Physiologia plantarum最新文献

Rac/Rop proteins, a kind of unique small GTPases in plants, play crucial roles in plant growth and development and in response to abiotic and biotic stresses. However, it is poorly understood whether cotton Rac/Rop protein genes are involved in mediating cotton resistance to Verticillium dahliae. Here, we focused on the function and mechanism of cotton Rac/Rop gene GhRac9 in the defense response to Verticillium dahliae infection. The expression level of GhRac9 peaked at 24 h after V. dahliae infection and remained consistently elevated from 24 to 48 h upon SA treatment. Furthermore, silencing GhRac9 using VIGS (Virus-induced gene silence) method attenuated cotton defense response to V. dahliae by reducing ROS (Reactive Oxygen Species) burst, peroxidase activity and lignin content in cotton plants. On the contrary, heterologous overexpression of GhRac9 enhanced Arabidopsis resistance to V. dahliae and significantly increased ROS production in Arabidopsis plants. Furthemore, transient overexpressing of GhRac9 significantly enhanced ROS burst and POD activity in cotton plants. In addition, GhRac9 positively regulated the expression levels of the genes related to SA signaling pathway in cotton plants. In conclusion, GhRac9 functioned as a positive regulator in the cotton defense response to V. dahliae, which provided important insights for breeding new cotton varieties resistant to V. dahliae.

Investigating the effects of drought stress and subsequent recovery on the structure and function of chloroplasts is essential to understanding how plants adapt to environmental stressors. We investigated Ctenanthe setosa (Roscoe) Eichler, an ornamental plant that can tolerate prolonged drought periods (40 and 49 days of water withdrawal). Conventional biochemical, biophysical, physiological and (ultra)structural methods combined for the first time in a higher plant with in vivo small-angle neutron scattering (SANS) were used to characterize the alterations induced by drought stress and subsequent recovery. Upon drought stress, no significant changes occurred in the chloroplast ultrastructure, chlorophyll content, 77K fluorescence emission spectra and maximal quantum efficiency of PSII (Qy dark), but the actual quantum efficiency of PSII (Qy light) decreased, the amounts of PSI-LHCII complexes and PSII monomers declined, and that of PSII supercomplexes increased. Thickness of the leaf and of the adaxial hypodermis, chloroplast length and granum repeat distance (RD) values decreased upon drought stress, as shown by light microscopy and SANS, respectively. Because of the very slight (nm-range) changes in RD values, the large biological variability (significant differences in RD values among the leaves and studied leaf regions) and the invasive sampling required for this method, transmission electron microscopy (TEM) hardly showed significant differences. On the other side, in situ SANS analyses provided a unique insight in vivo into the fast structural recovery of the granum structure of drought-stressed leaves, which happened already 18 h after re-watering, while functional and biochemical recovery took place on a longer time scale.

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.

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.

UDP-glycosyltransferases (UGTs) are the largest glycosyltransferase family developed during the evolution of the plant kingdom. However, their physiological significance in abiotic stress adaptation in land plants is largely unknown. In this study, we identified a UGT gene from Arabidopsis thaliana, UGT86A1, that was significantly induced by salt and drought stresses. To explore the potential biological role of UGT86A1 in salt and drought stress response, we created ugt86a1 knockout mutants and UGT86A1-overexpressing transgenic lines, and analyzed seed germination, seedling development and root growth. The results showed that ugt86a1 mutants are sensitive to drought and salt stresses, while overexpression lines show stronger resistance compared with WT, confirming the positive regulation role of UGT86A1 in abiotic stress response. Our following study indicated that UGT86A1 enhances plant resistance against salt and drought stresses via increasing soluble sugar concentration and promoting ROS scavenging capacity, thereby reducing the damage to plant organs and cells. Moreover, we identified that UGT86A1 largely contributes to the upregulation of multiple stress-induced genes under salt and drought stress conditions. Therefore, our results demonstrated that UGT86A1 is a crucial responsive gene to salt and drought stresses in a land plant, thus promoting the understanding of the physiological significance of the UGT family in plant evolution.

Low temperatures are one of the critical conditions affecting the performance and distribution of plants. Exposure to cooling results in the reprogramming of gene expression, which in turn would be mediated by epigenetic regulation. Antarctica is known as one of the most severe ecosystems, but several climate models predict an increase in average temperature, which may positively impact the development of Antarctic plants; however, under warmer temperatures, plants' vulnerability to damages from low-temperature events increases. Here, we evaluated the impact of these events on the acclimation process, with a focus on how methylation influences the induction of cold response genes. According to the results, an increase in the number of methylations in the promoter regions is associated with lower expression of these genes. Similarly, in populations where this relationship is observed, individuals acclimated to the projected climate change condition are more vulnerable, as their average temperature is lower in the face of a cold event compared to individuals acclimated to the current antarctic condition. This research is the first report highlighting the role of methylation in response to cold and its influence on the transcriptional responses of the antarctic plant Colobanthus quitensis facing climate change projections.