Physiologia plantarum最新文献

Abiotic stresses such as high salinity or alkalinity usually alter plant secondary metabolism, thereby affecting their defense against herbivorous insects. This study investigated the effects of changes in terpenoids and phenolics of black pine (Pinus thunbergii) induced by salt, alkali, and mixed saline-alkali stresses on the host selection, host fitness, and laboratory bioassays of red-haired bark beetle (Hylurgus ligniperda). Field experiments showed that saline-alkali stress resulted in a decreased proportion of (1R)-(+)-α-pinene, an increased proportion of β-pinene and sabinene, and reduced contents of tannins, total flavonoids, and total phenols in the phloem of P. thunbergii, and promoted the damage of H. ligniperda to P. thunbergii. Laboratory bioassays showed that changes in terpenoids had a significant impact on the electroantennogram (EAG) and behavioral responses of H. ligniperda, while changes in phenolics had little effect on its growth and development. Based on Partial Least Squares Path Model (PLS-PM) comparison and laboratory bioassays results, terpenoids were identified as the main factor promoting damage of H. ligniperda to P. thunbergii. Specifically, saline-alkali stress enhances the host-locating ability of H. ligniperda, leading to an increase in its population density and thus promoting damage to P. thunbergii. This study provides insights into the complex interactions between plant physiology and insect behavior under abiotic stress, delivering more precise strategies for pest management in salinized-alkaline forest environments.

Phytoene desaturase (PDS; EC 1.3.5.5) is a key enzyme of the carotenoid biosynthetic pathway, catalyzing the desaturation of phytoene, precursor of all carotenoids. In this study, several PDS-knockout (PDS-KO) transformants of the chlorophyte microalga Chlamydomonas reinhardtii were generated using a reverse genetics strategy. Two single guide RNAs (sgRNA) were designed to target the first exon of the PDS gene, and pre-assembled Cas9 ribonucleoprotein (RNPs) complexes were delivered into microalgal nuclei by electroporation. Multiple white PDS-KO transformants were successfully obtained by this approach, and three independent transformant lines were subsequently characterized. By integrating ultrastructural, pigment and transcriptomic analyses of dark-grown cells of several PDS-KO carotenoid-deficient mutants in comparison with the parental strain, it was demonstrated that carotenoids are indispensable components of multiple cellular architectures. Chromatographic analysis confirmed that the only carotenoid accumulated in these transformants was phytoene, which lacks the critical structural and photoprotective functions of its colored derivatives. Transmission Electron Microscopy (TEM) observations revealed profound ultrastructure alterations, including poorly developed chloroplasts and effects on other cellular structures that were either absent or severely disorganized. Consistently, clustering differentially expressed genes into functional groups revealed downregulation of pathways associated with photosynthesis, chlorophyll and carotenoid biosynthesis, ribosome biogenesis, and vesicle and membrane trafficking in the PDS-KO lines. Conversely, upregulation of regulatory and retrotransposon-inducing genes was observed. These findings underscore the central metabolic role of colored carotenoids in plant cells, highlighting their essential contribution to cellular homeostasis and photosynthetic competence.

High-density rice planting reduces light quality within the canopy, especially the red to far-red (R: FR) ratio, triggering a physiological shift that enhances elongation growth at the expense of weakened defence mechanisms. This is not a passive consequence but a coordinated regulation controlled by the Phytochrome B (PhyB)-Phytochrome Interacting Factor (PIF) signalling module. Under low R: FR, PhyB becomes inactive, stabilising key PIFs such as OsPIL13 and OsPIF4. These transcription factors promote shade-avoidance growth by enhancing auxin and gibberellin biosynthesis, which in turn suppresses salicylic acid (SA) and jasmonic acid (JA) signalling. They also directly repress the expression of core defence genes. Together, these changes lower immune readiness in shaded rice plants. Here, we propose a rice-specific model in which low R: FR light signals directly suppress immunity through PIF-mediated transcriptional repression, highlighting a monocot-specific mechanism that integrates light perception with immune downregulation.

The seedling stage is one of the stages during which rapeseed is most sensitive to saline-alkali stress. Enhancing the tolerance of rapeseed seedlings is crucial for achieving high biomass and yield when cultivating rapeseed in saline-alkaline soils. This study utilized the salt-sensitive rapeseed variety Yangyou 9 as experimental material to investigate the physiological and molecular mechanisms by which foliar application of zinc oxide nanoparticles (ZnO NPs) improves salinity tolerance under salt stress during the seedling stage. The results indicated that the 150 mM NaCl stress significantly inhibited the growth of rapeseed seedlings. However, foliar application of ZnO NPs at the concentration of 100 mg L^-1 resulted in significant increases in biomass, plant height, leaf width, and leaf area of the above-ground parts of the plants. Furthermore, the contents of soluble sugars and soluble proteins increased by 57.03% and 33.43%, respectively. Under salt stress conditions, the application of ZnO NPs significantly enhanced the activities of POD, SOD, and CAT compared to the untreated control, reduced the levels of reactive oxygen species (ROS), and decreased electrolyte leakage by 27.7% as well as malondialdehyde (MDA) content by 30.7%. These findings indicated that ZnO NPs treatment could significantly alleviate oxidative stress and damage to cell membranes. Non-destructive micro-measurement techniques showed that after ZnO NPs treatment, the rates of K⁺ efflux and Na⁺ influx in the root tips and leaf mesophyll tissues of rapeseed seedlings were significantly reduced, thus maintaining the sodium-potassium ion balance and enhancing the salt tolerance of rapeseed during the seedling stage.

The responses of Spartina alterniflora Loisel. roots to the interactive effects of drought and nitrogen (N) form, and the underlying mechanisms involved, remain poorly understood. We conducted a greenhouse experiment to evaluate the effects of N form (NH₄ ⁺, NO₃ ^-, and NO₃ ^-/NH₄ ⁺) and increasing water deficit on root performance, including growth, metabolite profiles, antioxidant activity, and N metabolism. Under well-watered conditions, NH₄ ⁺-fed plants exhibited the greatest root growth, nearly double that of NO₃ ^--fed plants. However, this growth advantage was lost under mild (50% field capacity, FC) and severe (25% FC) drought stress. In contrast, drought stress enhanced root growth in NO₃ ^--fed plants relative to well-watered conditions. Under well-watered conditions, NH₄ ⁺ nutrition increased the activities of superoxide dismutase, glutathione reductase, and ascorbate peroxidase compared to NO₃ ^- nutrition. Although drought stress further stimulated antioxidant enzyme activities in the roots of NH₄ ⁺-fed plants, this response did not mitigate drought-induced growth reductions. Antioxidant enzyme activities in the NO₃ ^-- and NO₃ ^-/NH₄ ⁺-fed plants were largely unaffected by drought, except for guaiacol peroxidase. Regardless of N form, glutamine synthetase activity increased under mild drought stress but declined under severe stress. Drought stress also enhanced glutamate dehydrogenase activity across all N treatments, particularly in NH₄ ⁺-fed plants, and was accompanied by increased total amino acid concentrations, especially proline. Despite these metabolic adjustments, drought stress reduced the overall performance of NH₄ ⁺-fed plants. These findings provide insights into N form-dependent drought responses and may help guide fertilizer management strategies to improve S. alterniflora productivity under water-limited conditions.

Understanding how treeline and nontreeline trees allocate carbon at their upper elevation limits is key to forecasting species shifts under climate warming. We compared a treeline deciduous broadleaf, Betula ermanii, with a nontreeline evergreen conifer, Picea jezoensis, at their species-specific upper limits and lower sites on Changbai Mountain. We measured leaf gas exchange and traced recent photoassimilates using in situ ¹³CO₂ pulse labeling. Within species, photosynthetic traits and carbon stocks did not differ between elevations, indicating no carbon-acquisition limitation. In contrast, allocation patterns diverged at the upper limits: B. ermanii retained a larger share of recent ¹³C aboveground and showed slower carbon flow with longer mean residence time in leaves, whereas P. jezoensis allocated more ¹³C belowground and exhibited faster turnover. These patterns indicate that aboveground carbon allocation is primarily determined by species-specific leaf habits (deciduous broadleaf vs. evergreen conifer), whereas belowground allocation is more strongly shaped by stress conditions associated with upper elevational limits. Patterns were consistent with the functional type driving aboveground allocation and elevation-related site context shaping belowground allocation. We infer that treeline B. ermanii prioritizes aboveground investment to maximize short-season carbon gain and support cold tolerance, while nontreeline P. jezoensis invests belowground to enhance resource uptake and cope with competition. Overall, contrasting sink-mediated allocation strategies, rather than source limitations, govern species responses at upper limits and inform predictions of composition, distribution, and upward migration under future climate change.

Ferredoxins (FDXs) are ubiquitous proteins that bind iron-sulfur (Fe-S) clusters and usually catalyse electron transfer reactions. In eukaryotic photosynthetic organisms, a relatively high number of [2Fe-2S] cluster-containing FDXs is present in plastids and mitochondria. These are mostly redox-active FDXs, except one mitochondrial FDX that no longer binds an Fe-S cluster and is a component of the respiratory complex I. We have performed a phylogenomic study to describe the content and distribution of FDXs in different phylogenetic groups of the Archaeplastida clade, including the two models Arabidopsis thaliana and Chlamydomonas reinhardtii. Important differences exist since the number of FDXs ranges from four to 19. From the sequence characteristics and phylogenetic analyses, they cluster in 10 clades: eight containing plastidial FDXs and two mitochondrial FDXs. Six clades are present in most organisms, while four clades comprising plastidial FDXs (FDX5, FDX7, FDX8, and FDX9) are present in a small subset of organisms, mostly algae and lower Embryophytes; the FDX5 and FDX9 clades are even only present in Chlorophyceae. The expression patterns of these two FDXs in Chlamydomonas combined with the physiological and biochemical studies performed with FDX5 suggest specific roles of FDX5 in anoxia and of FDX9 in the dark. Structural analyses provide additional support to the functional divergence among plastidial FDXs. Overall, these analyses revealed the existence of an important diversity within the FDX family and allowed refining the FDX classification in Archaeplastida. It also provides clues for future physiological analyses to decipher the functions of the uncharacterised FDXs.

Understanding the physiological and biochemical responses of spinach to salt stress through amino acid supplementation is crucial for improving crop resilience under increasing soil salinity conditions. Salt stress represents one of the most severe abiotic constraints limiting vegetable crop productivity worldwide, yet comprehensive studies examining organ-specific metabolic reprogramming across entire plant systems remain limited. However, knowledge about how different amino acids mediate these responses through distinct metabolic pathways is limited. We investigated mineral nutrition, antioxidant defense systems, and secondary metabolite profiles of spinach supplemented with three amino acids (asparagine, phenylalanine, and tryptophan) under salt stress conditions. Amino acid type, salt treatment, and organ significantly influenced all measured parameters (p ≤ 0.0001). Asparagine consistently demonstrated comprehensive protective effects, excluding toxic ions while promoting calcium uptake, maintaining photosynthetic capacity, and dramatically enhancing flavonol biosynthesis (quercetin and rutin accumulation increased several-fold) under combined stress compared to other treatments. Phenylalanine excelled in ionic homeostasis restoration, achieving superior Na/K ratio reduction and enhanced phenylpropanoid pathway activation through elevated cinnamic acid biosynthesis. Tryptophan uniquely triggered exceptional divalent cation accumulation (6-10-fold increases in magnesium, calcium, and phosphorus) and maximally enhanced antioxidant enzyme activities, though with notable protein synthesis trade-offs. Organ-specific accumulation patterns revealed leaves as primary sites for photosynthetic pigments and phenolic compounds, roots as storage organs for specialized flavonoids and catechins, and petioles showing exceptional rutin accumulation. These findings demonstrate that amino acid selection fundamentally reshapes metabolic priorities in salt-stressed spinach through divergent yet complementary biochemical strategies. We conclude that amino acid selection significantly influences spinach resilience to salt stress through divergent metabolic reprogramming strategies, with each amino acid offering distinct advantages depending on cultivation priorities. Differential metabolic responses between amino acids provide insights for precision agriculture applications, while the quantitative biochemical patterns identified offer valuable parameters for optimizing amino acid supplementation strategies under saline conditions.

AtATG8h and AtATG8i belong to a unique sub-group of the nine ATG8 proteins encoded in the Arabidopsis genome. Unlike other ATG8s that need ATG4 protease for cleavage to expose their C-terminal Gly residue for attachment of phosphatidylethanolamine (PE) and thus subsequent recruitment to the autophagosomal membranes, AtATG8h and AtATG8i directly carry a Gly residue at their C-termini and can be lipidated without the action of ATG4. We previously showed that CLATHRIN LIGHT CHAIN 2 (CLC2) participates in the autophagy process via interacting with AtATG8h and AtATG8i. Simultaneously knocking out AtATG8h and AtATG8i by CRISPR/CAS9 technology compromised autophagy, and as a consequence, enhanced the resistance to a biotrophic fungal pathogen. In this study, we took a gain-of-function approach to further investigate the roles of AtATG8h in disease resistance. Our results showed that overexpression of AtATG8h enhanced the resistance to biotrophic bacterial and fungal pathogens but compromised the resistance to a toxin secreted from a necrotrophic fungal pathogen. The enhanced resistance to the biotrophic pathogens was correlated with the increased expression of Pathogenesis-related (PR) gene, enhanced callose deposition and levels of both salicylic acid (SA) and H₂O₂, whereas the compromised resistance to the necrotrophic fungal toxin was correlated with the significantly reduced expression of the genes in the jasmonic acid (JA) pathway. These results indicated that either knocking out or overexpressing AtATG8h resulted in a similar outcome in Arabidopsis disease resistance. The underpinning molecular mechanism is discussed.

Graphene oxide (GO), a two-dimensional nanomaterial, has shown potential for improving plant stress tolerance. However, its involvement in, and mechanism of, regulating the drought stress response in apple plants remains unclear. In this study, we investigated the effects of GO on drought tolerance of M9-T337 plants under both short-term and long-term drought conditions. Results revealed that under short-term drought conditions, 0.1 and 1 mg L^-1 GO significantly alleviated drought-induced damage by reducing electrolytic leakage and MDA contents, while enhancing antioxidant enzyme activities and ROS scavenging. Under long-term drought conditions, 0.1 and 1 mg L^-1 GO improved photosynthetic rate and promoted root system development, thereby enhancing plant drought tolerance. Additionally, in M9-T337 plants, GO elevated the levels of γ-aminobutyric acid, proline, phenylalanine, arginine, and histidine, and upregulated the expression of MdCAT2, MdPOD2, MdDREB2A, MdERF1, and MdABI1. Taken together, this study connects GO with drought tolerance in apple plants, providing evidence that GO effectively enhances the drought tolerance of M9-T337 plants. These findings offer a promising strategy for the sustainable cultivation of apple in water-scarce regions through the application of nanomaterials.