Evolution of the Correlated Genomic Variation Landscape Across a Divergence Continuum in the Genus Castanopsis.

The heterogeneous landscape of genomic variation has been well documented in population genomic studies. However, disentangling the intricate interplay of evolutionary forces influencing the genetic variation landscape over time remains challenging. In this study, we assembled a chromosome-level genome for Castanopsis eyrei and sequenced the whole genomes of 276 individuals from 12 Castanopsis species, spanning a broad divergence continuum. We found highly correlated genomic variation landscapes across these species. Furthermore, variations in genetic diversity and differentiation along the genome were strongly associated with recombination rates and gene density. These results suggest that long-term linked selection and conserved genomic features have contributed to the formation of a common genomic variation landscape. By examining how correlations between population summary statistics change throughout the species divergence continuum, we determined that background selection alone does not fully explain the observed patterns of genomic variation; the effects of recurrent selective sweeps must be considered. We further revealed that extensive gene flow has significantly influenced patterns of genomic variation in Castanopsis species. The estimated admixture proportion correlated positively with recombination rate and negatively with gene density, supporting a scenario of selection against gene flow. Additionally, putative introgression regions exhibited strong signals of positive selection, an enrichment of functional genes, and reduced genetic burdens, indicating that adaptive introgression has played a role in shaping the genomes of hybridizing species. This study provides insights into how different evolutionary forces have interacted in driving the evolution of the genomic variation landscape.

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.

[Characterizations of soil enzyme activities and stoichiometry in three subtropical forest stands]. / äºšçƒ­å¸¦ä¸‰ç§æž—åˆ†åœŸå£¤é ¶æ´»æ€§å’Œé ¶åŒ–å­¦è®¡é‡æ¯”ç‰¹å¾.

We conducted in a common garden experiment to explore the differences in soil enzyme activity, stoichiometry, and their influencing factors among a secondary Castanopsis carlesii forest, 10-year-old C. carlesii plantation, and Cunninghamia lanceolata plantation. The results showed that compared to the secondary forest, the soil organic carbon, total nitrogen, and dissolved organic carbon significantly decreased by 42.6%, 47.4%, and 60.9% in C. carlesii plantation, and by 42.9%, 36.7%, and 61.1% in C. lanceolata plantation. Soil microbial biomass C, microbial biomass N (MBN), and microbial biomass phosphorus decreased significantly by 40.6%, 35.5%, and 45.9% in C. carlesii plantation, and by 53.7%、56.4%, and 61.7% in C. lanceolata plantation. Compared to the secondary forest, soil enzymes activities in C. carlesii plantation did not change significantly, but in C. lanceolata plantation, the activities of ß-1,4-glucosidase and cellobiohydrolase significantly decreased by 51.2% and 59.8%, ß-N-acetyl glucosaminidase and acid phosphatase decreased significantly by 41.0% and 29.8%, and enzymatic C:N acquisition ratio and enzymatic C:P acquisition ratio significantly decreased by 11.3% and 7.7%, respectively. Results of redundancy analysis indicated that MBN and NO3--N were the primary factors influencing soil enzyme activity and enzymic stoichiometry. Collectively, there were significant differences in soil enzyme activity and microbial nutrient demands among different forest stands. Compared to secondary forests, the establishment of C. lanceolata plantations would intensify nutrient competition between plants and microbes, and exacerbate the N and P limitations for microbes.

Castanea sativa Mill. By-Products: Investigation of Potential Anti-Inflammatory Effects in Human Intestinal Epithelial Cells.

Castanea sativa Mill. (C. sativa) processing and pruning generate several by-products, including leaves, burs, and shells (inner and outer teguments), which are considered an important source of high-value phytochemicals. Ellagitannins from C. sativa leaf extracts have been described to impair H. pylori viability and inflammation in gastric cells. Furthermore, chestnut shells showed an important anti-inflammatory effect in gastric epithelial cells. Dietary polyphenols, including tannins, have been reported to interfere with targets of inflammation, including the nuclear factor κB (NF-κB). A promising role as a further therapeutical target for gut disorders has been recently proposed for the regulatory subunit of hypoxia-inducible factor (HIF-1α), as a potential stabilizer of intestinal barrier integrity. Therefore, the main objective of this work is the chemical characterization of several chestnut by-products (bud, spiny bur, wood, pericarp and episperm), together with the exploitation of their anti-inflammatory properties in intestinal cells, scavenging capacity, and stability following gastrointestinal digestion. The chemical characterization confirmed the presence of bioactive polyphenols in the extracts, including ellagitannins. In CaCo-2 cells stimulated by an IL-1ß-IFN-γ cocktail, nearly all chestnut by-products (50 µg/mL) inhibited the release of proinflammatory mediators (CXCL-10, IL-8, MCP-1, ICAM), along with the NF-κB-driven transcription, and induced the HRE-driven transcription. The stability of the most promising extracts, identified through PCA and cluster analysis, was addressed by in vitro gastrointestinal digestion. Despite the significant reduction in total polyphenol index of chestnut bud and wood after gastric and intestinal digestion, the activity of these extracts on both scavenging and anti-inflammatory parameters remained promising. These data contribute to exploit the potential of chestnut by-products as sources of dietary polyphenols with anti-inflammatory properties at the intestinal level. Moreover, this study could represent an important step to encourage the recycling and valorization of chestnut by-products, promoting the circular economy and reducing the environmental impact related to the management of agriculture waste.

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.

The ectomycorrhizal fungus Paxillus involutus positively modulates Castanea sativa Miller (var. Marsol) responses to heat and drought co-exposure.

Castanea sativa Miller, a high-valuable crop for Mediterranean countries, is facing frequent and prolonged periods of heat and drought, severely affecting chestnut production. Aiming to tackle this problem, this study unraveled the influence of mycorrhizal association with the fungi Paxillus involutus (Batsch) on young chestnut plants' responses to combined heat (42 °C; 4 h/day) and drought (no irrigation until soil moisture reached 25%) over 21 days of stress exposure. Heat stress had no harmful effects on growth, photosynthesis, nor induced oxidative stress in either mycorrhizal (MR) or non-mycorrhizal (NMR) chestnut plants. However, drought (alone or combined) reduced the growth of NMR plants, affecting water content, leaf production, and foliar area, while also hampering net CO2 assimilation and carbon relations. The mycorrhizal association, however, mitigated the detrimental effects of both stresses, resulting in less susceptibility and fewer growth limitations in MR chestnut plants, which were capable of ensuring a proper carbon flow. Evaluation of the oxidative metabolism revealed increased lipid peroxidation and hydrogen peroxide levels in NMR plants under water scarcity, supporting their higher susceptibility to stress. Conversely, MR plants activated defense mechanisms by accumulating antioxidant metabolites (ascorbate, proline and glutathione), preventing oxidative damage, especially under the combined stress. Overall, drought was the most detrimental condition for chestnut growth, with heat exacerbating stress susceptibility. Moreover, mycorrhizal association with P. involutus substantially alleviated these effects by improving growth, water relations, photosynthesis, and activating defense mechanisms. Thus, this research highlights mycorrhization's potential to enhance C. sativa resilience against climate change, especially at early developmental stages.

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.

Genetic Insights into the Historical Attribution of Variety Names of Sweet Chestnut (Castanea sativa Mill.) in Northern Italy.

The sweet chestnut (Castanea sativa Mill.) is subject to the progressive disappearance of its traditional chestnut groves. In the northern part of Italy, where distribution of the sweet chestnut is fragmented, many local varieties continue to be identified mostly by oral tradition. We characterised by SSRs eleven historically recognised varieties of sweet chestnut in the area surrounding Lake Como, with the goal of giving a genetic basis to the traditional classification. We performed classical analysis about differentiation and used Bayesian approaches to detect population structure and to reconstruct demography. The results revealed that historical and genetic classifications are loosely linked when chestnut fruits are just "castagne", that is, normal fruits, but increasingly overlap where "marroni" (the most prized fruits) are concerned. Bayesian classification allowed us to identify a homogeneous gene cluster not recognised in the traditional assessment of the varieties and to reconstruct possible routes used for the propagation of sweet chestnut. We also reconstructed ancestral relationships between the different gene pools involved and dated ancestral lineages whose results fit with palynological data. We suggest that conservation strategies based on a genetic evaluation of the resource should also rely on traditional cultural heritage, which could reveal new sources of germplasm.

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.

A mechanistic study of chestnut starch retrogradation and its effects on in vitro starch digestion.

Starch retrogradation is a mechanism that is associated with the quality of starch-based food products. A thorough understanding of chestnut starch retrogradation behavior plays an important role in maintaining the quality of chestnut foods during processing and storage. In this study, we investigated the effects of storage time on the structural properties and in vitro digestibility of gelatinized chestnut starch by using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and solid-state 13C nuclear magnetic resonance (NMR). The results showed that the long-range crystallinity and short-range molecular order of retrograded chestnut starch first rapidly increased from 3 h to 3 d and then decreased from 3 d to 7 d, followed by a slight increase from 7 d to 14 d with retrogradation. With the extension of storage time at 4 °C, there were generally obvious increases in single and double helical structures, which were stacked into long-term ordered structure, resulting in increased enthalpy changes as detected by differential scanning calorimetry spectroscopy (DSC) and reduction of the digestion rate of retrograded chestnut starch. Overall, this study may provide important implications for manipulating and improving the quality of chestnut foods.

A genome-guided strategy for climate resilience in American chestnut restoration populations.

American chestnut (Castanea dentata) is a deciduous tree species of eastern North America that was decimated by the introduction of the chestnut blight fungus (Cryphonectria parasitica) in the early 20th century. Although millions of American chestnuts survive as root collar sprouts, these trees rarely reproduce. Thus, the species is considered functionally extinct. American chestnuts with improved blight resistance have been developed through interspecific hybridization followed by conspecific backcrossing, and by genetic engineering. Incorporating adaptive genomic diversity into these backcross families and transgenic lines is important for restoring the species across broad climatic gradients. To develop sampling recommendations for ex situ conservation of wild adaptive genetic variation, we coupled whole-genome resequencing of 384 stump sprouts with genotype-environment association analyses and found that the species range can be subdivided into three seed zones characterized by relatively homogeneous adaptive allele frequencies. We estimated that 21 to 29 trees per seed zone will need to be conserved to capture most extant adaptive diversity. We also resequenced the genomes of 269 backcross trees to understand the extent to which the breeding program has already captured wild adaptive diversity, and to estimate optimal reintroduction sites for specific families on the basis of their adaptive portfolio and future climate projections. Taken together, these results inform the development of an ex situ germplasm conservation and breeding plan to target blight-resistant breeding populations to specific environments and provides a blueprint for developing restoration plans for other imperiled tree species.

Cryopreservation-enhanced differentiation capacity of embryogenic cultures of Castanea mollissima.

A cryopreservation protocol has been developed for embryogenic cultures (ECs) of Castanea mollissima, an important economic species of the Castanea genus in China. We achieved 100 % regrowth when ECs were treated with Plant Vitrification Solution 2 (PVS2) for 30, 60 and 90 min on ice. Optimal PVS2 treatment for cryopreservation was determined to be 30 min on ice based on the highest biomass regrowth after thawing. Fluorescein diacetate (FDA) staining could rapidly and reliably determine post-thaw cell viability and its use facilitated the optimization of the cryopreservation protocols. Although the proliferation rate of the re-established ECs remained largely unchanged compared to non-cryopreserved ECs, the capacity of the re-established ECs to differentiate (on two media) into somatic embryos nearly doubled to approximately 2200-2300 globular somatic embryos per 1 g of re-established ECs. Based on cell cluster size analysis, this enhanced growth is primarily attributed to the presence of significantly greater cell clusters with a diameter of 100-200 µm, which have the highest level of differentiation ability. In order to understand the increased embryogenic potential following cryopreservation, we analyzed the expression of key genes related to somatic embryogenesis. Genes CmWUS and CmABP1 were downregulated while CmLEC1, CmAGL15, CmGRF2, and CmFUS3 were upregulated in re-established ECs when compared to non-cryopreserved ECs.

Comprehensive evaluation of drought tolerance of six Chinese chestnut varieties (clones) based on flavonoids and other physiological indexes.

Flavonoids are crucial secondary metabolites that possess the ability to mitigate UV damage and withstand both biotic and abiotic stresses. Therefore, it is of immense significance to investigate the flavonoid content as a pivotal indicator for a comprehensive assessment of chestnut's drought tolerance. This study aimed to determine the flavonoid content and drought tolerance-related physiological and biochemical indices of six chestnut varieties (clones) grafted trees-Qianxi 42 (QX42), Qinglong 45 (QL45), Yanshanzaofeng (YSZF), Yanzi (YZ), Yanqiu (YQ), and Yanlong (YL)-under natural drought stress. The results were used to comprehensively analyze the drought tolerance ability of these varieties. The study revealed that the ranking of drought tolerance indices in terms of their ability to reflect drought tolerance was as follows: superoxide (oxide) dismutase (SOD) activity, ascorbate peroxidase (APX) activity, flavone content, catalase (CAT) activity, proline (PRO) content, soluble sugar content, peroxidase (POD) activity, betaine content, flavonol content, hydrogen peroxide (H2O2) content, soluble protein content, superoxide ion (OFR) content, superoxide (ion OFR) production rate, malondialdehyde (MDA) content, chlorophyll content. Through principal component analysis, the contents of flavonoids and flavonols can be used as indicators for comprehensive evaluation of drought tolerance of chestnut. The comprehensive evaluation order of drought tolerance of grafted trees of 6 chestnut varieties (Clones) was: QL45 > QX42 > YQ > YZ > YSZF > YL.

The de novo, chromosome-level genome assembly of the sweet chestnut (Castanea sativa Mill.) Cv. Marrone Di Chiusa Pesio.

OBJECTIVES: The sweet chestnut Castanea sativa Mill. is the only native Castanea species in Europe, and it is a tree of high economic value that provides appreciated fruits and valuable wood. In this study, we assembled a high-quality nuclear genome of the ancient Italian chestnut variety 'Marrone di Chiusa Pesio' using a combination of Oxford Nanopore Technologies long reads, whole-genome and Omni-C Illumina short reads. DATA DESCRIPTION: The genome was assembled into 238 scaffolds with an N50 size of 21.8 Mb and an N80 size of 7.1 Mb for a total assembled sequence of 750 Mb. The BUSCO assessment revealed that 98.6% of the genome matched the embryophyte dataset, highlighting good completeness of the genetic space. After chromosome-level scaffolding, 12 chromosomes with a total length of 715.8 and 713.0 Mb were constructed for haplotype 1 and haplotype 2, respectively. The repetitive elements represented 37.3% and 37.4% of the total assembled genome in haplotype 1 and haplotype 2, respectively. A total of 57,653 and 58,146 genes were predicted in the two haplotypes, and approximately 73% of the genes were functionally annotated using the EggNOG-mapper. The assembled genome will be a valuable resource and reference for future chestnut breeding and genetic improvement.

Survey of Leafminers on American Chestnut and other Castanea spp. (Fagales: Fagaceae) on Long Island, NY.

The effect of the 20th-century functional extinction of the American Chestnut (Fagaceae: Castanea dentata (Marshall) Borkh) on associated herbivorous insects is unknown. These insects include leafminers that spend at least part of their larval phase feeding between the epidermises of leaves. We surveyed leafminers on C. dentata, nonnative Castanea spp., and hybrids on Long Island, NY. We found 10 leafminer species feeding on Castanea spp. A first New York State record was documented for Stigmella castaneaefoliella (Chambers) (Lepidoptera: Nepticulidae). New host records are established for 6 lepidopterans, including a new host genus for Phyllonorycter basistrigella (Clemens) (Lepidoptera: Gracillariidae). We found no significant differences in the mean intensity of S. castaneaefoliella leaf mines on native and nonnative Castanea spp.; however, our sample size was small. Thus, we guardedly conclude that nonnative Castanea spp. can serve as refugia for C. dentata leafminers native to North America while acknowledging that the extent to which nonnative species are utilized requires further investigation.

[Short-term nitrogen addition reduces soil microbial nitrogen fixation rate in subtropical Pinus taiwanensis and Castanopsis faberi forests]. / çŸ­æœŸæ°®æ·»åŠ é™ä½Žäºšçƒ­å¸¦é»„å±±æ¾æž—å’Œç½—æµ®æ ²æž—åœŸå£¤å¾®ç”Ÿç‰©å›ºæ°®é€ŸçŽ‡.

Biological nitrogen (N) fixation is an important source of N in terrestrial ecosystems, but the response of soil microbial N fixation rate to N deposition in different forest ecosystems still remains uncertain. We conducted a field N addition experiment to simulate atmosphere N deposition in subtropical Pinus taiwanensis and Castanopsis faberi forests. We set up three levels of nitrogen addition using urea as the N source: 0 (control), 40 (low N), and 80 g N·hm-2·a-1(high N) to examine the chemical properties, microbial biomass C, enzyme activities, and nifH gene copies of top soils (0-10 cm). We also measured the microbial N fixation rate using the 15N labeling method. Results showed that N addition significantly reduced the soil microbial N fixation rate in the P. taiwanensis and C. faberi forests by 29%-33% and 10%-18%, respectively. Nitrogen addition significantly reduced N-acquiring enzyme (i.e., ß-1, 4-N-acetylglucosaminidase) activity and nifH gene copies in both forest soils. There was a significant positive correlation between the microbial N fixation rate and soil dissolved organic C content in the P. taiwanensis forest, but a significant negative relationship between the rate of soil microbial nitrogen fixation and NH4+-N content in the C. faberi forest. Overall, soil microbial N fixation function in the P. taiwanensis forest was more sensitive to N addition than that in the C. faberi forest, and the factors affecting microbial N fixation varied between the two forest soils. The study could provide insights into the effects of N addition on biological N fixation in forest ecosystems, and a theoretical basis for forest management.

Investigation into the Anti-Acne Effects of Castanea sativa Mill Leaf and Its Pure Ellagitannin Castalagin in HaCaT Cells Infected with Cutibacterium acnes.

Acne vulgaris is a prevalent skin disorder affecting many young individuals, marked by keratinization, inflammation, seborrhea, and colonization by Cutibacterium acnes (C. acnes). Ellagitannins, known for their antibacterial and anti-inflammatory properties, have not been widely studied for their anti-acne effects. Chestnut (Castanea sativa Mill., C. sativa), a rich ellagitannin source, including castalagin whose acne-related bioactivity was previously unexplored, was investigated in this study. The research assessed the effect of C. sativa leaf extract and castalagin on human keratinocytes (HaCaT) infected with C. acnes, finding that both inhibited IL-8 and IL-6 release at concentrations below 25 µg/mL. The action mechanism was linked to NF-κB inhibition, without AP-1 involvement. Furthermore, the extract displayed anti-biofilm properties and reduced CK-10 expression, indicating a potential role in mitigating inflammation, bacterial colonization, and keratosis. Castalagin's bioactivity mirrored the extract's effects, notably in IL-8 inhibition, NF-κB inhibition, and biofilm formation at low µM levels. Other polyphenols, such as flavonol glycosides identified via LC-MS, might also contribute to the extract's biological activities. This study is the first to explore ellagitannins' potential in treating acne, offering insights for developing chestnut-based anti-acne treatments pending future in vivo studies.

Harmful self-pollination drives gynodioecy in European chestnut, a self-incompatible tree.

PREMISE: Gynodioecy is a rare sexual system in which two genders (sensu Lloyd, 1980), cosexuals and females, coexist. To survive, female plants must compensate for their lack of siring capacity and male attractiveness. In European chestnut (Castanea sativa), an outcrossing tree, self-pollination reduces fruit set in cosexual individuals because of late-acting self-incompatibility and early inbreeding depression. Could this negative sexual interaction explain the presence of females in this species? METHODS: We studied gender variation in wild populations of European chestnut. In addition, we compared fruit set (the proportion of flowers giving fruits) and other key female fitness components as well as reproductive allocation between genders. We then performed emasculation experiments in cosexual trees, by removing nectar-producing fertile male inflorescences. We also removed sterile but nectar-producing male inflorescences from female trees, as a control. RESULTS: We found a highly variable proportion of male-sterile individuals in the wild in European chestnut. In the experimental plot, trees from each gender had similar size, flower density, and burr set, but different fruit set. Removing nectar-producing male inflorescences from branches or entire trees increased fruit set in cosexual but not in female trees. CONCLUSIONS: These results show that self-pollination impairs fruit set in cosexual trees. Female trees avoid these problems as they do not produce pollen but continue to attract pollinators thanks to their rewarding male-sterile inflorescences, resulting in a much higher fruit set than in cosexuals. This demonstrates that even outcrossed plants can benefit from the cessation of self-pollination, to the point that unisexuality can evolve.

Insights into multiscale structure and digestive characteristic of starch from two cultivars of chestnut during kernel development.

Multiscale structure and digestive characteristic of starch during kernel development of Castanea henryi ('Jinzhui' (YS) and 'Baiyan No.1' (WS)) were investigated in this study. Structural analysis revealed that the surface of starch granules became smooth, the amylopectin content decreased (from 71.32 % to 70.47 %, from 71.44 % to 68.37 %, respectively), the chain length distribution of amylopectin reduced (the proportion of B1 chain decreased from 52.35 % to 50.60 %, from 52.22 % to 50.59 %, respectively) while the amorphous and semi-crystalline lamellae of starch increased during development, which was consistent with the decreasing relative crystallinity (from 28.79 % to 24.11 %, from 29.57 % to 23.66 %, respectively) and short-range ordering degree. The degradation of ordered structure further resulted in the increase of digestibility, especially in the late developmental stage, supported by a significant decrease of resistant starch content (from 70.21 % to 61.70 % and from 73.58 % to 58.86 %, respectively). Transcriptome analysis and RT-qPCR were performed to explore the possible molecular mechanisms affecting starch structure. The high expression of several key genes including AGPase, GBSS, SBE, SSS, ISA and PUL in late development stage might be the reason of structural changes during development. The results provided valuable information for starch accumulation during kernel development of Castanea henryi.

Genome-Wide Characterization and Functional Validation of the ACS Gene Family in the Chestnut Reveals Its Regulatory Role in Ovule Development.

Ovule abortion significantly contributes to a reduction in chestnut yield. Therefore, an examination of the mechanisms underlying ovule abortion is crucial for increasing chestnut yield. In our previous study, we conducted a comprehensive multiomic analysis of fertile and abortive ovules and found that ACS genes in chestnuts (CmACS) play a crucial role in ovule development. Therefore, to further study the function of ACS genes, a total of seven CmACS members were identified, their gene structures, conserved structural domains, evolutionary trees, chromosomal localization, and promoter cis-acting elements were analyzed, and their subcellular localization was predicted and verified. The spatiotemporal specificity of the expression of the seven CmACS genes was confirmed via qRT-PCR analysis. Notably, CmACS7 was exclusively expressed in the floral organs, and its expression peaked during fertilization and decreased after fertilization. The ACC levels remained consistently greater in fertile ovules than in abortive ovules. The ACSase activity of CmACS7 was identified using the genetic transformation of chestnut healing tissue. Micro Solanum lycopersicum plants overexpressing CmACS7 had a significantly greater rate of seed failure than did wild-type plants. Our results suggest that ovule fertilization activates CmACS7 and increases ACC levels, whereas an overexpression of CmACS7 leads to an increase in ACC content in the ovule prior to fertilization, which can lead to abortion. In conclusion, the present study demonstrated that chestnut ovule abortion is caused by poor fertilization and not by nutritional competition. Optimization of the pollination and fertilization of female flowers is essential for increasing chestnut yield and reducing ovule abortion.