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The objective of this study was to investigate the effect of exogenous selenium on selenium enrichment and antioxidant activity of germinated chestnuts. We treated 'Zaofeng' chestnuts with Na SeO at concentration of 0, 20, 40, 60 and 80 mg/L, and analyzed, during germination, the level of total Se, SeCys , MeSecys, Se , SeMet, Se , γ-aminobutyric acid (GABA), antioxidant enzyme (phenylalanine ammonialyase (PAL), glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT)) activity, non-enzymatic antioxidant substances (total polyphenols and flavonoids) content and antioxidant capacity (DPPH, ABTS). The results indicated that low concentrations of selenium (20-40 mg/L) significantly promoted the organic transformation of selenium, with a Se-enrichment rate over 74%. Antioxidant enzyme (PAL, SOD, CAT) activities and total phenol content were enhanced by 1.1 to 1.9-fold compared with the control, leading to a 12.2-29.2% improvement in antioxidant capacity (DPPH and ABTS). In contrast, the high concentration of selenium (80 mg/L) induced oxidative stress, inhibiting enzyme (PAL, SOD, CAT) activities (reduced by 14.1-20.5%) and decreasing antioxidant capacity (DPPH) by approximately 19.0%. During chestnut germination, selenite was absorbed by the embryo and subsequently transformed into organic Se in vivo, ultimately being stored mainly as SeCys . The selenium enrichment rate decreased significantly with increasing Na SeO treatment concentration: from 86.4% at 20 mg/L to 62.2% at 80 mg/L. Furthermore, treatment with 40 mg/L Na SeO led to a significant increase in GABA content of germinated chestnuts, reaching 1.3 times that of the control group. Overall, germination with 20-40 mg/L Na SeO is an effective condition for producing Se-enriched chestnut sprouts with enhanced GABA and antioxidant capacity, offering a potential functional food ingredient.

Background The genus Lithocarpus is a species-rich dominant woody lineage in East Asian evergreen broad-leaved forests. Despite its ecological and economic significance, the plastome structure and evolutionary history of the genus remain poorly understood. In this study, we comprehensively analyzed the 34 plastomes representing 33 Lithocarpus species. Of which, 21 were newly assembled. The plastome-based phylogenomic tree was reconstructed to reveal the maternal evolutionary patterns of the genus. Results The Lithocarpus plastomes exhibit a typical quadripartite structure, ranging in length from 161,010 to 161,476 bp, and containing 131 genes, including 86 protein-coding genes, 8 rRNA genes, and 37 tRNA genes. Remarkably, the inf A gene was identified as a pseudogene in 17 species. Significant variability was observed in simple sequence repeats (SSRs) as well as in the boundary regions between the two single-copy regions and the inverted repeat region (SC/IR) across the plastomes. Additionally, four genes ( acc D, atp F, rpl 32, and rps 8) were found to be under positive selection. The monophyletic status of Lithocarpus was strongly supported by plastome-based phylogeny; however, the phylogenetic tree topology showed a significant difference from that obtained by the nuclear genome-based phylogeny. Conclusions The plastome of Fagaceae is generally conserved. Nevertheless, genes related to metabolism, photosynthesis, and energy were under strong positive selection in Lithocarpus , likely driven by environmental pressures and local adaptation. The plastome-based phylogeny confirmed the monophyletic status of Lithocarpus and revealed a phylogeographic pattern indicating limited seed-mediated gene flow in the ancestral lineage. The prevalence of cytonuclear discordance in Lithocarpus and other Fagaceae genera suggests that ancient introgression, incomplete lineage sorting, and asymmetrical seed- and pollen-mediated geneflow might contribute to this discordance. Future studies are essential to test these hypotheses and further elucidate the divergence patterns of this unique Asian evergreen lineage.

The negative effect of soil pathogens on seedling survival varies considerably among conspecific individuals, but the underlying mechanisms are largely unknown. For variation between heterospecifics, a common explanation is the Janzen-Connell effect: negative density dependence in survival due to specialized pathogens aggregating on common hosts. We test whether an intraspecific Janzen-Connell effect exists, i.e., whether the survival chances of one population's seedlings surrounded by a different conspecific population increase with genetic difference, spatial distance, and trait dissimilarity between them. In a shade-house experiment, we grew seedlings of five populations of each of two subtropical tree species ( Castanopsis fissa and Canarium album ) for which we measured genetic distance using intersimple sequence repeat (ISSR) analysis and eight common traits/characters, and we treated them with soil material or soil biota filtrate collected from different populations. We found that the relative survival rate increased with increasing dissimilarity measured by spatial distance, genetic distance, and trait differences between the seedling and the population around which the soil was collected. This effect disappeared after soil sterilization. Our results provide evidence that genetic variation, trait similarity, and spatial distance can explain intraspecific variation in plant-soil biotic interactions and suggest that limiting similarity also occurs at the intraspecific level.

Background Class III peroxidases (PRXs) are plant-specific proteins crucial for growth, development, and stress responses. Castanea mollissima is an important woody crop; however, soil alkalization, a common environmental stressor, limits the sustainable development of its agricultural ecology. The evolution of the PRX gene family and its regulatory mechanisms under alkaline stress in this species remain unclear. Results In the Castanea mollissima genome, 98 CmPRX genes were identified, distributed unevenly across 12 chromosomes and classified into eight subfamilies. Tandem duplication was the primary driver of the expansion of this gene family. Under alkaline stress, key physiological indicators (SOD and CAT activities, MDA content) in leaves changed significantly, reflecting the plant’s physiological response and adaptive potential under such conditions. Integration of transcriptomic and physiological data revealed highly differentiated expression patterns among CmPRX members. The reliability of the RNA-seq data was validated by RT-qPCR analysis. Weighted Gene Co-expression Network Analysis (WGCNA) identified specific modules significantly correlated with antioxidant enzyme activities, suggesting a pivotal role for this gene family in regulating oxidative balance. Conclusions This study systematically clarifies the evolutionary characteristics of the CmPRX gene family and its expression regulatory network under alkaline stress. The findings provide a theoretical basis and candidate gene resources for improving alkaline tolerance in C. mollissima through genetic breeding, and offer important insights for selecting stress-tolerant varieties in regions affected by soil alkalization.

Premise of the Study Xylem vessels transition through different stages during their functional lifespan, including expansion and development of vessel elements, transition to vessel hydraulic functionality, and eventual transition to post‐functionality. We used information on vessel development and function to develop a model of vessel lifespan for woody plants. Methods We examined vessel functional lifespan using repeated anatomical sampling throughout the growing season, combined with active‐xylem staining to evaluate vessel hydraulic transport functionality. These data were combined with a literature review. The transitions between vessel functional lifespans for several species are illustrated, including grapevine (Vitis vinifera L., Vitaceae), English oak (Quercus robur L., Fagaceae), American chestnut [Castanea dentata (Marshall) Borkh.; Fagaceae], and several arid and semi‐arid shrub species. Key Results In intact woody plants, development and maturation of vessel elements may be gradual. Once hydraulically functional, vessel elements connect to form a vessel network that is responsible for bulk hydraulic flow through the xylem. Vessels become nonfunctional due to the formation of gas emboli. In some species and under some conditions, vessel functionality of embolized conduits may be restored through refilling. Blockages, such as tyloses, gels, or gums, indicate permanent losses in hydraulic functional capacity; however, there may be some interesting exceptions to permanent loss of functionality for gel‐based blockages. Conclusions The gradual development and maturation of vessel elements in woody plants, variation in the onset of functionality between different populations of vessels throughout the growing season, and differences in the timing of vessel transitions to post‐functionality are important aspects of plant hydraulic function.

Chestnut (Castanea mollissima) is a deciduous tree species with major economic and ecological value that is widely used in the study of floral development in woody plants due its monoecious and out-of-proportion characteristics. Squamosa promoter-binding protein-like (SPL) is a plant-specific transcription factor that plays an important role in floral development. In this study, a total of 18 SPL genes were identified in the chestnut genome, of which 10 SPL genes have complementary regions of CmmiR156. An analysis of the phylogenetic tree of the squamosa promoter-binding protein (SBP) domains of the SPL genes of Arabidopsis thaliana, Populus trichocarpa, and C. mollissima divided these SPL genes into eight groups. The evolutionary relationship between poplar and chestnut in the same group was similar. A structural analysis of the protein-coding regions (CDSs) showed that the domains have the main function of SBP domains and that other domains also play an important role in determining gene function. The expression patterns of CmmiR156 and CmSPLs in different floral organs of chestnut were analyzed by real-time quantitative PCR. Some CmSPLs with similar structural patterns showed similar expression patterns, indicating that the gene structures determine the synergy of the gene functions. The application of gibberellin (GA) and its inhibitor (Paclobutrazol, PP333) to chestnut trees revealed that these exert a significant effect on the number and length of the male and female chestnut flowers. GA treatment significantly increased CmmiR156 expression and thus significantly decreased the expression of its target gene, CmSPL6/CmSPL9/CmSPL16, during floral bud development. This finding indicates that GA might indirectly affect the expression of some of the SPL target genes through miR156. In addition, RNA ligase-mediated rapid amplification of the 5′ cDNA ends (RLM-RACE) experiments revealed that CmmiR156 cleaves CmSPL9 and CmSPL16 at the 10th and 12th bases of the complementary region. These results laid an important foundation for further study of the biological function of CmSPLs in the floral development of C. mollissima.

Background Gene tree incongruence is a well-documented, but the biological and analytical factors driving phylogenetic discordance remains incompletely understood. In this study, we investigated how different factors contribute to incongruence among gene trees in Fagaceae. Results Each dataset produced highly supported topologies, with Fagus and Trigonobalanus consistently placed as early-diverging lineages within the Fagaceae family. However, the cpDNA and mtDNA divided the remaining Fagaceae species into New World and Old World clades, a pattern that sharply contrasted with the phylogenetic relationships inferred from nuclear genome data. These discrepancies between the cytoplasmic and nuclear gene trees likely result from ancient interspecific hybridization within Fagaceae. The decomposition analyses revealed that gene tree estimation error, incomplete lineage sorting, and gene flow accounted for 21.19%, 9.84%, and 7.76% of gene tree variation, respectively. We further revealed that 58.1–59.5% of genes exhibited consistent phylogenetic signals (“consistent genes”), while 40.5–41.9% of genes displayed conflicting signals (“inconsistent genes”). Consistent genes showed stronger phylogenetic signals and were more likely to recover the species tree topology than inconsistent genes. However, consistent and inconsistent genes did not significantly differ in terms of sequence- and tree-based characteristics. By excluding a subset of inconsistent genes, the study significantly reduced inconsistencies between concatenation- and coalescent-based approaches. Conclusions This study illustrates how diverse factors contribute to gene tree incongruence, offering new insights into the evolutionary history of Fagaceae.

The anatomical structure of wood is complex and contains considerable information about its specific species, physical properties, growth environment, and other factors. While conventional wood anatomy has been established by systematizing the xylem anatomical features, which enables wood identification generally up to genus level, it is difficult to describe all the information comprehensively. This study apply two computer vision approaches to optical micrographs: the scale-invariant feature transform algorithm and connected-component labelling. They extract the shape and pore size information, respectively, statistically from the whole micrographs. Both approaches enable the efficient detection of specific features of 18 species from the family Fagaceae. Although the methods ignore the positional information, which is important for the conventional wood anatomy, the simple information on the shape or size of the elements is enough to describe the species-specificity of wood. In addition, according to the dendrograms calculated from the numerical distances of the features, the closeness of some taxonomic groups is inconsistent with the types of porosity, which is one of the typical classification systems for wood anatomy, but consistent with the evolution based on molecular phylogeny; for example, ring-porous group Cerris and radial-porous group Ilex are nested in the same cluster. We analyse which part of the wood structure gave the taxon-specific information, indicating that the latewood zone of group Cerris is similar to the whole zone of group Ilex. Computer vision approaches provide statistical information that uncovers new aspects of wood anatomy that have been overlooked by conventional visual inspection.

Background Chinese chestnut ( Castanea mollissima ) is an economically and ecologically important woody nut crop. In C. mollissima , flowering is fundamental for nut yield. The MADS-box gene APETALA 1 ( AP1 ) plays essential roles in floral initiation and floral organ development in many plants. However, the function of the AP1 gene CmAP1 in C. mollissima is still unclear. Here, we cloned the coding sequence (CDS) and promoter of CmAP1 and analyzed the function of this gene. Results The CDS of CmAP1 is 741 bp and encodes a 246–amino acid protein. Subcellular analysis revealed that CmAP1 localizes to the nucleus. GUS driven by the CmAP1 promoter was expressed in seedlings and in leaf margins, petals, and carpels of transgenic Arabidopsis ( Arabidopsis thaliana ). RNA in situ hybridization indicated that CmAP1 was mainly expressed in the inflorescence meristem, floral primordia, sepal primordia, petal primordia, stamen primordia, and carpel primordia during the early stage of flower development. An auxin response element (TGA element), jasmonic acid response element (TGACG motif), and WRKY binding site (W-box element) were identified in the CmAP1 promoter. Heterologous expression of CmAP1 in wild-type and ap1-11 Arabidopsis resulted in early flowering. Notably, the expression of CmAP1 rescued the loss of the petal whorl in the ap1-11 mutant. AtAP1 , AtSEP1 , AtSEP2 , AtSEP3 , and AtSEP4 were upregulated in CmAP1 -expressing Arabidopsis plants. Conclusions These findings suggest that CmAP1 promotes flowering and plays a key role in petal development. Our findings help reveal the regulatory mechanism of flowering and flower development in C. mollissima , providing a practical basis for increasing yield in Chinese chestnut.

The oak family Fagaceae is thought to have its evolutionary origins in northern temperate forests and Southeast Asia. Wilf et al. now report 52-million-year-old fossils from the Southern Hemisphere belonging to the still-living genus Castanopsis . Hypotheses of Fagaceae origins have focused only on the Northern Hemisphere. Ancestral Castanopsis may represent one of numerous paleo-Antarctic plant genera that are found with Castanopsis today in Southeast Asian rainforests. Science , this issue p. eaaw5139 Fossils of Castanopsis suggest an important Southern Hemisphere dispersal of ancestral beech family trees. The beech-oak family Fagaceae dominates forests from the northern temperate zone to tropical Asia and Malesia, where it reaches its southern limit. We report early Eocene infructescences of Castanopsis , a diverse and abundant fagaceous genus of Southeast Asia, and co-occurring leaves from the 52-million-year-old Laguna del Hunco flora of southern Argentina. The fossil assemblage notably includes many plant taxa that associate with Castanopsis today. The discovery reveals novel Gondwanan history in Fagaceae and the characteristic tree communities of Southeast Asian lower-montane rainforests. The living diaspora associations persisted through Cenozoic climate change and plate movements as the constituent lineages tracked post-Gondwanan mesic biomes over thousands of kilometers, underscoring their current vulnerability to rapid climate change and habitat loss.