Chestnut Research Articles

Whole genome sequencing of Castanea mollissima and molecular mechanisms of sugar and starch synthesis

The chestnut tree exhibits self-incompatibility, where the selection of the male parent (pollen xenia) significantly affects seed starch metabolism, as well as fruit yield and quality. Despite its importance, the molecular mechanisms underlying pollen xenia remains largely unknown. In this study, we utilized the ‘Lan You’ variety of C. mollissima to construct a high-quality reference genome. As a result, a first Telomere-to-telomere (T2T) gap-free genome for this species was successfully assembled. A total of 560 transcription factors and 22 structural genes were identified as consistent across the TO-GCNs, indicating a consistent regulation pattern in the co-expression of genes involved in starch accumulation. These networks were further divided into three sub-networks: T1, T2, and T3. Among these, the T1 and T2 sub-networks exhibited a higher number of structural genes with consistent regulation patterns and were closely associated with sugar biosynthesis. The gene SBE (Camol08G0254600) was identified as the hub gene with the highest degree of connectivity, encoding a key rate-limiting enzyme in the amylopectin biosynthesis pathway. This study provides a foundation for further research on C. mollissima population genetics, genetic improvement, and strategies aimed at enhancing yield and quality.

Omitting the Application of Nitrogen or Potassium Reduced the Growth of Young Chestnut (Castanea sativa) Trees, While a Lack of Boron Decreased Fruit Yield

The chestnut tree (Castanea sativa Mill.) is gaining importance in the mountainous regions of southern Europe due to the high value of its fruits. It is essential to establish effective cultivation protocols, considering that this species is still relatively understudied. In this study, we present the outcomes of the initial establishment of a chestnut orchard conducted through a nutrient omission trial for four years. The treatments included a fertilization plan with nitrogen, phosphorus, potassium, and boron (NPKB), the control, and four other treatments corresponding to the omission of each nutrient (-NPKB, N-PKB, NP-KB, NPK-B). The -NPKB and NP-KB treatments showed significantly lower trunk circumferences and canopy volumes compared to the other treatments. The NPK-B treatment resulted in the lowest fruit production, with a total accumulated yield (2020–2022) of 0.56 kg tree–1, a value significantly lower than that of NPKB (1.12 kg tree–1) and N-PKB (1.19 kg tree–1). The assessment of nutrient concentrations in the leaves revealed plants with deficient levels of B and K in treatments that did not receive these nutrients. Conversely, N levels in the leaves in the -NPKB treatment fell within the sufficiency range (20 to 28 g kg–1). This suggests that the sufficiency range should be adjusted to higher values, given the treatment’s effect on tree growth. It was also observed that the -NPKB treatment led to lower soil organic matter compared to the other treatments, likely due to reduced herbaceous vegetation development under the canopy, leading to decreased organic substrate deposition in the soil. The main findings of this study are that N and K were crucial elements for the optimal growth of chestnut trees, while B played a significant role in fruit production.

Variations on the chemical compositions of chestnut fruits collected at different locations

Chestnut is an essential food source in many countries. Nutritional quality and potential health benefits of Anatolian chestnut trees (Castanea sativa Mill.) have led to increased concern and interest in chestnut production. However, knowledge of the factors that influence the chemical content of chestnut fruits still needs to be improved. Thus, the chemical compositions were evaluated for Anatolian chestnut fruits collected at 14 different locations in northern Türkiye, which is one of the biggest chestnut producers in the world. The effects of latitude, longitude, altitude, aspect, mean annual temperature (°C) (TMA), and mean annual precipitation (mm) (PMA) of the study locations on the chemical compositions of chestnut fruits were monitored. The effects of these parameters on several chestnut characteristics were examined using a mixed-effects multiple regression model. Latitude, longitude, TMA, and PMA were correlated with the mean concentrations of sucrose, free amino acid, glycine betaine, nitrogen (N) (%), and total carbon (C) (%) of the chestnut samples. The moisture content of the fruits was affected by longitude. The antioxidant and mineral content of the chestnut samples also varied by location. These findings may be helpful in site selection, production, and conservation of chestnut cultivars.

Interactions between invasive pests and pathogens in a native chestnut forest

The introduction in the same area of different invasive species can result in novel interactions, with unpredictable consequences. We carried out a study in Galicia (northwestern Iberian Peninsula) with the aim of clarifying the interactions between two invasive species Cryphonectria parasitica and Dryocosmus kuriphilus. In 2018, we selected five chestnut plots affected by both species. We compared trees affected only by the insect and trees affected by both the insect and the fungus with respect to attack level, gall characteristics, female size and fecundity, and concentrations of nitrogen, water and secondary metabolites. We also evaluated female preferences in a greenhouse assay. There were higher levels of attack in trees affected by both invaders. However, the greenhouse assay showed that ovipositing females do not preferentially choose trees attacked by the fungus. The presence of the fungus had no effect on the size, wall thickness, or hardness of D. kuriphilus galls, but larvae were smaller in trees also affected by the fungus. The fecundity of females was strongly related to the presence of chestnut blight; the number of eggs per female was almost double in trees affected by the fungus. There were no relations between blight and the nitrogen or water content in the galls, where the insects feed. There were also no effects of chestnut blight on the concentration of terpenes or phenols, but condensed tannins were higher in trees with chestnut blight. The higher tannins induced by chestnut blight may directly or indirectly benefit gall wasps. Positive relationships between condensed tannin concentration and reproductive performance of other gall makers were previously reported. Tannins can also improve the negative effects of environmental conditions inside the gall. Our results indicate that the presence of chestnut blight can increase the suitability of chestnut trees for the invasive insect, D. kuriphilus, through the increase in tannins due to the presence of the fungus.

First report of Gnomoniopsis castaneae associated with branch dieback on chestnut tree (Castanea sativa) in Southern Chile.

European chestnut (Castanea sativa Mill.) currently reaches 1,470 ha, distributed from the Maule region to the Los Rios region in Chile. Almost 3000 tons of fruit have been exported in the last three years. A survey was carried out in January 2023 in an eight-year-old orchard located in Vilcún (38°34'46.22"S 72° 9'58.61"O), Araucanía Region. Chestnut trees with branch die back and reduced growth and vigor were detected. The incidence in the orchard was 3% (6 out of 200 trees) estimated by visual observation. Cross and longitudinal sections of the woody trunk of two trees were collected and examined, and an internal dark-brown discoloration to partial necrosis lesion was observed. To identify the causal agent, small pieces of wood from the edge of the symptomatic area were surface sterilized with 70% ethanol, rinsed twice with sterile distilled water, blotted on dry sterile filter paper, plated on potato dextrose agar (PDA) and incubated at 22°C. Fungal colonies were consistently isolated, and after 5 days, pure cultures were obtained by transferring mycelium to new PDA plates, preliminarily identified as Gnomoniopsis sp. (Visentin et al. 2012, Shuttleworth 2012). All cultures exhibited characteristics consistent with the description of G. castaneae (Syn. G. smithogilvyi), such as concentric development of greyish-brown mycelium, abundant stroma, hyaline conidia of 7.2 ±0.54 (6.1-8.1) X 2.3 ±0.26 (1.5-2.9) µm (n= 30), mainly biguttulate and fusoid. Total DNA was extracted, rDNA amplified using ITS1/ITS4 primers (White et al. 1990), and the fragment was Sanger sequenced and the sequence was deposited in GenBank (OR665735). BLAST analysis revealed a 99% identity to G. castaneae (MH384925). In addition, the DNA of the isolate was evaluated in a species-specific multiplex PCR (Silva-Campos et al. 2022), and the amplicons were electrophoretically separated, giving a similar band profile to G. smithogilvyi RGM 2903 and RGM 2904 strain from Chilean Collection of Microbial Genetic Resources. Pathogenicity of G. castaneae isolate (CV-11) was tested on ten replicates of 3-year-old C. sativa plants. Two wounds were made on the same season growing shoot and two on the previous season shoot. Longitudinal wounds (5 mm long, 4 mm wide and 2 mm depth) were made using a scalpel without removing the outer bark to inoculate the plants. Each wound was inoculated with a 5-mm mycelium plug, covered with the outer bark, and wrapped with Parafilm. Plugs of PDA were placed onto the wounds of two plants as control. The plants were kept in a growth chamber (22 ±1 0C and 90± 5% RH). All plants showed dark brown cankers measuring 20 to 40 mm long two weeks after inoculation. Also, most plants inoculated in the same season shoot presented wilted and chlorotic foliage. Mature conidiomata with cirri developed in most of the cankers. No symptoms were observed in the control. Fungal colonies of G. castaneae were reisolated on PDA from all inoculated chestnut plants and were not recovered from the controls. Recently, G. smithogilvyi has been identified as the causal agent of brown rot on chestnut nuts in Chile (Cisterna Oyarce et al. 2022); however, in several countries, it has also been associated as the causal agent of cankers in branch and stem of chestnut, as well as an endophyte in different hardwood species. Future studies on the incidence of this pathogen and its impact on chestnut yield should be carried out in the producing regions because it represents an emerging threat to Chilean chestnut production.

Sodium aescinate alleviates neuropathic pain through suppressing OGT-mediated O-GlcNAc modification of TLR3 to inactivate MAPK signaling pathway

Neuropathic pain results from damage to nerves or the brain, and is characterized by symptoms such as allodynia, spontaneous pain, and hyperalgesia. The causes of this type of pain are intricate, which can make it difficult to treat. Sodium aescinate (SA), a natural extract from horse chestnut tree seeds, has been shown to act as a neuroprotector by inhibiting microglia activation. This study aims to explore the therapeutic potential of SA for neuropathic pain and the molecular mechanisms regulated by SA treatment. Through in vivo animal models and experiments, we found that SA treatment significantly reduced mechanical allodynia and heat hyperalgesia in neuropathic pain models. Additionally, SA inhibited O-GlcNAc-transferase (OGT)-induced O-GlcNAcylation (O-GlcNAc) modification in neuropathic pain mice. OGT overexpression could impede the therapeutic effects of SA on neuropathic pain. Further investigation revealed that Toll-like receptor 3 (TLR3), stabilized by OGT-induced O-GlcNAc modification, could activate the Mitogen activated protein kinase (MAPK) signaling pathway. Further in vivo experiments demonstrated that TLR3-mediated p38 mitogen-activated protein kinase (p38MAPK) activation is involved in SA-mediated relief of neuropathic pain. In conclusion, this study uncovers a novel molecular pathway deactivated by SA treatment in neuropathic pain.

Ecophysiology of Mediterranean Chestnut (Castanea sativa Mill.) Forests: Effects of Pruning Studied through an Advanced IoT System

Chestnut (Castanea sativa Mill.) forests in the Mediterranean region are facing increasing abandonment due to a combination of factors, ranging from climate change to socioeconomic issues. The recovery of chestnut ecosystems and their preservation and valorization are key to ensuring the supply of the wide spectrum of ecosystem services they provide and to preventing detrimental environmental shifts. The study’s objective was to provide evidence on the effects of different management options on the ecophysiology of chestnut forests, with diverse pruning intensities (low, medium, and high intensity versus no pruning) tested in an abandoned chestnut stand in central Italy with the aim of recovering and rehabilitating it for fruit production. Innovative Internet of Things (IoT) ‘Tree Talker’ devices were installed on single trees to continuously monitor and measure ecophysiological (i.e., water transport, net primary productivity, foliage development) and microclimatic parameters. Results show a reduction in water use in trees subjected to medium- and high-intensity pruning treatments, along with a decrease in the carbon sequestration function. However, interestingly, the results highlight that trees regain their usual sap flow and carbon sink activity at the end of the first post-pruning growing season and fully realign during the following year, as also confirmed by the NDVI values. As such, this paper demonstrates the efficacy of recovering and managing abandoned chestnut forests, and the initial setback in carbon sequestration resulting from pruning is rapidly remedied with the advantage of reviving trees for fruit production. Additionally, the reduced water demand induced by pruning could represent a promising adaptation strategy to climate change, bolstering the resilience of chestnut trees to prolonged and intensified drought periods, which are projected to increase under future climate scenarios, particularly in the Mediterranean region.

Chromosome-level genome assembly of Oriental chestnut gall wasp (Dryocosmus kuriphilus)

Dryocosmus kuriphilus, commonly known as the chestnut gall wasp, belongs to the family Cynipidae and is native to China. It is a highly invasive insect species causing serious damage to chestnut trees and has rapidly spread to various continents, including Europe, North America, and Oceania. The D. kuriphilus has become one of the important pests of chestnut plants in the world and is listed as a quarantine object by the European and Mediterranean Plant Protection Organization (EPPO). In this study, we used PacBio long reads, Illumina short reads, and Hi-C sequencing data to construct a chromosome-level assembly of the D. kuriphilus genome. The assembled genome includes 14,729 contigs with a total length of 2.28 Gb and a contig N50 of 0.8 Mb. With Hi-C technology, 2.17 Gb (95.02%) of contigs were anchored and oriented into the 10 pseudochromosomes with the scaffold N50 of 198.8 Mb and the scaffold N90 of 158.8 Mb. In total, 24,086 protein-coding genes were predicted in the assembled D. kuriphilus genome as the reference gene set. A total of 1.82 Gb repeats (occupying 79.7% of the genome), including 1.42 Gb of transposable elements and 0.40 Gb of tandem repeats, were identified in D. kuriphilus genome. In the evaluation of completeness, the BUSCO analysis determined a level of 98.1% completeness for the assembled genome sequences based on the Insecta database (OrthoDB version 10). The high-quality genome assembly of D. kuriphilus will not only provide a valuable reference for the study of its evolutionary history and genetic structure but also facilitate the research of host-pest interactions and invasiveness. Moreover, this genome assembly will promote in the development of effective management strategies to mitigate the economic and ecological impacts of this invasive pest on chestnut trees and ecosystems.

Ellagitannin Content in Extracts of the Chestnut Wood Aesculus.

The chestnut tree (Castanea sativa Mill.) is a widespread plant in Europe, rich in high-value compounds, which can be divided mainly into monomeric polyphenols and tannins. These compounds exhibit various biological activities, such as antioxidant, as well as anticarcinogenic and antimicrobial properties. Chestnut wood (CW) extracts were prepared using different extraction techniques, process conditions, solvents, and their mixtures. This work aimed to test various extraction techniques and determine the optimal solvent for isolating enriched fractions of vescalagin, castalagin, vescalin, and castalin from CW residues. Supercritical CO2 extraction with a more polar cosolvent was applied at different pressures, which influenced solvent density. According to the results, the proportions of the components strongly depended on the solvent system used for the extraction. In addition, HPLC-DAD was used for semiqualitative purposes to detect vescalagin, castalagin, vescalin, and castalin. The developed valorization protocol allows efficient fractionation and recovery of the polyphenolic components of CW through a sustainable approach that also evaluates pre-industrial scaling-up.

Integrated sustainability assessment of wood building products: The case of larch and chestnut cascading systems in Northern Italy

Wood is increasingly being appreciated in construction due to its valuable environmental attributes. This paper explores the environmental and market performance of two wood supply chains in Northern Italy. Larch and chestnut wood are extracted and processed to obtain beams, planks, MDF panels and energy. LCA is performed to evaluate the environmental impacts of 1m3 of extracted wood through a cradle-to-gate approach. Then, a biogenic carbon analysis is carried out using the EN 16449:2014 standard including a comparison of different end-of-life treatments. Also, OSB is proposed as an alternative path for wood chips and contrasted to the current energy scenario. Moreover, solid wood beams and planks are compared with engineered wood products (EWPs). Lastly, a market analysis is conducted to assess the market trends of the different wood products studied.The LCA shows similar results for both wood species across most impact categories, with slightly higher values for the chestnut system. Most impacts are related to the production of MDF boards and the energy valorization of wood chips. Biogenic carbon analysis shows a negative balance of emissions with −314 and −205 kg of CO2 eq for larch and chestnut, respectively. It also suggests that OSB manufacturing can be a valuable alternative to the energy use of wood chips and that the end-of-life treatment with better results is recycling. The comparison of beams and planks with engineered wood products supports that solid wood poses a better environmental alternative in similar applications. Market analysis shows stagnation in the apparent consumption of wood products in the European market and a slight growth in the Italian one between 2018 and 2022. Overall, the systems studied suggest that the potential environmental benefits of using wood in construction are not being matched by current market trends.

Native and TMT Chestnut Extractives as Hydrophobic and Photostabylizing Additives for Wood Surfaces

Wood extractives have proven strong anti-oxidative properties which may be used to mitigate surface deterioration caused by photolytic effects and free radical formations. An interesting challenge regarding wood extractives is understanding how they behave in terms of treating natural wood surfaces to reduce anti-oxidative processes that arise from exposure to the main environmental factors. In this study, the possible efficacy of chestnut (Castanea sativa Mill.) extractives derived from native (CH) and thermally modified wood (TMT CH), as a means of protecting against UV exposure in poplar (Populus spp.) and spruce (Picea abies Karst.) wood, was evaluated. Chestnut wood was first thermally modified at 180 °C for 3 h, and the extractives were obtained by the accelerated solvent extraction technique (ASE) and subsequently used to treat wood surfaces. Samples were immersed in extractive solutions and exposed to artificial UV-weathering exposure, then contact angle and colour stability were monitored during the process. An FTIR analysis of the photo-degradation process of poplar and spruce surfaces was also executed. Extractives of TMT chestnut changed the total colour variation in both poplar and spruce wood. A much darker colour compared to the extractives of native wood was observed and an increase in ∆E* from 9.75 to 30.76 and 6.24 to 22.97 in poplar and spruce was calculated. The stability of the colour depended both on the surface wood and the type of extractive. The initial contact angle remained almost unchanged in the poplar wood surface and only slightly increased in spruce regardless of whether they were treated with extractives from native or TMT chestnut wood. A strong reduction in contact angle after the accelerated UV exposure test was observed, especially in spruce treated with CH extractives. FTIR analysis confirmed the lower levels of chemical degradation of surfaces observed by colorimetry, where TMT CH extractives formed more stable chemical bonds than native extractives. The comparative analysis in this study clarified the complex relationships between the effects of high-temperature modification of wood and the potential protective role of TMT extractives on some wood surfaces.

Impact of Wood Structure Variability on the Surface Roughness of Chestnut Wood

Wood constitutes a unique and valuable material that has been used from ancient times until nowadays in a wide variety of applications, in which the surface quality of wood often constitutes a critical factor. In this study, the influence of different wood areas and therefore, of different anatomical characteristic areas of chestnut wood (Castanea sativa Mill.) on the surface quality, was thoroughly studied, in terms of surface roughness. Five different chestnut tree trunks were harvested, from which five different disks were obtained corresponding to five different trunk heights. Surface roughness was measured on these disks on the transverse, radial, and tangential planes, on the areas of sapwood and heartwood, measuring the roughness in each point both vertically and in parallel to the wood grain. The results revealed that the examined roughness indexes (Ra, Rz, Rq) follow a parallel path to one another. In the case of all surfaces (transverse, radial, tangential) of the disks examined, when the measurement was implemented perpendicularly to the wood grain, a significantly higher roughness was recorded, compared to the wood grain measurements being implemented in parallel with the wood grain. Significant differences between heartwood and sapwood roughness were not demonstrated, although sapwood often appeared to exhibit a higher surface roughness than heartwood sites. Among the roughness values of the three different surfaces, the highest roughness in the vertical-to-wood-grain measurements was recorded by tangential surfaces, with slightly lower values on the transverse surfaces and the lowest roughness on radial surfaces. Meanwhile, for the measurements in parallel with the wood grain, the transverse surfaces presented significantly higher roughness values compared to the tangential and radial surfaces. Significant roughness differences were not detected among the surfaces at different trunk heights. Although, significant differences in roughness were recorded among different trees, it was observed that all the studied trees align with the identified and described within-tree trends.

Mural as a Living Element of Urban Space: Seasonal Dynamics and Social Perception of “The Four Seasons with Kora” in Warsaw

Street art, with a particular emphasis on murals, plays a crucial role in shaping the cultural DNA of contemporary cities. A prime example of this is the mural “Four Seasons with Kora” in Warsaw, which is dedicated to the renowned Polish artist Kora (Olga Jackowska). This large-scale mural, which combines the artist’s portrait with a chestnut tree motif, visually changes with the season, influencing the artist’s social perception. This study analyzed murals’ functions in social, cultural, and ecological contexts, highlighting their role in informal education and as a platform for social dialogue and integration. Using research methods such as visual analysis and examining comments and reactions on social media, this work aimed to understand how a mural integrates with its surroundings and is perceived throughout different seasons. The results indicated that the mural has become an important element of public space, not only for beautifying the city but also for stimulating social and cultural reflection.

Characterization of size-tuneable aescin-lipid nanoparticles as platform for stabilization of membrane proteins

Disc-like lipid nanoparticles stabilized by saponin biosurfactants display fascinating properties, including their temperature-driven re-organization. β-Aescin, a saponin from seed extract of the horse chestnut tree, shows strong interactions with lipid membranes and has gained interest due to its beneficial therapeutic implications as well as its ability to decompose continuous lipid membranes into size-tuneable discoidal nanoparticles. Here, we characterize lipid nanoparticles formed by aescin and the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine. We present site-resolved insights into central molecular interactions and their modulations by temperature and aescin content. Using the membrane protein bacteriorhodopsin, we additionally demonstrate that, under defined conditions, aescin-lipid discs can accommodate medium-sized transmembrane proteins. Our data reveal the general capability of this fascinating system to generate size-tuneable aescin-lipid-protein particles, opening the road for further applications in biochemical, biophysical and structural studies.

Potential of Castanea sativa for biomonitoring As, Hg, Pb, and Tl: A focus on their distribution in plant tissues from a former mining district

Bioavailability of potentially toxic elements (PTEs) from the Earth's crust in the soil, e.g., As, Hg, Tl, and Pb, can pose a potential environmental and health risk because of human activities, especially related to mining extraction. The biomonitoring allows to detect PTE contamination through their measurement in living organisms as trees. However, the choice of which plant species and tissue to analyse is a key point to be evaluated in relation to PTE absorption and translocation. The aim of this work was to assess the As, Hg, Tl, and Pb distribution in Castanea sativa Mill. plant tissues, given its importance for both biomass and food production. The study identified two sites in the Alpi Apuane (Italy), with similar environmental conditions (e.g., elevation, exposure, forest type, and tree species) but different soil PTE levels. The topsoil was characterized, and the PTE fractions with different bioavailability were measured. The PTE concentrations were also analysed in chestnut plant tissues (leaves, bark, wood, nuts, and shells) in parallel with and evaluation of plant health status through the determination of micro and macronutrient concentrations and the leaf C and N isotope composition (δ13C or δ15N). Chestnut trees showed a good health status highlighting its suitability for Tl, As, Hg, and Pb biomonitoring, displaying a tissue-specific PTE allocation. Thallium and Hg were detected in all plant tissues at similar concentrations, As was found in leaves, wood, and nuts while Pb only in the bark. The δ15N negatively correlated with leaf Mn and Tl concentrations, suggesting possible changes in N source and/or plant metabolism due to the high contamination level and acid soil pH. Thallium in La Culla site trees was associated with its presence in the carbonate rocks but not in the topsoil, highlighting the potentiality of chestnut in providing valuable information for geochemical surveying.

Location and differentiation of chestnut tree (Castanea sativa Mill.) individuals grafted with traditional cultivars using spatio-temporal analysis of remote-sensed imagery, dendro-chronological analysis, and SSR genotyping

Location and differentiation of chestnut tree (<i>Castanea sativa</i> Mill.) individuals grafted with traditional cultivars using spatio-temporal analysis of remote-sensed imagery, dendro-chronological analysis, and SSR genotyping

Anatomical Changes during Chestnut (Castanea mollissima BL.) Gall Development Stages Induced by the Gall Wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae).

This study delved into the larval development and the morphological and anatomical transformations that occur in the galls of chestnut trees (Castanea mollissima BL.) and are induced by the chestnut gall wasp Dryocosmus kuriphilus Yasumatsu (GWDK) across various stages: initial, growth, differentiation, maturity, and lignification. Chestnut galls in the five development stages were collected. Gall structural characteristics were observed with an anatomical stereomicroscope, and anatomical changes in galls were analyzed with staining and scanning electron microscope techniques. The chestnut gall wasp laid its eggs on young leaves and buds. Chestnut gall wasp parasitism caused plant tissues to form a gall chamber, with parenchyma, protective, and epidermal layers. The development of the gall structure caused by the infestation of the GWDK gall led to the weakening of the reactive oxygen species (ROS) elimination ability of the host. The accumulation of ROS led to cell wall peroxidation, resulting in structural damage and diminished host resistance, and the parenchyma layer exhibited significant nutrient supply and thickening. The thickness of the protective and epidermal layers varied notably across different growth stages. The oviposition of the chestnut gall wasp induced modifications in the original plant tissues, with gall formation being most favorable in young tissues, correlating with the maturity level of the host plant tissues. Variances in the internal structures of the galls primarily stemmed from nutrient supplementation, while those in the external structure were attributed to defensive characteristics. This research contributes a foundational understanding of gall development induced by the chestnut gall wasp in Chinese chestnut, offering valuable insights into the intricate interplay between insect infestation and plant physiology.

The Disease Triangle of Chestnut: A review of host, pathogen, and environmental interactions of chestnuts cultivated in the eastern United States

Chestnuts, the edible seeds of the genus Castanea, are a perennial food crop closely tied to the global migration of humans throughout history and have recently been gaining popularity in agriculture and forest restoration in eastern North America. Cultivation of chestnuts yields nutritionally balanced food while fostering economic development, food security, and environmental health. However, diseases and insect pests threaten successful ecological restoration and food production. In this review we explore conditions affecting chestnuts in the eastern United States through the lens of the disease triangle. A “host” in the disease triangle is not merely a single tree, but a tree including its constituent population of fungal endophytes. Chestnut trees are rich with microbial life, and the sustainability of chestnuts in forest and cultivated settings may lie in understanding and manipulating microbial communities to improve plant health and control destructive diseases. To benefit from the ecological and economic potential of chestnuts on the landscape, it may be necessary to select locally adapted chestnut trees, regardless of pedigree, that are resilient against cosmopolitan pathogens. With transport of plants and pathogens throughout the globe, and with landscape level environmental changes over the last century, chestnut trees in the eastern United States (U.S.) are in a unique disease landscape compared to their ancestors. Diseases of economic concern from fungi and fungal-like organisms include chestnut blight (Cryphonectria parasitica) and ink disease (Phytophthora cinnamomi) on American and European chestnuts, oak wilt (Bretziella fagacearum) on all chestnut species, and the emerging diseases of brown rot (Gnomoniopsis smithogilvyi) and chestnut anthracnose (Colletotrichum henanense). The eastern U.S. has experienced profound environmental changes over the 20th century and into the early 21st century. These changes happen to coincide with the demise of the American chestnut in the eastern forest, efforts to re-establish chestnut as a forest species, and the rise in cultivation of multiple chestnut species and hybrids as a culinary crop. Chestnut trees growing in the early 21st century face different environmental circumstances than the American chestnuts of pre-colonial times, including changes in forest composition, rainfall changes and acidification, industrialized agriculture’s increased chemical inputs, rising global temperatures, and increased levels of carbon dioxide in the atmosphere. We conclude that chestnut tree species for both forestry and agriculture should be considered based on current fitness, adaptability, and economic and ecological value considering continued dynamics in host and pathogens distributions and anthropogenically driven climatic and edaphic conditions.

Incidence of brown rot disease caused by Gnomoniopsis smithogilvyi on buds, flowers and chestnuts and rapid HRM-based detection of the disease

Chestnut production is considered one of the most important economic resources of rural mountainous areas in Greece. Lately, producers report a steep rise in the incidence of brown rot disease caused by the fungus Gnomoniopsis smithogilvyi (Gnomoniaceae, Diaporthales), which results in severe chestnut rot. The pathogen is considered an emerging pathogen in many countries worldwide (Italy, France, Switzerland, Australia, New Zealand). This study aimed at (a) exploring the incidence of the brown rot disease in Vria (Regional Unit of Pieria, Region of Central Makedonia, Greece), (b) isolating and identifying the causal agent of the disease, (c) exploring the fungus presence at different phenological stages of the chestnut trees, and (d) implementing species-specific Bar- High Resolution Melting Analysis (HRM) for the early detection of G. smithogilvyi in chestnuts. G. smithogilvyi occurrence in chestnut tissues was more severe in June (59 %), nearly disappeared in July (19 %) and August (7 %) and increased again during harvesting time in September (57 %). This result could be attributed to a sum of different factors, including climate conditions. Moreover, it was demonstrated that G. smithogilvyi can be identified using a Bar-HRM analysis of chestnut tissues (buds, flowers and nuts). Results of this study clearly demonstrate that Bar-HRM can be used for the accurate, rapid and reliable identification of G. smithogilvyi universally on infected samples from different localities.

Seeing the wood for the trees: active human–environmental interactions in arid northwestern China

Abstract. Due largely to demographic growth, agricultural populations during the Holocene became increasingly more impactful ecosystem engineers. Multidisciplinary research has revealed a deep history of human–environmental dynamics; however, these pre-modern anthropogenic ecosystem transformations and cultural adaptions are still poorly understood. Here, we synthesis anthracological data to explore the complex array of human–environmental interactions in the regions of the prehistoric Silk Road. Our results suggest that these ancient humans were not passively impacted by environmental change; rather, they culturally adapted to, and in turn altered, arid ecosystems. Underpinned by the establishment of complex agricultural systems on the western Loess Plateau, people may have started to manage chestnut trees, likely through conservation of economically significant species, as early as 4600 BP. Since ca. 3500 BP, with the appearance of high-yielding wheat and barley farming in Xinjiang and the Hexi Corridor, people appear to have been cultivating Prunus and Morus trees. We also argue that people were transporting preferred coniferous woods over long distances to meet the need for fuel and timber. After 2500 BP, people in our study area were making conscious selections between wood types for craft production and were also clearly cultivating a wide range of long-generation perennials, showing a remarkable traditional knowledge tied into the arid environment. At the same time, the data suggest that there was significant deforestation throughout the chronology of occupation, including a rapid decline of slow-growing spruce forests and riparian woodlands across northwestern China. The wood charcoal dataset is publicly available at https://doi.org/10.5281/zenodo.8158277 (Shen et al., 2023).