Juglans Regia Research Articles

Population genetic insights into the conservation of common walnut (Juglans regia) in Central Asia

The common walnut (Juglans regia) is one of the most economically important nut trees cultivated worldwide. Despite its importance, no comprehensive evaluation of walnut tree population genetics has been undertaken across the range where it originated, Central Asia. In this study, we investigated the genetic diversity and population structure of 1082 individuals from 46 populations across Central Asia. We found moderate genetic diversity of J. regia across Central Asia, with 46 populations clustered into three groups with a weak relationship between genetic and geographic distance. Our findings reveal that the western Himalaya might be the core region of common walnut genetic diversity in Central Asia and that, except for two populations in Gongliu Wild Walnut Valley, humans might have introduced walnut populations to Xinjiang, China. The observed distribution of the genetic landscape has probably been affected by historical climate fluctuation, breeding system, and prolonged anthropogenic activity. We propose the conservation of the core genetic diversity resources in the western Himalaya and pay special attention to populations from Gongliu in Xinjiang. These findings enhance our understanding of the genetic variation throughout the distribution range of J. regia in Central Asia, which will provide a key prerequisite for evidence-based conservation and management.

Cascade computational model for prediction impact of transient depth change on combustion parameters of certain timber species under continuous heating rate

The purpose of this research is to examine the effects of depth variation and exposure duration on the combustion characterization of the Maple wood species (Acer platanoides L.) and Walnut (Juglans regia L.) according to ISO 5660–1 in case of exposing the specimens to a constant heating rate 50 kWm−2. The delivered experimental data by cone calorimeter apparatus is used to train, test, and validate the optimized cascade forward artificial neural network with topology 2–8–8–12–2. This structure is simulated to predict the target parameters: the heat release rate (HRR) and the mass burning rate (MBR). With real systems, it is possible to achieve a reasonable performance and the closest approximations for the cascade model. The experimental combustion parameters: time of flame out, average specific mass burning rate, total heat release, maximum average rate of heat emission, and fire growth index are considered to make a systematic analysis and assessment with change depth. Three regions are considered for investigation of output target curves, thermally thin (d ≤ 1.1 cm), thermally medium (1.1 cm < d< 1.5 cm), thermally thick (d≥ 1.5cm). The findings demonstrate that independent of exposure period, an increase in depth change causes a sizable reduction in the HRR and MBR. Beyond 1.5 cm of depth in thermally thick regions, there is no discernible effect of time instant on changes in target parameters. In contrast, HRR and MBR gradients across depth in thermally thin regions are striking.

Stilbocrea banihashemiana, an emerging fungal pathogen associated with canker and dieback diseases in walnut trees

Persian walnut (Juglans regia L.), a globally significant and economically important tree, is cultivated worldwide for its valuable wood and nutritious nuts. In this study, we conducted a comprehensive survey of the trees exhibiting signs of distress, such as trunk and branch cankers, dieback, and wood discoloration, in the central region of Fars Province in Iran. Initial morphological identification indicated that the fungal isolates recovered from the canker symptoms belonged to a newly emerged ascomycete pathogen, Stilbocrea banihashemiana. The identification was further confirmed by utilizing species-specific primer pairs for S. banihashemiana. Pathogenicity assessments on detached shoots and one-year-old saplings revealed the isolates' ability to induce wood necrosis symptoms. The cross-pathogenicity test with isolates of S. banihashemiana from walnut and other reported hosts, including fig, loquat, and pomegranate was performed on detached branches. The results indicated varying levels of aggressiveness of the isolates across the different host species examined. To our knowledge, this is the first global confirmation of the isolation of S. banihashemiana from infected Persian walnut trees and the assessment of its pathogenicity on this new host.

JrGA20ox1-transformed rootstocks deliver drought response signals to wild-type scions in grafted walnut.

Targeted regulation using transgrafting technology has become a trend. However, the mechanisms of transgene-derived signal communication between rootstocks and scions remain unclear in woody plants. Here, we grafted wild-type (WT) walnut (Juglans regia L.) on WT (WT/WT), JrGA20ox1 (encodes a gibberellin 20-oxidase)-overexpressing (WT/OE), and JrGA20ox1-RNAi transformation (WT/RNAi) walnut in vitro. We aimed to elucidate the mechanisms of JrGA20ox1-derived signal communication under PEG-simulated drought stress between rootstocks and scions in walnut. We demonstrated that JrGA20ox1-OE and JrGA20ox1-RNAi rootstocks could transport active gibberellins (GAs) and JrGA20ox1-RNAi vector-produced sRNAs to WT scions under PEG-simulated drought stress, respectively. The movement of sRNAs further led to a successive decline in JrGA20ox1 expression and active GA content. Meanwhile, unknown mobile signals may move between rootstocks and scions. These mobile signals reduced the expression of a series of GA-responsive and GA-non-responsive genes, and induced ROS production in guard cells and an increase in ABA content, which may contribute to the drought tolerance of WT/RNAi, while the opposite occurred in WT/OE. The findings suggest that JrGA20ox1-derived rootstock-to-scion movement of signals is involved in drought tolerance of scions. Our research will provide a feasible approach for studying signal communication in woody plants.

Test and analysis of walnut (Juglans regia L.) tree vibration transfer based on a low-frequency shaking table

Clarifying the low-frequency vibration transfer law of fruit trees is an important prerequisite for studying the intelligent harvesting operation of a low-frequency shaker. Through a vibration transmission test involving vibration parameters, tree parameters, and proportional acceleration, this study found that vibration frequency, amplitude, pre-tension, and rope length were the most significant influencing factors of proportional acceleration. Among them, amplitude and pre-tension have positive effects on proportional acceleration, vibration frequency and rope length have negative effects on proportional acceleration, and the interaction between amplitude and vibration frequency has significant effects on proportional acceleration. The proportional acceleration has a maximum response of 8.12 m/s2 when the vibration frequency is 6.86 Hz, the amplitude is 64.92 mm, the pre-tension is 1007.02 N, and the rope length is 6 m. The results of the study can guide research on and development of a low-frequency intelligent shaking machine as well as its field operation.

Evaluation of anthelmintic efficacy of ethanolic leaf extract of Juglans regia L. on Ascaridia galli: a comprehensive in vitro and in vivo study.

Anthelmintic resistance in livestock animals has been spreading across the world in prevalence and severity. As a result, researchers are exploring alternative strategies to combat this issue, and one promising avenue is the utilization of medicinal plants. This study aims to investigate the anthelmintic efficacy of the crude ethanolic extract (CEE) derived from the leaves of Juglans regia against one of the most detrimental nematode parasites affecting poultry, namely Ascaridia galli (A. galli). For the in vitro studies, adult A. galli worms were collected from the naturally infected chickens and the efficacy of CEE was measured at the concentration of 25, 50, and 100mg/ml using adult worm motility inhibition (WMI) assay. In addition, levamisole (0.55mg/ml) was used as the positive control. Likewise, Phosphate buffered saline (PBS) was used as the negative control. For the in vivo studies, CEE of J.regia at the doses of 500, 1000, and 2000mg/kg were evaluated in chickens experimentally infected with A. galli. The anthelmintic efficacy was monitored using faecal egg count reduction (FECR) and worm count reduction (WCR) assays. In vitro studies revealed significant (P < 0.001) anthelmintic effects of CEE of J.regia on the motility of A. galli worms at different hours post-exposure. At the concentration of 100mg/ml, CEE resulted in 96.5% inhibition of worm motility at 24h post-exposure. While the synthetic anthelmintic drug, levamisole caused the highest inhibition of worm motility (100%) at the same time period. The in vivo anthelmintic activity of CEE of J. regia demonstrated a maximum effect on day 14 post-treatment by inducing 67.28% FECR and 65.03% WCR. We observed no significant difference (P > 0.05) in worm counts between the negative control group and the chickens treated with CEE at the dosage of 500mg/kg. Together, the results of the present study suggest that CEE of J. regia leaves possess anthelmintic properties and could be a potential source of novel anthelmintic compounds for controlling helminth parasites.

Genome-wide identification of walnut (Juglans regia) PME gene family members and expression analysis during infection with Cryptosphaeria pullmanensis pathogens

Walnuts exhibit a higher resistance to diseases, though they are not completely immune. This study focuses on the Pectin methylesterase (PME) gene family to investigate whether it is involved in disease resistance in walnuts. These 21 genes are distributed across 12 chromosomes, with four pairs demonstrating homology. Variations in conserved motifs and gene structures suggest diverse functions within the gene family. Phylogenetic and collinear gene pairs of the PME family indicate that the gene family has evolved in a relatively stable way. The cis-acting elements and gene ontology enrichment of these genes, underscores their potential role in bolstering walnuts' defense mechanisms. Transcriptomic analyses were conducted under conditions of Cryptosphaeria pullmanensis infestation and verified by RT-qPCR. The results showed that certain JrPME family genes were activated in response, leading to the hypothesis that some members may confer resistance to the disease.

Investigation of cytogenetic, electrophoretic, histopathological and biochemical effects of walnut (juglans regia l.) Leaf extract in rats experimentally induced diabetes by streptozotocin

In this study, the effects of Juglans regia L. (JR) leaf extract on histological damage and cytogenetic, electrophoretic, and biochemical parameters in the liver and kidney tissues of diabetic rats were investigated. In the study, 60 male rats (Sprague-Dawley) were separated into six groups. According to sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) data, it was determined that there were increases and decreases in different serum protein expressions because of the treatment of JR leaf extract in the diabetes group. In the kidney tissue of the diabetes group, an increase in volume in the glomeruli and narrowing of the Bowman's space as well as thickening of the walls of tubules were detected. Vacuolization and shedding were observed in the epithelial cells of tubules in the cortical regions in kidney. In diabetic + JR extract groups administered JR leaf extract at doses of 250 mg/kg and 500 mg/kg, serum AST and ALT levels were reduced compared to the diabetic group. Diabetic rats' livers showed spotted necrosis and fibrosis in the portal area, biliary tract proliferation, mild inflammation, increased vascularization, unicellular necrosis in hepatocytes, and sinusoidal dilatation. The JR leaf extract group did not exhibit these problems. JR leaf extract influences reducing hepatotoxic and oxidative damage due to diabetes and increasing the level of antioxidant enzymes. As a result, it was concluded that the application of JR leaf extract may have a protective effect against damage caused by diabetes.

Anti-inflammatory, antioxidant activity, and acetylcholinesterase inhibitory activity of leaf extract of Juglans regia: Insight into the treatment of neurodegenerative diseases

Neuroinflammation, depletion of acetylcholine and neuronal oxidative stress are hallmarks of neurodegenerative diseases such as Alzheimer’s disease. This study sought to investigate in vitro acetylcholinesterase inhibitory activity, free radical scavenging, antioxidant activity, and anti-inflammatory activity of aqueous leaf extract of Juglans regia. The antioxidant, anti-inflammatory, and acetylcholinesterase-inhibitory activities of the extract were evaluated using different appropriate techniques. The extract showed substantial free radical scavenging and antioxidant activity by markedly scavenging hydroxyl radical, DPPH, nitric oxide, hydrogen peroxide, with concomitant high free radical reducing power. Similarly, lipid peroxidation and inflammation were significantly inhibited by the extract. The extract elicited acetylcholinesterase-inhibitory potential of 45.49%, suggesting they could be beneficial in managing neurodegenerative diseases. These biological activities can be attributed to the phytochemical constituents of the extract. Preliminary phytochemical screening of the extract showed the presence of polyphenols, flavonoids, and tannins and GCMS identified phytochemicals including vanillic acid, p-Coumaric acid, caffeic acid, squalene. This study concluded that the aqueous leaf extract of J. regia exhibited significant antioxidant, anti-inflammatory and acetylcholinesterase-inhibitory activities which could be beneficial in mitigating the pathological features of Alzheimer’s disease and other neurodegenerative diseases, thus, it could be explored as health-promoting dietary supplements/ products.

The ethnobotanical heritage of Lotkuh, a high-altitude tribal haven of Chitral, the Eastern Hindu Kush, Pakistan

BackgroundIn northwestern Pakistan, Lotkuh is a high-altitude terrain nestled within the eastern Hindu Kush region. Enclaved by towering peaks and harboring a unique culture, the region mirrors the geographical and cultural diversity of Pakistan. In this geographically isolated region, a treasure trove of ethnobotanical knowledge unfolds through generations of interaction between the inhabitants and indigenous plants, resulting in a profound understanding of the plant uses in nutritional, medicinal, cultural, and ritual contexts. Thus, the study seeks to gather, analyze, and document the indigenous knowledge of plant utilization of the distinct tribal culture.MethodsThrough semi-structured questionnaires, inventory interviews, and participatory workshops, data were collected by engaging a cohort of 120 local respondents. The collected data were then classified into nine distinct use categories, following which quantitative indices were calculated.ResultsThe research identified a total of 150 plant species spanning across 59 different families and categorized them into 9 distinct usage groups. Among these, Astragalus oihorensis, Astragalus owirensis, Cicer nuristanicum, Geranium parmiricum, and Rochelia chitralensis stand out as novel species with distinctive applications. Notably, medicinal use garnered 600 reports, while animal feed, veterinary applications, human consumption, and toxicity recorded 500, 450, 425, and 104 reports, respectively. Informant consensus was high ranging between 0.8 and 0.9 with most agreement on human food and animal feed category. Platanus orientalis and Juglans regia, with RFC 0.91, were the most cited. The Family Importance Value (FIV) of Juglandaceae and Platanaceae, each with an FIV of 0.91, and Capparidaceae with an FIV of 0.83 indicate the intricate role the families play.ConclusionsIn this study, we explore 150 ethnobotanical species, uncovering novel entries within ethnobotanical literature. Among these, several species showcase unique uses previously undocumented in Pakistani literature. Our research sheds light on the intricate interaction between plants and the distinct cultural landscape of the Lotkuh region.

Removal of Heavy Metal Ions(Fe2+, Mn2+, Cu2+ and Zn2+) on to Activated Carbon Prepared from Kashmiri Walnut Shell (Juglans regia)

Heavy metal pollution poses significant threats to the environment and human health, even at trace concentrations. In this study, activated carbon derived from Kashmiri walnut shell (Juglans regia) was investigated for its potential to adsorb heavy metal ions (Fe2+, Mn2+, Cu2+, and Zn2+). Standard solutions containing heavy metal ions at concentrations ranging from 10 to 50 ppm were prepared for adsorption experiments, i.e., at temperature 25 °C, and adsorbent dosage 1 g using a column mechanism. The activated carbon was first treated with 0.1M HCl and 0.5M ammonia solutions, and then washed with demineralised water. Subsequently, the metal ion solutions were passed through the column individually, and the filtrates were analyzed for heavy metal ion presence. The experimental results demonstrated that walnut shell-derived activated carbon exhibited promising adsorption capacity spanning from 0.36 mg/g for Zn2+, 0.5 mg/g for both Mn2+ and Cu2+ and 0.54 mg/g for Fe2+ thus showing the adsorption trend as Fe2+ &gt; Mn2+ = Cu2+ &gt; Zn2+. This study highlights the potential of using walnut shell-derived activated carbon as an effective and cost-efficient method for mitigating heavy metal pollution in contaminated water sources.

Supercritical CO2 extraction of Walnut (Juglans regia L.) oil: Extraction kinetics and solubility determination

Experimental and modelling investigations of supercritical CO2 extraction of oil from Juglans regia L. kernels were conducted at 200 and 400 bar, 313 and 333 K at a CO2 flow rate of 0.1 kg/h. Regardless of the pressure and the temperature, the highest achievable yield was estimated at about 0.7 kgoil / kgbiomass. The extraction kinetics were modeled with Sovová’s broken and intact cells model. Walnut oil apparent solubility in supercritical CO2 was determined and modelled with the Chrastil equation. A retrograde solubility behaviour was observed at 200 bar, the faster extraction kinetics were found at 400 bar and 333 K. The fatty acid composition of the supercritical CO2 extracted oil was compared to the quality of the oil extracted by press and n-hexane Soxhlet extraction.

Biochar addition can negatively affect plant community performance when altering soil properties in saline-alkali wetlands.

Biochar is a widely proposed solution for improving degraded soil in coastal wetland ecosystems. However, the impacts of biochar addition on the soil and plant communities in the wetland remains largely unknown. In this study, we conducted a greenhouse experiment using soil seed bank from a coastal saline-alkaline wetland. Three types of biochar, including Juglans regia biochar (JBC), Spartina alterniflora biochar (SBC) and Flaveria bidentis biochar (FBC), were added to the saline-alkaline soil at ratios of 1%, 3% and 5% (w/w). Our findings revealed that biochar addition significantly increased soil pH, and increased available potassium (AK) by 3.74% - 170.91%, while reduced soil salinity (expect for 3% SBC and 5%SBC) by 28.08% - 46.93%. Among the different biochar types, the application of 5% FBC was found to be the most effective in increasing nutrients and reducing salinity. Furthermore, biochar addition generally resulted in a decrease of 7.27% - 90.94% in species abundance, 17.26% - 61.21% in community height, 12.28% - 56.42% in stem diameter, 55.34% - 90.11% in total biomass and 29.22% - 78.55% in root tissue density (RTD). In particular, such negative effects was the worst in the SBC samples. However, 3% and 5% SBC increased specific root length (SRL) by 177.89% and 265.65%, and specific root surface area (SRSA) by 477.02% and 286.57%, respectively. The findings suggested that the plant community performance was primarily affected by soil pH, salinity and nutrients levels. Furthermore, biochar addition also influenced species diversity and functional diversity, ultimately affecting ecosystem stability. Therefore, it is important to consider the negative findings indirectly indicate the ecological risks associated with biochar addition in coastal salt-alkaline soils. Furthermore, Spartina alterniflora was needed to desalt before carbonization to prevent soil salinization when using S. alterniflora biochar, as it is a halophyte.

Classification and Status by Geological Periods Relicts, Rare Species of Zakatala and Belokan Districts

The article provides data on period III relicts and rare tree and shrub species common in the forest ecosystems of the Zakatala and Belokan districts of Azerbaijan, and their classification and status by geological periods is given. As a result of research and analysis, the species Taxus baccata L., Hedera pastuchovii Woronow ex Woronow and Smilax excelsa L. were included in the relicts of the Poltava flora. In the forest ecosystems of the study areas, 6 tree and shrub relict species belonging to 6 families and 6 genera of the subtropical evergreen Poltava flora (mesothermal relicts of the Arctic flora of the III period) were identified: Taxus baccata L., Platanus orientalis L., Punica granatum L., Hedera pastuchovii Woronow ex Woronow, Smilax excelsa L. and Diospyros lotus L. With the exception of Smilax excelsa L., other 5 species are listed in the Red Book of the Azerbaijan Republic. In the Zakatala and Belokan districts, relict tree and shrub plants belonging to 15 families, 23 genera and 30 species of Arctic and deciduous Turgai flora (mesothermal relicts of the Arctic flora of the III period) are widespread. Of these, 10 species (Pinus kochiana Klotzsch ex K. Koch = Pinus sylvestris var. hamata Steven, Fraxinus coriariifolia Scheele, Castanea sativa Mill., Quercus iberica Steven ex M. Bieb., Pterocarya pterocarpa (Michx.) Kunth ex Iljinsk., Juglans regia L., Acer pseudoplatanus L., Acer hyrcanum Fisch. ex C. A. Mey., Corylus colurna L., Vitis vinifera L., are considered rare plants of Azerbaijan. It was established that 38 rare tree and shrub species belonging to 35 there are 23 families.

Identification and expression analysis of Jr4CLs gene family based on transcriptome and physiological data in walnut (Juglans regia)

Identification and expression analysis of Jr4CLs gene family based on transcriptome and physiological data in walnut (Juglans regia)

Effects of Green Husks of Hungarian-Bred Cultivars on Their Walnut Bacterial Blight Susceptivity

The Persian walnut (Juglans regia L.) is one of Central Europe's most grown nut trees. In the green husks of walnuts, among the most important bioactive compounds are phenolics (hydroxybenzoic acids, hydroxycinnamic acids, flavonoids, naphthoquinones), which play an important role in the plant defense mechanisms against stress caused by various pathogens e.g., Xanthomonas arboricola pv. juglandis, furthermore mentioned as Xaj. The study examined the full Hungarian walnut assortment to detect the difference in phenolic profiles of their green husk and the relationship between the concentration of phenolic compounds, as well as their effects on tolerance against Xaj. All the phenological stages were recorded by Ctifl scheme. The phenolic compounds were determined by HPLC-DAD-ESI-QDA method, after which susceptibility test was carried out. The results show that concentration of the phenolic compounds varied by cultivars; it was higher in the locally-bred cultivars compared to ‘Chandler’, a more widespread cultivar. Phenolic compounds inhibited the artificial Xaj infection in the green husk. This effect had a strong correlation with the high phenols’ concentration, except for ‘Bonifác’. It is likely that the phenolics’ concentration in the walnut green husk has an important role in their defense against Xaj infection.

Evaluation of fungicides for management of Botryosphaeriaceae associated with dieback in Australian walnut orchards

Dieback of fruiting spurs, stems and branches of walnut trees (Juglans regia L.), caused by Botryosphaeriaceae, is widespread in walnut orchards in Australia. Five species of Botryosphaeriaceae (Diplodia seriata, Dothiorella omnivora, Neofusicoccum macroclavatum, N. parvum, and Spencermartinsia viticola) were recovered from the Australian walnut orchards in a previous study, with D. seriata and N. parvum being the most prevalent. The present study evaluated inhibitory effects of ten fungicides on mycelium growth of those five species and on conidium germination of D. seriata and N. parvum. It investigated the preventative and curative efficacy of selected fungicides on disease incidence in glasshouse and field trials. In vitro experiments showed that nine of the fungicides reduced mycelium growth, and all ten inhibited conidium germination, but to varying extents. Tebuconazole, prochloraz manganese chloride, fluazinam, fludioxonil and pyraclostrobin were the most effective for inhibiting mycelium growth (EC50 &lt; 0.14 µg a.i. mL-1), whereas pyraclostrobin, fluxapyroxad, fluopyram, penthiopyrad and tebuconazole were the most effective for inhibiting conidium germination (EC50 &lt; 2.2 µg a.i. mL-1). In planta experiments with five fungicides confirmed that preventative treatments had greater efficacy than curative treatments. A field trial with four commercial fungicide formulations demonstrated that tebuconazole and tebuconazole + fluopyram provided protection of walnut trees for the longest period. The field trial also confirmed the efficacy of pyraclostrobin and the inhibitory effect of fluazinam. This study is the first in Australia to evaluate fungicides in different classes and with different modes of action for efficacy against Botryosphaeriaceae recovered from walnut orchards in Australia, and provides a wider selection of active ingredients for a fungicide rotation programme than that which is currently available to the Australian walnut industry.

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.

Utilizing SSR markers to examine the population structure and molecular genetic diversity of walnut (Juglans regia L.) genotypes in the Northwestern Himalayan region of Jammu and Kashmir

By using 16 simple sequence repeat (SSR) markers, the genetic relatedness of 21 exceptional walnut genotypes was assessed. A significant degree of genetic diversity was observed within a given population, as indicated by the number of alleles per locus ranging from 2 to 4. WGA-1, WGA-4, and WGA-79 contained the greatest number of alleles (4), followed by WGA-118, WGA-202, and WGA-42. Conversely, WGA-27, WGA-69, and WGA-32 contained the fewest alleles. The range of the PIC value was 0.11 to 0.38. Using model-based cluster analysis, all genotypes were categorized into two primary clusters according to the UPGMA dendrogram, with varying degrees of sub-clustering. All the genotypes were categorized into six genetically distant subpopulations. The genotypes were genetically distinct but had variable degrees of admixture. The anticipated heterozygosity at a specific locus ranged from 0.563 to 0.741. Additionally, population differentiation (Fst) ranged between 0.176 and 0.261. These findings highlight the importance of considering germplasm diversity in walnut breeding programs and conservation efforts aimed at enhancing walnut cultivation in the region. Overall, this study contributes to our understanding of walnut genetic diversity in the Northwestern Himalayan region of Jammu and Kashmir and informs future breeding and conservation strategies.