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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., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

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., (© 2024 The Authors. American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)

We evaluated an alternative small stem assay (AltSSA) for blight resistance in backcross hybrid chestnut trees ( Castanea dentata/mollissima ). Whereas standard small stem assays (SSAs) are done by inoculating small incisions in stems, in our AltSSA, 4- to 5-mm stems are cut off, and the exposed (living) stem tips are inoculated with discs of Cryphonectria parasitica inoculum and temporarily covered with plastic sleeves. Intended primarily for forward selection, this method was designed to be easy to implement, to consistently induce cankering, and to better enable seedling recovery via the development of lateral shoots from the lower stem. After 90+ days, cankers are evaluated and removed, and seedlings are prepared for out-planting. Previous results showed that AltSSAs performed at least as well as a common SSA method in distinguishing resistant and susceptible types. In this follow-up analysis of 35 lines of backcross seedlings studied in 2020 and 2021, we showed that mean orange zone canker length (OZCL) and a multifactor principal components analysis-based blight resistance index gave results consistent with predictions derived from two methods of blight resistance phenotyping and percentage of American chestnut ancestry of the parents of each line. As expected, based upon the apparent polygenic inheritance of blight resistance in backcross chestnut trees, mean OZCL of backcross families ranged from intermediate (F 1 hybrid-level) to low (wild-type American chestnut-level). Consistent with prior results, canker production was near 100%, survivorship after out-planting was very high, and postinoculation stem dieback was not apparently related to the stem tip inoculations. Altogether, these results suggest that the AltSSA is a viable method for early detection of relative blight resistance in seedlings and may enable a reduction in the numbers of trees out-planted and placed under care for long-term evaluation and breeding. Thus, the AltSSA can prevent time, resources, and orchard space from being used on susceptible trees., Competing Interests: The author(s) declare no conflict of interest.

Castanea henryi is a monoecious plant with a low female-to-male ratio, which limits its yield. The phytohormone cytokinin (CK) plays a crucial role in flower development, especially gynoecium development. Here, the feminizing effect of CK on the development of C. henryi was confirmed by the exogenous spraying of N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU). Spraying CPPU at 125 mg·L -1 thrice changed the male catkin into a pure female catkin, whereas at 5 mg·L -1 and 25 mg·L -1 , only a part of the male catkin was transformed into a female catkin. A comparative transcriptome analysis of male catkins subjected to CPPU was performed to study the mechanism of the role of CKs in sex differentiation. Using Pearson's correlation analysis between hormone content and hormone synthesis gene expression, four key genes, LOG1 , LOG3 , LOG7 and KO , were identified in the CK and GA synthesis pathways. Moreover, a hub gene in the crosstalk between JA and the other hormone signaling pathways, MYC2 , was identified, and 15 flowering-related genes were significantly differentially expressed after CPPU treatment. These results suggest that CK interacts with other phytohormones to determine the sex of C. henryi , and CK may directly target floral organ recognition genes to control flower sex.

Premise: Although chestnuts and chinquapins are some of the best known and most widely loved of any plants in North America, relatively little genomic sequencing has been done, and much is still unknown about their evolution., Methods: We used double-digest restriction-site-associated DNA (ddRAD) sequencing data to infer the species-level phylogeny for Castanea and assess the phylogeography of the North American species using samples collected from populations that span the full extent of the species' ranges. We also constructed species distribution models using digitized herbarium specimens and observational data from field surveys., Results: We identified strong population structure within Castanea dentata (American chestnut) that reflects a stepwise northern migration since the last glacial maximum. Our species distribution models further confirmed this scenario and matched closely with the Castanea fossil pollen record. We also found significant structure within the Castanea pumila lineage, most notably a genetic cluster that corresponds to the frequently recognized Castanea pumila var. ozarkensis., Conclusions: The two North American Castanea species have contrasting patterns of population structure, but each is typical of plant phylogeography in North America. Within the C. pumila complex, we found novel genetic structure that provides new insights about C. pumila taxonomy. Our results also identified a series of distinctive populations that will be valuable in ongoing efforts to conserve and restore chestnuts and chinquapins in North America., (© 2021 Botanical Society of America.)

We tested an alternative small stem assay (SSA) for blight resistance in chestnuts ( Castanea spp.). Whereas standard SSAs are done by inoculating small incisions in stems, we cut off stems (4 to 5 mm diameter), inoculated the cut ends with discs of Cryphonectria parasitica inoculum, and covered them with plastic sleeves. This method was designed to be simple to implement, to consistently induce cankering, and to better enable seedlings to recover by developing shoots from the lower stem (standard SSAs delay removal of blighted stems until late in the growing season, if at all). We conducted six experiments with seedlings and orchard trees of Castanea dentata (susceptible), Castanea mollissima (resistant), and hybrids expected to vary in resistance. Experiments with seedlings and two of the three orchard experiments showed clear differentiation between susceptible and resistant types, especially >90 days postinoculation and when the orange-colored zone of the canker was measured. One orchard experiment failed to give clear results but was ended earlier (60 days) than the other experiments. We observed only two failed inoculations out of >200 performed. Comparisons with other studies suggest that this SSA method performs at least as well as the standard SSA method in distinguishing resistant and susceptible types, at least in seedlings. Survivorship after 1 year for seedlings inoculated in 2018 ranged from 70% for C. dentata to 100% for C. mollissima , and in 2019 they ranged from 40% in hybrids to 100% for C. mollissima. Deaths of seedlings after SSAs were mostly unrelated to the inoculations (e.g., root rot).

Pollination is essential for efficient reproduction in pollinator-dependent crops that rely on the attraction of pollinators to flowers. Especially, floral nectar is considered to be an important factor attracting pollinator like honey bees, but differences among major chestnut species ( Castanea crenata , C. mollissima , C. dentata , and C. sativa ) are still little explored. This study aims to evaluate the value of honey source by analyzing floral nectar characteristics and comparing the composition of volatile organic compounds (VOCs) that mediate plant-pollinator interaction. In this study, we analyzed nectar samples obtained from male flowers using HPLC and HS-SPME/GC-MS. The five chestnuts showed significant differences between the volume of secreted nectar, free sugar composition, amino acid content and VOCs composition. Furthermore, C. crenata (Japanese cultivar 'Ungi') was revealed to emit the highest total amounts of VOCs and high levels of benzenoid compounds that are generally associated with flower-visiting insects. The sugar content per catkin, which is used to determine the honey yield, was the highest in C. crenata , suggesting that C. crenata 'Ungi' can be highly valued as a honey tree. Therefore, a better understanding of the relationship between pollinator and nectar characteristics of C. crenara could contribute to a prospective honey plant.

This study combined phytosanitary surveys, laboratory analyses, and mathematical modeling to show how hail-induced wounds can foster the infections of the blight pathogen Cryphonectria parasitica , locally associated with extensive dieback of chestnut ( Castanea sativa ). Orchards and coppices located within and outside the assessed dieback area in a single location in the North West of Italy were inspected to appraise the abundance of hail-induced wounds and C. parasitica infections. The incidence of C. parasitica was significantly higher within the dieback area compared with outside (92% versus 60%; P < 0.05). Hail-induced wounds were observed on small branches and shoots of all trees sampled within the dieback area, whereas they were less abundant outside (20% of trees), suggesting either that the dieback was directly associated with the injuries caused by the hailstorms or that those injuries may have facilitated infections of C. parasitica . Isolations conducted on 359 branches and shoots showed that hail-induced wounds served as infection courts for C. parasitica and that infections depended on the size rather than on the number of hail wounds. We fitted a logistic model showing that hail-induced wounds whose perimeter was larger than 66 mm were at particular risk of C. parasitica infection. A newly designed geometrical-based model is proposed to relate hailstones size, hail wound perimeter, and the risk of infection. We established that hail-induced wounds are entry points for virulent and hypovirulent strains of C. parasitica , since 6.5% of isolates were infected by Cryphonectria hypovirus-1.

The oriental gall wasp Dryocosmus kuriphilus represents a limiting pest for the European Chestnut (Castanea sativa, Fagaceae) as it creates severe yield losses. The European Chestnut is a deciduous tree, having major social, economic and environmental importance in Southern Europe, covering an area of 2.53 million hectares, including 75,000 ha devoted to fruit production. Cultivars show different susceptibility and very few are resistant to gall wasp. To deeply investigate the plant response and understand which factors can lead the plant to develop or not the gall, the study of transcriptome is basic (fundamental). To date, little transcriptomic information are available for C. sativa species. Hence, we present a de novo assembly of the chestnut transcriptome of the resistant Euro-Japanese hybrid 'Bouche de Bétizac' (BB) and the susceptible cultivar 'Madonna' (M), collecting RNA from buds at different stages of budburst. The two transcriptomes were assembled into 34,081 (BB) and 30,605 (M) unigenes, respectively. The former was used as a reference sequence for further characterization analyses, highlighting the presence of 1444 putative resistance gene analogs (RGAs) and about 1135 unigenes, as putative MiRNA targets. A global quantitative transcriptome profiling comparing the resistant and the susceptible cultivars, in the presence or not of the gall wasp, revealed some GO enrichments as "response to stimulus" (GO:0050896), and "developmental processes" (e.g., post-embryonic development, GO:0009791). Many up-regulated genes appeared to be transcription factors (e.g., RAV1, AP2/ERF, WRKY33) or protein regulators (e.g., RAPTOR1B) and storage proteins (e.g., LEA D29) involved in "post-embryonic development". Our analysis was able to provide a large amount of information, including 7k simple sequence repeat (SSR) and 335k single-nucleotide polymorphism (SNP)/INDEL markers, and generated the first reference unigene catalog for the European Chestnut. The transcriptome data for C. sativa will contribute to understand the genetic basis of the resistance to gall wasp and will provide useful information for next molecular genetic studies of this species and its relatives.

Oak honeydew and chestnut honeys often share the same production area in Atlantic landscapes. Consequently these honeys have common physicochemical properties and pollen composition, making their differentiation by routine methods, a difficult task. The increase in the demands of consumers for clear honey labelling, identifying floral make-ups and the substantial health properties of both honey types, make it necessary to improve methods to differentiate the honeys. Statistical multivariate techniques were used to study the differences in the physicochemical composition and pollen spectra between chestnut honey and oak honeydew honey. Palynological analysis, moisture, pH, electrical conductivity, hydroxymethylfurfural, diastase number, colour, phenolic content, minerals and sugars were used for this purpose. The variables that had more weight in the differentiation by principal component analysis were Castanea, Cytisus type, CIELab coordinates (a * and L), RSA, Mg and trehalose; 97.6% of the honey samples were correctly classified by linear discriminant analysis., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Retrotransposons (RTNs) contribute for genome evolution, influencing its size and structure. We investigated the utility of the RTN-based markers inter-primer binding site (iPBS) for the molecular characterization of 25 Fagaceae species from genera Castanea, Fagus and Quercus. The assessment of genetic diversity, relationships and structure, as well as taxonomic classification of Fagaceae based on molecular data is important for definition of conservation, forestry management strategies and discrimination among natural hybrids and their parents since natural hybridization may increase with the climate changes. Here, iPBS primers designed by other authors were tested alone and combined. Some of them were discriminative, revealed polymorphism within and among taxa allowing the production of a total of 150 iPBS markers. In addition, several monomorphic iPBS markers were also amplified in each taxon. The UPGMA dendrogram based on the pooled iPBS data revealed 27% of genetic similarity among species. The individuals were clustered per genus and most of the oaks per infrageneric group corroborating the adopted taxonomy. Globally, the iPBS markers demonstrated suitability for DNA fingerprinting, determination of phylogenies and taxonomic discrimination in Fagaceae, and could constitute a useful and alternative tool for germplasm characterization, and for definition of conservation strategies and forestry management. Moreover, these markers would be useful for fingerprinting natural hybrids that share morphological similarities with their parents. Since iPBS markers could also enable insights about RTNs evolution, an eventual correlation among iPBS polymorphism, variability of RTN insertions and/or genome size in Fagaceae is discussed.

A key question in insect community ecology is whether parasitoid assemblages are structured by the food plants of their herbivore hosts.Tritrophic communities centred on oak‐feeding cynipid gallwasps are one of the best‐studied tritrophic insect communities. Previous work suggests that host plant identity is a much stronger predictor of oak–cynipid interactions than of cynipid–parasitoid interactions. However, these relationships have not been formally quantified.We reason that the potential for 'bottom‐up' effects should increase with host plant phylogenetic diversity. We, therefore, generated quantified interaction network data for previously unstudied tritrophic cynipid communities in Sichuan, China, where, in addition to Quercus, cynipid host plants include Castanea, Castanopsis and Lithocarpus. We characterise these communities taxonomically and compare the extent to which host plant taxonomy predicts plant–herbivore and plant–parasitoid associations.We sampled 42,620 cynipid galls of 176 morphotypes from 23 host plant species, yielding over 4500 specimens of 64 parasitoid morphospecies. Many parasitoids were identifiable to chalcidoid taxa present in other Holarctic oak cynipid communities, with the addition of Cynipencyrtus (Cynipencyrtidae). As elsewhere, Sichuan parasitoid assemblages were dominated by generalists.Gallwasp–plant interaction networks were significantly more modular than parasitoid–plant association networks. Gallwasps were significantly more specialised to host plants (i.e. had higher mean d' values) than parasitoids. Parasitoid assemblages nevertheless showed significant plant‐associated beta diversity, with a dominant turnover component.We summarise parallels between our study and other Fagaceae‐associated cynipid communities and discuss our findings in light of the processes thought to structure tritrophic interactions centred on endophytic insect herbivores. [ABSTRACT FROM AUTHOR]

Fungi of the genus Cryphonectria are of special interest to tree pathologists because they cause bark disease in numerous species of the Fagaceae and Betulaceae. Despite this special attention, several Cryphonectria species were not recognized as such for a long time. This also affected the identity of eight isolates with outdated names that have been deposited in our laboratory since 1954. The present study reconstructs the history of the Cryphonectria cultures M282–M289 using primary bibliographic sources. To verify the species identity, all isolates were DNA barcoded and taxonomic affiliation was assessed using a phylogenetic approach. The taxonomic identity combined with the history of the isolates confirms that the chestnut blight epidemic (Cryphonectria parasitica) in Spain was caused by the planting of Asian chestnuts and that the first documented case of bark canker in 1940 was caused by Cryphonectria radicalis on Japanese chestnuts imported from France. The history of isolate M289 could be traced back to CBS 165.32, which proved to be the oldest preserved isolate of the rare Cryphonectria naterciae, confirming the presence of this fungus in Europe for at least 100 years. Based on the ITS barcoding of the 32‐year‐old type specimen, Cryphonectria decipiens must be reclassified as a later synonym of Cryphonectria radicalis. The reconstruction of the history of isolates M282–M289 takes us on a scientific journey from Italy to France, Spain and Portugal in the early twentieth century and offers new insights into the historical context of the invasion of Cryphonectria parasitica in Europe. [ABSTRACT FROM AUTHOR]

Key message: In arboriculture, the number and diversity of pollen donors can have a major impact on fruit production. We studied pollination insurance in hybrid chestnut orchards (C. sativa × C. crenata) provided by nearby wild European chestnuts (C. sativa) in southwestern France. Most fruits were sired by hybrid pollenizers rather than by wild chestnuts. When these hybrid pollenizers were too scarce, a frequent situation, pollen produced by wild chestnut trees did not compensate for the lack of compatible pollen and fertilization rates and fruit production collapsed. Context: The demand for chestnuts has been increasing in recent years in many European countries, but fruit production is not sufficient to meet this demand. Improving pollination service in chestnut orchards could increase fruit production. Aims: Investigate pollination service in chestnut orchards. Evaluate the contribution to pollination of trees growing in chestnut woods and forests. Methods: We investigated five orchards planted with hybrid chestnuts (C. sativa × C. crenata) cultivars in southwestern France. We combined fruit set data, which provide information about pollination rate, with genetic data, which provide information about pollen origin. We used this information to estimate the contribution of nearby C. sativa forest stands to the pollination of each orchard. Results: Pollination rates vary considerably, being fivefold higher in orchards comprising numerous pollen donors than in monovarietal orchards. Because of asymmetric hybridization barriers between hybrid and purebred cultivars, the surrounding chestnut forests provide very limited pollination insurance: less than 14% of the flowers in these monovarietal orchards had been pollinated by forest trees. Conclusion: Because chestnut orchards are now increasingly relying on hybrid cultivars, surrounding wild European chestnut trees are no longer a reliable pollen source. To achieve maximal fruit set, efforts must therefore concentrate on orchard design, which should include enough cultivar diversity. [ABSTRACT FROM AUTHOR]

Gnomoniopsis castaneae is internationally recognized as a destructive pathogen of chestnut species. Primarily associated with nut rot, it has also been associated with branch and stem cankers of chestnut and as an endophyte of multiple additional hardwood species. The present study evaluated implications of the recently reported United States presence of the pathogen for domestic Fagaceae species. Stem inoculation assays of Castanea dentata, C. mollissima, C. dentata x C. mollissima, and Quercus rubra (red oak) seedlings were utilized to examine the cankering ability of a regional isolate of the pathogen. The pathogen induced damaging cankers in all assessed species and significant stem girdling in all chestnut species. No previous study has associated the pathogen with damaging infection in Quercus species, and its presence in the United States has the potential to compound ongoing chestnut recovery programs and oak regeneration problems within forest systems. [ABSTRACT FROM AUTHOR]

Chestnut, Castanea sativa Miller (Fagales: Fagaceae), is an ecologically and economically important tree species of the forest ecosystem in Southern Europe, North-Western Europe, Western Asia, North Africa, and the Caucasus. The distributional range of chestnut in Europe has been highly modified by humans since ancient times. Biotic and abiotic factors have dramatically changed its distribution. Historic anthropogenic range expansion makes it difficult to identify habitat requirements for natural stands of chestnut. In the Caucasus, natural stands of chestnut survived in glacial forest refugia and landscapes that have been difficult for humans to colonize. To identify the species reliable habitat requirements, we estimated the relationship between climatic variables and 620 occurrence locations of natural chestnut stands from the Caucasus and validated the model using GBIF data from outside the Caucasus. We found that our best model is reasonably accurate and the data from the Caucasus characterize chestnut stands throughout the species range well. [ABSTRACT FROM AUTHOR]

Cryphonectria carpinicola is an ascomycetous fungus that has been regularly found in its asexual form on European hornbeam (Carpinus betulus) in Europe over the past two decades. Here we describe the discovery of C. carpinicola in Japan and report for the first time its sexual state on Carpinus species. No symptomatic trees were observed, but stromata were found saprotrophically on broken branches of Carpinus species on the forest floor. The sexual structures of C. carpinicola resembled that of other Cryphonectria species and strongly resembled those of the closely related species C. radicalis. A phylogenetic tree based on the internal transcribed spacer sequences showed monophyly for the Japanese and European isolates of C. carpinicola. Further studies on the distribution and host range of C. carpinicola in Japan and on the life history strategies of this fungus are needed. [ABSTRACT FROM AUTHOR]

Premise: Intersexual mating facilitation in flowering plants has been largely underexplored. Duodichogamy is a rare flowering system in which individual plants flower in the sequence male‐female‐male. We studied the adaptive advantages of this flowering system using chestnuts (Castanea spp., Fagaceae) as models. These insect‐pollinated trees produce many unisexual male catkins responsible for a first staminate phase and a few bisexual catkins responsible for a second staminate phase. We hypothesized that duodichogamy increases female mating success by facilitating pollen deposition on stigmas of the rewardless female flowers through their proximity with attractive male flowers responsible for the minor staminate phase. Methods: We monitored insect visits to 11 chestnut trees during the entire flowering period and explored reproductive traits of all known duodichogamous species using published evidence. Results: In chestnuts, insects visited trees more frequently during the first staminate phase but visited female flowers more frequently during the second staminate phase. All 21 animal‐pollinated duodichogamous species identified are mass‐flowering woody plants at high risk of self‐pollination. In 20 of 21 cases, gynoecia (female flower parts) are located close to androecia (male flower parts), typically those responsible for the second minor staminate phase, whereas androecia are often distant from gynoecia. Conclusions: Our results suggest that duodichogamy increases female mating success by facilitating pollen deposition on stigmas by means of the attractiveness of the associated male flowers while effectively limiting self‐pollination. [ABSTRACT FROM AUTHOR]

As in other megalopterans, the life of adult dobsonflies in the natural habitats remains largely unexplored. Here, we report the foraging habits of the nocturnal dobsonflies Protohermes grandis and Protohermes immaculatus. Our field observations from a close distance revealed that adult P. grandis feeds on the floral nectar of the Japanese chestnut Castanea crenata (Fagaceae). Moreover, based on strong circumstantial evidence (the finding of a dozen pollen‐bearing adults and their pollen‐containing excrement), we concluded that adult P. immaculatus routinely visit the flowers of Schima wallichii ssp. noronhae (Theaceae). The present study is the first one to document floral resource utilization by adult dobsonflies in their natural habitats, and provides further evidence for anthophilous corydalids. We have briefly discussed why the flower‐visiting habits of corydalids have been missed so far. [ABSTRACT FROM AUTHOR]

Castanea crenata (Fagaceae) is a species of chestnut tree that is endemic to the Republic of Korea and Japan. While its kernels are consumed, chestnut by-products such as shells and burs, which account for 10–15% of the total weight, are discarded as waste. Phytochemical and biological studies have been carried out to eliminate this waste and develop high-value products from its by-products. In this study, five new compounds (1–2, 6–8) along with seven known compounds were isolated from the shell of C. crenata. This is the first study to report diterpenes from the shell of C. crenata. Comprehensive spectroscopic data including 1D, 2D NMR, and CD spectroscopy were used to determine the compound structures. All isolated compounds were examined for their ability to stimulate dermal papilla cell proliferation using a CCK-8 assay. In particular, 6β,7β,16α,17-Tetrahydroxy-ent-kauranoic acid, isopentyl-α-L-arabinofuranosyl-(1→6)-β-D-glucopyranoside, and ellagic acid exhibited the most potent proliferation activity of all. [ABSTRACT FROM AUTHOR]

The unintentional introduction and rapid spread of chestnut blight (caused by Cryphonectria parasitica (Murr.) Barr) in the early 20th century resulted in the demise of American chestnut (Castanea dentata (Marsh.) Borkh.; Fagaceae) as a major component of forest canopies resulting in negative impacts on eastern forest communities. Research efforts over the last century have documented the persistence of occasional trees and root crown/ stump sprouts throughout much of the species' historic range, providing the basis for ongoing breeding of blight-resistant trees and restoration efforts. Here we use environmental niche modeling to investigate whether environmentally suitable habitat remains for remnant trees throughout the southwestern historical range, and to evaluate the reintroduction potential of this relatively understudied part of the historical distribution. We also use stage-structured matrix projection models to investigate the potential demographic future of C. dentata near the historical southwestern range limit based on observations of American chestnut in these areas over the last several decades. We found suitable upland habitat with areas of high forest canopy cover occurs throughout much of the southwestern portion of the historical range and that populations of American chestnut in these areas are predicted to drastically decline over the coming decades. These results highlight the continued presence of suitable C. dentata habitat throughout the southwestern extent of its historical distribution, which should be incorporated into evaluations for future reintroduction, and emphasize the need for efforts to locate, conserve, and introduce genetic material from individuals with locally adapted genotypes into active restoration programs. [ABSTRACT FROM AUTHOR]

Chestnut (Castanea spp., Fagaceae family) is an economically and ecologically valuable species. The main goals of chestnut production vary among species and countries and depend on the ecological characteristics of orchards, agronomic management, and the architecture of chestnut trees. Here, we review recent research on chestnut trees, including the effects of fungal diseases (Cryphonectria parasitica and Phytophthora cinnamomi) and insect pests (Dryocosmus kuriphilus Yasumatsu), molecular markers for breeding, ecological effects, endophytic fungi, and extracts with human health benefits. We also review research on chestnut in the food science field, technological improvements, the soil and fertilizer used for chestnut production, and the postharvest biology of chestnut. We noted differences in the factors affecting chestnut production among regions, including China, the Americas, and Europe, especially in the causal agents of disease and pests. For example, there is a major difference in the resistance of chestnut to C. parasitica in Asian, European, and American countries. Our review provides new insights into the integrated disease and pest management of chestnut trees in China. We hope that this review will foster collaboration among regions and help to clarify differences in the direction of breeding efforts among countries. [ABSTRACT FROM AUTHOR]

Simple Summary: Fumigation is the most effective method for the control of Curculio sikkimensis in chestnuts. The effects of ethyl formate (EF) as a fumigant were investigated to evaluate its potential for practical use by farmers. A dose of 180.0 g/m3 and 12 h of fumigation resulted in 100% mortality on a small scale (2 m3). The results of these experiments indicate that EF could be conveniently used as a fumigant by farmers. Castanea crenata Siebold & Zucc. (Fagales: Fagaceae), a species of chestnut native to Korea and Japan, is distributed in Korea, Japan, and northeastern China, where chestnuts are a major economic agroforest product. Curculio spp. is among the main known pests of chestnuts around the world. In Korea, only phosphine (PH3) is permitted for the fumigation of C. sikkimensis larva-infested chestnuts. However, it is applied for large-scale fumigation, and its use is restricted. Moreover, it requires a long exposure time and an application device; thus, it cannot be used by small-scale farmers. In this study, the activity of ethyl formate (EF) as a fumigant against Curculio sikkimensis in chestnuts was investigated, and its potential for practical use by farmers was evaluated. The sorption of EF according to the filling ratio (FR) and fumigation time was tested, and the results revealed that 2.5% FR was the most effective. For C. sikkimensis in chestnuts, the mortality rate increased proportionately with the dose of EF. After exposure to 160 g/m3 of EF in a 12 L desiccator, the adult C. sikkimensis showed 100% mortality. According to the time–dose mortality data collected over 12 h of fumigation, the LCT90 and LCT99 values were estimated as 1052.0 and 1952.0 g·h/m3. The results revealed that immersion was not an effective method for controlling C. sikkimensis. According to the LCT values, a dose of 180.0 g/m3 and 12 h of fumigation resulted in 100% mortality on a small scale (2 m3). The results of this experiment indicate that EF could be conveniently used as a fumigant by farmers. [ABSTRACT FROM AUTHOR]

Key message: Pollination is a key step for fruit production. To provide a tool for future in-depth analysis of pollination in chestnut, we describe in detail a chestnut orchard (location, genotype, phenotype and seed-set of all trees). Context: Chestnuts, which are insect-pollinated trees, have been massively planted around the world for nut production. Orchards are planted with clonal varieties selected from crosses between the European chestnuts (Castanea sativa) and Japanese chestnuts (C. crenata) or Chinese chestnuts (C. mollissima) because these two last species are tolerant to blight and ink diseases. Aims: To characterize chestnut genetic resources and accurately model male and female fitness as well as pollen exchanges in orchards, we characterized all chestnuts of the INRAE chestnut germplasm collection located near Bordeaux (France). Methods: All chestnut trees were geolocated and genotyped using 79 SNP and 98 SSR loci. We scored their flowering phenology using chestnut BBCH scale and precisely described their phenotype (height, diameter a breast height (DBH), canopy diameter...), their capacity to produce pollen (flower type, catkins length...) and their fruit production (number of burrs, seed-set...). Results: We geolocated 275 trees and genotyped 273 of them. We identified 115 unique genotypes and assigned each genotype to species. To assess phenology, we evaluated 244 trees twice a week, for 6 weeks from early June to mid-July. We also described tree phenotypes with 11 variables, pollen production with 5 variables and fruit production with 3 variables. All measures were recorded in 2018 except seed set that was measured two consecutive years, in 2018 and 2019. Conclusion: The data collected is very detailed and allows modelling precisely pollen exchanges between trees. Parts of this data have been successfully published in scientific articles. Data are available at: https://data.inrae.fr/dataset.xhtml?persistentId=doi:10.15454/GSJSWW Associated metadata are available at:https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/02c5ca07-1536-4f89-9a0c-9e8d44a91287 [ABSTRACT FROM AUTHOR]

The genus Castanea in North America contains several tree and shrub taxa of conservation concern. The two species within the group, American chestnut (Castanea dentata) and chinquapin (C. pumila sensu lato), display remarkable morphological diversity across their distributions in the eastern United States and southern Ontario. Previous investigators have hypothesized that hybridization between C. dentata and C. pumila has played an important role in generating morphological variation in wild populations. A putative hybrid taxon, Castanea alabamensis, was identified in northern Alabama in the early 20th century; however, the question of its hybridity has been unresolved. We tested the hypothesized hybrid origin of C. alabamensis using genome-wide sequence-based genotyping of C. alabamensis, all currently recognized North American Castanea taxa, and two Asian Castanea species at > 100,000 single-nucleotide polymorphism (SNP) loci. With these data, we generated a high-resolution phylogeny, tested for admixture among taxa, and analyzed population genetic structure of the study taxa. Bayesian clustering and principal components analysis provided no evidence of admixture between C. dentata and C. pumila in C. alabamensis genomes. Phylogenetic analysis of genome-wide SNP data indicated that C. alabamensis forms a distinct group within C. pumila sensu lato. Our results are consistent with the model of a nonhybrid origin for C. alabamensis. Our finding of C. alabamensis as a genetically and morphologically distinct group within the North American chinquapin complex provides further impetus for the study and conservation of the North American Castanea species. [ABSTRACT FROM AUTHOR]

• A spatiotemporal model was developed to understand the Fagaceae acorn persistence. • Fagaceae acorns use three mechanisms to cope with post-dispersal conditions. • Climate change will significantly affect the persistence and germination ecology of Fagaceae acorns. Fagaceae is an iconic plant family with 1000+ species distributed predominantly in the northern hemisphere. The reproductive ecology of the Fagaceae species is highly complex, and in the past three centuries, understanding the fruit masting strategies, dispersal, pathogen pressure, and storage has enjoyed steady research interest. However, the interrelationship between these factors is surprisingly less explored, undermining how acorns survive the post-dispersal period. The ability of fruits (acorns, nuts) to survive post-dispersal conditions starts during the maturation drying stage. Successful fruit production depends on the maternal environment, with a 'good fruit production year' occurring every few years. This phenomenon might out-maneuver predators by providing sufficient numbers to be consumed but still leaving enough for germination. Because most Fagaceae species have desiccation-sensitive (DS) fruits, survival after dispersal is challenging due to frequent dry spells. Fruit size is not phylogenetically conserved within the genus, with the average fruit mass of Castanea being 50 times higher than the desiccation-tolerant genus Fagus. Larger fruit size may be an adaptation in dry areas because prolonged drying continuously desiccates large-sized cotyledons before desiccating embryos. For species adapted to dry environments, synchronizing dispersal with the growing season could be beneficial, but exceptions exist. Many consumers, such as rodents, aid in the dispersal of fruits, but some fruits are killed in the process, especially those predated late. Upon settling on a site, the pericarp protects the embryo to a certain extent; if drying occurs, the cotyledons become the first site of water loss. However, under extreme drying, survival depends on sporadic rainfall, i.e., wet-dry cycle, which aids in maintaining the critical moisture content required by the fruits for survival. Nonetheless, these adaptive mechanisms are challenged by climate change, which affects the maturation, persistence, and seedling establishment of numerous Fagaceae species. [ABSTRACT FROM AUTHOR]

Masting is the synchronous and highly variable production of fruit within a population. Although several hypotheses have been proposed to explain why and how masting evolved in plants as a reproductive strategy, the factors that trigger a large reproductive effort in a particular year are still not well understood. While both weather and resources have been proposed to play an important role, testing these hypotheses has been challenging due to a lack of long-term data and appropriate experimental designs. In this manuscript, we used 18 years of acorn production data to analyze the relationship between resources, weather, and masting in black oak (Quercus velutina) and chestnut oak (Q. montana). The data were collected in southeast Ohio as part of the Fire and Fire Surrogate (FFS) study, which applied silvicultural treatments (i.e., thinning and prescribed fires) to reduce competition and manipulate resources. We found species-specific responses to the thinning and fire treatments, with an overall increase in acorn production for chestnut oak in the thin + burn treatment and an increase for black oak in the thin-only treatment compared to the control. Chestnut oak reproduction also had strong positive relationships with warm spring temperatures, and a positive change in summer temperatures compared to the previous year (i.e., summer temperatures that went from cool to warm). For black oak, warm spring temperatures increased acorn production while later starts to spring warming the year before decreased acorn production. These results support the hypotheses that both resources and weather (as a cue and as a limiting factor) are important for masting in oaks. Thus, both factors should be included in predictive models for acorn production under current and future climate conditions. [ABSTRACT FROM AUTHOR]

The American chestnut (Castanea dentata) was once widespread in eastern North America and an ecologically important hardwood tree of deciduous forest communities prior to its near-eradication by chestnut blight (Cryphonectria parasitica). Remnant populations occur across much of its historical range, especially in older forests of the Appalachians and northeastern U.S. However, broad swaths of the southwestern portion of the species' historical range remain poorly documented, potentially limiting the representation of genetic variation important for local adaptation in restoration efforts. Ongoing discovery and life-history characterization efforts for remnant C. dentata remains a priority to better understand the distribution and ecological status of this once important species, while identifying potential genetic sources of locally adapted or blight resistant trees. Here, we report the discovery of 22 C. dentata at four sites in southwestern Tennessee, adding novel observations that extend the range of known extant occurrences to the extreme western edge of the historical distribution in Fayette County. These observations include potentially reproductive individuals that should be revisited to assess reproductive and blight status, and that should be evaluated for current germplasm collection and restoration efforts. [ABSTRACT FROM AUTHOR]

The Oriental chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae), is a global invasive pest that causes serious damage to almost all chestnut species belonging to the Castanea genus (Fagaceae). Dryocosmus zhuili Liu et Zhu is a recently described sibling species of D. kuriphilus, which induces galls on Castanea henryi (Skan) Rehd. et Wils. There are many indigenous parasitoid species in China which play an important role in the natural regulation of their population dynamics. Wolbachia is a maternally inherited α‐proteobacterium widely found in arthropods. This study screened for the presence of Wolbachia in the two chestnut gall wasps and in six parasitoid species from 12 populations, to investigate the prevalence patterns of Wolbachia in the chestnut gall wasp‐parasitoid communities. We found that D. zhuili and four parasitoid species were infected with Wolbachia; among them, all individuals of the two populations of Megastigmus sp. had multiple Wolbachia infections. By using multilocus sequence types to characterize bacterial strains, three new sequence types were identified. The Wolbachia strains infecting D. zhuili (ST‐507), Torymus sinensis Kamijo (ST‐508), and Sycophila variegata (Curtis) (ST‐508) belonged to supergroup A, whereas the Wolbachia strain infecting Megastigmus nipponicus Kamijo (ST‐503) belonged to supergroup B. Our results also suggested that horizontal transmission of Wolbachia occurs between chestnut gall wasps and their parasitoids. Moreover, multiple Wolbachia infections of Megastigmus sp. may be due to gene recombination and horizontal transmission. [ABSTRACT FROM AUTHOR]

American chestnut (Castanea dentata [Marsh.] Borkh.) was once the dominant hardwood species in Eastern North America before an exotic fungal pathogen, Cryphonectria parasitica (Murrill) Barr, functionally eliminated it across its range. One promising approach toward restoring American chestnut to natural forests is development of blight‐tolerant trees using genetic transformation. However, transformation and related processes can result in unexpected and unintended phenotypic changes, potentially altering ecological interactions. To assess unintended tritrophic impacts of transgenic American chestnut on plant–herbivore interactions, gypsy moth (Lymantria dispar L.) caterpillars were fed leaf disks excised from two transgenic events, Darling 54 and Darling 58, and four control American chestnut lines. Leaf disks were previously treated with an LD50 dose of either the species‐specific Lymantria dispar multiple nucleopolyhedrovirus (LdMNPV) or the generalist pathogen Bacillus thuringiensis subsp. kurstaki (Btk). Mortality was quantified and compared to water blank controls. Tree genotype had a strong effect on the efficacies of both pathogens. Larval mortality from Btk‐treated foliage from only one transgenic event, Darling 54, differed from its isogenic progenitor, Ellis 1, but was similar to an unrelated wild‐type American chestnut control. LdMNPV efficacy was unaffected by genetic transformation. Results suggest that although genetic modification of trees may affect interactions with other nontarget organisms, this may be due to insertion effects, and variation among different genotypes (whether transgenic or wild‐type) imparts a greater change in response than transgene presence. [ABSTRACT FROM AUTHOR]

Sweet chestnut (Castanea sativa) is an endemic species of genus Castanea in Europe, which is widespread in the southern part of continental Europe. The complete genome sequence of chloroplast was determined through Illumina NovaSeq platform. Totally the genome of chloroplast was 160,938 bp in length, GC rich (36.8%), comprising a pair of 25,726 bp inverted repeat sequences, separated by a 90,519 bp large and 18,967 bp small single-copy regions. There were 129 genes, including 37 transfer RNA genes, 8 ribosomal RNA genes, and 84 protein-coding genes. The phylogenetic tree analysis showed that C. sativa exhibited the closest relationship with Castanea henryi. [ABSTRACT FROM AUTHOR]

Abstract: In response to the introduction and spread of the chestnut gall wasp Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) in metropolitan France, including Corsica, the exotic parasitoid Torymus sinensis Kamijo (Hymenoptera: Torymidae) was deliberately introduced in more than 50 locations covering most of the areas of chestnut production. To test the impact of propagule pressure (i.e., the number and size of introductions) on establishment success and post‐release dynamics, the introductions were done according to three experimental modalities: (1) a single introduction of 100 females, (2) two sequential introductions of 50 females, or (3) a single introduction of 1 000 females. Post‐release surveys demonstrated a very high local establishment of T. sinensis, regardless of the introduction modality. Post‐introduction dynamics were found to follow a two‐phase process. First, early dynamics were characterized by an exponential growth of T. sinensis populations without a significant decrease in D. kuriphilus populations. Later, middle‐term dynamics indicated a global decrease in both D. kuriphilus and T. sinensis populations. Quite surprisingly, propagule pressure had a limited effect on post‐introduction dynamics, with a lasting demographic advantage for the largest introductions, but no influence of the number of introductions. Finally, site connectivity had a positive effect on T. sinensis population size, suggesting successful colonization and establishment at a wide spatial scale beyond the introduction sites. In addition, we observed that some T. sinensis exhibited a very short developmental time compared to the majority of the emerged individuals, which may be interpreted as a diversified bet hedging strategy against environmental stochasticity. These findings confirm the strong potential of T. sinensis for successful establishment and sustainable control of the chestnut gall wasp in Europe. [ABSTRACT FROM AUTHOR]

• Soil fungi with Fagaceae reforestation shifts similarly between oaks and chestnuts. • Chestnut species and backcrossed hybrids share many common ectomycorrhizae. • Many taxa, including ectomycorrhizal fungi are established during planting. • American chestnut had fewer plant pathogens detected than other species. Forests of the Southern Appalachian Mountains were historically dominated by hardwood species within the family Fagaceae, e.g., American chestnut (Castanea dentata) and white oak (Quercus alba) among others. Due to numerous biotic and abiotic stressors, including pathogen pressure, populations of many Fagaceae have been greatly reduced, or functionally eliminated as is the case with American chestnut. This has led to reforestation efforts designed to increase American chestnut and white oak populations in this region, but success has been minimal. Since soil fungal communities are crucial to plant health, understanding how reforestation efforts alter soil fungal communities will inform reforestation efforts. Here, using nursery-reared bareroot seedlings of American chestnut, Chinese chestnut, 3rd generation backcross chestnut hybrids (BC 3 F 3), and white oaks outplanted at a locally xeric site in the Southern Appalachian Mountains, we investigated if and how these species and backcross families within species differentially impact soil fungal communities. We demonstrate that after three years of growth, plant-associated soil fungal communities change similarly among different Fagaceae and are distinct from pre-planting soil communities. Interestingly, we observed differential shifts in fungal functional guilds among the Fagaceae species, although these were rather minimal. Taken together, the largely convergent shifts in soil communities across Fagaceae species suggest that these tree species may have similar impacts on soils and/or share similar communities that become enriched in closely related fungal species. The similarity in shared mutualist fungal communities suggests that companion planting or reforestation of genetically disease resistant American chestnut adjacent to establishing white oak trees might enhance survival and growth of both species at xeric sites. [ABSTRACT FROM AUTHOR]

Our knowledge about gall wasps associated with the diverse East Asian oaks, Castanopsis and Cyclobalanopsis, is limited due to the lack of extensive field studies. Here, we describe twelve new oak gall wasp species, Dryocosmus cannoni Schwéger & Tang, D. caputgrusi Tang & Schwéger, D. crinitus Schwéger & Tang, D. harrisonae Melika & Tang, D. hearni Melika &Tang, D. hualieni Schwéger & Tang, D. konradi Tang & Melika, D. liyingi Melika & Tang, D. moriius Tang & Melika, D. quadripetiolus Schwéger & Tang, D. salicinai Schwéger & Tang, and D. taitungensis Tang & Melika, from Taiwan and mainland China. Seven newly described species induce galls on Quercus subgenus Cyclobalanopsis and five on other Fagaceae genus, Castanopsis. All of the new species concepts are supported by morphological and molecular data. We provide descriptions, diagnoses, host associations for the new species and an illustrated identification key to Eastern Palaearctic Dryocosmus species. We represent natural language phenotypes in a semantic format supported by biomedical ontologies to increase the accessibility of morphological data. [ABSTRACT FROM AUTHOR]

• Fagaceae performed well after planting on a xeric site in North Carolina, USA. • Interspecies and genetic differentiation evident in chestnut and oak after outplanting. • Root system morphology poorly explains survival and growth differences in chestnut. • Soil fungi does not predict plant survival or blight occurrence well. • Soil fungal communities are differentiated between tree performance categories. The loss of Fagaceae species is an increasing concern globally, including in North American where American chestnut (Castanea dentata) has been virtually eliminated by non-native pathogens, and oaks (Quercus) are experiencing widespread regeneration failures and declines. Tree improvement and breeding programs are producing trees for disease resistance or improved performance traits but require field testing to refine efforts. We established a study in 2015 on a xeric pitch pine (Pinus rigida) site in the Blue Ridge Mountains of North Carolina to regenerate American chestnut and interspecies hybrids (BC 3 F 3) and the co-occurring species of white oak (Q. alba) through planting bare-root, quality-graded seedlings. Chinese chestnut (C. mollissima) was also tested as a control species. We used pedigreed seed sources from open-pollinated genetic families that were nursery grown (1–0 bareroot seedlings for chestnut, 2–0 bareroot seedlings for white oak) to maximize overall size and competitive ability. Though there was variability within and among plant families in performance, American chestnut and BC 3 F 3 hybrids generally outperformed Chinese chestnut (at least 13 % taller) and white oak (at least 29 % taller) for the first three years, but intraspecies differences among genetic families were significant for nearly all traits tested. Initial seedling root morphology poorly explained field performance (R2 < 0.17), but this relationship was significant for both white oak families and the only northern BC 3 F 3 seed source. American chestnuts and BC 3 F 3 hybrids had higher stem height to ground diameter ratios compared to white oak (at least 11 % greater), indicating that white oak likely concentrates more resources to root development while chestnut concentrates more resources to maintaining above-ground competitive advantages. Additionally, we investigated soil fungal communities, both pre- and post-tree establishment and tested if these fungal communities can be used to predict plant performance or health. Soil fungi did a poor job predicting plant performance. Our results indicate that co-occurring Fagaceae species can be established in restoration plantings using well developed quality seedlings on relatively xeric sites. Managers should use diverse seed sources to avoid planting poor performing families and expect that chestnuts bred for blight resistance will outcompete planted white oak, at least in the short-term. [ABSTRACT FROM AUTHOR]

Salvia castanea Diels f. tomentosa Stib. is an endemic medicinal plant distributed in China, and the notably high content of tanshinone IIA in the root is proven effective for the therapy of heart diseases. Hairy root induction of this Salvia species was inoculated with Agrobacterium rhizogenes strain ATCC 15834. Transformed hairy root was cultured in 6,7-V liquid medium for growth kinetics assessment and elicitation. An S curve was present in the hairy root cultures based on the fresh and dry weights with an interval of 3 days. An optimum concentration of the applied elicitors (15 μM Ag, 200 μM methyl jasmonate, and 200 mg l yeast extract elicitor) benefitted both the growth status and tanshinone accumulation in the hairy root cultures. Tanshinone IIA contents were mostly stimulated 1.8-fold and 1.99-fold compared with the control by Ag and methyl jasmonate elicitation, respectively. Yeast extract dramatically enhanced dry mass accumulation, while it promoted cryptotanshinone content of 2.84 ± 0.33 mg g dry weight at most in the hairy root cultures. Selected elicitors diversely influenced tanshinone accumulation in the time courses of hairy root cultures within 7 days. Furthermore, transcripts of selected genes in the tanshinone biosynthetic pathway were remarkably upregulated with elicitation. Yeast extract elicitor heightened 13.9-fold of isopentenyl diphosphate isomerase expression level at 12 h, while it increased 16.7-fold of geranylgeranyl diphosphate synthase transcript at 24 h compared with that of the control, which was more effective than Ag and methyl jasmonate. This study provided a convenient hairy root culture system of S. castanea Diels f. tomentosa Stib. for tanshinone production for the first time. [ABSTRACT FROM AUTHOR]

The article focuses on a study which evaluates the potential of the inter-simple sequence repeats markers, which have been used for genetic diversity analyses, DNA fingerprinting, and estimation of interspecific and traspecific relationships, for assessing the intraspecific genetic diversity among individuals belonging to the seven species of Fagaceae. It also examines the phylogenetic relationships of the species as well as the materials and methods used in the study such as DNA extraction.

The Ozark chinkapin (Castanea ozarkensis Ashe [Fagaceae]) is a true chestnut that is native to the Ozark Highlands of Missouri, Arkansas, and Oklahoma and to the Ouachita Mountains of Arkansas. It has been decimated by chestnut blight, and the species' long-term survival is precarious. Few seed-producing trees can now be found in the wild, and the species requires very specific soil and site conditions, making it difficult to cultivate. We studied grafting Ozark chinkapin scions to its readily grown congener, Chinese chestnut (Castanea mollissima Blume) in controlled orchard settings at 2 Missouri sites, with orchard establishment in 2007 and grafting conducted in 2008. Our grafting success was 56% over all experimental parameters, but up to 83% with optimal combination of site, grafting technique, and scionwood type. Whip-and-tongue grafts were slightly (but not significantly) more successful than chip-bud grafts; however, a more vigorous scionwood type yielded significantly greater graft success (75%) compared with a second scionwood source (38%). By 2014, no indications of interspecific graft incompatibility were evident, and grafted trees were producing abundant nut yields. The successful demonstration that Chinese chestnut can be used as a rootstock for Ozark chinkapin has profound implications for the rapid propagation of Ozark chinkapin germplasm in ex situ orchards and as an important tool in a larger conservation context. In such settings, research, breeding, and mass propagation efforts with the threatened Ozark chinkapin can become much more simple, successful, and cost-efficient. [ABSTRACT FROM AUTHOR]

Castanea Mill. (chestnut) is a multipurpose deciduous tree and member of the family Fagaceae, widely distributed throughout North America, Europe, and Asia. The evaluation of the genetic diversity of chestnut species is crucial for the effective conservation of this economically and ecologically valuable tree. In this study, we applied 4 DNA markers to detect the genetic variability among and within Castanea species and to compare the effectiveness of each system in estimating genetic variation. We amplified 106 random amplified polymorphic DNA (RAPD), 228 amplified fragment length polymorphism (AFLP), 42 intersimple sequence repeat (ISSR), and 36 simple sequence repeat (SSR) polymorphic markers using 12, 5, 4, and 5 primer combinations, respectively. The findings on the effective multiplex ratio, polymorphism information content, and marker index revealed that AFLP was the most effective molecular marker system used in this study. Each marker system classified the species under investigation into clear but incompletely separated clusters, although partial agreement was achieved with respect to species relationships when the RAPD method was employed. The comparison of the correlation coefficient of RAPD marker data and the other markers showed a higher correlation [(r = 0.69, P < 0.01), (r = 0.77, P < 0.01), and (r = 0.47, P < 0.01) with AFLP, ISSR, and SSR, respectively]. When variance was partitioned among and within groups, AFLP (94.62%) showed greater variation within the groups and reverse RAPD (67.87%) yielded greater variation among the groups. Overall, the results indicate that the AFLP represents an efficient molecular marker system for the assessment of chestnut genetic diversity and, hence, the development of effective conservation strategies to preserve this valuable tree species. [ABSTRACT FROM AUTHOR]

The Chinese chestnut ( Castanea mollissima) carries resistance to Cryphonectria parasitica, the fungal pathogen inciting chestnut blight. The pathogen, introduced from Asia, devastated the American chestnut ( Castanea dentata) throughout its native range early in the twentieth century. A highly informative genetic map of Chinese chestnut was constructed to extend genomic studies in the Fagaceae and to aid the introgression of Chinese chestnut blight resistance genes into American chestnut. Two mapping populations were established with three Chinese chestnut parents, 'Mahogany', 'Nanking', and 'Vanuxem', totaling 337 progeny. The transcriptome-based genetic map was created with 329 simple sequence repeat and 1,064 single nucleotide polymorphism markers all derived from expressed sequence tag sequences. Genetic maps for each parent were developed and combined to establish 12 consensus linkage groups spanning 742 cM, providing the the most comprehensive genetic map for a Fagaceae species to date. Over 75 % of the mapped markers from the Chinese chestnut consensus genetic map were placed on the physical map using overgo hybridization, providing a fully integrated genetic and physical map resource for Castanea spp. About half (57 %) of the Chinese chestnut genetic map could be assigned to regions of segmental homology with 58 % of the peach ( Prunus persica) genome assembly. A three quantitative trait loci (QTL) model for blight resistance was verified using the new genetic markers and an existing interspecies ( C. mollissima × C. dentata) F mapping population. Two of the blight resistance QTLs in chestnut shared synteny with two QTLs for powdery mildew resistance in peach, indicating the potential conservation of disease resistance genes at these loci. [ABSTRACT FROM AUTHOR]

Ring shake is a defect that strongly affects chestnut ( Castanea sativa Mill.) use and its occurrence is known to be mainly related to mechanical stress within a tree; however, few investigations have compared the physico-mechanical properties of healthy and shaken trees. Hence, the aim of this study is to compare the density, compression strength, bending strength (MOR), and shrinkages between healthy and shaken trees in coppice stands. The investigation was carried out in the Lazio Region in central Italy in trees with a cambial age between 6 and 25 years. The results showed that shaken trees had lower mechanical strength and shrinkages than healthy ones and that the physico-mechanical parameters might be used to predict ring shake occurrence in a specific geographic area. Geographical location strongly affected the physico-mechanical properties of the chestnut wood, and this factor influenced ring shake occurrence. MOR value was assumed to be the parameter that could be applied at almost all study sites to distinguish between shaken and healthy trees. There was no difference between the shaken and healthy portions of a disk inside the same tree. [ABSTRACT FROM AUTHOR]

Two new species of Dryocosmus (Hymenoptera: Cynipidae: Cynipini), D. sefuriensis Ide, Wachi et Abe, sp. nov. and D. sakureierisis Ide, Wachi et Abe, sp. nov., are described from Japan. A key to species of Dryocosmus in East Asia is given. Although the members of Dryocosmus have been known to induce galls on the subgenus Quercus of the genus Quercus and the genera Castanea, Castanopsis, Chrysolepis, and Lithocarpus of Fagaceae, this is the first record of this gall wasp genus from the strictly Asian subgenus Cyclobalanopsis of the genus Quercus. The discovery of two new species of Dryocosmus associated with Q. (C.) acuta suggests the exceptionally diverse host range of Dryocosmus and the species richness of Cynipini on this plant subgenus in Asia. [ABSTRACT FROM AUTHOR]

North American Castanea consists of three morphologically variable species: Castanea dentata, Castanea pumila, and Castanea ozarkensis. Taxonomy of these species has been complicated by intermediate morphology, similarity in growth habit due, in part, to the chestnut blight, and putative naturally occurring hybridization in the southern Appalachians. The primary goal of this study was to determine if chloroplast DNA (cpDNA) distribution reflects the morphological variation observed in North American Castanea. To that end, we sequenced a single cpDNA gene region for 233 accessions collected from much of the range of the genus in North America. Once samples were grouped into haplotypes, we sequenced additional cpDNA regions to ensure that the observed haplotypic relationships were robust. We identified four main lineages and observed that for three of these, leaf and twig morphology are reliable predictors of haplotype identity (especially outside of the southern Appalachians). Haplotypes of the fourth lineage are shared among accessions of C. dentata and C. pumila, and trees with intermediate morphology. Geographic mapping of the haplotypes showed that they are largely found in separate geographic ranges but overlap in the southern Appalachians. While three clades closely correspond to the morphology of North American Castanea, it appears that the fourth lineage may have been recognized in the past as the hybrid taxon Castanea x neglecta because of its morphology that is intermediate between C. dentata and C. pumila. [ABSTRACT FROM AUTHOR]

An overview of recent achievements and development of genomic resources in the Fagaceae is provided, with major emphasis on the genera Castanea and Quercus. The Fagaceae is a large plant family comprising more than 900 species belonging to 8-10 genera. Using a wide range of molecular markers, population genetics and gene diversity surveys were the focus of many studies during the past 20 years. This work set the stage for investigations in genomics beginning in the early 1990s and facilitated the application of genetic and quantitative trait loci mapping approaches. Transferability of markers across species and comparative mapping have indicated tight macrosynteny between Quercus and Castanea. Omic technologies were more recently developed and the corresponding resources are accessible via electronic and physical repositories (expressed sequence tag sequences, single-nucleotide polymorphisms, candidate genes, cDNA clones, bacterial artificial chromosome (BAC) libraries) that have been installed in North America and Europe. BAC libraries and physical maps were also constructed in Castanea and Quercus and provide the necessary resources for full nuclear genome sequencing projects that are currently under way in Castanea mollissima (Chinese chestnut) and Quercus robur (pedunculate oak). [ABSTRACT FROM AUTHOR]

Oaks, chestnuts, and beeches are economically important species of the Fagaceae. To understand the relationship between these members of this family, a deep knowledge of their genome composition and organization is needed. In this work, we have isolated and characterized several AFLP fragments obtained from Quercus rotundifolia Lam. through homology searches in available databases. Genomic polymorphisms involving some of these sequences were evaluated in two species of Quercus, one of Castanea, and one of Fagus with specific primers. Comparative FISH analysis with generated sequences was performed in interphase nuclei of the four species, and the co-immunolocalization of 5-methylcytosine was also studied. Some of the sequences isolated proved to be genus-specific, while others were present in all the genera. Retroelements, either gypsy-like of the Tat/ Athila clade or copia-like, are well represented, and most are dispersed in euchromatic regions of these species with no DNA methylation associated, pointing to an interspersed arrangement of these retroelements with potential gene-rich regions. A particular gypsy-sequence is dispersed in oaks and chestnut nuclei, but its confinement to chromocenters in beech evidences genome restructuring events during evolution of Fagaceae. Several sequences generated in this study proved to be good tools to comparatively study Fagaceae genome organization. [ABSTRACT FROM AUTHOR]

Leaves of 41 species of Castanopsis, six species of Castanea, and Chrysolepis chrysophyllum Hjelmq. were examined. In Castanopsis, all species possessed cyclocytic stomata with thickened subsidiary cells; thin-walled peltate trichomes are the most frequent type on the abaxial surface of the leaves of this genus. In Castanea, stomata are transitional between cyclocytic and anomocytic; thin-walled peltate trichomes were recorded for the first time on the abaxial surface of Castanea leaves. In Chrysolepis, cyclocytic stomata with non-thickened subsidiary cells and thick-walled peltate trichomes were observed. The thickened subsidiary cells support the placement of the “ fissa-group” in Castanopsis. The results of this study support the idea that Castanopsis and Castanea are sister groups. Thick-walled peltate trichomes were only recorded in Chrysolepis, thus supporting its taxonomic separation from Castanopsis. The phylogenetic distribution of trichome types among genera of Fagaceae is summarized. The evolutionary trends of trichome types in Castanopsis are discussed, as are the implications of stomatal and trichome features on fossil identification and ecology. [ABSTRACT FROM AUTHOR]