Transcription factors and plant hormones mediate wax metabolism in response to drought stress.

Plants have, throughout evolution, developed a hydrophobic cuticle to protect them from various stresses in the terrestrial environment. The cuticle layer is mainly composed of cutin and cuticular wax, a mixture of very-long-chain fatty acids and their derivatives. With the progress of transcriptome sequencing and other research methods, the key enzymes, transporters and regulatory factors in wax synthesis and metabolism have been gradually identified, especially the study on the regulation of wax metabolism by transcription factors and others in response to plant stress has become a hot topic. Drought is a major abiotic stress that limits plant growth and crop productivity. Plant epidermal wax prevents non-stomatal water loss and improves water use efficiency to adapt to arid environments. In this study, the ways of wax synthesis, transport, metabolism and regulation at different levels are reviewed. At the same time, the regulation of wax by different transcription factors and plant hormones in response to drought is elaborated, and key research questions and important directions for future solutions are proposed to enhance the potential application of epidermal wax in agriculture and the environment.

Functional Identification of Malus halliana MhbZIP23 Gene Demonstrates That It Enhances Saline-Alkali Stress Tolerance in Arabidopsis thaliana.

Saline-alkali stress is a significant abiotic stress that restricts plant growth globally. Basic region leucine zipper (bZIP) transcription factor proteins are widely involved in plants in response to abiotic stress such as saline-alkali stress. Based on transcriptome and quantitative real-time PCR (qRT-PCR), we found that the MhbZIP23 gene could respond to saline-alkali stress. Despite this discovery, the underlying mechanism by which the MhbZIP23 transcription factor responds to saline-alkaline stress remains unexplored. To address this gap in knowledge, we successfully cloned the MhbZIP23 (MD05G1121500) gene from Malus halliana for heterologous expression in Arabidopsis thaliana, facilitating the investigation of its functional role in stress response. Compared to the wild type (WT), Arabidopsis plants demonstrated enhanced growth and a lower degree of wilting when subjected to saline-alkali stress. Furthermore, several physiological indices of the plants altered under such stress conditions. The transgenic Arabidopsis plants (OE-5, 6, and 8), which grew normally, exhibited a higher chlorophyll content and had greater root length in comparison to the control check (CK). MhbZIP23 effectively regulated the levels of the osmoregulatory substance proline (Pro), enhanced the activities of antioxidant enzymes such as peroxidase (POD) and superoxide dismutase (SOD), and reduced the levels of malondialdehyde (MDA) and relative conductivity (REC). These actions improved the ability of plant cells in transgenic Arabidopsis to counteract ROS, as evidenced by the decreased accumulation of O2- and hydrogen peroxide (H2O2). In summary, the MhbZIP23 gene demonstrated effectiveness in alleviating saline-alkali stress in M. halliana, presenting itself as an outstanding resistance gene for apples to combat saline-alkali stress.

Electricity-driven dealkalization of bauxite residue based on thermodynamics, kinetics, and mineral transformation.

High alkalinity content of bauxite residue is a major factor that hinders resource reutilization and pollutes the environment. Although acid neutralization is a direct and effective method, the amount of acid and secondary waste of sodium salt are still difficult problems to solve. Herein, we innovatively integrated an electric field into the acid neutralization dealkalization of bauxite residue and analyzed the dealkalization behavior by thermodynamics, kinetics, and mineral transformation. The results show that the pH of the anode chamber was maintained at the acidic levels of 3-6 after 30 min of galvanostatic electrolysis, and bauxite residue can realize dealkalization by acid neutralization. In the anode chamber, Na+ was released into the leachate via the reactions of Na3Al3Si3O12 and the removal of encapsulated soluble alkali. The stainless steel wire mesh anode exhibited its superiority and decreased the Na2O content in bauxite residue from 9.48 to 3.13% through convective mass transfer driven by the electric field and steady-state diffusion under stirring. This research provides a promising method for the electricity-driven dealkalization of bauxite residue, thus facilitating the development of multifield coupling theory and the application of electric fields in the alumina industry.

Genome-wide identification and expression analysis of the ALDH gene family and functional analysis of PaALDH17 in Prunus avium.

ALDH (Aldehyde dehydrogenase), as an enzyme that encodes the dehydroxidization of aldehydes into corresponding carboxylic acids, played an important role inregulating gene expression in response to many kinds of biotic and abiotic stress, including saline-alkali stress. Saline-alkali stress was a common stress that seriously affected plant growth and productivity. Saline-alkali soil contained the characteristics of high salinity and high pH value, which could cause comprehensive damage such as osmotic stress, ion toxicity, high pH, and HCO3-/CO32- stress. In our study, 18 PaALDH genes were identified in sweet cherry genome, and their gene structures, phylogenetic analysis, chromosome localization, and promoter cis-acting elements were analyzed. Quantitative real-time PCR confirmed that PaALDH17 exhibited the highest expression compared to other members under saline-alkali stress. Subsequently, it was isolated from Prunus avium, and transgenic A. thaliana was successfully obtained. Compared with wild type, transgenic PaALDH17 plants grew better under saline-alkali stress and showed higher chlorophyll content, Superoxide dismutase (SOD), Peroxidase (POD) and Catalase (CAT) enzyme activities, which indicated that they had strong resistance to stress. These results indicated that PaALDH17 improved the resistance of sweet cherries to saline-alkali stress, which in turn improved quality and yields. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01444-7.

Effects of Salt Stress on Salt-Repellent and Salt-Secreting Characteristics of Two Apple Rootstocks.

The effects of NaCl-induced salinity on biomass allocation, anatomical characteristics of leaves, ion accumulation, salt repellency, and salt secretion ability were investigated in two apple rootstock cultivars (Malus halliana '9-1-6' and Malus baccata), which revealed the physiological adaptive mechanisms of M. halliana '9-1-6' in response to salt stress factors. This experiment was conducted in a greenhouse using a nutrient solution pot. Salt stress was simulated by treating the plants with a 100 mM NaCl solution, while 1/2 Hoagland nutrient solution was used as a control (CK) instead of the NaCl solution. The results showed that the two rootstocks responded to salt environments by increasing the proportion of root biomass allocation. According to the stress susceptibility index, '9-1-6' exhibits a lower salt sensitivity index and a higher salt tolerance index. The thickness of the leaf, upper and lower epidermis, palisade tissue, and mesophyll tissue compactness (CTR) of the two rootstocks were significantly decreased, while the thickness of sponge tissue and mesophyll tissue looseness (SR) were significantly increased, and the range of '9-1-6' was smaller than that of M. baccata. With an extension of stress time, the accumulation of Na+ increased significantly, and the accumulation of K+ decreased gradually. The stem and leaves of '9-1-6' showed a lower accumulation of Na+ and a higher accumulation of K+, and the roots displayed a higher ability to reject Na+, as well as young and old leaves showed a stronger ability to secrete Na+. In conclusion, within a certain salt concentration range, the '9-1-6' root part can maintain lower salt sensitivity and a higher root-to-shoot ratio by increasing the proportion of root biomass allocation; the aerial part responds to salt stress through thicker leaves and a complete double-layer fence structure; the roots and stem bases can effectively reduce the transportation of Na+ to the aerial parts, as well as effectively secrete Na+ from the aerial parts through young and old leaves, thereby maintaining a higher K+/Na+ ratio in the aerial parts, showing a strong salt tolerance.

Comprehensive analysis revealed that titanium dioxide nanoparticles could strengthen the resistance of apple rootstock B9 to saline-alkali stress.

Apple growth and development can be adversely affected by saline-alkali stress, which has become a significant factor restricting the high yield of the apple industry. In recent years, nanomaterials have become a potential source for plant growth and development. Titanium dioxide nanoparticles (TiO2 NPs) play an important role in multiple plant development processes, including mitigating environmental stress. In this study, one-year-old apple rootstock B9 stem cuttings were used as research objects. Different concentrations of TiO2 NPs were applied to the roots before saline-alkali treatment. Principal component analysis showed that 1gkg-1 TiO2 NPs treatment had the best effect in alleviating the stress for B9. It significantly reduced the damage to B9 under salt-alkali stress, increased the content of photosynthetic pigment, enhanced the performance of Photosystem II, and promoted photosynthesis. At the same time, the content of K+ was increased, and the ion toxicity was alleviated. In addition, TiO2 NPs have also been shown to reduce B9 cell damage and lipid peroxidation, increase antioxidant enzyme activity, and regulate the accumulation of solutes. Overall, this study provides a theoretical basis for TiO2 NPs to mitigate the adverse effects of plants under saline-alkali stress and provides useful insights for managing other plants affected by global salinity and alkalinity.

Transcription factors dealing with Iron-deficiency stress in plants: focus on the bHLH transcription factor family.

Iron (Fe), as an important micronutrient element necessary for plant growth and development, not only participates in multiple physiological and biochemical reactions in cells but also exerts a crucial role in respiration and photosynthetic electron transport. Since Fe is mainly present in the soil in the form of iron hydroxide, Fe deficiency exists universally in plants and has become an important factor triggering crop yield reduction and quality decline. It has been shown that transcription factors (TFs), as an important part of plant signaling pathways, not only coordinate the internal signals of different interaction partners during plant development, but also participate in plant responses to biological and abiotic stresses, such as Fe deficiency stress. Here, the role of bHLH transcription factors in the regulation of Fe homeostasis (mainly Fe uptake) is discussed with emphasis on the functions of MYB, WRKY and other TFs in the maintenance of Fe homeostasis. This review provides a theoretical basis for further studies on the regulation of TFs in Fe deficiency stress response.

Analgesic Effect of Diprospan in Rats with Trigeminal Neuralgia / 华中科技大学学报（医学）（英德文版）

This study examined the analgesic effect of diprospan in rats with trigeminal neuralgia.Rat model of trigeminal neuralgic pain was established by loosely ligating the left infraorbital branch of the trigeminal nerve.After allodynia developed,the rats were randomly divided into 2 groups (n=20 in each):diprospan group,in which the rats received diprospan (7 mg/mL,0.1 mL) injected to the left infraorbital foramen area; control group,in which saline (0.1 mL) was administered as the same manner as the diprospan group.The pain threshold (PT) in the left infraorbital area was measured before and 2,6,and 8 weeks after the administration.The expression of neuropeptides [substance P,preprotachykinin A (PPTA),calcitonin gene-related peptide (CGRP)] in the trigeminal nerve was detected at the same time points as the PT measurement by immunohistochemistry or in siru hybridization method.The results showed that in the diprospan group,the PT was 10.65± 1.26,10.77± 1.19 and 14.13± 1.34 g 2,6,and 8 weeks after the administration respectively,significantly higher than that before the administration (PT value:0.36±0.11) (P＜0.05 for each).In the saline group,the PT was 0.37±0.13,0.66±0.09,4.45±1.29 and 13.72±1.72 g before and 2,6,and 8 weeks after the administration respectively with differences being significant between before and 6,8 weeks after the administration (P＜0.01).No significant difference existed in the PT between the diprospan group and the saline group at pre-administration (P＞0.05).The PT in the diprospan group was significantly greater than that in the saline group 2 and 6weeks post-administration (P＜0.05).In the diprospan group,the expression levels of neuropeptides were significantly reduced as compared with those in the saline group 2 and 6 weeks post-administration (P＜0.05).It was concluded that diprospan has an obvious analgesic effect on the trigeminal neuropathic pain partly by reducing the expression of neuropeptides in the trigeminal ganglia.