Juglans Regia Research Articles

Investigation of the influence of walnut shell extract on chromium (VI) content in leather

The effect of walnut shell extract ( Juglans regia) on chromium (VI) formation in leather during the finishing process is investigated in this study. The walnut shell extract composition was determined using gas chromatography. To enable chromium (VI) formation, finished leather samples were aged under various conditions, including exposure to ultraviolet light. The amount of chromium (VI) in each leather sample was measured using a Shimadzu UV-1601 PC UV-visible spectrophotometer at 540 nm based on the ISO/FDIS 17075 standard method. The results showed that the extracts from walnut shell ( Juglans regia) significantly reduced chromium (VI) formation in the leather under all aging conditions.

A Preliminary Study on the Identification of Genes Involved in Lignification in the Endocarp of Bared-Nut Walnut (Juglans regia L.) in Xinjiang, China

This study focused on the “Xinlu” walnut and explored the molecular regulatory mechanism of lignin synthesis in the endocarp, aiming to explain the formation of bared-nut walnuts through morphological, metabolomic, and transcriptomic techniques. It was found that the synthesis of lignin, cellulose, p-coumaryl alcohol, and sinapyl alcohol was severely inhibited in the pulpy-hue (PUH) of the endocarp. We obtained 14 modules (gene sets) significantly correlated with the lignification factor (LIG) and 1548 hub genes. Additionally, we identified a MEplum3 module involved in endocarp lignin synthesis, primarily participating in phenylalanine biosynthesis and the lignin biosynthetic process. Meanwhile, we constructed a gene co-expression network for the MEplum3 module and identified a key hub gene for lignin synthesis—JrCAD10. Among the different tissues of “Xinlu”, the expression level of JrCAD10 in the scleritic-hue (SCH) was significantly higher than in other tissues, with a relative copy number (RCN) of 3.2. However, JrCAD10 expression was severely suppressed in the PUH. The suppression of JrCAD10 expression led to the inhibition of lignin monomer synthesis, which further resulted in inhibited lignin synthesis, thus forming the bared-nut walnut. Our findings provide new insights into understanding the regulation of lignin synthesis and offer a possible explanation for the formation of bared-nut walnuts.

Influence of Cold Stress on Physiological and Phytochemical Characteristics and Secondary Metabolite Accumulation in Microclones of Juglans regia L.

The current study investigated the impact of cold stress on the morphological, physiological, and phytochemical properties of Juglans regia L. (J. regia) using in vitro microclone cultures. The study revealed significant stress-induced changes in the production of secondary antioxidant metabolites. According to gas chromatography-mass spectrometry (GC-MS) analyses, the stress conditions profoundly altered the metabolism of J. regia microclones. Although the overall spectrum of metabolites was reduced, the production of key secondary antioxidant metabolites significantly increased. Notably, there was a sevenfold (7×) increase in juglone concentration. These findings are crucial for advancing walnut metabolomics and enhancing our understanding of plant responses to abiotic stress factors. Additionally, study results aid in identifying the role of individual metabolites in these processes, which is essential for developing strategies to improve plant resilience and tolerance to adverse conditions.

A Novel Study on Antioxidant Activity and Catalytic Reduction of Methylene Blue using ZnO Nanoparticles Synthesized via the Middle Part of Walnut Shell (Juglans regia) Extract

Abstract: The synthesized ZnO nanoparticles were characterized using UV-Vis spectroscopy, SEM, XRD, FTIR, and TEM analysis. The catalytic activity of the prepared green catalyst ZnO nanoparticles was also investigated in the dye methylene blue (MB) decomposition. The catalytic decomposition reaction completed within 20 minutes, demonstrating the excellent catalytic properties of ZnO nanoparticles in reducing MB. This research describes the green synthesis of ZnO nanoparticles using an extract of the middle part of a walnut shell (Juglans regia). The antioxidant activities (radical capture capacity) of the synthesized ZnO nanoparticles were evaluated by the 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) assay at different ZnO nanoparticle concentrations, and the radical capture activity was achieved at IC50 = 146.32 μg / mL. The radical capture activity was achieved at IC50 = 146.32 μg / mL. The biosynthesis of ZnO nanoparticles was caused by hydroxide precipitation at room temperature after calcination at 450°C.

Identification and expression profiles of Tubby‑like proteins coding genes in walnut (Juglans regia L.) in response to stress and hormone treatments

Tubby-like proteins (TLPs) constitute a diverse multigene family found across a broad range of eukaryotic organisms, from single-celled to multicellular eukaryotes. Despite their importance, the existence of TLPs in walnuts (Juglans regia L.) has not been reported until now. In this study, we identified 12 members of the JrTLP gene family in the walnut genome, revealing a pattern of gene replication events. Notably, all JrTLPs exhibited a split gene structure, containing two to eight introns, and these genes could be divided into five distinct categories based on their evolutionary relationships. The majority of TLP proteins possess two signature domains: the F-box and Tubby domains. Subcellular localization prediction and experiments confirmed that JrTLP2 was located in the nucleus and membrane. Expression profiling revealed that multiple JrTLPs respond to a range of stimuli, including pathogen infection, hormonal treatment (such as auxin, ABA, MeJA, and GA), and abiotic stress conditions such as cold, heat, and salt. This study represents the first comprehensive identification of the walnut TLP family, providing valuable insights into the function and regulation of TLP in walnut and laying the foundation for future functional dissection, particularly in the context of stress tolerance.

Evaluation of the Effects of Consumption of Portuguese Walnuts (Juglans regia L.) on the Risk Factors Related to Cardiovascular Diseases

(1) Background: Walnut consumption has been associated with having a positive effect on controlling and/or reducing the co-morbidities associated with cardiovascular disease (CVD). The effects of consuming walnuts of Portuguese origin on risk factors related to CVD were evaluated by measuring glucose, urea, TC, HDL-C, LDL-C, TG, AST, and ALT levels, anthropometric profiles, and blood pressure. (2) Methods: This trial study involved 24 volunteers, both female (n = 15) and male (n = 9), from Fernando Pessoa University, Porto. It consisted of a daily intake of 25 g of walnut kernels over a period of 45 days. Before and after intake, biochemical parameters, BMI and BP were measured. (3) Results: Despite the intake of nuts revealing a reduction in mean values of most of the parameters assessed, a significant drop was only observed in AST (p = 0.04).There was also a significant reduction in the mean values for Glu (p = 0.01), UR (p = 0.01) and HDL-C (p = 0.02) for women but not for men. (4) Conclusions: The dose and the period of intake were not effective in lowering the lipid profile but may have had a protective effect on liver function. The benefits were greater in women than in men.

Global Perspectives on the Medicinal Implications of Green Walnut and Its Benefits: A Comprehensive Review

Green walnuts have been valued for their health and medicinal effects for many years. Green walnuts have several bioactive metabolites, including polyphenols, flavonoids, and tannins, that have antioxidant, anti-inflammatory, antimicrobial, and anticancer properties. With previous records of increased inclination towards natural or botanical sources of therapeutics, green walnuts have regained the uniqueness of therapeutic prominence globally. This comprehensive review provides a deep understanding of the use of green walnut (Juglans regia L.) around the globe and shows its potential pharmacological benefits. It explores the different therapeutic and medicinal uses of green walnuts, including their historical use in traditional medicine throughout different continents and regions, including Asia, Europe, America, Africa, and the Middle East. This review also provides the substantial studies conducted on green walnuts, which investigate the bioactive substances found in various parts of the walnut tree, including the kernel, shell, leaves, shoots, bark, and roots, indulging in their health advantages. It also diversifies the antibacterial, antioxidant, anti-inflammatory, cardiovascular, and antihypertensive activities of the green walnut, which clearly shows the prospective use of the walnut in nutraceutical and medicinal applications. This review continues by emphasizing the necessity for further research to focus on and attract global researchers to aim for a detailed understanding of the pharmacological implications of green walnuts and enhance their use in traditional and modern medicine.

Importance of Flora in the Economy of Local Inhabitants of Karnah in Jammu and Kashmir India

Present study, conducted in Karnah, Jammu and Kashmir, from February 2022 to August 2023, rigorously collected data through interviews, discussions, and observations. The Study investigated the economic significance of local flora, documenting 28 plant species across 20 families. Pinaceae (14%) stood out. Trees (n=18), herbs (n=10), and one shrub (n=1) were noted. Wild species (16) surpassed cultivated (12). Plant parts had varied economic uses; a significant difference (χ2=90.587, df=7, p<0.001) was observed. Notably, Juglans regia, Prunus cornuta, Celtis tetrandra, Ficus carica, Morus alba, and Cynodia oblang were highlighted for economic applications. "Whole plant" (51%), leaves (20%), fruits (17%), bulb and seeds (6% each) were the most used components. Six uses (Medicine, food, timber, fuel, aesthetic, and industrial) contributed to the local economy. This pioneering study sheds light on the economic role of plant taxa in the Karnah region of Jammu and Kashmir.

Assessment of the Application Possibilities of Dried Walnut Leaves (Juglans regia L.) in the Production of Wheat Bread

The main aim of this work was to assess the possibility of using dried walnut leaves (Juglans regia L.) in the production of wheat bread. In the developed recipe, wheat flour was partially replaced with dried and powdered walnut leaves (WLs) in amounts of 0.5%, 1.0%, 1.5%, 2.0% and 2.5%. Serving as a control sample was wheat bread without WLs. The bread was made using a single-phase method using yeast. As part of the research methodology, laboratory baking parameters (dough yield, total oven loss, bread yield), loaf volume and loaf specific volume were determined. Additionally, the colors of the dough, crust and bread crumb were determined in the CIE L*a*b* space. The crumb texture profile was assessed using the TPA test. Additionally, the antioxidant power and the total phenolic content of the dough and bread were tested. The consumer acceptability of the sensory features of the bread was also assessed. The test results were statistically analyzed using a one-way ANOVA. It was found that enriching the bread recipe with WLs had a significant impact on its quality. The control bread had the highest volume, and replacing wheat flour with dried leaves resulted in a significant reduction in volume, which was greater at higher WLs contents. Similarly, as the proportion of WLs in the recipe increased, a significant decrease in the brightness of both the dough and the crumb of the obtained bread was observed. A texture analysis showed that bread with a WLs content of 2.5% was the most different from the control bread and other tested breads. However, it was found that enriching bread with the unconventional addition of walnut leaves had a very good effect on its health benefits. The antioxidant activity and the content of total phenolics in the bread grew with the increase in the share of WLs in the recipe.

Exploring the Ecological Implications, Gastronomic Applications, and Nutritional and Therapeutic Potential of Juglans regia L. (Green Walnut): A Comprehensive Review.

The green walnut, which is frequently overlooked in favor of its more mature sibling, is becoming a topic of great significance because of its unique ecological role, culinary flexibility, and therapeutic richness. The investigation of the bioactive substances found in green walnuts and their possible effects on human health has therapeutic potential. Juglans regia L. is an important ecological component that affects soil health, biodiversity, and the overall ecological dynamic in habitats. Comprehending and recording these consequences are essential for environmental management and sustainable land-use strategies. Regarding cuisine, while black walnuts are frequently the main attraction, green walnuts have distinct tastes and textures that are used in a variety of dishes. Culinary innovation and the preservation of cultural food heritage depend on the understanding and exploration of these gastronomic characteristics. Omega-3 fatty acids, antioxidants, vitamins, and minerals are abundant in green walnuts, which have a comprehensive nutritional profile. Walnuts possess a wide range of pharmacological properties, including antioxidant, antibacterial, antiviral, anticancer, anti-inflammatory, and cognitive-function-enhancing properties. Consuming green walnuts as part of one's diet helps with antioxidant defense, cardiovascular health, and general well-being. Juglans regia L., with its distinctive flavor and texture combination, is not only a delicious food but also supports sustainable nutrition practices. This review explores the nutritional and pharmacological properties of green walnuts, which can be further used for studies in various food and pharmaceutical applications.

Description of Phenological Events of Persian Walnut (Juglans regia L.) according to the Extended BBCH Scale and Historical Scales

Walnut trees are grown worldwide for their edible fruits, which have high nutritional value. To address climate change, researchers have studied walnut phenology to create cultivars adapted to warmer climates. The objective of this study is to propose a scale for phenological Persian walnut observations using the Biologische Bundesanstalt, Bundessortenamt, und CHemische Industrie (BBCH) codification and alignment with historical alphameric scales. Here, the principal growth stages (PGSs) of Persian walnut (Juglans regia L.) are described using stages from a previously available alphanumeric scale. This standardised phenological scale describes Persian walnut growth from the dormant vegetative state through reproductive budding and senescence. This phenological scale is expected to increase the efficiency of walnut phenological monitoring. Fifty-seven stages are used to describe the life cycle of Persian walnut in this BBCH scale. Of these 57 stages, 3 stages are dedicated to seed germination (PGS-0), 4 stages are dedicated to bud development (PGS-0), 7 stages are dedicated to leaf development (PGS-1), 4 stages are dedicated to stem elongation (PGS-3), 8 stages are dedicated to inflorescence emergence (PGS-5), 5 stages are dedicated to male flowering (PGS-6), 5 stages are dedicated to female flowering (PGS-6), 5 stages are dedicated to fruit development (PGS-7), 12 stages are dedicated to fruit ripening (PGS-8), and 4 stages are dedicated to leaf senescence (PGS-9).

Diversity of specific indicators of walnut fruits during selection using various methods

Walnut (Juglans regia L.) is a particularly valuable plant for humans. This is due to its multifaceted beneficial properties and qualities as a food, medicinal, technical, recreational and environmental tree species. The main goal of nut breeding is to obtain high-quality fruits. In the Russian Federation for the selection of individuals that provide such products, two methods are mainly used: method 1 – «Program and method for breeding walnuts» (Sukhorukikh et al., 2007) and method 2 – «Program and method for the study of fruit, berry and nut crops» (1999). The purpose of the study is to study the diversity of promising forms of walnut identified on the basis of methods 1 and 2 in terms of taste, kernel extractability and the overall score of the breeding value (quality) of the fruit. Other characteristics assessed identically or similarly are not considered. The object of the research was the literature data of the authors assessing the quality of nuts using methods 1, 2. For statistical processing, the Stadia 8.0/prof. program was used, and Microsoft Excel was used for graphical construction. Diversity was assessed using coefficients of variation and indices of distributed rank diversity (IRRR) based on known methods. It was established that the coefficients of variation of the studied indicators, assessed using various methods, did not have a significant statistical difference, and the selection gradations of taste and kernel extractability were equally distributed. When assessed using method 1, the statistical distribution of the total score of the selection value of fruits had a normal distribution, when using method 2 it differed from normal. When assessing diversity using IRRR values, method 1, compared to method 2, turned out to be more sensitive and provided greater diversity of the allocated gene pool in terms of the overall score of the breeding value of walnut fruits. The results can be used in walnut breeding.

Investigating the potential of Juglans regia phytoconstituents for the treatment of cervical cancer utilizing network biology and molecular docking approach.

The fourth most frequent type of cancer in women and the leading cause of mortality for females worldwide is cervical cancer. Traditionally, medicinal plants have been utilized to treat various illnesses and ailments. The molecular docking method is used in the current study to look into the phytoconstituents of Juglans regia's possible anticancer effects on cervical cancer target proteins. This work uses the microarray dataset analysis of GSE63678 from the NCBI Gene Expression Omnibus database to find differentially expressed genes. Furthermore, protein-protein interactions of differentially expressed genes were constructed using network biology techniques. The top five hub genes (IGF1, FGF2, ESR1, MYL9, and MYH11) are then determined by computing topological parameters with Cytohubba. In addition, molecular docking research was performed on Juglans regia phytocompounds that were extracted from the IMPPAT database versus hub genes that had been identified. Utilizing molecular dynamics, simulation confirmed that prioritized docked complexes with low binding energies were stable.

Isolation and Characterization of the Sulfate Transporter Gene Family and Its Expression Pattern in Response to Selenium and Abiotic Stress in Walnuts (Juglans regia L.)

The sulfate transporter (SULTR) is responsible for the transport and uptake of sulfate, which plays an indispensable role in the growth cycle of plants and adaptation to plant stress. However, there are few reports on the response and regulation of SULTR gene family members in walnuts (Juglans regia L.) to sodium selenate, low temperatures, high temperatures, and simulated drought stress. In this study, the whole genome of the SULTR genes family in walnuts was identified and analyzed by the bioinformatics method. The results show that the walnut genome contains seventeen JrSULTR genes, which are unevenly distributed on eight chromosomes and can be divided into four subfamilies. Cis-acting elements that respond to stress and participate in the regulation of plant hormones were found in the promoter sequence of the JrSULTR genes. The analysis of transcriptome data showed that the expression of JrSULTR1.2b was significantly upregulated under sodium selenate treatment, and the results of qRT-PCR analysis were basically consistent with the transcriptome data. The expression of JrSULTR3.1a and JrSULTR3.4b increased with the prolongation of simulated drought stress time. The transcription levels of JrSULTR1.2b and JrSULTR3.1a were significantly increased after low-temperature treatment. After 9 h of high-temperature treatment, the expression levels of JrSULTR3.1a and JrSULTR3.3 were significantly increased. JrSULTR1.2b and JrSULTR3.1a showed significant expression specificity under stress treatment. At the same time, we also performed subcellular localization of these two genes, which was consistent with the predicted results and was in the cell membrane, and their regulatory functions need to be further studied. These studies laid the foundation for us to explore the specific function of the JrSULTR genes in alleviating abiotic stress in walnuts.

First Report of Neofusicoccum parvum Causing Fruit Rot on Psidium guajava in China.

Guava (Psidium guajava L.), a nutrient-rich and economically significant fruit, is extensively cultivated in southern China. In six continuous years (from 2018 to 2023), dark-purple rotted guava with sunken lesion were observed on guava trees (variety 'Zhenzhu', aged over 5 years) in Dongguan and Panyu districts, Guangdong Province. Annually, the incidence of fruit rot disease in the affected fields reached 30% to 50% and significantly reduced the yield and quality of harvest guava. The initial symptoms on the epicarp of the fruits were black, needle-like dots that rapidly spread, causing partial or complete fruit rot within two to three weeks. To identify the causative agent, six symptomatic fruits were collected from two different orchards. Samples of 0.5 cm³ were excised from the lesion margins of each fruit. These samples were surface-sterilized with 70% ethanol for 30 seconds, followed by 0.2% NaClO for 2-3 minutes, and rinsed in sterile water three times. The samples were then cultured on potato dextrose agar (PDA) at 25°C for five days. This process yielded eight fungal isolates with similar morphological. Initially, the colonies were white with dense aerial mycelium becoming dark gray after 4 to 5 days. The mycelia were septate and branched. No spores were observed on PDA. To induce spore formation, the isolates were cultured on water agar for 20 days. This process led to the production of hyaline, aseptate, ellipsoid conidia, which were thin-walled, smooth-surfaced, and measured 3.7-5.1 × 1.6-2.2 μm (n = 100). Three isolates, including at least one from each orchard (Np1, Np2, Np3), were selected for further analysis. Genomic DNA was extracted using Axygen MAG-FRAG-I-50 (Axygen Bio-Tek). The internal transcribed spacer of rDNAs (ITS), beta-tubulin (tub2), the nuclear ribosomal large subunit (LSU), and translation elongation factor 1-α (tef1-α) gene regions were amplified using the primers ITS1/4, Bt2a/Bt2b, LR5/LR0R, and EF1-728F/EF1-986R (Golzar and Burgess 2011) and sequenced. Sequence analysis using MEGA 7.0 (Kumar et al., 2018) revealed 100% similarity among the isolates. BLAST searches of the ITS, tub2, LSU, and tef1-α sequences (accession nos. MN907637, MT537938, MT528156, MT537939) showed the highest nucleotide similarities (99.24 to 100%) to Neofusicoccum parvum strains (Crous et al. 2006). A phylogenetic tree was constructed with MEGA 7.0 based on the nucleotide sequence tub2 using the maximum likelihood method. Pathogenicity tests on 10 healthy guava fruits using mycelium-inoculated and control fruits confirmed the causative agent. The inoculated fruits, maintained at 25°C under a 12-h light/dark cycle, exhibited symptoms identical to the field infections within four to seven days, while control fruits remained symptomless. The fungus, reisolated from the inoculated fruits, was morphologically identical to the original isolates, fulfilling Koch's postulates. In conclusion, based on molecular, morphological, and pathogenic analysis, N. parvum as the causal agent of the fruit rot disease on guava. Previously, N. parvum has been reported in association with fruit rot on Eriobotrya japonica and Juglans regia (Zhai et al. 2019; Chen et al. 2019). To our knowledge, this is the first report of N. parvum affecting guava in China.

Morphological and pomological assessments of seedling-originated walnut (Juglans regia L.) trees to select the promising late-leafing genotypes.

In many parts of the world, including Iran, walnut (Juglans regia L.) production is limited by late-spring frosts. Therefore, the use of late-leafing walnuts in areas with late-spring frost is the most important method to improve yield. In the present study, the phenotypic diversity of 141 seedling genotypes of walnut available in the Senejan area, Arak region, Markazi province, Iran was studied based on morphological traits to obtain superior late-leafing genotypes in the cropping seasons of 2022 and 2023. Based on the results of the analysis of variance, the studied genotypes showed a significant variation in terms of most of the studied morphological and pomological traits. Therefore, it is possible to choose genotypes for different values ​​of a trait. Kernel weight showed positive and significant correlations with leaf length (r = 0.32), leaf width (r = 0.33), petiole length (r = 0.26), terminal leaflet length (r = 0.34), terminal leaflet width (r = 0.21), nut length (r = 0.48), nut width (r = 0.73), nut weight (r = 0.83), kernel length (r = 0.64), and kernel width (r = 0.89). The 46 out of 141 studied genotypes were late-leafing and were analyzed separately. Among late-leafing genotypes, the length of the nut was in the range of 29.33-48.50mm, the width of the nut was in the range of 27.51-39.89mm, and nut weight was in the range of 8.18-16.06g. The thickness of shell was in the range of 1.11-2.60mm. Also, kernel length ranged from 21.97-34.84mm, kernel width ranged from 21.10-31.09mm, and kernel weight ranged from 3.10-7.97g. Based on important and commercial traits in walnut breeding programs, such as nut weight, kernel weight, kernel percentage, kernel color, and ease of kernel removal from nuts, 15 genotypes, including no.92, 91, 31, 38, 33, 18, 93, 3, 58, 108, 16, 70, 15, 82, and 32 were superior and could be used in walnut breeding programs in line with the introduction of new cultivars and the revival of traditional walnut orchards to commercialize them.

Dimensional variations in fusiform and ray initials over different seasons of year in Juglans regia Linn. from temperate type of climate of Kashmir Himalaya

Dimensional variations in fusiform and ray initials over different seasons of year in Juglans regia Linn. from temperate type of climate of Kashmir Himalaya

Pest categorisation of Crisicoccus seruratus.

Following the commodity risk assessments of Acer palmatum plants grafted on A. davidii from China, in which Crisicoccus matsumotoi (Hemiptera: Pseudococcidae) was identified as a pest of possible concern, the European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of C. matsumotoi for the territory of the European Union. Recent taxonomic revision of the genus Crisisoccus concluded that C. matsumotoi is a synonym of C. seruratus; therefore, the categorisation will use the current valid name C. seruratus. It is an insect pest native to Japan, feeding on species in 13 plant families. There are reports of its presence also in China and the Republic of Korea, but there is great uncertainty about the identity of the species for these records. Therefore, there is uncertainty about the species referred to as C. matsumotoi in the commodity risk assessments of A. palmatum. C. seruratus is a multivoltine species. It has three generations per year and overwinters as a nymph. The most important crops that may be affected by C. seruratus are figs (Ficus carica), grapes (Vitis spp.), nashi pears (Pyrus pyrifolia var. culta), persimmons (Diospyros kaki) and walnuts (Juglans regia). Plants for planting and fruits provide potential pathways for entry into the EU. Host availability and climate suitability suggest that the central, northern and some areas of southern EU countries would be suitable for the establishment of C. seruratus. The introduction of this mealybug would likely have an economic impact in the EU through yield reduction and fruit downgrading because of honeydew deposition and the consequent growth of sooty moulds. This insect is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. Phytosanitary measures are available to reduce the likelihood of entry and spread of this species into the EU. C. seruratus satisfies the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Growth responses of Persian walnut (Juglans regia L.) to climate variation along its full elevational range in Kyrgyzstan

Kyrgyzstan features the largest naturally occurring walnut forests in the world. Their high plant biodiversity, including wild relatives to modern-day fruit species such as apple and pear, make them a valuable guardian of genetic diversity. Further, walnut forests have a high economic importance for the country. Climate change, however, poses a major threat to these ecosystems, in particular since rises in temperature are projected that are well above global average. As studies on effects of changing environmental conditions on the growth of walnut are missing, we investigate the climate sensitivity and temporal stability thereof as well as extreme growth responses of walnut along its full elevational gradient in Kyrgyzstan. Whereas we expected to find a shift from water- to temperature-limitation over the elevational gradient, which may move upwards with recent warming, we found walnut growth to be temperature-limited along the entire elevational gradient. In recent decades, negative correlations between the drought index SPEI and tree growth, however, weakened. An up until now low importance of drought stress for walnut growth is also substantiated by a pointer-year analysis. Overall, our results show that walnut growth is already affected by climate change, though imminent risks of drought-induced vitality loss seem still low. With ongoing climate change, this may, however, rapidly change.

Identification and Analysis of Expression Patterns of the Caleosin Genes in Hickory (Carya cathayensis Sarg.)

The deciduous tree hickory (Carya cathayensis) holds economic significance in China due to its high oil content, particularly in unsaturated fatty acids. Oil bodies are crucial for storing triacylglycerol (TAG), with caleosin serving as a predominant oil body protein that aids in oil body formation and stability maintenance. Our study utilized bioinformatics techniques to identify caleosin genes within Carya cathayensis, Carya illinoinensis, and Juglans regia. Three caleosin genes were discovered in the genomes of Carya cathayensis, Carya illi-noinensis, and Juglans regia. These genes encode hydrophilic proteins. Additionally, all caleosin proteins feature a single Ca2+-binding EF-hand, a conserved “proline knot” motif, and a C-terminal hydrophilic region with four potential phosphorylation sites. The caleosin proteins in Carya cathayensis consist of α-helix, β-corner, extended chain, and random curl structures. Cis-acting elements related to stress response and hormone signaling were identified in Carya cathayensis, Carya illinoinensis, and Juglans regia, with distinct cis-acting elements implicated in seed-specific regulation in Carya cathayensis. Additionally, subcellular localization analysis confirmed that CcaCLO1 and CcaCLO2 were localized within oil bodies. Transcriptome analysis and quantitative real-time polymerase chain reaction (qRT-PCR) data demonstrated a significant up-regulation of CcaCLO1 expression during the developmental stages of the Carya cathayensis embryo. Furthermore, qPCR findings indicated that caleosins from Carya cathayensis were responsive to salt stress, with a significant up-regulation of CcaCLO1 following exposure to salt stress treatment. Consequently, caleosin genes in Carya cathayensis, Carya illinoinensis, and Juglans regia share similar physicochemical characteristics and conserved motifs. Specifically, CcaCLO1 in Carya cathayensis primarily responds to embryo development and salt stress. These findings offer foundational insights for future investigations into the regulatory mechanisms of oil accumulation and response to salt stress in hickory.