Journal of Experimental Botany最新文献

A considerable quantity of locally respired CO2 in stems can be assimilated via woody tissue photosynthesis (Pwt). Hence, Pwt locally provides carbon fueling radial stem growth and therefore plays a major role in the stem carbon balance. It is, however, not straightforward to quantify or visualize its dynamic behavior, especially on small spatial scales. To assess Pwt we traced xylem-transported 11CO2 in detached branches of Populus tremula L. and used positron autoradiography to visualize and quantify its dynamics on a submillimeter scale, while manipulating light exposure to the branch. Experiments using 18F-fluoride were conducted to study water transport. In light-exposed branch segments 11C was found to be highly retained whereas light-excluded parts solely indicated transport of 11CO2 by the sap. The latter results were confirmed by visualizing sap transport through 18F-labelling. Analogue experiments with 13CO2 unambiguously revealed assimilation of xylem-transported CO2 into fructose and glucose, and also suggest light-independent fixation in light-excluded parts. The combination of stable and unstable isotope experiments highlight that (i) Pwt is highly light-responsive in young branches; and (ii) xylem-transported CO2 is fixed by photosynthetic cells in bark and locally provides sugars for growth and energy to woody tissues.

Plant development is a sequence of precisely timed and spatially coordinated events that produce organs such as leaves and flowers. In Arabidopsis thaliana, for example, the development of leaves (called bracts in the inflorescence) halts once the first flower forms. Understanding how this transition is regulated is key for decoding how developmental programmes are coordinated during the floral transition. In this study, we investigated a natural phenotypic variation that uncouples bract repression from flower initiation. We discovered that the continued formation of bracts after the floral transition involves complex genetic interactions across at least four loci. Interestingly, none of these loci included known floral identity genes previously linked to bract repression, pointing to novel regulators in the coordination of bract and flower development. Using time-series transcriptomics and curve registration, we found that differences in gene expression levels when bracts persist are mainly driven by a massive desynchronization of gene dynamics. This affects a wide range of biological processes beyond those associated with leaf identity. These findings align with the 'inverse hourglass' model, which proposes that transcriptomic divergence at transitional stages contributes to morphological variation. Our results suggest that this model may also explain trait variability within species, highlighting how transcriptome dynamics shape phenotypic robustness during developmental transitions.

Sulfur (S) assimilation directly or indirectly affects the uptake, translocation, and homeostasis of essential and beneficial micronutrients, as well as detoxification of toxic metal(loid)s in plants. This review synthesizes the multifaceted roles of S assimilation and metabolites in trace element dynamics. Sulfate transporters mediate the uptake of structurally similar oxyanions such as selenate, molybdate and chromate, while S availability modulates the biosynthesis and secretion of phytosiderophores required for iron (Fe) acquisition in gramineous plant species. S-metabolite derived ligands, notably phytochelatins (PCs), metallothioneins (MTs), and nicotianamine (NA), perform essential functions in cytosolic chelation, buffering free ion concentrations to prevent toxicity, facilitating intracellular trafficking, and delivering trace metals to enzymes and organelles. Sulfur also is indispensable for the biosynthesis of critical cofactors including the Fe-S clusters and molybdenum (Mo) cofactor (Moco). On the other hand, Fe deficiency and metal(loid) stresses modulate the uptake and homeostasis of S. This intricate interplay positions S metabolism as a key regulator of micronutrient efficiency and metal(loid) detoxification. Optimizing S assimilation pathways has the potential to biofortify micronutrients and prevent excessive accumulation of toxic metal(loid)s in food crops.

Arbuscular mycorrhizal fungi establish mutualistic associations with the roots of most vascular plants, enhancing plant immunity and activating mycorrhiza-induced resistance (MIR). MIR is a crucial mechanism for plant protection against a wide variety of attackers that is mediated by the priming of jasmonate-dependent defense responses, but the contribution of self-damage perception to MIR remains unexplored. We hypothesised that differential recognition of endogenous damage signals contributes to MIR in tomato plants. To test this hypothesis, we compared responses in mycorrhizal and non-mycorrhizal tomato plants after applying the cell-wall derived damage signal oligogalacturonides (OGs). We explored early plant defense responses to OGs at the proteomic, metabolic, and transcriptomic level, and the later effects on plant resistance to the necrotrophic pathogen Botrytis cinerea. We demonstrate that mycorrhizal plants are more sensitive to the damage signals, responding stronger to lower doses as compared to non-mycorrhizal plants. Specifically, mycorrhizal plants show primed accumulation of defense proteins, receptor kinases, flavonoids, and primed activation of the jasmonic acid and ethylene signaling pathways in response to OGs. Expression levels of the tomato wall-associated kinase 1 (slWAK1) gene are elevated in mycorrhizal plants, and MIR against B. cinerea is abolished in a wak1 mutant. Together, these results provide the first indication that self-damage recognition contributes to inducing MIR against B. cinerea.

Alternative splicing (AS) of precursor mRNAs (pre-mRNAs) constitutes a major means to increase transcriptome complexity in higher eukaryotes and critically contributes to the re-programming of gene expression in response to internal and environmental signals. Technological advances have enabled us to determine transcriptome-wide AS patterns at unprecedented accuracy, depth, and throughput. Furthermore, powerful tools for examining the regulatory mechanisms underlying AS decisions have been successfully established for plants, including methods for profiling the in vivo interaction landscape of splicing regulatory proteins with their target pre-mRNAs. Combining these novel approaches with functional studies of individual AS events identified many critical components of the plant splicing code, consisting of cis-regulatory elements on the pre-mRNA and trans-acting factors, such as splicing regulatory proteins. Their concerted action affects splice site selection by the spliceosome, thereby generating highly dynamic and complex AS outputs. Here, we will review our current knowledge of AS regulation by RNA sequence and structural motifs in cis and networks of trans-acting splicing regulators. We will also discuss how, despite overall low complexity of the target motifs for binding of splicing regulators and their often-redundant functions, high levels of precision and specificity in AS can be achieved.

Effectors are small molecules secreted by microbial pathogens that disrupt host basal functioning and responses during infection by targeting various plant susceptibility factors. This study reports a candidate selection approach for identifying novel, potential plant nuclear localized effectors from Fusarium graminearum secretory proteins. From a dataset of core secretory proteins conserved across several Fusarium strains, candidates were selected based on predicted nuclear localization, structural characteristics, and expression profiles during infection. Transient expression in Nicotiana benthamiana confirmed accumulation in the plant nucleus, that were further confirmed in wheat protoplasts. One of these proteins was selected for yeast two-hybrid (Y2H) screening to identify wheat protein targets, using a Fusarium-infected wheat spike cDNA library specifically generated for this study. The screening identified a high confident interaction with a nuclear-localized wheat beta-amylase 2. The structural modeling of the protein complex between beta-amylase 2 and the putative effector was used to predict interacting amino acid residues and informed a deletion analysis to disrupt the interaction. This research identifies a Fusarium graminearum secretory core protein that interacts with a conserved wheat beta-amylase 2, showcasing a method to select pathogenicity factors conserved across multiple pathogens and host plants, with implications for developing broad-spectrum resistance strategies.

Genomic Selection (GS) has revolutionised breeding programs by enabling the prediction of phenotypes based on genetic data. However, GS often only explains a portion of the phenotypic variation. This review paper explores the potential of integrating various data types beyond genomics to enhance the prediction ability of phenotypes. The paper categorises data integration strategies into five categories: eliminate, facilitate, aggregate, incorporate, and modulate. Eliminating refers to removing the effect of non-genomic data on the phenotype, such as environmental data. Facilitating methods leverage non-genomic data to improve the accuracy of GS models. Aggregating approaches combine different data types for analysis, potentially revealing variation components not captured by individual data sources. Incorporation focuses on explicitly modelling interactions between data types. Modulating methods transform data into formats suitable for advanced models like deep learning convolutional neural networks (CNNs). The review discusses the advantages and limitations of each strategy, providing a comprehensive overview of the current state of the field. The paper concludes by emphasising the prospects of multi-data phenotypic prediction toward the development of a holistic prediction approach that facilitates a more comprehensive understanding of complex biological systems and significantly enhances prediction accuracy.

For many people, the culture of plant science, and science more broadly, can feel alienating and intimidating, which often leads to them leaving the discipline for other opportunities. However, studies show that there is a correlation between creative problem solving and increased diversity, and plant science cannot afford to lose talented individuals. Here we report on strategies to promote diversity, inclusion, and a sense of belonging for all within plant science. We address ways that institutions, organizations, communities, educators, and individuals can contribute to this needed cultural change. We urge all plant scientists to participate in these efforts; for each other, for the discipline, and for the future.

Alternative splicing (AS) represents a pivotal post-transcriptional regulatory mechanism, profoundly expanding proteomic diversity and functional complexity by enabling single genes to generate multiple mRNA isoforms. In plants, AS serves as a survival toolkit, dynamically modulating stress-responsive signaling pathways, transcriptional networks, and protein functional specialization to optimize environmental fitness. Recent advances in high-throughput sequencing technologies and computational tools have significantly deepened our understanding of AS regulation in plants. Notably, breakthroughs such as long-read transcriptome sequencing and single-cell RNA analysis have revolutionized the resolution at which we can characterize AS landscapes. These developments have collectively illuminated the critical role of AS in mediating plant responses to diverse abiotic stresses, including drought, salinity, and extreme temperatures. The resulting discoveries have opened transformative avenues for crop improvement through precision manipulation of splicing patterns. Innovative strategies such as CRISPR-Cas9-based splice editing and engineered SFs now provide powerful platforms for developing climate-resilient, high-yielding crop varieties with enhanced stress tolerance and nutritional quality. This review systematically examines the molecular mechanisms underlying AS-mediated plant stress responses, and cutting-edge applications of AS engineering in precision agriculture. By synthesizing fundamental insights with biotechnological innovations, we highlight the transformative potential of AS manipulation in addressing the pressing global agricultural challenges.

Phytochrome (phy) A and phyB are red and far-red photoreceptors that play essential roles in modulating seed germination. Despite extensive research on the roles of hormones and light signaling, the metabolic characteristics of phytochromes during the red-light-mediating seed germination remain largely unknown. Using high-throughput non-targeted metabolomics, this study profiled Arabidopsis seeds including the wild-type (Col-0), single mutants (phyA-211, phyB-9), double mutant phyAB, and the pifq mutant during red-light-induced germination, and identified a total of 164 metabolites linked to primary and secondary metabolism. Comparative analysis of the metabolome revealed that the levels of flavonols including quercetin, kaempferol and relevant glycosides were increased in phyA-211, decreased in Col-0 and phyB-9, and exhibited less change in phyAB, demonstrating that phyA and phyB antagonistically regulate flavonoid biosynthesis. Flavonoid biosynthesis was upregulated in pifq under red light. Exogenous quercetin and kaempferol treatment modestly inhibited Col-0 and pifq seed germination. Taken together, these results unveil the comprehensive metabolic networks, highlight the flavonoid metabolism under red light, and elucidate the synergistic and antagonistic roles of phyA and phyB in regulating seed metabolism. This study provides novel insight into the functional mechanisms of flavonoid metabolism and light signaling in plant development.