Frontiers in Plant Science最新文献

Introduction: Streptomyces rochei D74 promotes growth and enhances quality in crops such as wheat and tomato. However, its potential role and optimal application method in tobacco production remain unclear. This study for the first time investigated the effects of S. rochei D74 with different application methods on tobacco growth and quality, soil physicochemical properties, and rhizosphere microbial community structure.

Methods: S. rochei D74 was applied via basal application (BA), foliar spray (FS), and their combination (BA-FS) under field conditions. Tobacco growth parameters, leaf yield and quality indicators, soil physicochemical properties, and rhizosphere microbial community structure were analyzed and compared across treatments.

Results: Different microbial treatments promoted tobacco growth compared to the control, as exemplified by notable increases in plant height (by 5.3~10.5%) and stem girth (by 7.0~15.6%), while also reducing the proportion of low-grade leaves (by 10.2~28.4%, p < 0.05). Particularly, the BA-FS treatment achieved the highest leaf yield and output value, alongside elevating the contents of total nitrogen (by 29.0~36.2%) and total alkaloids (by 34.3~66.8%) in C3F and B2F grade leaves, increasing the potassium-to-chlorine ratio, and reducing carbohydrate accumulation (e.g., starch). There were corresponding improvements in soil available nutrient contents, including nitrogen, manganese, phosphorus, and iron. Microbial treatments resulted in a lower relative abundance of Fusarium in the fungal community, despite not causing a significant shift in bacterial α-diversity. Microbial treatments increased the proportion of positive correlations in bacterial networks and heightened the complexity of fungal networks, thereby likely fostering more cooperative microbial interactions that supported improved nutrient acquisition and plant growth. Mantel analysis revealed that fungal and bacterial community abundances strongly influenced soil nutrient contents and tobacco leaf quality.

Discussion: The findings indicate that combined root and foliar application of S. rochei D74 optimally improves tobacco growth and quality by modifying microecological conditions in rhizosphere soil.

Microalgae are a potential source of renewable biofuel with several advantages over conventional crops. Under stress conditions, oleaginous microalgae such as Chlorella vulgaris accumulate high levels of neutral lipids, mainly in the form of triacylglycerol (TAG), which can be converted into biodiesel. However, the growth under stress conditions limits biomass accumulation. DGAT enzymes catalyze the final step in TAG biosynthesis, by transferring a fatty acyl-CoA to diacylglycerol. We describe here the first case in which a higher plants DGAT3-type enzyme has been overexpressed in an oleaginous microalga. Higher plants DGAT3 enzymes differ in their properties from other types of DGAT enzymes and also from the distantly related group of enzymes nominated DGAT3 in algae. We overexpressed in C. vulgaris the DGAT3 of Arachis hypogaea (peanut), since this enzyme utilizes oleoyl-CoA as the preferred acyl donor. Oleic acid is a favorable fatty acid constituent of biofuel due to its low melting point and a relatively low vulnerability to oxidation. The sequence and regulatory regions of AhDGAT3 were optimized for supporting efficient expression. The transformed algal lines showed up to a five-fold increase in the content of neutral lipids. This increase occurred under normal growth conditions, which do not limit biomass accumulation. The transformed algae also showed a four-fold increase in the percentage of oleic acid and a 25% reduction in the percentage of linolenic acid among the lipid-derived fatty acids. Both changes are favorable for biodiesel utilization. This work demonstrates that higher plants DGAT3 enzymes, and particularly the peanut DGAT3, can be utilized for obtaining improved microalgal feedstocks for biofuel production.

Soil salinization threatens global agricultural productivity, making halotolerant plant growth promoting bacteria (PGPB) crucial for sustainable farming in marginal areas. This study isolated and characterized PGPB from perennial glasswort (Arthrocaulon macrostachyum) collected at two sites in Margherita di Savoia, Apulia (Italy), during spring 2023. From rhizosphere and endosphere samples, 110 bacterial isolates (100 rhizobacteria, 10 endophytes) were obtained and characterized. Functional screening revealed: 18 isolates (16%) capable of phosphate solubilization, 25 isolates (23%) for silicon solubilization, 20 isolates (18%) producing indole acetic acid, 34 isolates (31%) producing siderophores, and 50 isolates (45%) demonstrating salt tolerance above 10% NaCl, with 28 isolates (25%) tolerating concentrations up to 17.5%. Using RAPD-PCR differentiation and Principal Component Analysis of PGPB traits, three promising halotolerant candidates were selected: Pseudomonas sp. (105S), Bacillus safensis (80S), and Peribacillus frigotolerans (114S), each exhibiting complementary plant growth promoting characteristics. These isolates represent valuable candidates for future field validation as biofertilizers in salt-affected agricultural systems.

Fluctuating irradiance forces leaves to balance energy conversion with protection against reactive oxygen species (ROS) produced when light harvesting exceeds metabolic demand. In chloroplasts, this balance is strongly governed by the thylakoid proton motive force (pmf, ΔμH⁺) and by its partitioning between a pH gradient (ΔpH) and an electric field (Δψ). A proton-circuit framework in which proton deposition by linear and cyclic electron flow builds pmf, chloroplast ATP synthase spends pmf as ATP with an effective proton conductivity g(H⁺), and counter-ion fluxes reshape ΔpH:Δψ on seconds-to-minutes timescales. Δψ-relieving anion pathways (VCCN1, CLCe) promote rapid ΔpH expression during light increases, enabling timely engagement of PsbS-dependent qE and ΔpH-dependent photosynthetic control at cytochrome b₆f, whereas the K⁺/H⁺ antiporter KEA3 accelerates ΔpH relaxation after transitions to lower light to speed recovery. These dynamics link to stromal metabolism by describing how stromal alkalinization and Mg²⁺/thioredoxin regulation activate Calvin-Benson-Bassham enzymes, how CEF pathways (PGR5/PGRL1 and NDH) increase pmf without net NADPH production, and how phosphate recycling and triose-phosphate utilization constrain ATP synthase flux. This review examines how thylakoid architecture could generate spatial heterogeneity in proton dynamics and highlight what remains inferred versus directly measured. Finally, we present an operating-regime map and a minimal diagnostic toolkit-multiwavelength ECS (pmf, ΔpH/Δψ, g(H⁺)) combined with NPQ, P700, and gas exchange-to translate mechanism into testable predictions and improve cross-study comparability. The unifying design principle is timing: rapid ΔpH formation to protect PSI during upshifts, followed by timely relaxation to minimize unnecessary quenching and sustain CO₂ assimilation.

To explore the relationship between carbon storage and environmental factors in Populus plantations of different stand ages, and to reveal the carbon sequestration mechanisms of Populus plantations across different age classes, this study employed field surveys and laboratory analysis to investigate the distribution patterns and influencing factors of carbon storage in trunk-branch-leaf-root-soil systems of Populus plantations with different stand ages (10 y, 30 y, 40 y, 50 y) in the Luxi Yellow River floodplain. The results showed that the carbon storage in trunks, branches, and roots increased gradually with increasing stand age, while the carbon storage in leaves reached a maximum of 7.52 t·hm² at 40 y, followed by a gradual decrease. Soil carbon storage increased consistently with stand age. Overall, the total carbon storage of Populus plantations across different age classes exhibited a linear increasing trend with advancing standage. Correlation analysis, principal component analysis, and structural equation modeling indicated that diameter at breast height (DBH), tree height (H), tree age (AGE), and stand density (SD) were the key factors affecting carbon storage in Populus plantations. The findings of this study can provide theoretical basis and technical support for enhancing carbon sequestration and sink capacity, as well as ecological restoration of Populus plantations in the Luxi Yellow River floodplain.

Introduction: Maize is a crucial cereal crop, yet it is highly susceptible to heat stress, which considerably limits its grain yield. The opening of spikelets is a critical prerequisite for pollen shedding. Jasmonate (JA) plays significant roles in responding to abiotic stress and regulating spikelet development in plants.

Methods: To investigate the molecular mechanisms underlying heat tolerance in maize, a heat-tolerant inbred line, Chang 7-2 (C7), and two heat-sensitive inbred lines, Yu727 and Y8201 (Y7 and Y8), were exposed to heat stress, followed by JA application, and subsequently analyzed using RNA sequencing.

Results and discussion: Our results indicate that under heat stress conditions, JA markedly enhances the seed-setting rate, spikelet opening rate, and spikelet opening angle in both Y7 and Y8. Moreover, JA effectively alleviates oxidative stress induced by heat stress in maize. KEGG analysis identified phenylpropanoid biosynthesis, flavonoid biosynthesis, and starch and sucrose metabolism as potential contributors to JA-mediated heat stress resistance in maize. Finally, Venn analysis of differentially expressed genes (DEGs) identified three transcription factors (TFs) involved in JA-mediated heat stress resistance in maize: MYBS3 and WRKY33, which play positive roles, and HOX22, which plays a negative role. Our findings collectively elucidate a fundamental regulatory network mediated by JA that enhances maize yield under heat stress conditions, offering viable gene targets for the genetic enhancement of maize yield in such environments.

Understanding the complex interactions between climate change and stand developmental dynamics in forest growth and carbon sequestration is essential for implementing sustainable management under climate change and for supporting China's dual-carbon goals. Using data from 243 permanent national forest inventory plots (each 0.0667 ha in size), this study developed a climate- and stage-sensitive forest growth and yield model (FGYM) for natural Larix gmelinii forests in Northeast China. The model incorporates the De Martonne aridity index (MAI) to represent climatic water availability and the stand developmental stage index, categorized into Stage 1 (early), Stage 2 (middle), and Stage 3 (late), to capture the intrinsic biological progression of forest structure. It simultaneously simulates (i) stand basis structure attributes, (ii) timber yields across different assortments, and (iii) carbon stocks in different tree components and end-use categories. Comparative analyses demonstrated that the stage-sensitive model outperformed the baseline models, revealing pronounced stage- and climate-dependent divergences in stand volume and carbon stock trajectories. For a representative stand [age = 100 years, site class index (SCI) = 16 m], the stage-sensitive model predicted 2.96% higher volume and 3.11% higher carbon stocks at Stage 2, but 15.02% and 15.70% lower values at Stage 3, indicating strong sensitivity to ontogenetic transitions and increasing climatic aridity. Across all combinations of MAI, SCI, and developmental stage, the FGYM consistently captured structural and carbon dynamics that the conventional model did not reproduce. Our findings highlight that integrating both climatic drivers and developmental heterogeneity substantially enhances model accuracy and ecological realism, providing a robust tool for assessing the future productivity and carbon sequestration potential of L. gmelinii forests under future climate change scenarios.

Vertical farming systems (VFs) offer high production efficiency in controlled environments (CEA), but their energy requirement and associated carbon footprint are strongly constrained by the high energy demand of artificial lighting is strongly constrained by the energy demand of artificial lighting. This study assessed whether different combinations of photoperiod and photosynthetic photon flux density (PPFD; 16 L:8 D at 250 µmol m⁻² s⁻¹, 12 L:12 D at 340 µmol m⁻² s⁻¹, and continuous 24 L:0 D at 170 µmol m⁻² s⁻¹) affect growth, physiology, and energy performance of two crisphead lettuce cultivars [(Lactuca sativa L. var. crispa - 'Falstaff' (green) and 'Copacabana' (red)] when the daily light integral (DLI) is maintained constant (14.4 mol m⁻² day⁻¹). Yield, morphological traits, chlorophyll fluorescence, and gas exchange parameters did not differ among lighting treatments, indicating comparable photosynthetic functioning under all photoperiod-PPFD combinations. However, continuous lighting (24 L:0 D) improved energy use efficiency (EUE) and light use efficiency (LUE), while reducing lighting costs per unit of produced biomass and demonstrating a clear benefit in terms of resource utilization. Cultivar-related differences were more pronounced than treatment effects, with red lettuce showing higher levels of phenolic compounds, carotenoids, anthocyanins, and antioxidant capacity, while maintaining similar morphological responses. Overall, the results show that under a constant DLI, photoperiod manipulation obtained by adjusting PPFD has a limited impact on plant physiology but can substantially influence yield and energy efficiency. Continuous moderate-intensity lighting thus emerges as an effective strategy to enhance the economic and environmental sustainability of VFs without compromising crop performance.

Nitrogen (N) management is critical for improving productivity and nutrient-use efficiency in substrate-based soilless wolfberry cultivation; therefore, this study aimed to quantify the effects of nutrient-solution N concentration on vegetative growth, nutrient uptake, fruit yield, fruit quality, and nutrient-use efficiency, and to identify an optimal N level for fertigation management. A controlled two-year experiment (2023-2024) was conducted in arid northwestern China with four N concentrations (250, 300, 350, and 400 mg L^-1) applied via drip fertigation, with three replicates per treatment. Moderate N supply (350 mg L^-1, T3) enhanced vegetative growth and nutrient uptake and produced the highest yield (2759.65 kg ha^-1 in 2023 and 2930.93 kg ha^-1 in 2024), while also improving 100-berry weight and quality-related traits, including β-carotene, crude protein, and essential amino acids. In contrast, the highest N level (400 mg L^-1, T4) did not further increase yield and was associated with lower nutrient-use efficiency; NUE, PUE, and KUE were higher under low-to-moderate N inputs and declined under high N. An entropy weight-TOPSIS evaluation further ranked T3 as the best overall treatment when multiple indicators were jointly considered, suggesting that optimizing nutrient-solution N concentration to around 350 mg L^-1 can improve yield and fruit quality while maintaining nutrient-use efficiency under the tested soilless cultivation conditions.

Pseudomonas syringae functions as a model phytopathogen causing numerous crop diseases, resulting in substantial economic losses in global agriculture. Presently, management of P. syringae predominantly depends on chemical pesticides; however, their prolonged application has contributed to escalating resistance and environmental contamination, highlighting urgent requirement for sustainable biological control approaches. In this review, we examine recent advances in the utilization and mechanistic understanding of natural products derived from plants, animals, and microorganisms for the control of P. syringae. Plant-derived compounds-including flavonoids, terpenoids, and alkaloids-inhibit P. syringae infection by targeting the bacterial type III secretion system (T3SS), disrupting cell membrane integrity, promoting reactive oxygen species (ROS) accumulation, and activating plant immune signaling pathways such as salicylic acid (SA) and jasmonic acid (JA) cascades. Animal-derived substances, such as chitosan, propolis, and antimicrobial peptides, primarily exert antibacterial effects through membrane disruption and immune system stimulation. Microbial-derived natural products contribute to synergistic disease suppression by modulating host immunity and interfering with the pathogen's quorum sensing mechanisms. Evidence indicates that these natural products possess multi-target antimicrobial properties, offering a rich repository of candidate molecules, such as baicalein, lignans, and carvacrol, for the development of eco-friendly antibacterial agents. Future investigations should focus on detailed characterization of these bioactive compounds and their specific disease targets, optimization of extraction methodologies to improve stability and bioavailability, and comprehensive assessment of environmental safety to advance the industrial implementation of sustainable biocontrol strategies.