European and American chestnuts: An overview of the main threats and control efforts

Chestnuts are multipurpose trees significant for the economy and wildlife. These trees are currently found around the globe, demonstrating their genetic adaptation to different environmental conditions. Several biotic and abiotic stresses have challenged these species, contributing to the decline of European chestnut production and the functional extinction of the American chestnut. Several efforts started over the last century to understand the cellular, molecular, and genetic interactions behind all chestnut biotic and abiotic interactions. Most efforts have been toward breeding for the primary diseases, chestnut blight and ink disease caused by the pathogens, Cryphonectria parasitica and Phytophthora cinnamomi, respectively. In Europe and North America, researchers have been using the Asian chestnut species, which co-evolved with the pathogens, to introgress resistance genes into the susceptible species. Breeding woody trees has several limitations which can be mostly related to the long life cycles of these species and the big genome landscapes. Consequently, it takes decades to improve traits of interest, such as resistance to pathogens. Currently, the availability of genome sequences and next-generation sequencing techniques may provide new tools to help overcome most of the problems tree breeding is still facing. This review summarizes European and American chestnut’s main biotic stresses and discusses breeding and biotechnological efforts developed over the last decades, having ink disease and chestnut blight as the main focus. Climate change is a rising concern, and in this context, the adaptation of chestnuts to adverse environmental conditions is of extreme importance for chestnut production. Therefore, we also discuss the abiotic challenges on European chestnuts, where the response to abiotic stress at the genetic and molecular level has been exploredinfo:eu-repo/semantics/publishedVersio

GIS-Based Assessment of the Chestnut Expansion Potential: A Case-Study on the Marvão Productive Area, Portugal

Sweet chestnut is a relevant species in Europe for the production of timber and fruit, alongside environmental effects such as biodiversity of protection against soil erosion. In Portugal, chestnut is cultivated mainly for fruit production, in two areas, in the North and the South of the country, with moderate water deficit and low slope and at altitudes higher than 500 m. The current area (845 ha) of the southern so-called Marvão Protected Designation of Origin, of a fortyfold lower order of magnitude by comparison with the Northern productive area, has a significant expansion potential, given its similarity with contiguous areas in the same region. In this context, the main objective of the present work was the evaluation through geographic information analysis of that expansive potential, by comparison of physiographic profiling of the current production area with contiguous areas. A GIS-based characterization of current and potential chestnut areas in Marvão is presented. The methodology involved (i) digital profiling of the main classes/values of the geographical spatial ecological fingerprint considering topography, soil and microclimate variables in the areas currently occupied with sweet chestnut stands and (ii) the evaluation of the distribution of that environmental fingerprint in the whole Marvão productive area, for extending the cultivation to contiguous areas with a similar ecological fingerprint. An enlarged 9889 ha chestnut area was proposed, allocated for high forest stands aiming at agroforestry fruit production and coppiced stands for timber production and environmental protection, corresponding to 4590 ha and 5299 ha, respectively. Fruit production was proposed to field slopes of 0–4% and 4–8%, and altitudes between 400 m and 500 m. Presumable high-quality sites allocated to temporary dry/irrigated cultivations were also proposed for fruit production, in the same slope classes and altitudes higher than 500 m. Timber production and environmental protection were proposed for slopes within 812% and >12% ranges. This selection took into account the logistical feasibility facilitated in lower slopes for intensive mechanized management operations. This methodology permits a future field evaluation of site indexes, productivity, and correlations between environmental variables and stand biometryinfo:eu-repo/semantics/publishedVersio

Castanea crenata Ginkbilobin-2-like recombinant protein reveals potential as an antimicrobial against Phytophthora cinnamomi, the causal agent of ink disease in European chestnut

The European chestnut tree (Castanea sativa Mill.) is widely cultivated throughout the world’s temperate regions. In the Mediterranean region, it has a significant economic role mainly because of the high quality of its edible nuts. The Oomycete Phytophthora cinnamomi is one of the most severe pathogens affecting European chestnuts, causing ink disease and significant losses in production. Ginkgobilobin-2 (Gnk2) in Ginkgo biloba is a secreted protein with a plant-specific cysteine-rich motif that functions as a lectin, and its carbohydrate-binding properties are closely related to its antifungal activity. The binding of lectins to mannose residues of the cell wall of Phytophthora species may disturb and disrup the cell wall structure. This work determined that the amino acid sequence has a signal peptide that directs the final protein peptide to the apoplast. The Cast_Gnk2-like expression was performed and optimized, and different in vitro antagonism tests were done against P. cinnamomi using different purified protein concentrations. As a result of one of these assays, Cast_Gnk2-like significantly reduced the mycelia growth of P. cinnamomi in liquid medium as shown by the mycelia weight (g) in control treatments was 377% higher than in the treatments. These insights reveal the potential of Cast_Gnk2-like for agricultural uses and biotechnological developments for the pathosystem chestnut/P. cinnamomi.info:eu-repo/semantics/publishedVersio

First interspecific genetic linkage map for Castanea sativa x Castanea crenata revealed QTLs for resistance to Phytophthora cinnamomi

Research ArticleThe Japanese chestnut (Castanea crenata) carries resistance to Phytophthora cinnamomi, the destructive and widespread oomycete causing ink disease. The European chestnut (Castanea sativa), carrying little to no disease resistance, is currently threatened by the presence of the oomycete pathogen in forests, orchards and nurseries. Determining the genetic basis of P. cinnamomi resistance, for further selection of molecular markers and candidate genes, is a prominent issue for implementation of marker assisted selection in the breeding programs for resistance. In this study, the first interspecific genetic linkage map of C. sativa x C. crenata allowed the detection of QTLs for P. cinnamomi resistance. The genetic map was constructed using two independent, control-cross mapping populations. Chestnut populations were genotyped using 452 microsatellite and single nucleotide polymorphism molecular markers derived from the available chestnut transcriptomes. The consensus genetic map spans 498,9 cM and contains 217 markers mapped with an average interval of 2.3 cM. For QTL analyses, the progression rate of P. cinnamomi lesions in excised shoots inoculated was used as the phenotypic metric. Using non-parametric and composite interval mapping approaches, two QTLs were identified for ink disease resistance, distributed in two linkage groups: E and K. The presence of QTLs located in linkage group E regarding P. cinnamomi resistance is consistent with a previous preliminary study developed in American x Chinese chestnut populations, suggesting the presence of common P. cinnamomi defense mechanisms across species. Results presented here extend the genomic resources of Castanea genus providing potential tools to assist the ongoing and future chestnut breeding programsinfo:eu-repo/semantics/publishedVersio

A new clonal propagation protocol develops quality root systems in chestnut

Technical NoteThere is, at the present time, a great demand for chestnut rootstocks with improved resistance to Phytophthora cinnamomi Rands in the nurseries. New genotypes are emerging from European chestnut breeding programs and the production of thriving plants to restore old orchards with low yields due to a high incidence of diseases, namely root rot, is necessary. Micropropagation is a useful technique for clonal propagation. Nevertheless, in vitro culture propagation is genotype-dependent. Consequently, the existing protocols may demonstrate poor reproducibility and low e cacy. Thus, the need to contribute to the development of new micropropagation protocols suitable for large production of emerging genotypes. As a contribution to fill this gap, a three-step protocol was developed by using new combinations of Murashige & Skoog, Woody Plant, and adapted modified Melin-Norkrans media in di erent stages of the propagation process. About 90% of shoots were rooted, and after three months of acclimatization, 85% of these plants survived and were capable of continuous growth in the field. Currently, this protocol is being used in the production of several hybrid genotypes (with improved resistance to P. cinnamomi), selected from our ongoing breeding program and also in Castanea sativa Mill. and Castanea crenata Siebold and Zucc. speciesinfo:eu-repo/semantics/publishedVersio

First Interspecific Genetic Linkage Map for \u3cem\u3eCastanea sativa\u3c/em\u3e x \u3cem\u3eCastanea crenata\u3c/em\u3e Revealed QTLs for Resistance to \u3cem\u3ePhytophthora cinnamomi\u3c/em\u3e

The Japanese chestnut (Castanea crenata) carries resistance to Phytophthora cinnamomi, the destructive and widespread oomycete causing ink disease. The European chestnut (Castanea sativa), carrying little to no disease resistance, is currently threatened by the presence of the oomycete pathogen in forests, orchards and nurseries. Determining the genetic basis of P. cinnamomi resistance, for further selection of molecular markers and candidate genes, is a prominent issue for implementation of marker assisted selection in the breeding programs for resistance. In this study, the first interspecific genetic linkage map of C. sativa x C. crenataallowed the detection of QTLs for P. cinnamomi resistance. The genetic map was constructed using two independent, control-cross mapping populations. Chestnut populations were genotyped using 452 microsatellite and single nucleotide polymorphism molecular markers derived from the available chestnut transcriptomes. The consensus genetic map spans 498,9 cM and contains 217 markers mapped with an average interval of 2.3 cM. For QTL analyses, the progression rate of P. cinnamomi lesions in excised shoots inoculated was used as the phenotypic metric. Using non-parametric and composite interval mapping approaches, two QTLs were identified for ink disease resistance, distributed in two linkage groups: E and K. The presence of QTLs located in linkage group E regarding P. cinnamomi resistance is consistent with a previous preliminary study developed in American x Chinese chestnut populations, suggesting the presence of common P. cinnamomi defense mechanisms across species. Results presented here extend the genomic resources of Castanea genus providing potential tools to assist the ongoing and future chestnut breeding programs

Dual transcriptomic analysis reveals early induced Castanea defense-related genes and Phytophthora cinnamomi effectors

Funding Information: The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by FCT -Funda\u00E7\u00E3o para a Ci\u00EAncia e Tecnologia, I.P. under the project 414103 FCT-Lx-FEDER-28760, Ph.D. grant SFRH/BD/115424/2016 (awarded to PaF), project reference UIDB/00239/2020 of the Forest Research Centre and DOI identifier 10.54499/UIDB/00239/2020, and project reference UIDB/04129/2020 of LEAF (Linking Landscape, Environment, Agriculture and Food) Research Center and DOI identifier 10.54499/UIDB/04129/2020. Funding Information: The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by FCT -Funda\u00E7\u00E3o para a Ci\u00EAncia e Tecnologia, I.P. under the project 414103 FCT-Lx-FEDER-28760, Ph.D. grant SFRH/BD/115424/2016 (awarded to PaF), project reference UIDB/00239/2020 of the Forest Research Centre and DOI identifier 10.54499/UIDB/00239/2020, and project reference UIDB/04129/2020 of LEAF (Linking Landscape, Environment, Agriculture and Food) Research Center and DOI identifier 10.54499/UIDB/04129/2020. Acknowledgments Publisher Copyright: Copyright © 2024 Fernandes, Pimentel, Ramiro, Silva, Fevereiro and Costa.Phytophthora cinnamomi Rands devastates forest species worldwide, causing significant ecological and economic impacts. The European chestnut (Castanea sativa) is susceptible to this hemibiotrophic oomycete, whereas the Asian chestnuts (Castanea crenata and Castanea mollissima) are resistant and have been successfully used as resistance donors in breeding programs. The molecular mechanisms underlying the different disease outcomes among chestnut species are a key foundation for developing science-based control strategies. However, these are still poorly understood. Dual RNA sequencing was performed in C. sativa and C. crenata roots inoculated with P. cinnamomi. The studied time points represent the pathogen’s hemibiotrophic lifestyle previously described at the cellular level. Phytophthora cinnamomi expressed several genes related to pathogenicity in both chestnut species, such as cell wall–degrading enzymes, host nutrient uptake transporters, and effectors. However, the expression of effectors related to the modulation of host programmed cell death (elicitins and NLPs) and sporulation-related genes was higher in the susceptible chestnut. After pathogen inoculation, 1,556 and 488 genes were differentially expressed by C. crenata and C. sativa, respectively. The most significant transcriptional changes occur at 2 h after inoculation (hai) in C. sativa and 48 hai in C. crenata. Nevertheless, C. crenata induced more defense-related genes, indicating that the resistant response to P. cinnamomi is controlled by multiple loci, including several pattern recognition receptors, genes involved in the phenylpropanoid, salicylic acid and ethylene/jasmonic acid pathways, and antifungal genes. Importantly, these results validate previously observed cellular responses for C. crenata. Collectively, this study provides a comprehensive time-resolved description of the chestnut–P. cinnamomi dynamic, revealing new insights into susceptible and resistant host responses and important pathogen strategies involved in disease development.publishersversionpublishe

Dual transcriptomic analysis reveals early induced Castanea defense-related genes and Phytophthora cinnamomi effectors

Phytophthora cinnamomi Rands devastates forest species worldwide, causing significant ecological and economic impacts. The European chestnut (Castanea sativa) is susceptible to this hemibiotrophic oomycete, whereas the Asian chestnuts (Castanea crenata and Castanea mollissima) are resistant and have been successfully used as resistance donors in breeding programs. The molecular mechanisms underlying the different disease outcomes among chestnut species are a key foundation for developing science-based control strategies. However, these are still poorly understood. Dual RNA sequencing was performed in C. sativa and C. crenata roots inoculated with P. cinnamomi. The studied time points represent the pathogen’s hemibiotrophic lifestyle previously described at the cellular level. Phytophthora cinnamomi expressed several genes related to pathogenicity in both chestnut species, such as cell wall–degrading enzymes, host nutrient uptake transporters, and effectors. However, the expression of effectors related to the modulation of host programmed cell death (elicitins and NLPs) and sporulation-related genes was higher in the susceptible chestnut. After pathogen inoculation, 1,556 and 488 genes were differentially expressed by C. crenata and C. sativa, respectively. The most significant transcriptional changes occur at 2 h after inoculation (hai) in C. sativa and 48 hai in C. crenata. Nevertheless, C. crenata induced more defense-related genes, indicating that the resistant response to P. cinnamomi is controlled by multiple loci, including several pattern recognition receptors, genes involved in the phenylpropanoid, salicylic acid and ethylene/jasmonic acid pathways, and antifungal genes. Importantly, these results validate previously observed cellular responses for C. crenata. Collectively, this study provides a comprehensive time-resolved description of the chestnut–P. cinnamomi dynamic, revealing new insights into susceptible and resistant host responses and important pathogen strategies involved in disease development

Comparative transcriptomic response of two Pinus species to infection with the pine wood nematode Bursaphelenchus xylophilus

Pine wilt disease (PWD) caused by pine wood nematode (PWN), Bursaphelenchus xylophilus, is a serious threat to global forest populations of conifers, in particular Pinus spp. Recently, the presence of PWN was reported in dead Yunnan pine (Pinus yunnanensis) trees under natural conditions. To further understand the potential impact caused by PWN in Yunnan pine populations, a transcriptional profiling analysis was performed over di erent time points (0 hours (h), 6 h, 24 h, 48 h, and 7 days) after PWN inoculation. A total of 9961 di erentially expressed genes were identified after inoculation, which suggested a dynamic response against the pathogen, with a more intense pattern at 48 h after inoculation. The results also highlighted a set of biological mechanisms triggered after inoculation that provide valuable information regarding the response of Yunnan pine to PWN infection. When compared with maritime pine (Pinus pinaster), the Yunnan pine response was less complex and involved a smaller number of di erentially expressed genes, which may be associated with the increased degree of resistance to PWN displayed by Yunnan pine. These results revealed di erent strategies to cope with PWN infection by these two pine species, which display contrasting degrees of susceptibility, especially in the timely perception of the infection and response magnitudeinfo:eu-repo/semantics/publishedVersio

Endoscopy Timing in Patients with Acute Upper Gastrointestinal Bleeding

Background/Aims The role of very early (≤12 hours) endoscopy in nonvariceal upper gastrointestinal bleeding is controversial. We aimed to compare results of very early and early (12–24 hours) endoscopy in patients with upper gastrointestinal bleeding demonstrating low-risk versus high-risk features and nonvariceal versus variceal bleeding. Methods This retrospective study included patients with nonvariceal and variceal upper gastrointestinal bleeding. The primary outcome was a composite of inpatient death, rebleeding, or need for surgery or intensive care unit admission. Endoscopy timing was defined as very early and early. We performed the analysis in two subgroups: (1) high-risk vs. low-risk patients and (2) variceal vs. nonvariceal bleeding. Results A total of 102 patients were included, of whom 59.8% underwent urgent endoscopy. Patients who underwent very early endoscopy received endoscopic therapy more frequently (p=0.001), but there was no improvement in other clinical outcomes. Furthermore, patients at low risk and with nonvariceal bleeding who underwent very early endoscopy had a higher risk of the composite outcome. Conclusions Very early endoscopy does not seem to be associated with improved clinical outcomes and may lead to poorer outcomes in specific populations with upper gastrointestinal bleeding. The actual benefit of very early endoscopy remains controversial and should be further clarified