Physiologia plantarum最新文献

The genus of Phytophthora includes numerous phytopathogens that have devastating impacts on agricultural production. However, the limited availability of selection markers for numerous pathogenicity pathogens of the genus Phytophthora genetic transformation hinders further research on their pathogenic functional genes. Here we report a gene of NAT I, which serves as a novel selection marker for the Phytophthora sojae transformation. Additionally, we developed a new genetic manipulation toolkit based on vectors containing NAT I, which facilitates gene editing in P. sojae. With the toolkit, the gene PsGH7d of P. sojae, which encodes a glycosyl hydrolase, was edited consecutively via the CRISPR/Cas9 system to obtain gene knockout and enzymatic active site mutation strains. The pathogenicity analysis of these transformants revealed that PsGH7d is a virulence factor dependent on its bifunctional glucanase-xylanase activities. This study develops an updated toolkit for the genus Phytophthora genetic transformation and provides initial insights into the virulence of the bifunctional enzyme PsGH7d.

In response to phosphate (Pi) starvation stress, plants exhibit diverse adaptive strategies, including carbohydrate accumulation and transport to roots, which are critical for Pi deficiency signaling. However, the functional characterization of sugar metabolic genes is often hindered by the infertility of null mutants, and the role of carbohydrate biosynthetic genes in phosphorus (P) homeostasis remains unclear. Here, we functionally characterized Ugp1, a highly expressed gene in rice (Oryza sativa) that encodes UDP-glucose pyrophosphorylase. Ugp1 was expressed throughout the rice plant and was transcriptionally induced by Pi starvation in shoot tissues. Localized to the cytosol, Ugp1 was found to be responsible for the biosynthesis of the major sugar sucrose. Homozygous mutation of Ugp1 resulted in an infertile phenotype, decreased sucrose content, retarded growth and increased Pi accumulation, while heterozygous Ugp1 plants exhibited intermediate phenotypes. The increased Pi accumulation in osugp1 mutants was accompanied by the upregulation of Pi starvation-responsive genes. Notably, in vivo ³¹P-nuclear magnetic resonance analysis revealed an increase in vacuolar and a decrease in cytoplasmic Pi concentration in osugp1 mutants. These findings indicate that Ugp1 plays a critical role in sucrose biosynthesis and is essential for sustaining normal growth and P homeostasis in rice. Its mutation will lead to impaired sucrose synthesis, retarded growth, and altered phosphorus accumulation and distribution. These results highlight the close relationship between carbon metabolism and P homeostasis, offering new perspectives for understanding the molecular mechanisms of plant responses to Pi starvation and providing a theoretical basis for future research on plant nutrient regulation.

Soil alkalization is a global ecological problem that constrains food security and sustainable socio-economic development. As a wild relative of soybean, wild soybean (Glycine soja) exhibits strong salt and alkali stress resistance and its cotyledons play a key role during the emergence (VE) stage. This study aimed to compare variations in growth parameters, cotyledon ultrastructure, photosynthetic physiology, mineral ion and metabolite contents, and gene expression in two ecotypes of wild soybean to elucidate the regulatory mechanisms underlying alkali stress resistance in salt-tolerant wild soybean cotyledons during the VE stage. The results showed that salt-tolerant wild soybean cotyledons exhibited relatively stable growth parameters, dense and orderly chloroplast structure, high photosynthetic rates, as well as high K⁺ and Ca²⁺ contents under alkali stress. Metabolomics, transcriptomics, and weighted gene co-expression network analyses revealed that salt-tolerant wild soybean cotyledons adapted to alkali stress during the VE stage by enhancing photosynthetic carbon assimilation pathways, increasing methionine and proline biosynthesis, and enhancing gamma-aminobutyric acid biosynthesis, thereby maintaining a stable carbon and nitrogen balance. In addition, upregulation of the expression of ICL, MS, and ACO₂ led to the accumulation of various organic acids, such as pyruvic, aconitic, succinic, oxalic, malic, and fumaric acids, thereby promoting the synthesis of organic acid metabolism modules. This study provides novel insights into the key metabolic modules by which wild soybeans resist alkali stress.

The cell cycle is predominantly controlled by Cyclins/Cyclin-Dependent Kinases (Cyc/CDK) complexes, which phosphorylate targets involved in cellular proliferation. Evidence suggests that Cyc/CDK targets extend beyond traditional proteins and include enzymes that regulate the central carbon metabolism. Maize embryo axes rapidly internalize and metabolize glucose. After 24 h of imbibition in glucose-rich media, axes exhibited increased length and weight, with more pronounced effects at 72 h. This morphology enhancement was impaired when RO-3306, a specific CDK inhibitor, was added. The protein profile of maize embryo extracts at 18 and 24 h indicated altered phosphorylation patterns following CDK activity inhibition. Metabolomic analysis at 24 h of imbibition revealed that maize embryos without sugar in the media, with or without RO-3306, had a decreased sugar and amino acid content. Conversely, axes exposed to glucose demonstrated increased conversion into various mono and di-saccharides such as fructose, mannitol, galactose, and maltose but not sucrose. This pattern was reversed upon the addition of RO-3306. Glucose promoted the accumulation of amino acids such as cysteine, valine, leucine, and intermediates of the tricarboxylic acid (TCA) cycle, such as malate and citrate. The CDK inhibitor redirected the glucose metabolism toward increased serine levels, followed by other amino acids like phenylalanine, valine, and leucine. Additionally, TCA cycle intermediates and sterols significantly decreased. Overall, these results contribute to understanding the role of CDK in maize morphogenesis during germination and underscore its impact on modulating various central carbon pathways, including glycolysis, amino acid catabolism/anabolism, TCA cycle, and sterols biosynthesis.

Genetic transformation is a powerful tool in plant biotechnology. However, its application is limited to species that are well-studied and easy to transform. There is a critical need to establish transformation protocols for non-model species. A stable transformation method using Agrobacterium rhizogenes for hairy root transformation and regeneration of transgenic Linum grandiflorum was established. This protocol shows the successful co-transformation of different T-DNA fragments from both the native Ri plasmid and the binary vector with the reporter gene. Hairy roots were produced after inoculation with Agrobacterium rhizogenes from which later shoots were formed from the callus, and subsequently, whole plants were regenerated. This protocol significantly facilitates genomic studies in Linum grandiflorum, particularly in investigating genes at the S-locus supergene, which are crucial for understanding self-incompatibility. Moreover, the established transformation method enables the production of hairy root lines, which can be utilized for the biosynthesis of medically useful and commercially valuable plant metabolites.

Climate change has exacerbated precipitation variability, profoundly impacting vegetation dynamics and community structures in arid ecosystems. There remains a notable knowledge gap regarding the ecological effects of altered precipitation on crassulacean acid metabolism (CAM) plants and their interactions with other photosynthetic types. This study investigated the response of the typical obligate CAM plant Orostachys fimbriata to extended watering intervals (WI4-WI8) and various competitive patterns (M₁-M₄) with the C₃ grass Melilotus officinalis and the C₄ grass Setaria viridis through greenhouse experiments. The results showed that: (1) In species mixtures, CAM plants had slightly reduced the total biomass (TB) compared to monocultures, yet maintained competitiveness by increasing the root-to-shoot biomass (R:S) ratio, stabilizing plant height, and sustaining their photosynthetic rates. (2) As watering intervals increased, CAM plants adapted by further elevating the R:S ratio, reducing height, and decreasing aboveground biomass. However, their height, CO₂ assimilation rate, and above- and below-ground biomass were significantly suppressed, particularly when coexisting with C₄ plants. More extreme watering regime caused a 47.6% decrease in TB of CAM plants in M₄, while C₃ and C₄ grasses declined by 53.2% and 37.8%, respectively. (3) Given the predicted extension of drought intervals and the intensification of individual rainfall events under future climate conditions, the competitive pressure from C₄ plants with high drought tolerance and resource acquisition advantages may limit the expansion potential of CAM plants in drylands. This study enhances the understanding of adaptive mechanisms of CAM plants competing and coexisting with grasses under variable environments, providing scientific bases for predicting arid ecosystem dynamics.

Antarctica has one of the most sensitive ecosystems to the negative effects of Persistent Organic Pollutants (POPs) on its biodiversity. This is because of the lower temperatures and the persistence of POPs that promote their accumulation or even biomagnification. However, the impact of POPs on vascular plants is unknown. Moreover, fungal symbionts could modulate the effects on host plants to cope with this stress factor. This study investigates the molecular and ecophysiological responses of the Sub-Antarctic and Antarctic plant Colobanthus quitensis to POPs in different populations along a latitudinal gradient (53°- 67° S), emphasizing the role of endophytic fungi. The results show that exposure of POPs in C. quitensis generates oxidative stress and alters its ecophysiological performance. Nevertheless, C. quitensis in association with fungal endophytes and POPs exposure, shows lower lipid peroxidation, higher proline content and higher photosynthetic capacity, as well as higher biomass and survival percentage, compared to plants in the absence of fungal endophytes. On the other hand, the antarctic plant population (67°S) with endophytic fungi presents better stress modulating upon POPs exposure. Endophytic fungi would be more necessary for plant performance towards higher latitudes with extreme conditions, contributing significantly to their general functional adaptation. We develop a transcriptomics analyses n the C. quitensis-fungal endophytes association from the Peninsula population. We observed that fungal endophytes promote tolerance to POPs stress through upregulated genes for the redox regulation based on ascorbate and scavenging mechanisms (peroxidases, MDAR, VTC4, CCS), transformation (monooxygenases) and conjugation of compounds or metabolites (glutathione transferases, glycosyltransferases, S-transferases), and the storage or elimination of conjugates (ABC transporters, C and G family) that contribute to detoxification cell. This work highlights the contribution of endophytic fungi to plant resistance in situations of environmental stress, especially in extreme conditions such as in antarctica exposed to anthropogenic impact. The implications of these findings are relevant for the biosecurity of one of the last pristine bastions worldwide.

Molecular hydrogen (H₂) is a promising energy carrier, and its production by photosynthetic microorganisms holds substantial potential for advancing renewable energy generation. The nitrogenase-mediated H₂ production using heterocyst-forming cyanobacteria represents a promising approach, as the process utilizes light energy and photosynthetic reductants while being naturally protected from O₂-rich environments by its restriction to microoxic heterocyst cells. We investigated the impact of deleting the vegetative cell-specific flavodiiron protein, Flv3A, on the long-term H₂ photoproduction of the model heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. The H₂ photoproduction response was evaluated under varying atmospheric conditions, with or without N₂ and O₂, and compared to the ∆hupL mutant, which is deficient in the large subunit of uptake hydrogenase, and the ∆hupL/flv3A double mutant. Unlike the ΔhupL mutant, H₂ photoproduction in Δflv3A is not enhanced by increased nitrogenase activity or high accumulation of sugars in cells. Our results suggest that the absence of the vegetative cell-localized Flv3A positively affects H₂ photoproduction in heterocysts by simultaneously downregulating hupL expression and enhancing the O₂ tolerance of nitrogenase via a yet unexplored mechanism. These findings advance our understanding of nitrogenase-driven H₂ production and provide a new strategy to address key limitations in long-term photobiological H₂ production.

The classic plant growth-promoting phytohormone cytokinin has been identified and established as a mediator of pathogen resistance in different plant species. However, the resistance effect of structurally different cytokinins appears to vary and may regulate diverse mechanisms to establish resistance. Hence, we comparatively analysed the impact of six different adenine- and phenylurea-type cytokinins on the well-established pathosystem Nicotiana tabacum-Pseudomonas syringae. The efficiency of resistance effects was evaluated based on impacts on the host plant defence response by scoring infection symptoms and the direct impact on the pathogen by assessment of proliferation in planta. To identify common and cytokinin-specific components involved in resistance effects, transcriptome profiling and targeted metabolomics were conducted in leaves treated with the different cytokinins. We observed clearly different potentials of the tested cytokinins in either suppressing infection symptoms or pathogen proliferation. Gene regulation and metabolite analyses revealed cytokinin-type specific impacts on defence components, such as salicylic acid and related signalling, expression of PR proteins, and regulation of specialised metabolism. Cytokinins also strongly affected plant cell physiological parameters, such as a remarkable decrease in amino acid pools. Hence, this study provides comparative information on the efficiency of diverse cytokinins in mediating resistance in one well-studied pathosystem and insights into the specific regulation of resistance effects mediated by different cytokinin molecules. This is particularly relevant for studies on the function of cytokinins or other phytohormones and compounds interacting with cytokinin activities in the context of pathogen infections and other stress scenarios, considering the diverse cytokinins present in plants.

Sulforaphane (SF) is a sulfur (S)-containing isothiocyanate found in cruciferous vegetables and is known for its potent anticancer properties. Broccoli sprouts, in particular, are considered safe and healthy dietary choices due to their high SF content and other beneficial biological activities, such as enhanced metabolite ingestion. The application of selenium (Se) is an excellent approach to enhance the abundance of SF. Previous studies have often focused on gene expression and changes in the synthetic substrates of glucoraphanin (RAA) to explain SF variation in response to Se application. However, the regulatory network and other physiological and biochemical reactions involved in the regulation of SF biosynthesis are poorly understood. In this study, Se-treated broccoli sprouts had higher SF and RAA contents; they increased with increasing Se application. Using RNA-seq in combination with KEGG, GO, phenotypic, and WGCNA analyses, it was observed that not only gene expression was induced but also that glutathione serves as an S donor for SF biosynthesis and acts as an oxidative stress reliever as a result of Se treatment. Additionally, a module related to glucosinolate biosynthesis was identified. Yeast one-hybrid system and dual luciferase reporter assay were utilized. These assays demonstrated the hub transcription factors GATA22, ERF12-like, and MYB108 would directly bind to SUR1 promoter and positively regulate its expression. Our study presents the first global overview of the role of GSH metabolism in response to Se for SF biosynthesis, and provides a novel and valuable gene resource for the molecular breeding of high-SF broccoli.