Journal of Experimental Botany最新文献

Endoplasmic reticulum-plasma membrane contact sites (ER-PM CS) are central hubs that coordinate lipid metabolism, membrane remodelling, calcium signalling and stress responses in plant cells. This review summarizes current knowledge on the molecular architecture and functions of ER-PM CS, with emphasis on the three tether families (synaptotagmins/SYTs, multiple-C2-domain and transmembrane region proteins/MCTPs, and VAMP-associated protein 27/VAP27 proteins) and the lipid-transfer proteins (SMP-domain proteins and oxysterol-binding protein-related/ORPs) described to date. SYTs and MCTPs use C2 domains to read PM phosphoinositides and Ca2+ signals to dynamically modulate tethering, while VAP27s scaffold multimeric complexes via MSP-FFAT interactions and link the ER to the cytoskeleton. Lipid transfer at ER-PM CS sustain the phosphatidylinositol (PI) cycle and prevents accumulation of cone-shaped lipids such as diacylglycerol (DAG) at the PM. In plants, SYT1/SYT3 form a module with diacylglycerol kinases (DGKs) to clear DAG from the PM and to channel DAG into metabolism. ORP family members function as PI/PS (and sterol) exchangers and integrate contact-site lipid exchange with signalling and autophagy. ER-PM CS also intersect with endocytosis, autophagosome biogenesis, plasmodesmata function and unfolded protein response signalling, underlining their multi-functional roles in cellular homeostasis and stress adaptation.

Ensuring an adequate food supply amidst a growing global population and climate change challenges, necessitates innovative strategies to enhance crop productivity. Previous studies have demonstrated that the simultaneous stimulation of different photosynthesis-related processes can increase the rate of photosynthetic carbon assimilation and plant biomass. This study evaluates an approach based on modelling aimed at simultaneously increasing photosynthetic and sink capacities in Nicotiana tabacum by overexpressing three key enzymes: Sedoheptulose-1,7-bisphosphatase (SBPase), Fructose-1,6-bisphosphate aldolase (FBP aldolase), and ADP-glucose pyrophosphorylase (AGPase). Our results showed that this strategy does not significantly improve growth or carbon assimilation in Nicotiana tabacum under the tested conditions. This suggests that while the model informing our work offers a valuable framework, its application may require adjustments based on species and environmental conditions. Future research should explore these genetic modifications in species with larger sink capacities and under a range of growth conditions to fully realize the potential of photosynthetic optimization.

Volatiles play an important role in biotic plant-environment interactions. While major research has been conducted on the emission of herbivore-induced plant volatiles in annual herbaceous species, little comparable information is available about long-living plant species. This study shows that herbivory by gypsy moth (Lymantria dispar) caterpillars or poplar leaf beetles (Chrysomela populi) on purple willow (Salix purpurea) leaves led to the induced emission of complex volatile bouquets, including a wide range of mono- and sesquiterpenes. Further comprehensive sequence and phylogenetic analyses enabled the identification of a mid-sized terpene synthase (TPS) family within the S. purpurea genome. The heterologous overexpression of identified S. purpurea TPS candidate genes in E. coli revealed their respective activities in the formation of the monoterpene alcohol linalool, as well as the sesquiterpenes (E,E)-α-farnesene and germacrene D, among others. Moreover, the majority of the herbivore-induced terpenoid volatile bouquet of S. purpurea leaves could be reconstituted in the volatile blend of the heterologous host Nicotiana benthamiana by overexpression of the respective TPS candidate genes.

Sulfur is an essential macronutrient, yet its role in grapevine (Vitis vinifera L.) physiology is poorly understood. Following reduced atmospheric sulfur deposition, sulfur fertilisation is increasingly required to prevent deficiencies, which are difficult to diagnose before they impair grapevine and subsequent wine quality. Therefore, the metabolic responses of grapevines to isolated and combined sulfur and nitrogen deficiencies were investigated. Using a non-targeted metabolomics and ionomics approach under controlled sulfur and nitrogen supplies, it was shown that isolated sulfur deficiency led to a massive accumulation of nitrogen rich amino acids and activation of the GABA shunt. This metabolic imbalance, and its disruptive effect on the concentration of other plant nutrients, was significantly alleviated under combined sulfur deficiency and low nitrogen, while additive effects also occurred. Sulfur deficiency uniquely induced a drastic increase in transpiration, significantly reducing intrinsic water use efficiency. We identified specific metabolic markers for each nutrient status and evaluated diagnostic indicators. The interaction between sulfur and nitrogen is important and demonstrates that adequate sulfate nutrition is essential for optimising water use efficiency and metabolic balance, suggesting nitrogen management strategies should consider sulfur availability to ensure crop resilience in a changing climate.

Angiosperm AGAMOUS-like (AG-like) genes are essential for flower formation. The molecular basis underlying the functions and divergence of rice four AG-like genes that belong to the AG lineage (OsMADS3 and OsMADS58) and AGL11 lineage (OsMADS13 and OsMADS21) has been poorly revealed. In this work, we created each AG-like in situ overexpressing (AGisOE) transgenic rice plant with AG-like fusion with GFP. The AG-like expression domains in AGisOE were found to be similar to those in the wild type, although their expression levels exhibited varying degree of elevation. In situ overexpression of OsMADS3, OsMADS13, and OsMADS21 differentially perturbed floral robustness and divergently affected flowering time, male fertility, seed-setting rate, and seed-borne fungal growth. Overall, the fitness of transgenic rice plants was reduced in these AGisOEs. Genome-wide characterizations of molecular interactions associated with these rice AG-like genes revealed that the phenotypic divergences observed in these AGisOEs were well supported by corresponding variations in their direct target genes, putative trans-acting factors, and protein-protein interaction partners. Our results provide new insights into the molecular basis underlying the functional divergence of rice AG-like duplicates in reproductive organs, and reveal the potential significance of expression dosage variation of a gene in plant evolution, new function display, and crop improvement.

Sulfur (S) is an essential macronutrient for plant growth and resilience. The S-amino acids cysteine (Cys) and methionine (Met) are indispensable for protein synthesis and structural integrity, as well as redox homeostasis and cofactor assembly. Over the past several decades, biochemical and molecular genetic studies demonstrated the core steps in sulfate (SO42-) uptake and assimilation pathways, while it has become increasingly evident that S homeostasis in plants cannot be understood in isolation. Robust and reciprocal regulatory interactions link S with phosphorus (P), nitrogen (N), and iron (Fe). Plants remodel membrane lipid compositions, replacing the phospholipids with sulfolipids under P deficiency. Cys/Met biosynthesis is coordinated with N metabolism. The Fe-S cluster assembly requires a balanced supply of Fe and S. These interactions are orchestrated through shared regulatory circuits and specific hub-regulatory transcription factors, including SULFUR LIMITATION 1 (SLIM1), PHOSPHATE STARVATION RESPONSE 1 (PHR1), NIN-LIKE PROTEIN 7 (NLP7), and FER-LIKE IRON DEFICIENCY-INDUCED FACTOR (FIT). Comparative studies reveal both species-specific and evolutionarily conserved regulatory networks. This review deliberately focuses on mechanistic insights into the regulatory circuits revealed from studies with the model plant Arabidopsis thaliana, where the genetic and molecular resolution enabled detailed dissection of the signaling and regulatory networks. This review also highlights unresolved mechanistic gaps and provides insights into systems-level understanding and potential translational approaches that can be implemented to improve crop nutrient use efficiency and stress resilience.

Ribosome-associated quality control (RaQC) pathways, including no-go decay (NGD) and non-stop decay (NSD), are essential for maintaining translational fidelity and regulating gene expression in eukaryotes. Central to these pathways is the conserved ribosome rescue factor PELOTA, which resolves stalled ribosomes and promotes the clearance of aberrant mRNAs and nascent polypeptides. While NGD and NSD have been extensively characterized in yeast and animals, our understanding of these processes in plants remains limited. Nevertheless, emerging evidence indicates that PELOTA plays a pivotal role in plant biology, contributing to key developmental processes and regulating immune responses to bacterial and viral pathogens. In this review, we provide an overview of the core NGD and NSD machinery in eukaryotes and synthesize current knowledge of these pathways in plants, highlighting both conserved mechanisms and regulatory features that appear to be plant-specific. We further discuss the roles of PELOTA in plant development and biotic stress responses and draw on insights from other eukaryotic systems to identify major gaps and open questions. By consolidating existing findings and outlining future research directions, this review aims to underscore the importance of ribosome-associated quality control in plants and aims to stimulate further investigation into this still underexplored field.

The plant cell wall hemicellulose xyloglucan in most dicot species consists of repeating units of three consecutive xylosylated Glc residues followed by an unsubstituted Glc (XXXG). Available evidence suggests that galactosylation of the second and the third Xyl side chains of XXXG is carried out regiospecifically by two xyloglucan galactosyltransferases XLT2 and MUR3, respectively, resulting in XLXG and XXLG units, but the mechanism underlying their regiospecificity remains elusive. In this report, we demonstrated that recombinant MUR3 and XLT2 proteins of Arabidopsis, poplar and duckweed were able to regiospecifically galactosylate not only XXXG, but also XLXG and XXLG, respectively, to generate XLLG. Interestingly, they were also able to galactosylate mono- and di-xylosylated xyloglucan oligomers. Protein structural modeling revealed that Arabidopsis and poplar MUR3 proteins contained an α-helical lid-like domain covering their active site clefts and its deletion led to increased galactosyltransferase activity. Molecular docking of the structural models of MUR3 and XLT2 identified amino acid residues interacting with UDP-Gal and XXXG in their active site clefts. Furthermore, site-directed mutagenesis uncovered critical roles of these substrate-interacting residues in the catalytic activity. Together, these findings provide biochemical insights into the molecular determinants of the regiospecificity of MUR3 and XLT2 in xyloglucan galactosylation.

Cysteine biosynthesis is the entry point of reduced sulfur into plant metabolism and underlies the formation of numerous sulfur-containing compounds essential for stress adaptation. Cysteine is produced by the consecutive action of serine acetyltransferase (SERAT) and O-acetylserine(thiol)lyase (OAS-TL), which assemble into the cysteine synthase complex (CSC). CSC formation is reversible and regulated by the cysteine precursors O-acetylserine (OAS) and sulfide, linking cysteine production to the cellular status of carbon, nitrogen, and sulfur. Traditionally, the CSC has been hypothesized as a metabolic sensor of the carbon/nitrogen and sulfur supply for cysteine biosynthesis. However, recent studies reveal a broader role. The CSC is present in multiple subcellular compartments and shows functional diversity across plant species. Emerging evidence shows that CSC dynamics are tightly integrated with environmental signaling pathways, enabling plants to coordinate sulfur metabolism with responses to stress conditions such as high light, drought, heavy metals, and pathogen challenge. In this review, we synthesize recent advances in the characterization of SERAT and OAS-TL proteins and highlight the CSC as a regulatory hub that integrates metabolic status with stress signaling to respond to specific environmental stimuli.