Fruit set after successful pollination is key for the production of sweet cherries, and a low fruit-setting rate is the main problem in production of this crop. As gibberellin treatment can directly induce parthenogenesis and satisfy the hormone requirement during fruit growth and development, such treatment is an important strategy for improving the fruit-setting rate of sweet cherries. Previous studies have mainly focused on physiological aspects, such as fruit quality, fruit size, and anatomical structure, whereas the molecular mechanism remains clear. In this study, we analyzed the transcriptome of ‘Meizao’ sweet cherry fruit treated with gibberellin during the anthesis and hard-core periods to identify genes associated with parthenocarpic fruit set. A total of 25,341 genes were identified at the anthesis and hard-core stages, 765 (681 upregulated, 84 downregulated) and 186 (141 upregulated, 45 downregulated) of which were significant differentially expressed genes (DEGs) at the anthesis and the hard-core stages after gibberellin 3 (GA3) treatment, respectively. Based on DEGs between the control and GA3 treatments, the GA3 response mainly involves parthenocarpic fruit set and cell division. Exogenous gibberellin stimulated sweet cherry fruit parthenocarpy and enlargement, as verified by qRT-PCR results of related genes as well as the parthenocarpic fruit set and fruit size. Based on our research and previous studies in Arabidopsis thaliana, we identified key genes associated with parthenocarpic fruit set and cell division. Interestingly, we observed patterns among sweet cherry fruit setting-related DEGs, especially those associated with hormone balance, cytoskeleton formation and cell wall modification. Overall, the result provides a possible molecular mechanism regulating parthenocarpic fruit set that will be important for basic research and industrial development of sweet cherries.

Xyloglucan endotransglucosylase/hydrolases (XTHs) are a class of cell wall-associated enzymes involved in the construction and remodeling of cellulose/xyloglucan crosslinks. However, knowledge of this gene family in the model monocot Brachypodium distachyon is limited. A total of 29 BdXTH genes were identified from the whole genome, and these were further divided into three subgroups (Group I/II, Group III, and the Ancestral Group) through evolutionary analysis. Gene structure and protein motif analyses indicate that closely clustered BdXTH genes are relatively conserved within each group. A highly conserved amino acid domain (DEIDFEFLG) responsible for catalytic activity was identified in all BdXTH proteins. We detected three pairs of segmentally duplicated BdXTH genes and five groups of tandemly duplicated BdXTH genes, which played vital roles in the expansion of the BdXTH gene family. Cis-elements related to hormones, growth, and abiotic stress responses were identified in the promoters of each BdXTH gene, and when roots were treated with two abiotic stresses (salinity and drought) and four plant hormones (IAA, auxin; GA3, gibberellin; ABA, abscisic acid; and BR, brassinolide), the expression levels of many BdXTH genes changed significantly. Transcriptional analyses of the BdXTH genes in 38 tissue samples from the publicly available RNA-seq data indicated that most BdXTH genes have distinct expression patterns in different tissues and at different growth stages. Overexpressing the BdXTH27 gene in Brachypodium led to reduced root length in transgenic plants, which exhibited higher cellulose levels but lower hemicellulose levels compared to wild-type plants. Our results provide valuable information for further elucidation of the biological functions of BdXTH genes in the model grass B. distachyon.

Background: Xyloglucan endotransglucosylase/hydrolases (XTHs) are a class of cell wall-associated enzymes involved in the construction and remodeling of cellulose/xyloglucan crosslinks. However, knowledge of this gene family in the model monocot Brachypodium distachyon is limited. Results: A total of 29 BdXTH genes were identified from the reference genome, and these were further divided into three main groups (Group I/II, Group III, and the Ancestral Group) through comparative phylogenetic analysis. Gene structure and protein motif analysis indicate that closely clustered BdXTH genes are relatively conserved within each group. A highly conserved amino acid domain (DEIDFEFLG) responsible for catalytic activity was identified in all BdXTH proteins. We detected three pairs of segmentally duplicated BdXTH genes and five groups of tandemly duplicated BdXTH genes, which have played important roles in the expansion of the BdXTH gene family. Cis -elements related to hormones, growth, and abiotic stress responses were identified in the promoters of each BdXTH gene. Most BdXTH genes have distinct expression patterns in different tissues and growth stages. Furthermore, when roots were treated with two abiotic stresses (salinity and drought) and four plant hormones (IAA, auxin; GA3, gibberellin; ABA, abscisic acid and BR, brassinolide), the expression levels of many BdXTH genes changed significantly, suggesting possible roles in response to various environmental stimuli and plant hormones. Conclusion: In this study, we performed genome-wide identification, characterization, and expression pattern analysis of the XTH gene family in Brachypodium, which provide valuable information for further elucidation of the biological functions of BdXTH genes in the model grass B. distachyon.

Microplastics, as a novel environmental pollutant, are now widely distributed in agricultural soils globally and pose a threat to plant growth and development. Within apple orchards, the ageing and degradation of agricultural plastic films leads to soil microplastic contamination, inhibiting the growth of apple trees. This study employed apple rootstocks 'M9' and 'B9' alongside the apple cultivar 'Gala3', treating them with polystyrene nanoplastics (PS-NPs) at varying concentrations (0, 5, 10, 20, 40, 80 mg/L). Results indicate that low PS-NP concentrations promote apple seedling growth, whereas high concentrations inhibit root development and growth while reducing antioxidant capacity. Sensitivity to PS-NPs varies among genotypes, with 'M9' exhibiting the lowest sensitivity and 'Gala3' the highest. Based on these phenotypic differences, transcriptomic and metabolomic sequencing was performed on these two cultivars. Integrated transcriptomic-metabolomic analysis revealed that PS-NPs disrupted zeatin metabolic homeostasis by upregulating CKX gene and downregulating UGT73C gene. This accelerated the metabolism of active zeatin (e.g., trans-zeatin) and leading to dihydrozeatin (DHZ) accumulation, thereby impairing the activation capacity of the antioxidant defence system and ultimately exacerbating oxidative damage. These findings establish a foundation for systematic investigation into the molecular mechanisms underlying apple responses to nanoplastics, offering novel perspectives for future crop production and environmental safety.