The Plant Journal最新文献

Receptor-like proteins (RLPs) are key components in the plant immune system. Loss of the RLP SUPPRESSOR OF NPR1-1, CONSTITUTIVE 2 (SNC2) in Arabidopsis results in enhanced disease susceptibility, whereas the gain-of-function mutant snc2-1D exhibits autoimmunity including a dwarfed morphology and constitutively activated defense responses. SNC2 function is fully dependent on the transmembrane protein BIAN DA 1 (BDA1). SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1) and CALMODULIN-BINDING PROTEIN 60 g (CBP60g) are two transcription factors required for the autoimmunity of snc2-1D. Constitutive defense responses in snc2-1D are attenuated by the cbp60g single mutant, but fully abolished by the sard1 cbp60g double mutant. In this study, we identified and characterized the ADAPTOR PROTEIN 4 (AP4) complex in SNC2-mediated plant immunity. By performing a suppressor screen in the cbp60g-1 snc2-1D background, mutations in AP4μ, a subunit of the AP4 complex, were identified. Interestingly, AP4μ associates with BDA1, and Y18 and Y257 of BDA1 seem to play important roles in such interaction. Knocking out genes of other subunits in the AP4 complex consistently suppressed cbp60g-1 snc2-1D autoimmunity, suggesting that the AP4 complex is required for SNC2 signaling. Furthermore, mutating AP4μ in wild-type plants compromises basal defense and pattern- and effector-triggered immunity, indicating a broader role of the AP4 complex in plant immunity.

Brassica napus is one of the most important oilseed crops worldwide and improving its oil content is a key research focus. The transcription factor (TF) BnMYB96 was found to be upregulated during oil accumulation under drought conditions, but the molecular regulation pathway remains unclear. Here, a cDNA library was constructed in a B. napus line with high oil content. BnLEA4 was first screened using BnMYB96 as bait, which was confirmed by yeast two-hybrid (Y2H), co-immunoprecipitation (Co-IP), bimolecular fluorescence complementation (BiFC), and pull-down assays. BnMYB96 can interact with BnLEA4 and regulate downstream BnLTP2, as confirmed by yeast one-hybrid (Y1H), dual-luciferase reporter (LUC) assay, electrophoretic mobility shift assay (EMSA), and β-glucuronidase (GUS) assay. Overexpression of BnMYB96 and BnLTP2 increased oil content and drought resistance through photosynthetic physiological processes and reactive oxygen species (ROS) metabolism. In contrast, opposite trends were observed in the CRISPR/Cas9 knockout lines. Hybrids (six-line crosses) between the two genes (BnMYB96 and BnLTP2) with increased or reduced expression showed stronger trends in drought tolerance and lipid accumulation. Single-cell and bulk transcriptome sequencing analyses showed that genes involved in carbon fixation and fatty acid (FA) synthesis in photosynthetic organisms were upregulated by BnMYB96 and BnLTP2, enhancing photosynthesis and FA synthesis. This study elucidates the BnLEA4-BnMYB96-BnLTP2 regulatory pathway that coordinates oil accumulation and drought resistance in B. napus. These findings provide a theoretical basis for improving the drought resistance and oil content of plants.

Ethylene is a key plant hormone regulating growth, development, and stress responses, yet the structural basis of its perception and signaling remains only partially understood. Ethylene receptors, which reside in the endomembrane network, act as dynamic signaling hubs that integrate hormone binding, copper (Cu⁺) cofactor coordination, and protein-protein interactions to control downstream pathways. Despite progress in characterizing individual domains, the full-length structural organization of receptors and the mechanisms linking copper (Cu⁺) coordination to conformational signaling remain unclear. Equally, the functional significance of receptor multimerization and higher order clustering in shaping signaling robustness and cross-talk is only beginning to emerge. To address these gaps, integrative approaches that combine structural biology, advanced spectroscopic techniques, targeted mutagenesis, molecular dynamics simulations, and molecular bioinformatics are employed. Recent advances in cryo-electron microscopy (cryo-EM), cross-linking mass spectrometry, and super-resolution imaging offer unprecedented opportunities to capture conformational states, map transient receptor interfaces, and visualize clustering dynamics in living cells. Complementary structure prediction tools together with hybrid quantum/classical simulations and perturbation analyses further connect local binding events to long-range allosteric communication. This review focuses on these multidisciplinary strategies that pave the way toward a unified mechanistic framework of ethylene signaling.

Plants delay flowering in response to low ambient temperatures. The WD40 domain-containing protein FVE regulates histone acetylation and flowering time, but how it responds to low ambient temperatures to modulate flowering time is largely unknown. Here, we report that FVE regulates flowering time in Arabidopsis (Arabidopsis thaliana) at low ambient temperature through SHORT VEGETATIVE PHASE (SVP). Loss of FVE function resulted in late flowering at both 16 and 22°C. The flowering time of fve plants at 16°C was similar to that at 22°C. We demonstrated that FVE and SVP form a protein complex by interacting with the β isoform of FLOWERING LOCUS M (FLM-β). FVE removes histone H3 lysine 9 acetylation (H3K9ac) marks at the FLOWERING LOCUS T (FT) locus. FVE occupancy at FT requires SVP. The svp-32 fve-21 double mutant flowered at the same time as the svp-32 single mutant and at similar times at 16 and 22°C. FVE also interacted with CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) in vitro and in vivo. We determined that COP1 promotes the ubiquitination and degradation of FVE. Loss of COP1 function resulted in increased FVE occupancy and decreased H3K9ac levels at FT. These findings reveal that FVE is regulated by COP1 and forms a protein complex with SVP and FLM-β to modulate flowering time at low ambient temperatures.

The epidermis plays essential physiological roles in plants, yet its underlying gene regulatory programs remain poorly defined. To address this gap, we integrated 11 public single-cell RNA-seq datasets of Arabidopsis shoots and leaves, extracted 30 247 epidermal cells, and constructed a single-cell gene co-expression network, AtEpidermisGGM, using the SingleCellGGM algorithm. From this network, we identified 120 co-expression modules, termed gene expression programs (GEPs), that delineate key developmental and metabolism processes of epidermal lineages. Spatial-temporal analysis revealed GEPs associated with L1-layer epidermis in the shoot apical meristem, asymmetric and symmetric cell divisions during early stomatal development, and subsequent guard cell initiation, maturation, and functioning. Leveraging these GEPs, we discovered and validated the roles of DMS1/2-expressed during the symmetric cell division stage of stomatal development-in regulating stomatal density, and of DGC1/2/3-specifically expressed in mature stomata-in controlling stomatal movement. Overall, AtEpidermisGGM provides a comprehensive map of epidermal gene programs, uncovering molecular modules that coordinate epidermal development and metabolism, and offering a valuable resource for advancing plant epidermal biology.

Long-term domestication and cultivation have led to the differentiation of Salvia miltiorrhiza genetic resources in different regions of China, accompanied by differences in the accumulation of pharmacological components represented by tanshinones in the roots. Tanshinone, as a key biomarker with significant therapeutic effects on cardiovascular and cerebrovascular diseases, has become the primary target for improvement in S. miltiorrhiza breeding. It is particularly important to deeply analyze the differentiation of tanshinones biosynthetic pathways in S. miltiorrhiza of different ecotypes, systematically revealing the evolution mechanism of geoherbs driven by metabolic networks. Based on integrated omics strategies, the metabolic regulatory network of tanshinones was constructed in different ecotypes, and WRKY70 was identified as a core transcription factor in the regulatory network of tanshinones metabolism. Transgene, Yeast-one-hybrid, EMSA, and Dual-LUC demonstrated that WRKY70 positively regulates tanshinones biosynthesis by targeting the promoter of CYP76AK1 and ABCG1. Yeast-two-hybrid, BiFC, Luciferase complementation, and Co-IP confirmed that WRKY70 formed a stable protein complex with SnRK2.6, which in turn mediated the ABA signaling pathway dependent tanshinones metabolic regulation and drought stress adaptation. Overall, we report that a bifunctional transcription factor, WRKY70, promotes tanshinones synthesis while enhancing plant adaptation to drought, which is expected to be used as a breeding target to save the deficiency of tanshinones and enhance stress resistance in specific ecotype S. miltiorrhiza.

The use of wild relatives to introduce original diversity in the genome of bread wheat (Triticum aestivum L.) is an interesting approach to face the challenges of sustainable agriculture and the impact of climate change on wheat production. However, the influence of these wild-species introgressions on meiosis in inter-varietal wheat hybrids remains poorly understood. We analyzed the French wheat variety Renan (Re) carrying Aegilops ventricosa (Aev)-derived 2AS/2NS and 7DL/7DvL introgressions, the reference cultivar Chinese Spring (CS), which lacks these introgressions, and their inter-varietal hybrid Chinese Spring × Renan (CSRe). This analysis combined cytogenetic approaches with the assessment of reproductive performance. Furthermore, we generated a cytological atlas of meiosis in wild tetraploid Aev, quantifying bivalent configurations and chiasma frequency. We observed a reduced pollen viability and a slight decrease in floret fertility in the hybrid CSRe. Exploration of the meiotic behavior showed that CSRe exhibited increased numbers of rod bivalents and univalents, leading to a reduced average chiasma number and frequent chromosome bridges and fragmentations, whereas the parental lines maintained stable chromosome pairing. These rearrangements indicate that homologous chromosome pairing and recombination are affected in CSRe. We applied introgression-specific oligo-Fluorescent In Situ Hybridization to localize alien segments in CSRe, providing a novel strategy to investigate the meiotic behavior of introgressed regions. The 2AS/2NS introgressed segments in CSRe were frequently located on rod bivalents or univalents, while 7DL/7DvL segments consistently formed ring bivalents. Our results provide a foundation for guiding alien gene introgression and for understanding the behavior of chromosomes with introgressions in the wheat genome.

MicroRNAs (miRNAs) are key regulators of plant growth, development, and immunity. However, their role in kiwifruit and other perennial fruit trees remains poorly characterized. Here, we demonstrate that Ac-miR156a functions as a negative regulator of kiwifruit resistance to Pseudomonas syringae pv. actinidiae (Psa). In the resistant cultivar "Jinkui," Ac-miR156a expression was significantly suppressed upon Psa infection, whereas it was markedly induced in the susceptible cultivar "Hongyang." Overexpression of miR156a increased kiwifruit susceptibility to Psa, while silencing miR156a via short-tandem target mimic (STTM) constructs enhanced resistance. We identified 14 SQUAMOSA-PROMOTER-BINDING PROTEIN-LIKE (SPL) transcription factors as direct targets of Ac-miR156a, among which AcSPL6c and AcSPL14c were rapidly upregulated in the resistant cultivar and shown to positively regulate immunity against Psa. Furthermore, we revealed that the Ac-miR156a-SPL module regulates kiwifruit immunity by reprogramming the hormonal levels between salicylic acid (SA) and jasmonic acid (JA) signaling pathways, favoring SA-dominated defense against the biotrophic pathogen Psa. Collectively, our study elucidates a complete Ac-miR156a-AcSPL6c/14c regulatory pathway that fine-tunes kiwifruit immune outcomes through hormonal redistribution, providing both mechanistic insights and potential genetic targets for improving disease resistance in kiwifruit breeding programs.

Both abscisic acid (ABA) and brassinosteroids (BRs) antagonistically regulate growth and abiotic stress responses; however, the mechanisms by which these phytohormones synergistically influence growth and salt tolerance in halophytes have not yet been fully elucidated. In this study, an NAC gene from Reaumuria trigyna, RtNAC081, was found to enhance growth and salt tolerance in transgenic poplar via the ABA and BR pathways, and its suppression led to decreased callus growth and greater sensitivity to salt stress. Under normal conditions, RtNAC081 increased wood formation and shoot growth, whereas saline conditions induced RtNAC081 transcription. RtNAC081 activated RtNCED1.1 expression and promoted BR synthesis through the RtNAC081-RtBZR1 axis, and also activated BR signaling. Synergistic interactions between ABA and BR were rapidly disrupted under extreme stress. Higher ABA levels inhibited RtBZR1 expression, causing growth retardation that improved salt tolerance through physical interaction with RtNAC081. RtNAC081 activated RtAPX5 to modulate reactive oxygen species balance and photosynthetic efficiency, which ultimately improved salt tolerance. Together, our results demonstrate the intricate interplay between the BR and ABA signaling pathways in modulating the balance between plant growth and salt stress adaptation, highlighting the pivotal role of RtNAC081 in this regulatory network.

SMAX1-LIKE (SMXL) proteins, previously linked to strigolactone and karrikin signalling, play diverse and partially redundant roles in plant development. The divergent SMXL4 superclade-comprising SMXL3, SMXL4 and SMXL5-is not subject to strigolactone- or karrikin-dependent proteolysis. Although these proteins have been associated with phloem differentiation and primary root growth in Arabidopsis thaliana, their broader functions remain underexplored. In this present work, we used double mutants and a series of complementing lines to investigate the in vivo functions of SMXL3 and its prominent motifs. Loss of both SMXL3 and SMXL5 resulted in spontaneous adventitious root formation on the hypocotyl, a phenotype suppressed in etiolated seedlings and modulated by carotenoid-derived signals. In contrast, anchor root formation, maintenance of primary root tip dominance and vertical root growth orientation were redundantly controlled by all SMXL4 superclade members and required an intact EAR repression motif in SMXL3. Beyond the root system, SMXL3, SMXL4 and SMXL5 collectively influenced vegetative growth, while the combined activity of SMXL3 and SMXL4 limited higher-order inflorescence branching and promoted embryo development. Together, our findings reveal that SMXL4 superclade proteins act in a combinatorial manner to control developmental timing and root architecture through both EAR motif-dependent and -independent mechanisms, with root-associated phenotypes likely reflecting altered auxin redistribution or local auxin accumulation. Overall, SMXL proteins emerge as key components controlling plant development in a context-dependent manner.