Physiologia plantarum最新文献

Ca is a key nutrient for fruit quality due to its role in bonding with pectin in the cell wall, providing strength through cell-to-cell adhesion, thus increasing fruit firmness and extending post-harvest life. However, Ca accumulation is mostly limited to the initial stages of fruit development due to anatomical and physiological changes that occur as fruits develop. The objective of this study was to evaluate fruit transpiration, cuticle thickness, and pedicel vessel changes during cranberry fruit development and the effect these parameters might have on Ca translocation. 'Stevens' cranberry fruits were collected weekly, starting seven days after full bloom (DAFB) until 70 DAFB. For each collection date, fruit transpiration was evaluated in the field, and samples were taken to analyze total fruit Ca content, stomata density, cuticle thickness, pedicel anatomical changes, and xylem functionality. Ca accumulation in the fruit exhibited a sigmoidal curve, beginning at 0.04 mg per berry at 7 DAFB, increasing to a maximum of 0.1 mg per berry at 28 DAFB, and remaining constant until harvest (70 DAFB). Fruit Ca accumulation was mostly explained by fruit transpiration, which exhibited a similar sigmoidal pattern. The rapid decline in fruit transpiration was largely modulated by increases in cuticle thickness, as well as anatomical changes in the pedicel xylem, thereby reducing the capacity to transport water and nutrients into the fruit. Thus, this research could help cranberry growers maximize fruit Ca content by prioritizing fertilization during the early stages of fruit development.

Stomatal abundance sets plants' potential for gas exchange, impacting photosynthesis and transpiration and, thus, plant survival and growth. Stomata originate from cell lineages initiated by asymmetric divisions of protodermal cells, producing meristemoids that develop into guard cell pairs. The transcription factors SPEECHLESS, MUTE, and FAMA are essential for stomatal lineage development, sequentially driving cell division and differentiation events. Their absence produces stomataless epidermis, hindering analysis of their roles during lineage development. MUTE drives the transition from proliferating meristemoids to guard mother cells, committed to stomatal fate. We aim to explore the molecular mechanisms underlying MUTE activity, using partial loss-of-function alleles predicted to impair DNA-binding and to potentially alter MUTE transcriptional activity. We engineered mutant allele coding sequences, generated Arabidopsis lines carrying them and analyzed their epidermal and transcriptional phenotypes using microscopy and RNA-seq. Synthetic alleles driven by the MUTE promoter rescued the stomata less phenotype of the seedling-lethal mute-3 mutant, enabling stomata differentiation and resulting in viable, fertile plants. Further examination of the developmental consequences of MUTE partial loss-of-function revealed arrested lineages, reduced stomatal abundance and altered stomatal spacing. Transcriptomic analysis of very young cotyledons from complemented lines indicated that only some MUTE targets require an intact MUTE bHLH domain. Comparison with existing lineage cell-specific transcriptional profiles showed that lineage development in the mutant lines was delayed compared to the wild-type but followed similar gene networks. These synthetic alleles provide new insight into MUTE ability to accurately and timely specify stomata formation.

Ethylene is an important plant hormone whose production relies on the action of key enzymes, one of which is 1-aminocyclopropane-1-carboxylate synthase (ACS). There are three classes of ACS, which are all partially regulated by degradation through the ubiquitin-proteasome system (UPS), which regulates ethylene production. Arabidopsis has a single class III ACS, ACS7, but although it is known to be degraded by the 26S proteasome, the UPS proteins involved are poorly characterised. In this work, we used mass spectrometry to identify novel components of the ubiquitin system that may contribute to the regulation of ethylene biosynthesis via ACS7. We found two HECT-type ligases, UPL1 and UPL2, which regulate ACS7 stability. In vitro experiments showed that UPL1 and UPL2 E3 ligases directly control ACS7 turnover. In addition, increased ethylene levels were observed in UPL1- and UPL2-knockout plants in response to NaCl and NaCl+MG132 treatment, respectively. Under the same conditions, we observed increased ACS7 transcript levels in upl1 compared to WT plants under control and stress conditions, further confirming that UPL1 and UPL2 regulate ACS7-dependent ethylene production in response to stress. We used molecular modelling to predict ACS7 ubiquitylation sites and cell-free degradation assays to verify that lysine residues at positions 174, 238 and 384 regulate ACS7 protein stability. Overall, this study provides new insights into the regulation of ACS7 protein stability, and hence ethylene production, in plant growth and development and the response to stress.

Plant chemical composition is a trait gaining increasing importance in plant ecology. However, there is limited research on the patterns and drivers of its variation among different plant functional groups and bioclimatic regions. We conducted an analysis of ionomes utilising X-ray fluorescence on 83 plant species from four distinct functional groups (grasses, legumes, forbs and woody species); we marked plots across 15 sites located in both the desert and Mediterranean bioclimatic regions. The primary factors influencing variations in ionomes are predominantly attributed to bioclimatic factors rather than soil composition. Across all functional groups, plants from the Mediterranean region are characterised by greater association with calcium, whereas desert plants exhibit a higher affinity for strontium (Sr), suggesting its potential role in drought tolerance. Among functional groups, grasses uniquely exhibit distinct ionomic features, primarily due to their higher silicon (Si) concentrations. Plant species' affinities for certain elements and their interactions are likely driven by physiological constraints, whereas variations within a functional group are mostly driven by environmental conditions. We conclude that interactions among elements form physiological phenotypes shaped by natural selection under large-scale environmental variability, making plant ionome composition an important plant functional trait.

Optimizing photosynthetic lighting is essential for maximizing crop production and minimizing electricity costs in controlled environment agriculture (CEA). Traditional lighting methods often neglect the impact of environmental factors, crop type, and light acclimation on photosynthetic efficiency. To address this, a chlorophyll fluorescence-based biofeedback system was developed to adjust light-emitting diode (LED) intensity based on real-time plant responses, rather than using a fixed photosynthetic photon flux density (PPFD). This study used the biofeedback system to maintain a range of target quantum yield of photosystem II (Φ_PSII) and electron transport rate (ETR) values and to examine if the adjustment logic (Φ_PSII or ETR-based) and crop type influence LED light intensity. The system was tested in a growth chamber with lettuce (Lactuca sativa) 'Green Towers' and cucumber (Cucumis sativus) 'Diva' to maintain six ETR levels (30, 50, 70, 90, 110, 130 μmol·m^-2·s^-1) and five Φ_PSII levels (0.65, 0.675, 0.7, 0.725, 0.75) during a 16-hour photoperiod. The ETR-based biofeedback quickly stabilized the target ETR within 30-45 minutes, whereas the Φ_PSII-based system needed more time. The system adjusted light intensities according to target values, acclimation status, and crop-specific responses. For example, to maintain a target ETR of 130 μmol·m^-2·s^-1, the gradual increase in Φ_PSII over time due to light acclimation allowed the required PPFD to decrease by 35 μmol·m^-2·s^-1. Lettuce showed higher photosynthetic efficiency and lower heat dissipation than cucumber, leading to higher PPFD adjustments for lettuce. This biofeedback system effectively controls LED light, optimizing photosynthetic efficiency and potentially reducing lighting costs.

This study investigates the physiological and morphological responses of wheat (Triticum aestivum) and pea (Pisum sativum) grown in a mixture of lunar soil (LS) simulant and organic soil (OS). The experiment compared the growth of both pea and wheat in 100% organic soil (OS) and a 3:2 mixture of OS and LS (OS: LS). Wheat exhibited increased branching and root growth in OS: LS, while pea plants showed enhanced aerial elongation and altered branch morphology. Photochemical efficiency (Fv/Fm) and pigment concentrations were significantly affected, with both pea and wheat showing reduced chlorophyll content in OS: LS. Oxidative stress indicators, such as lipid peroxidation, exhibited higher levels in pea plants than wheat plants, particularly in the OS: LS mixture. Hormonal analysis performed by LC-MS/MS indicated significant increases in abscisic acid (ABA) and its catabolites in both pea and wheat in OS: LS, suggesting an adaptive response to suboptimal conditions. The results highlight species-specific growth strategies, with wheat investing more in root development and pea plants promoting aerial growth. These findings provide important insights into how essential crops could adapt to extraterrestrial soils, contributing to the development of sustainable agricultural practices for space exploration. Future research should focus on optimising crop performance based on species-specific adaptative responses in mixed-soil environments.

Halophytes display distinctive physiological mechanisms that enable their survival and growth under extreme saline conditions. This makes them potential candidates for their use in saline agriculture. In this research, tomato (Solanum lycopersium Mill.) was cultivated in moderately saline conditions under two different managements involving Arthrocaulon macrostachyum L., a salt accumulator shrub: intercropping, i.e., co-cultivation of tomato/halophyte; and crop rotation, in which tomato is grown where the halophyte was previously cultivated. The effect of these crop managements was evaluated in tomato plants in comparison with tomato in monoculture, with regards to physiological and biochemical variables and metabolomic and proteomic profiles. Both halophyte-based managements reduced soil salinity. Crop rotation enhanced photosynthesis and protective mechanisms at the photosynthetic level. In addition, both crop managements altered the hormone profile and the antioxidant capacity, whereas a reactive oxygen species over-accumulation in leaf tissues indicated the establishment of a controlled mild oxidative stress. However, tomato production remained unchanged. Metabolomic and proteomic approaches suggest complex interactions at the leaf level, driven by the influence of the halophyte. In this regard, an interplay of ROS/lipid-based signalling pathways is proposed. Moreover, improved photosynthesis under crop rotation was associated with accumulation of sugar metabolism-related compounds and photosynthesis-related proteins. Likewise, acylamino acid-releasing enzymes, a class of serine-proteases, remarkably increased under both halophyte-based managements, which may act to modulate the antioxidant capacity of tomato plants. In summary, this work reveals common and distinctive patterns in tomato under intercropping and crop rotation conditions with the halophyte, supporting the use of A. macrostachyum in farming systems.

Soil salinization adversely impacts plant and soil health. While amendment with chemicals is not sustainable, the application of bioinoculants suffers from competition with indigenous microbes. Hence, microbiome-based rhizosphere engineering, focussing on acclimatization of rhizosphere microbiome under selection pressure to facilitate plant growth, exhibits promise. This study aimed to acclimatize a salt-susceptible tomato cultivar to high salt concentration through a microbiome-based top-down approach of rhizosphere engineering. Multiple passaging of the rhizosphere microbiome of the cultivar was performed for twelve plant growth cycles in the presence of increasing salt stress. The rhizosphere microbiome of the phenotypically best-grown plant under stress was transferred as inoculum to the next plant growth cycle. Plant growth attributes and stress marker levels were assessed, expression levels of plant salt stress-responsive genes were examined, and the bacterial community composition in the initial and final plant growth cycles was analysed. Rhizosphere microbiome inoculation promoted plant growth under increasing salt concentrations. Stress markers were reduced in plants inoculated with an acclimatized microbiome, while the root architecture was enhanced, indicating salt tolerance. The salt stress-responsive genes were downregulated in salt-treated plants, whereas upregulation of these genes was observed upon microbiome inoculation. The relative abundance of Exiguobacterium, Arthrobacter, and Lysobacter was higher in microbiome-treated plants under salt stress compared to the salt-treated plants without microbiome inoculation. The strategy of acclimatizing the rhizosphere microbiome of a salt-susceptible tomato cultivar was successfully implemented for stress amelioration and plant growth promotion, thereby offering a sustainable means with immense potential for application in other crops.

Cyanobacteria are important model organisms for studying the process of photosynthesis and the effects of environmental stress factors. This study aimed to identify the inhibitory sites of NaCl in the whole photosynthetic electron transport in Synechocystis sp. PCC 6803 WT cells by using multiple biophysical tools. Exposure of cells to various NaCl concentrations (200 mM to 1 M) revealed the inhibition of Photosystem II (PSII) activity at the water oxidizing complex and between the Q_A and Q_B electron acceptors. In contrast to the inhibition of PSII, electron flow through Photosystem I (PSI) was accelerated, indicating enhanced cyclic electron flow. The oxygen-evolving capacity of the cells was inhibited to a larger extent when only CO₂ was the final electron acceptor in the Calvin-Benson-Bassham (CBB) cycle than in the presence of the PSII electron acceptor DMBQ, suggesting important NaCl inhibitory site(s) downstream of PSI. Measurements of NADPH kinetics revealed NaCl-induced inhibition of light-induced production of NADPH as well as retardation of NADPH consumption both in the light and in the initial dark period after switching off the light. Chlorophyll fluorescence kinetics, measured in parallel with NADPH fluorescence, showed the enhancement of post-illumination fluorescence rise up to 500 mM NaCl, which was however inhibited at higher NaCl concentrations. Our results show, for the first time, that NaCl inhibits the activity of the CBB cycle at least at two different sites, and confirm earlier results about the NaCl-induced inhibition of the PSII donor and acceptor side and the enhancement of electron flow through PSI.

Interest in natural herbicides has been growing due to government policies restricting synthetic herbicide use in many countries. In that regard, this study investigates the potential of Nigrospora oryzae extract as a natural herbicide against the aquatic invasive weed Eichhornia crassipes. A stable formulation was developed with a droplet size of 36.44 ± 0.36 nm and a zeta potential of -62.59 mV. Pot-based experiments revealed the N. oryzae extract induced 38.33% phytotoxicity within 24 hours, increasing to 84.72% by 28 days post-treatment. Scanning electron microscopy demonstrated morphoanatomical changes in epidermal tissue and stroma of E. crassipes, such as erosion of epicuticular waxes and degeneration of epidermis cells. The treatment significantly reduced the photosynthetic pigment content while increasing hydrogen peroxide (46.26%), malondialdehyde (17.49%), and proline (19.16%) levels, causing cellular electrolyte leakage. Activities of superoxide dismutase, catalase, ascorbate peroxidase, and guaiacol peroxidase were significantly elevated (p<0.05), indicating oxidative damage. These findings demonstrate that N. oryzae extract can disrupt growth and photosynthesis and induce oxidative stress in E. crassipes, suggesting its potential as a source of natural herbicide for industrial application.