpressing AtUVR3 showed that the photoreactivation is the main repair pathway responsible for the removal of these lesions in both organelles. The GFP-tagged AtUVR3 was predominantly located in nuclei with a small fraction present in chloroplasts and mitochondria of transgenic Arabidopsis thaliana and Nicotiana tabacum lines. In chloroplasts, this photolyase co-localized with the nucleoid marked by plastid envelope DNA binding protein., Conclusions: Photolyases are mainly localized in plant nuclei, with only a small fraction present in chloroplasts and mitochondria. Despite this unbalanced distribution, photoreactivation is the primary mechanism responsible for the removal of 6 - 4 photoproducts from nuclear and chloroplast DNA in adult leaves. The amount of the AtUVR3 photolyase is the limiting factor influencing the photoreactivation rate of 6 - 4 photoproducts. The efficient photoreactivation of 6 - 4 photoproducts in 35S: AtUVR3-GFP Arabidopsis and Nicotiana tabacum is a promising starting point to evaluate whether transgenic crops overproducing this photolyase are more tolerant to high UV irradiation and how they respond to other abiotic and biotic stresses under field conditions., (© 2024. The Author(s).)

Protein S-nitrosylation, which is defined by the covalent attachment of nitric oxide (NO) to the thiol group of cysteine residues, is known to play critical roles in plant development and stress responses. NO promotes seedling photomorphogenesis and NO emission is enhanced by light. However, the function of protein S-nitrosylation in plant photomorphogenesis is largely unknown. E3 ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) and transcription factor ELONGATED HYPOCOTYL 5 (HY5) antagonistically regulate seedling photomorphogenesis. COP1 inhibits plant photomorphogenesis by targeting photomorphogenic promoters like HY5 for 26S proteasome degradation. Here, we report that COP1 is S-nitrosylated in vitro. Mass spectrometry analyses revealed that two evolutionarily well conserved residues, cysteine 425 and cysteine 607, in the WD40 domain of COP1 are S-nitrosylated. S-nitrosylated glutathione (GSNO) is an important physiological NO donor for protein S-nitrosylation. The Arabidopsis (Arabidopsis thaliana) gsnor1-3 mutant, which accumulates higher level of GSNO, accumulated higher HY5 levels than wildtype (WT), indicating that COP1 activity is inhibited. Protein S-nitrosylation can be reversed by Thioredoxin-h5 (TRXh5) in plants. Indeed, COP1 interacts directly with TRXh5 and its close homolog TRXh3. Moreover, catalase 3 (CAT3) acts as a transnitrosylase that transfers NO to its target proteins like GSNO reductase (GSNOR). We found that CAT3 interacts with COP1 in plants. Taken together, our data indicate that the activity of COP1 is likely inhibited by NO via S-nitrosylation to promote the accumulation of HY5 and photomorphogenesis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Exogenous abscisic acid (ABA) presents a novel approach to mitigate heavy metal (HM) accumulation in plants, yet its efficacy against multiple HMs and potential enhancement methods remain underexplored. In this study, we demonstrated that the exogenous ABA application simultaneously decreased Zn, Cd and Ni accumulation by 22-25 %, 27-39 % and 60-62 %, respectively, in wild-type (WT) Arabidopsis. Conversely, ABA reduced Pb in shoots but increased its root concentration. ABA application also modulated the expression of HM uptake genes, inhibiting IRT1, NRAMP1, NRAMP4, and HMA3, and increasing ZIP1 and ZIP4 expressions. Further analysis revealed that overexpressing the ABA-importing transporter (AIT1) in plants intensified the reduction of Cd, Zn, and Ni, compared to WT. However, the inhibitory effect of exogenous ABA on Pb accumulation was mitigated in shoots with higher AIT1 expression. Furthermore, HMs-induced growth inhibition and the damage to photosynthesis were also alleviated with ABA treatment. Conclusively, AIT1's synergistic effect with ABA effectively reduces Cd, Zn and Ni accumulation, offering a synergistic approach to mitigate HM stress in plants., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Acquired osmotolerance induced by initial exposure to mild salt stress is widespread across Arabidopsis thaliana ecotypes, but the mechanism underlying it remains poorly understood. To clarify it, we isolated acquired osmotolerance-deficient 1 (aod1), a mutant highly sensitive to osmotic stress, from ion-beam-irradiated seeds of Zu-0, an ecotype known for its remarkably high osmotolerance. Aod1 showed growth inhibition with spotted necrotic lesions on the rosette leaves under normal growth conditions on soil. However, its tolerance to salt and oxidative stresses was similar to that of the wild type (WT). Genetic and genome sequencing analyses suggested that the gene causing aod1 is identical to CONSTITUTIVELY ACTIVATED CELL DEATH 1 (CAD1). Complementation with the WT CAD1 gene restored the growth and osmotolerance of aod1, indicating that mutated CAD1 is responsible for the observed phenotypes in aod1. Although CAD1 is known to act as a negative regulator of immune response, transcript levels in the WT increased in response to osmotic stress. Aod1 displayed enhanced immune response and cell death under normal growth conditions, whereas the expression profiles of osmotic response genes were comparable to those of the WT. These findings suggest that autoimmunity in aod1 is detrimental to osmotolerance. Overall, our results suggest that CAD1 negatively regulates immune responses under osmotic stress, contributing to osmotolerance in Arabidopsis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Potassium (K + ) selectivity of high-affinity K + uptake systems is crucial for plant growth under low K + and in the presence of inhibitors of K + uptake that are toxic to plants such as Na + or Cs + . Here, we express a mutated version of the Arabidopsis AtHAK5 high-affinity K + transporter consisting on a change of phenylalanine 130 to serine (F130S) in athak5 akt1 double mutant plants. F130S-expressing plants show better growth, increased K + uptake from low external concentrations and higher K + contents when grown at low K + (10 μM) and when grown at low K + in the presence of Na + (15 mM) or Cs + (1 μM). In addition, these plants accumulate less Na + and Cs + , resulting in lower Na + /K + and Cs + /K + ratios, which are important determinants of plant tolerance to salt stress and to Cs + -polluted soils. Structure analysis of AtHAK5 suggest that the F130 residue approaches the intracellular gate of the K + tunnel of AtHAK5, affecting somehow its ionic selectivity. Modification of transport systems has a large potential to face challenges of future agriculture such as sustainable production under abiotic stress conditions imposed by climate change., Competing Interests: Declaration of competing interest The authors declare no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Over the last decade, the composition of the C-to-U RNA editing complex in embryophyte organelles has turned out to be much more complex than first expected. While PPR proteins were initially thought to act alone, significant evidences have clearly depicted a sophisticated mechanism with numerous protein-protein interaction involving PPR and non-PPR proteins. Moreover, the identification of specific functional partnership between PPRs also suggests that, in addition to the highly specific PPRs directly involved in the RNA target recognition, non-RNA-specific ones are required. Although some of them, such as DYW1 and DYW2, were shown to be the catalytic domains of the editing complex, the molecular function of others, such as NUWA, remains elusive. It was suggested that they might stabilize the complex by acting as a scaffold. We here performed functional complementation of the crr28-2 mutant with truncated CRR28 proteins mimicking PPR without the catalytic domain and show that they exhibit a specific dependency to one of the catalytic proteins DYW1 or DYW2. Moreover, we also characterized the role of the PPR NUWA in the editing reaction and show that it likely acts as a scaffolding factor. NUWA is no longer required for efficient editing of the CLB19 editing sites once this RNA specific PPR is fused to the DYW catalytic domain of its partner DYW2. Altogether, our results strongly support a flexible, evolutive and resilient editing complex in which RNA binding activity, editing activity and stabilization/scaffolding function can be provided by one or more PPRs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The circadian clock plays a critical role in regulating plant physiology and metabolism. However, the way in which the clock impacts the regulation of lipid biosynthesis in seeds is partially understood. In the present study, we characterized the seed fatty acid (FA) and glycerolipid (GL) compositions of pseudo-response regulator mutants. Among these mutants, toc1 (timing of cab expression 1) exhibited the most significant differences compared to control plants. These included an increase in total FA content, characterized by elevated levels of linolenic acid (18:3) along with a reduction in linoleic acid (18:2). Furthermore, our findings revealed that toc1 developing seeds showed increased expression of genes related to FA metabolism. Our results show a connection between TOC1 and lipid metabolism in Arabidopsis seeds., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The gene encoding EARLY FLOWERING3 (ELF3) is necessary for photoperiodic flowering and the normal regulation of circadian rhythms. It provides important information at the cellular level to uncover the biological mechanisms that improve plant growth and development. ELF3 interactions with transcription factors such as BROTHER OF LUX ARRHYTHMO (BOA), LIGHT-REGULATED WD1 (LWD1), PHYTOCHROME-INTERACTING FACTOR 4 (PIF4), PHYTOCHROME-INTERACTING FACTOR 7 (PIF7), and LUX ARRHYTHMO (LUX) suggest a role in evening complex (EC) independent pathways, demanding further investigation to elucidate the EC-dependent versus EC-independent mechanisms. The ELF3 regulation of flowering time about photoperiod and temperature variations can also optimize crop cultivation across diverse latitudes. In this review paper, we summarize how ELF3's role in the circadian clock and light-responsive flowering control in crops offers substantial potential for scientific advancement and practical applications in biotechnology and agriculture. Despite its essential role in crop adaptation, very little is known in many important crops. Consequently, comprehensive and targeted research is essential for extrapolating ELF3-related insights from Arabidopsis to other crops, utilizing both computational and experimental methodologies. This research should prioritize investigations into ELF3's protein-protein interactions, post-translational modifications, and genomic targets to elucidate its contribution to accurate circadian clock regulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

The toxic heavy metal cadmium (Cd) restricts plant growth. However, how plants fine-tune their growth to modulate Cd resistance has not been determined. Ethylene response factors (ERFs) are key regulators of Cd stress, and Arabidopsis thaliana ERF13 and ERF6 (AtERF13 and AtERF6) negatively regulate growth. We previously demonstrated that AtERF13 is a transcriptional activator that binds a Cd-responsive element. Herein, we report that Arabidopsis plants improve Cd tolerance by repressing AtERF13 and AtERF6. We found that AtERF13 and AtERF6 were strongly downregulated by Cd stress and that AtERF6 weakly bound Cd-responsive elements. Moreover, AtERF13 physically interacted with AtERF6. Importantly, AtERF13 and AtERF6 double knockout mutants, but not single mutants or overexpression lines, grew better, tolerated more Cd and had higher Cd contents than did the wild type. Comparative transcriptome analysis revealed that the double mutants regulate the defense response to cope with Cd toxicity. Accordingly, we propose that, upon Cd stress, Arabidopsis plants repress AtERF13 and AtERF6 to relieve their growth inhibition effects and adjust the transcriptome to adapt to Cd stress, leading to increased Cd tolerance. Our findings thereby provide deep mechanical insights into how dual-function transcription factors fine-tune growth and the transcriptome to promote Cd tolerance in plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Oxidative stress represents a critical facet of the array of abiotic stresses affecting crop growth and yield. In this paper, we investigated the potential differences in the functions of two highly homologous Arabidopsis DSS1 proteins in terms of maintaining genome integrity and response to oxidative stress. In the context of homologous recombination (HR), it was shown that overexpressing AtDSS1(I) using a functional complementation test increases the resistance of the Δ dss1 mutant of Ustilago maydis to genotoxic agents. This indicates its conserved role in DNA repair via HR. To investigate the global transcriptome changes occurring in dss1 plant mutant lines, gene expression analysis was conducted using Illumina RNA sequencing technology. Individual RNA libraries were constructed from three total RNA samples isolated from dss1(I) , dss1(V) , and wild-type (WT) plants under hydrogen peroxide-induced stress. RNA-Seq data analysis and real-time PCR identification revealed major changes in gene expression between mutant lines and WT, while the dss1(I) and dss1(V) mutant lines exhibited analogous transcription profiles. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed significantly enriched metabolic pathways. Notably, genes associated with HR were upregulated in dss1 mutants compared to the WT. Otherwise, genes of the metabolic pathway responsible for the synthesis of secondary metabolites were downregulated in both dss1 mutant lines. These findings highlight the importance of understanding the molecular mechanisms of plant responses to oxidative stress.