Understanding and predicting plant water dynamics during and after water stress is increasingly important but challenging because the high-dimensional nature of the soil-plant-atmosphere system makes it difficult to identify mechanisms and constrain behaviour. Datasets that capture hydrological, physiological and meteorological variation during changing water availability are relatively rare but offer a potentially valuable resource to constrain plant water dynamics. This study reports on a drydown and re-wetting experiment of potted Populus trichocarpa, which intensively characterised plant water fluxes, water status and water sources. We synthesised the data qualitatively to assess the ability to better identify possible mechanisms and quantitatively, using information theory metrics, to measure the value of different measurements in constraining plant water fluxes and water status. Transpiration rates declined during the drydown and then showed a delayed and partial recovery following rewatering. After rewatering, plant water potentials also became decoupled from transpiration rates and the canopies experienced significant yellowing and leaf loss. Hormonal mechanisms were identified as a likely driver, demonstrating a mechanism with sustained impacts on plant water fluxes in the absence of xylem hydraulic damage. Quantitatively, the constraints offered by different measurements varied with the dynamic of interest, and temporally, with behaviour during recovery more difficult to constrain than during water stress. The study provides a uniquely diverse dataset offering insight into mechanisms of plant water stress response and approaches for studying these responses.

Salt accumulation can degrade soil properties, decrease its productivity, and harm its ecological functions. Introducing salt-tolerant plant species associated with arbuscular mycorrhizal fungi (AMF) can act as an effective biological method for restoring salinized soils. AMF colonize plant roots and improve their nutrient acquisition capacity. However, there is limited knowledge on how AMF affects the production of signaling molecules, e.g., abscisic acid (ABA), salicylic acid (SA), and jasmonic acid (JA), related to plant-microbe interactions under salinity. Here, we assess the potential benefits of the AMF Rhizophagus intraradices in enhancing plant growth and nutrient uptake in addition to modulating stress hormone signaling levels (ABA, SA, and JA) of the facultative halophyte Sulla carnosa under saline conditions. Plants were grown in pots filled with soil and irrigated with 200 mM NaCl for 1 month. AMF symbiosis substantially increased the shoot dry weight (+107%), root dry weight (+67%), photosynthetic pigment content (chlorophyll a, chlorophyll b, and carotenoids), and nutrient uptake (C, N, P, K, Cu, and Zn) while significantly limiting the increase in the shoot Na+ concentration and H2O2 content caused by salinity stress. Mycorrhizal symbiosis significantly enhanced the root and shoot SA levels by 450% and 32%, respectively, compared to the stressed non-inoculated plants, potentially contributing to enhanced systemic resistance and osmotic adjustment under saline conditions. Salt stress increased the shoot ABA content, especially in R. intraradices-inoculated plants (113% higher than in stressed non-mycorrhizal plants). These findings confirm that AMF mitigated the adverse effects of salinity on S. carnosa by increasing the SA and ABA levels and reducing oxidative damage.

Salinization is a significant global issue causes irreversible damage to plants by reducing osmotic potential, inhibiting seed germination, and impeding water uptake. Seed germination, a crucial step towards the seedling stage is regulated by several hormones and genes, with the balance between abscisic acid and gibberellin being the key mechanism that either promotes or inhibits this process. Additionally, mucilage, a gelatinous substance, is known to provide protection against drought, herbivory, soil adhesion, and seed sinking. However, limited information is available on the structure and thickness of seed mucilage in halophytes under different salinity conditions. In this study, the mucilage structure of the extreme halophyte Schrenkiella parvula was compared with the glycophyte Arabidopsis thaliana in response to salinity. We found differences in the expression levels of genes such as ABI5, RGL2, DOG1, ENO2, and DHAR2, which are involved in seed germination and antioxidant activity, as well as in the mucilage structure of seeds of S. parvula and A. thaliana seeds at different salt concentrations. The responses of seed germination of S. parvula to salinity indicate that it is more salt-tolerant than A. thaliana. Additionally, it was found that S. parvula mucilage decreased under salt conditions but not under mannitol conditions, whereas in A. thaliana mucilage did not change under both conditions, which is one of the adaptation strategies of S. parvula to salt conditions. We believe that these fundamental analyzes will provide a foundation for future molecular and biochemical studies comparing the responses of crops and halophytes to salinity stress.

Soil salinity presents a dual challenge for plants, involving both osmotic and ionic stress. In response, plants deploy distinct yet interconnected mechanisms to cope with these facets of salinity stress. In this investigation, we observed a substantial overlap in the salt (NaCl)- induced transcriptional responses of Arabidopsis roots with those triggered by osmotic stress or the plant stress hormone abscisic acid (ABA), as anticipated. Notably, a specific cluster of genes responded uniquely to sodium (Na+) ions and are not regulated by the known monovalent cation sensing mechanism MOCA1. Surprisingly, expression of sodium- induced genes exhibited a negative correlation with the ABA response and preceded the activation of genes induced by the osmotic stress component of salt. Elevated exogenous ABA levels resulted in the complete abolition of sodium- induced longed sodium- induced gene expression, coupled with increased root cell damage and root swelling under high salinity conditions. Moreover, ABA biosynthesis and signaling mutants were unable to redirect root growth to avoid high sodium concentrations and had increased sodium accumulation in the shoot. In summary, our findings unveil an by salinity stress and modulating sodium- induced responses in plant roots.

The use of plant growth-promoting microorganisms is an effective agricultural practice to improve plant growth, especially under abiotic stress. In this study, the combined impact of three plant growth-promoting bacteria (PGPB) namely Brevibacterium halotolerans (Sd-6), Burkholderia cepacia (Art-7), Bacillus subtilis (Ldr-2) were tested with Trichoderma harzianum (Th) (possessing ACC deaminase producing activity) in Ocimum basilicum L. cv. Saumya to reduce drought-induced damages to the plants under different level of drought stress [i.e. wellwatered (100 %), moderate (60 %), severe (40 %)]. These PGPB strains, along with Th, were found to be tolerant against osmotic stress when tested in growth media containing different concentrations of polyethylene glycol (PEG 8000), and all were found to endure -0.99 MPa water potential. Compared to non-inoculated control, Th+Ldr-2 treatment improved fresh herb weight (62.45 %) and oil content (61.54 %) and higher photosynthetic rate under severe drought. Besides, in relation to control, the above treatment enhanced nutrient uptake, reduced ABA, ACC as well as ethylene levels and increased IAA content in addition to an increase in important constituents of essential oil, indicating better performance in terms of plant growth under drought. Higher RWC, decreased MDA, and reduced antioxidant activities in Th+Ldr-2 treated plants compared to non-inoculated control under drought support the mechanism of the microbes providing tolerance against drought. Colony forming unit of microbes and scanning electron microscopy (SEM) study support the effective colonisation behaviour of Th+Ldr-2, which protects plants against drought stress. A consortium of diverse microbes, found to improve plant growth under drought through increased nutrient uptake, reducing the levels of ACC and ABA, improving the content of IAA, antioxidant enzymes probably reducing the effect of drought stress and improving plant biomass could be a useful tool to reduce drought-induced losses in crop plants.

The investigation of the response mechanisms of Cyperus esculentus to water and salt stresses is crucial for the enhancement of the productivity of saline soils. Previous studies have indicated that plant hormones, antioxidant systems, and osmoregulation may contribute to the stabilization of yield. However, the contributions and interactions of these mechanisms remain poorly understood under combined water and salt stress in natural environments. A dual-factor (salt and water) orthogonal test was used to investigate the growth and biochemical responses of C. esculentus, under combined salt and water stress in a field experiment conducted on a typical saline area in northern China. The findings reveal that C. esculentus adjusted its biomass allocation strategies and activated hormone responses, antioxidant system, and osmoregulation mechanisms to maintain stable yield. Due to the negative synergism when salt and water stress coexist, the homogeneous limitations of both are weakened. Thus, the key to maintaining yields under combined water and salt stress may depend on indirectly enhancing tolerance to oxidative damage through abscisic acid, rather than focusing on accumulating low molecular weight osmoregulants and antioxidant enzymes to directly alleviate homogeneous limitations. Also, under combined salt and water stress, insufficient irrigation may have a greater impact on morphological characteristics than high salinity. The above results contribute to a deeper understanding of the process of adapting C. esculentus to combined salt and water stress.

Spikelet degeneration in rice (Oryza sativa L.) is a serious physiological defect, and can be regulated by soil moisture status and phytohormones. This study investigated the possibility that brassinosteroids (BRs) in collaboration with abscisic acid (ABA) are involved in mediating the effect of soil drying during meiosis on spikelet degeneration in rice. Three rice cultivars were field grown and three irrigation regimes including well watered (WW), moderate soil drying (MD), and severe soil drying (SD) were imposed during meiosis. MD significantly decreased spikelet degeneration in comparison with WW, due mainly to the alleviation in oxidative damage via enhancing ascorbate-glutathione (AsA-GSH) cycle activity in young panicles, and SD exhibited the opposite effects. Enhanced AsA-GSH cycle strength, decreased oxidative stress, and spikelet degeneration rate were closely associated with the synergistically elevated BR and ABA levels in young panicles in MD. In contrast, low BR and excessive ABA levels led to an increase in spikelet degeneration in SD. The three cultivars exhibited the same tendencies. The intrinsic link among AsA-GSH cycle, oxidative stress, spikelet degeneration rate, and BR and ABA levels was further verified by using transgenic rice lines and chemical regulators. BRs or ABA play a unique role in regulating spikelet degeneration. Synergistically increased BR and ABA levels in MD could work together to strengthen AsA-GSH cycle activity, leading to a reduction in oxidative damage and spikelet degeneration. On the other hand, a severe imbalance between low BR and excessive ABA levels may have contributed to the opposite effects in SD. Enhanced brassinosteroid (BR) and abscisic acid (ABA) levels in a moderate soil-drying regime during meiosis can synergistically suppress spikelet degeneration in rice, whereas a severe imbalance between low BR and excessive ABA levels in a severe soil-drying regime leads to an increase in spikelet degeneration.

In recent years, alkaline soda soil has stimulated numerous biological research on plants under carbonate stress. Here, we explored the difference in physiological regulation of rice seedlings between saline (NaCl) and alkaline carbonate (NaHCO3 and Na2CO3) stress. The rice seedlings were treated with 40 mM NaCl, 40 mM NaHCO3 and 20 mM Na2CO3 for 2 h, 12 h, 24 h and 36 h, their physiological characteristics were determined, and organic acid biosynthesis and metabolism and hormone signalling were identified by transcriptome analysis. The results showed that alkaline stress caused greater damage to their photosynthetic and antioxidant systems and led to greater accumulation of organic acid, membrane damage, proline and soluble sugar but a decreased jasmonic acid content compared with NaCl stress. Jasmonate ZIM-Domain (JAZ), the probable indole-3-acetic acid-amido synthetase GH3s, and the protein phosphatase type 2Cs that related to the hormone signalling pathway especially changed under Na2CO3 stress. Further, the organic acid biosynthesis and metabolism process in rice seedlings were modified by both Na2CO3 and NaHCO3 stresses through the glycolate/glyoxylate and pyruvate metabolism pathways. Collectively, this study provides valuable evidence on carbonate-responsive genes and insights into the different molecular mechanisms of saline and alkaline stresses.

This study, focusing on porous sheet mulching cultivation for high -quality and annual steady production of Satsuma mandarin, investigated trees photosynthetic oxidation stress according to the soil moisture in the porous mulching cultivation. Leaf, vesicle tissue water status, chlorophyll fluorescence, plant hormone abscisic acid (ABA) and jasmonic acid (JA) activity were measured using a phychrometer sample chamber, potable fluorescene meter and UHPLC and MS/MS were measured. Leaf water potential fluctuated according to the change in soil moisture content between the non -sheet mulching (control) and restoring the porous sheet (mulching) groups throughout this experiment period, and about 2 weeks intervals drip irrigation after the mulching (Mul. + Drip). In September, the leaf water potential of the control (-0.9 similar to -1.3 MPa) was higher than that of the mulching (-2.5 similar to -2.7 MPa), and Mul. + Drip (-2.2 similar to -2.3 MPa) groups. In October, due to continuous dry weather, the results of control and mulching were -3.0 MPa and -4.0 MPa or below respectively, which were lower than Mul. + Drip (-2.64 MPa). The water potential of vesicle tissue also fluctuated similarly to that of the leaf water potential. The osmotic potential was tendentially higher in the control than that in mulching and Mul. + Drip group. The turgor pressure remained constant at 0.5 MPa in October and November except for the time in September. The soluble solids content (SSC) of fruit at harvest was higher at 14.55 degrees Brix in the mulching and 13.96 degrees Brix in the Mul. + Drip, which were both higher than 11.05 degrees Brix in the control, showing a significant difference and confirming a rise in the SCC caused by osmotic control. The degree of oxidative damage according to water stress level caused by drought stress was investigated by the comparison of the maximum quantum efficiency value of (Fv/Fm), the initial fluorescence value (Fo) value, and the change in photosynthetic rate. The concentration of ABA in the leaf, fruit peel, and flesh was relevant to the leaf moisture stress and fruit sugar content. The concentration of JA varied as the concentration of ABA changed. In conclusion, Fv/Fm and Fo of chlorophyll PSII and ABA regarding photosynthetic oxidative damage were found to be indicators of the degree of damage according to tree water stress levels.