The “circular bioeconomy” offers numerous opportunities for the health, cosmetic, and nutrition sectors through the potential reuse of Castanea sativa by-products. This abundant and sustainable resource provides valuable bioactive secondary metabolites with antioxidants and anti-inflammatory properties. The transformation of these by-products into high-value products for human health can contribute to sustainable economic growth and reduce the environmental impact of traditional waste disposal practices, thus creating added value from previously underutilized resources. In the present study, we investigated the antioxidant capacity, phytochemical composition and in vitro antioxidant and anti-inflammatory activity of C. sativa burrs (CSB) aqueous extract. The spectrophotometric study yielded optimal total phenolic content (TPC) values, along with significant antioxidant and anti-radical properties. The utilization of UPLC-MS-MS techniques for phytochemical investigation resulted in the identification of a total of 56 metabolites, providing confirmation of the presence of phenolic compounds in CSB. In addition, CSB significantly downregulated pro-inflammatory mediators in LPS-stimulated RAW 264.7 macrophage cells without significant cell toxicity.

Phase change refers to the process of maturation and transition from the juvenile to the adult stage. In response to this shift, certain species like chestnut lose the ability to form adventitious roots, thereby hindering the successful micropropagation of adult plants. While auxin is the main hormone involved in adventitious root formation, other hormones, such as ethylene, are also thought to play a role in its induction and development. In this study, experiments were carried out to determine the effects of ethylene on the induction and growth of adventitious roots. The analysis was performed in two types of chestnut microshoots derived from the same tree, a juvenile-like line with high rooting ability derived from basal shoots (P2BS) and a line derived from crown branches (P2CR) with low rooting responses. By means of the application of compounds to modify ethylene content or inhibit its signalling, the potential involvement of this hormone in the in-duction of adventitious roots was analyzed. Our results show that ethylene can modify the rooting competence of mature shoots, while the response in juvenile material was barely affected. To further characterize the molecular reasons underlying this maturation-derived shift in behaviour, specific gene expression analyses were developed. Findings suggest that several mechanisms, including ethylene signalling, auxin transport and epigenetic modifications, relate to the modu-lation of the rooting ability of mature chestnut microshoots and their recalcitrant behaviour.

This study delves into the impact of contrasting management practices on epiphytic bryolichenic communities, shedding light on their divergent responses to management regimes on Castanea sativa orchards. Lichens and bryophytes were sampled in managed and abandoned plots, in 95 trees, in north and south sides and at two heights in Galicia (NW Spain). The studied groups exhibit opposing reactions to these management practices, bryophytes suffer adverse effects in managed stands, experiencing reduced cover and species richness compared to abandoned orchards, while lichens displayed heightened cover and species diversity. The size of trees, included as a covariate in our analyses, displayed no significant impact on the overall species richness of lichens or bryophytes, although it did influence the cover of specific functional traits. These differing outcomes are linked to alterations in environmental conditions brought by management interventions. Furthermore, the study uncovers divergent responses within the taxonomic and functional composition of epiphytic communities. Different species and functional groups exhibit varying reactions to changing environmental conditions, making predictions a complex endeavor. In conclusion, this research emphasizes the need for management strategies that account for the diverse ecological requirements of different species and functional groups. Since no single management regime will suit all species or functional groups.

Cryphonectria is a fungal genus associated with economically significant disease of trees. Herein we characterized a novel double-stranded RNA virus from the fungal species Cryphonectria naterciae, a species unexplored as a virus host. De novo assembly of RNA-seq data and Sanger sequencing of RACE (rapid amplification of cDNA ends) clones gave the complete, non-segmented genome (10,164 bp) of the virus termed Cryphonectria naterciae fusagravirus (CnFGV1) that was phylogenetically placed within the previously proposed viral family Fusagraviridae. Of 31 field-collected strains of C. naterciae, 40% tested CnFGV1-positive. Co-cultivation resulted in within-species transmission of CnFGV1 to virus-free strains of C. naterciae. Comparison of the mycelium phenotype and the growth rate of CnFGV1-infected and virus-free isogenic strains revealed frequent sectoring and growth reduction in C. naterciae. Co-culturing also led to cross-species transmission of CnFGV1 to Cryphonectria carpinicola and Cryphonectria radicalis, but not to Cryphonectria parasitica. The virus-infected C. naterciae and the experimentally infected Cryphonectria spp. readily transmitted CnFGV1 through asexual spores to the next generation. CnFGV1 strongly reduced conidiation and in some cases vegetative growth of C. carpinicola, which is involved in the European hornbeam disease. This study is the first report of a fusagravirus in the family Cryphonectriaceae and lays the groundwork for assessing a hypovirulence effect of CnFGV1 against the hornbeam decline in Europe.

The mechanisms underlying the de novo regeneration of adventitious roots are still poorly understood, particularly in trees. In this study, we developed a system for studying different modulators of adventitious rooting (AR) at physiological and molecular levels by using for the first time leaves excised from chestnut microshoots. The rooting response of leaves was ontogenetic-stage dependent, and similar to that of the original microshoots. Initiation of root primordia and root development were inhibited by application of N-1-naphthyl-phthalamic acid (NPA), although the effect of this inhibitor of auxin polar transport (PAT) depended on the timing of application. Expression of CsSCL1, an auxin-inducible gene in juvenile and mature shoots during AR, was upregulated by auxin only in rooting-competent leaves during the novo root organogenesis and the expression was reduced by the NPA treatment. This inhibitory effect on gene expression was detected during reprograming of rooting competent cells towards root initials in response to auxin, indicating that PAT-mediated upregulation of CsSCL1 is required in the initial steps of AR in chestnut leaves. The localized expression of CsSCL1 in the quiescent center (QC) also suggests a role for this gene in the maintenance of meristematic competence and root radial patterning.