Recalcitrant chestnut seeds are rich in γ-aminobutyric acid (GABA), which negatively regulates adventitious root development by altering carbon/nitrogen metabolism. However, little is known regarding the role of this metabolite in chestnut seeds. In this study, we investigated the effects of GABA changes on the germination of chestnut seeds treated with exogenous GABA and vigabatrin (VGB, which inhibits GABA degradation). Both treatments significantly inhibited seed germination and primary root growth and resulted in the considerable accumulation of H₂O₂, but the endogenous GABA content decreased before germination at 48 h. Soluble sugar levels increased before germination, but subsequently decreased, whereas starch contents were relatively unchanged. Changes to organic acids were observed at 120 h after sowing, including a decrease and increase in citrate and malate levels, respectively. Similarly, soluble protein contents increased at 120 h, but the abundance of most free amino acids decreased at 48 h. Moreover, the total amino acid levels increased only in response to VGB at 0 h. Accordingly, GABA and VGB altered the balance of carbon and nitrogen metabolism, thereby inhibiting chestnut seed germination. These results suggested that changes to GABA levels in chestnut seeds might prevent seed germination. The study data may also help clarify the dormancy and storage of chestnut seeds, as well as other recalcitrant seeds.

This study aimed to identify fungal species causing fruit rot of chestnut (Castanea mollissima Blume) in Hebei Province, China and analyze the resistance differences among major cultivars. A total of 220 fungal isolates were obtained from healthy and diseased kernels, which were classified into six distinct genera: Diaporthe (48.6%), Talaromyces (22.3%), Alternaria (10.5%), Mucor (9.5%), Fusarium (5.5%), and Rhizopus (3.6%). Based on both morphological and molecular analyses, six representative isolates of the six genera were identified as Diaporthe eres Nitschke, Talaromyces rugulosus Samson, N. Yilmaz, Frisvad & Seifert, Alternaria alternata (Fr.) Keissl., Mucor circinelloides Tiegh., Fusarium proliferatum (Matsush.) Nirenberg, and Rhizopus stolonifer (Ehrenb.) Vuill. Among these, D. eres was first reported to cause fruit rot on C. mollissima in China. Moreover, disease resistance evaluation of major cultivars showed significant differences: YG, YSSF, and DBH exhibited strong resistance under both natural conditions (with 1.67% to 5.27% DI after 180 days storage) and artificial inoculation (with 32.96 ± 0.64 to 52.61 ± 0.55 DI); while YJ was highly susceptible (with 47.71% decay incidence and 70.50 ± 7.22 DI). Correlation analysis revealed that the disease index was negatively correlated with sucrose and sorbitol contents, but positively correlated with stachyose and fructose contents. This study advances the understanding of postharvest chestnut fruit rot and provides a theoretical basis for breeding resistant cultivars and developing control strategies to mitigate losses and ensure food safety.

Introduction: The programmed cell death of buds directly affects the formation of a dwarf and compact crown in chestnut ( Castanea mollissima BL.), making it an agronomically important trait; however, the molecular and metabolic regulatory mechanisms underlying this process remain unclear. Methods: This study used ‘the abscission bud’ cultivar ‘Tima Zhenzhu’ and ‘the non abscission bud’ cultivar ‘Dabanhong’ as materials. By integrating histology, widely targeted metabolomics, transcriptomics, and hormone quantification, we systematically analyzed the dynamic changes that occurred during key stages of bud programmed cell death (PCD). Results: During bud abscission, typical PCD features were observed, including degradation of the cytoskeleton, cell wall shrinkage, and disintegration of vacuoles, nuclei, and other organelles. Hormone dynamics further revealed that the levels of active cytokinins decreased, whereas auxin precursors, ABA, jasmonic acid, and ethylene accumulated markedly, jointly driving the PCD process. At the S25 and S30 stages, 705 and 4,731 differentially expressed genes (DEGs) were identified, along with 241 and 345 differentially accumulated metabolites (DAMs), respectively. These molecules were significantly enriched in pathways such as plant hormone signal transduction, secondary metabolite biosynthesis, sugar metabolism, and lipid metabolism. Based on multi omics data, this study predicts a co regulatory network for bud PCD, illustrating how ordered programmed cell death is achieved through suppression of growth signals, activation of autophagy and antioxidant systems, and reprogramming of secondary metabolic flux. Discussion: These findings not only revealed the intrinsic molecular landscape of bud abscission in ‘Tima Zhenzhu’, but also provided potential targets and strategic insights for future metabolic engineering or genetic improvement.

This study aimed to identify fungal species causing fruit rot of chestnut (Castanea mollissima) in Hebei Province, China and analyze the resistance differences among major cultivars. A total of 220 fungal isolates were obtained from healthy and diseased kernels, which were classified into six distinct genera. Based on both morphological and molecular analyses, these isolates were identified as Diaporthe eres (48.6% isolation frequency), Talaromyces rugulosus (22.3%), Alternaria alternata (10.5%), Mucor circinelloides (9.5%), Fusarium proliferatum (5.5%), and Rhizopus stolonifer var. stolonifer (3.6%). Among these, D. eres was first ly report ed to caus e fruit rot on C. mollissima in China. Moreover, disease resistance evaluation of major cultivars showed significant differences: YG, YSSF, and DBH exhibited strong resistance under both natural conditions (with 1.7% to 5.3% DI after 180 days storage) and artificial inoculation (with 33.0±0.6 to 52.6±4.0 DI ); while YJ was highly susceptible (with 47.7% decay incidence and 70.5±7.2 DI ). Correlation analysis revealed that the disease index was negatively correlated with sucrose and sorbitol contents, but positively correlated with stachyose and fructose contents. This study advances the understanding of postharvest chestnut fruit rot, and provide a theoretical basis for breeding resistant cultivars and developing control strategies to mitigate losses and ensure food safety.