Plant Cell Reports最新文献

Key message: BrSWEET11 accelerated Arabidopsis thaliana flowering, while silencing Brsweet11 in Brassica rapa delayed flowering relative to controls. BrSWEET11 is involved in sucrose transport after being induced by long-day conditions. SWEETs (Sugars Will Eventually Be Exported Transporters) are sugar outflow transporters that may participate in the regulation of plant flowering. In this study, the open reading frame of Brassica rapa ssp. pekinensis SWEET11 (BrSWEET11) was cloned and found to be 858 bp in length and encode 285 amino acids, which is typical of SWEET family proteins. The BrSWEET11 gene was strongly expressed in reproductive growth organs, particularly flowers, according to tissue expression analyses and GUS histochemical staining. BrSWEET11 promotes early flowering in Arabidopsis thaliana by 3-4 days, whereas Brsweet11 silencing in Brassica rapa delays flowering by 8-12 days relative to controls. BrSWEET11 promoted early flowering in A. thaliana, and compared with that in control plants, flowering was delayed in Brsweet11-silenced Brassica rapa. Transcriptome analysis of BrSWEET11-overexpressing A. thaliana and wild-type (WT) plants was performed and the results showed that eight key flowering genes jointly regulated flowering time, which was also validated in the Brsweet11-silenced plants. In addition, through photoperiod treatments and sugar content measurements, it was found that the expression of BrSWEET11 is induced by long-day conditions and is involved in sucrose transport. Further investigation using yeast library screening, yeast two-hybrid, and bimolecular fluorescence complementation assay techniques revealed that the BrSWEET11 protein interacts with the sugar transporter 4a (BrSUT4a) protein. Therefore, BrSWEET11 was induced by long-day conditions, and may promote early flowering in Brassica rapa through sucrose transport. This study provides a theoretical basis for elucidating the molecular mechanism through which SWEET genes are involved in flowering time regulation in Brassica rapa.

Key message: A total of 24 genes of vacuolar H⁺-translocating pyrophosphatases H⁺-PPases (VPP) genes were identified in Saccharum spontaneum AP85-441 and the ScVPP1-overexpressed Arabidopsis plants conferred salt tolerance. The vital role of vacuolar H⁺-translocating pyrophosphatases H⁺-PPases (VPP) genes involved in plants in response to abiotic stresses. However, the understanding of VPP functions in sugarcane remained unclear. In this study, a total of 24 VPP genes (SsaVPP1-SsaVPP24) were identified in the Saccharum spontaneum genome of haploid clone AP85-441. These genes were distributed in two phylogenetic groups. The SsaVPPs displayed diverse physio-chemical and gene structure attributes. The SsaVPP family genes have expanded through segmental duplication (20 gene pairs) rather than tandem duplication. A full-length cDNA of ScVPP1 was cloned from the sugarcane cultivar ROC22 and shared 99.48% sequence identity (amino acid) with homologous gene SsaVPP21 from AP85-441. In ROC22, the ScVPP1 gene was considerably upregulated by NaCl and ABA treatments among leaf, root, and stem tissues, while this gene was exclusively upregulated in the root with PEG treatment. Under NaCl and ABA stresses, yeast cells transfected by the ScVPP1 plasmid showed distinct growth rates compared to control yeast cells transfected by the empty vector. In transgenic Arabidopsis lines overexpressing ScVPP1, the seed gemination and survival rate were enhanced under NaCl treatment but not under ABA stress as compared to wild-type plants. These results suggested that the ScVPP1 gene conferred tolerance to slat and may be used as a salt resistance gene source for sugarcane breeding.

Key message: MiPEPs regulate growth, development and stress response. Identification of rice miPEPs plays a crucial role in elucidation of molecular functions of rice miPEPs and rice genetic improvement. MicroRNAs (miRNAs) are derivatives of primary miRNAs (pri-miRNAs) and govern the expression of target genes. Plant pri-miRNAs encode regulatory peptides known as miPEPs, which specifically boost the transcription of their originating pri-miRNA. Although there are hundreds of pri-miRNAs in rice, research on whether they encode functional peptides is limited. In this study, we identified 10 miPEPs using a transient protoplast expression system. Among these, we focused our attention on OsmiPEP162a, which influences growth. OsmiPEP162a-edited plants exhibited reduced plant height, similar to mature OsmiR162-edited plants. Transcriptome-focused molecular analysis unveiled significant alterations in transcription profiles following the depletion of OsmiPEP162a. In addition, knocking out OsmiPEP162a led to decreased expression levels of mature OsMIR162a and OsMIR162b. This study suggests that OsmiPEP162a potentially plays a crucial role in stabilizing mature OsMIR162.

Key message: N-Sulfonated IAA was discovered as a novel auxin metabolite in Urtica where it is biosynthesized de novo utilizing inorganic sulfate. It showed no auxin activity in DR5::GUS assay, implying possible inactivation/storage mechanism. A novel auxin derivative, N-sulfoindole-3-acetic acid (IAA-N-SO₃H, SIAA), was discovered in stinging nettle (Urtica dioica) among 116 sulfonated metabolites putatively identified by a semi-targeted UHPLC-QqTOF-MS analysis of 23 plant/algae/fungi species. These sulfometabolites were detected based on the presence of a neutral loss of sulfur trioxide, as indicated by the m/z difference of 79.9568 Da in the MS² spectra. The structure of newly discovered SIAA was confirmed by synthesizing its standard and comparing retention time, m/z and MS² spectrum with those of SIAA found in Urtica. To study its natural occurrence, 73 species in total were further analyzed by UHPLC-QqTOF-MS or targeted UHPLC-MS/MS method with a limit of detection of 244 fmol/g dry weight. However, SIAA was only detected in Urtica at a concentration of 13.906 ± 9.603 nmol/g dry weight. Its concentration was > 30 times higher than that of indole-3-acetic acid (IAA), and the SIAA/IAA ratio was further increased under different light conditions, especially in continuous blue light. In addition to SIAA, structurally similar metabolites, N-sulfoindole-3-lactic acid, 4-(sulfooxy)phenyllactic acid and 4-(sulfooxy)phenylacetic acid, were detected in Urtica for the first time. SIAA was biosynthesized from inorganic sulfate in seedlings, as confirmed by the incorporation of exogenous ³⁴S-ammonium sulfate (1 mM and 10 mM). SIAA exhibited no auxin activity, as demonstrated by both the Arabidopsis DR5::GUS assay and the Arabidopsis phenotype analysis. Sulfonation of IAA may therefore be a mechanism for IAA deactivation and/or storage in Urtica, similar to sulfonation of the jasmonates in Arabidopsis.

Key message: The Arabidopsis transcription factor ATAF1 negatively regulates thermomorphogenesis by inhibiting the expression of key genes involved in thermoresponsive elongation. DET1-mediated ubiquitination promotes ATAF1 degradation. In response to warmer, non-stressful average temperatures, plants have evolved an adaptive morphologic response called thermomorphogenesis to increase their fitness. This adaptive morphologic development is regulated by transcription factors (TFs) that control the expression of heat-induced genes that gate thermoresponsive growth. No apical meristem (NAM), Arabidopsis thaliana-activating factor 1/2 (ATAF1/2), and cup-shaped cotyledon 2 (CUC2) (collectively known as NAC) TFs regulate morphogenesis and respond to temperature stress, but whether they regulate thermomorphogenesis remains largely unknown. Here, we identified ATAF1 as a negative regulator of thermomorphogenesis and revealed that the E3-ligase component de-etiolated 1 (DET1) mediated ATAF1 ubiquitination and degradation. Our results revealed that ATAF1 negatively regulates warm temperature-induced hypocotyl elongation and inhibits the expression of thermoresponsive genes. Moreover, ATAF1 directly targeted and repressed the expression of YUCCA 8 (YUC8) and phytochrome interacting factor 4 (PIF4), two key regulators involved in elongation. At the post-translational level, elevated ambient temperatures negatively modulated the stability of ATAF1 by inducing the DET1-mediated ubiquitination pathway. Our results demonstrated the presence of a DET1-ATAF1-PIF4/YUC8 control module for thermomorphogenesis in plants, which may increase fitness by fine-tuning thermoresponsive gene expression under warm temperatures.

Key message: A novel fluorescent i-motif DNA silver nanoclusters system has been developed for visualization of reactive oxygen species in plants, enabling the detection of intracellular signaling in plant cells. Reactive oxygen species (ROS) are crucial in plant growth, defense, and stress responses, making them vital for improving crop resilience. Various ROS sensing methods for plants have been developed to detect ROS in vitro and in vivo. However, each method comes its own advantages and disadvantages, leading to an increasing demand for a simple and effective sensory system for ROS detection in plants. Here, we introduce novel DNA silver nanoclusters (DNA/AgNCs) sensors for visualizing ROS in plants. Two sensors, C₂₀/AgNCs and FAM-C₂₀/AgNCs-Cy5, detect intracellular ROS signaling in response to stimuli, such as abscisic acid, salicylic acid, ethylene, and bacterial peptide elicitor flg22. Notably, FAM-C₂₀/AgNCs-Cy5 exceeds the sensing capabilities of HyPer7, a widely recognized ROS sensor. Taken together, we suggest that fluorescent i-motif DNA/AgNCs system is an effective tool for visualizing ROS signals in plant cells. This advancement is important to advancing our understanding of ROS-mediated processes in plant biology.

Key message: SlNAC12 enhances salt stress tolerance of transgenic tomato by regulating ion homeostasis, antioxidant activity and flavonoids biosynthesis Soil salinization is a major environmental factor that adversely affects plant growth and development. NAC (NAM, ATAF1/2, and CUC2) is a large family of plant-specific transcription factors that play crucial roles in stress response. Here, we investigated the role of a novel NAC transcription factor, SlNAC12, in conferring salt stress tolerance in tomato (Solanum lycopersicum). Subcellular localization and yeast assays studies revealed that SlNAC12 is localized in the nucleus with weak transcriptional activity. SlNAC12 transcript was induced by salt stress in the leaves and roots of tomato seedlings. Overexpression of SlNAC12 in tomato led to significantly reduced plant height and root length. Transgenic tomato lines overexpressing of SlNAC12 (OE#1 and OE#3) exhibited enhanced tolerance to salinity, as evidenced by reduced the inhibitory effect of growth parameters under salt stress compared to wild type (WT). Overexpression of SlNAC12 in tomato affected Na⁺ and K⁺ homeostasis, leading to reduced Na⁺/K⁺ ratio, enhanced activity of antioxidant enzymes and decreased reactive oxygen species (ROS) accumulation under salt stress. Furthermore, the transcript levels of several genes involved in flavonoids metabolism and the levels of flavonoids accumulation were increased in SlNAC12-overexpressing tomato lines. Collectively, this study suggests that SlNAC12 transcription factor enhances salt stress tolerance in tomato is correlated with ion homeostasis, antioxidant enzyme systems, and flavonoids accumulation.

Key message: All ten dehydrin genes from three Medicago species are responsive to different kinds of abiotic stress, and CAS31 confers transgenic plants salt tolerance by down-regulating HKT1 expression. Dehydrins are protective proteins playing crucial roles in the tolerance of plants to abiotic stresses. However, a full-scale and systemic analysis of total dehydrin genes in Medicago at the genome level is still lacking. In this study, we identified ten dehydrin genes from three Medicago species (M. truncatula, M. ruthenica, and M. sativa), categorizing the coding proteins into four types. Genome collinearity analysis among the three Medicago species revealed six orthologous gene pairs. Promoter regions of dehydrin genes contained various phytohormone- and stress-related cis-elements, and transcriptome analysis showed up-regulation of all ten dehydrin genes under different stress conditions. Transformation of dehydrin gene CAS31 increased the tolerance of transgenic seedlings compared with wild-type seedlings under salt stress. Our study demonstrated that transgenic seedlings maintained the more chlorophyll, accumulated more proline and less hydrogen peroxide and malondialdehyde than wild-type seedlings under salt stress. Further study revealed that CAS31 reduced Na⁺ accumulation by down-regulating HKT1 expression under salt stress. These findings enhance our understanding of the dehydrin gene family in three Medicago species and provide insights into their mechanisms of tolerance.

Key message: Identification of salt-responsive calcineurin B-like protein-interacting protein kinases (CIPKs) in Populus. Calcineurin B-like protein-interacting protein kinases (CIPKs) play vital roles in plant growth and abiotic stress responses. Currently, the regulatory mechanisms underlying these processes mediated by CIPK proteins are not completely understood in woody species. This study provided the first systematic analysis of 31 Populus CIPK genes and investigated their evolutionary relationships, gene structures, motif compositions, and salt stress responses. A total of 11 pairs of paralogous PtCIPK genes were identified, of which three pairs may be resulted from whole genome duplication, and two pairs that may be created by tandem duplications. RT-qPCR analysis revealed that 93.5% (29/31) genes showed altered expression levels in roots after salt treatment. Ectopic expression of PdCIPK21 or PdCIPK31 in Arabidopsis resulted in significant increases of seed germination, root elongation and fresh weight under salt stress conditions. Cytological observation revealed that PdCIPK21/31 overexpression lines showed increased number, lumen area and cell wall thickness of xylem vessels, and higher lignin content in stems compared with the wild type, with decreased sensitivity to long-term salt stress treatment. Our results suggest that PdCIPK21/31 serve as candidate genes for improving wood production and enhancing salt tolerance of tree species.

Key message: Fusarium oxysporum disrupts redox homeostasis in Vigna mungo, likely by interfering with salicylic acid signaling, which can be ameliorated by boosting PAL and its related pathways via salicylic acid pretreatment. Fusarium oxysporum, a widespread soil-borne fungus, significantly threatens global crops. This study centers on elucidating the infection strategies employed by F. oxysporum against a new and underexplored host Vigna mungo, a leguminous crop of high agronomic value, and the defense mechanisms that can be activated against the infection, aiming to uncover how these responses can be leveraged to develop potential countermeasures. Building on prior work demonstrating the in vitro antifungal efficacy of phytohormones, including salicylic acid (SA), this study further investigates SA pretreatment at 100 µM, which previously reduced reactive oxygen species (ROS) and improved germination under Fusarium stress. Through a comprehensive analysis of V. mungo plants pretreated with SA and subjected to F. oxysporum infection, we observed that fungal exposure reduced growth, chlorophyll content, and levels of proteins, phenolics and flavonoids, while increasing stress markers and antioxidant activity. SA pretreatment mitigated these effects by boosting antioxidant molecules and activating the phenylalanine ammonia-lyase (PAL) pathway, thereby enhancing endogenous SA and ROS scavenging. Furthermore, qRT-PCR analysis confirmed SA-mediated upregulation of antioxidant (catalase and peroxidase), fungal stress response genes ((pathogenesis-related gene 4 (PR4) and defensin (DEF)) and SA synthesis and regulator genes (PAL and WRKY70) involved in plant systemic resistance, while LC-MS data revealed an altered metabolic profile with increased phytoalexins and antioxidants synthesis. Overall, SA pretreatment confers resistance against F. oxysporum in V. mungo by modulating endogenous SA and metabolic profile to activate key defense pathways and redox homeostasis, highlighting its potential in plant defense strategies and reinforcing our proposed model of SA action.