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Superoxide dismutases (SODs), as the first line of defense against reactive oxygen species (ROS), play an essential role in protecting plants from adverse elicitors during plant growth and development. However, little is known about the SOD gene family and their response to salinity stress and fruit development in cultivated strawberries (Fragaria × ananassa). In this study, 32 SOD genes consisting of 16 Cu/ZnSODs, 11 FeSODs, and 5 MnSOD were identified, which presented three well-resolved clades in the phylogenetic tree. Each clade had similar motifs, and exon–intron structures, which in turn supported the evolutionary classification. Cis-acting element analysis suggested that FaSOD genes might be involved in the plant response to abiotic and biotic stresses, hormones, and light. The analysis of previously published transcriptome data revealed that FaSOD genes are expressed variably under salt stress. Among these SODs, FaMSD5 was expressed at relatively high levels in strawberry root and leaf, and its transcript abundance significantly increased after salt treatment. Some transcription factors related to photomorphogenesis, hormone signaling pathways, and hyperosmotic salinity response were predicted to bind to the FaMSD5 promoter. These outcomes implied that FaMSD5 might play an important role in protection against salt stress. In addition, the comprehensive transcriptome analysis of FaSOD genes in strawberry fruit showed that almost all FaCSDs and FaMSDs were more highly expressed than FaFSDs at different developmental stages, and the expression patterns of FaCSD1, FaCSD2, FaCSD7, FaCSD8, and FaCSD10 suggested that they were likely to be involved in fruit development and ripening. This study provides a basis for further exploration of the function of the FaSOD gene family in strawberry and provides candidate FaSOD genes for enhancing salinity tolerance and regulating fruit development and ripening.

Tillering is an important part in strawberry growth, and strawberries can reproduce nutritionally through stolons to generate genetically stable offspring. However, excessive tillering during the fruit-growing stage can negatively impact fruit yield and quality. In this study, different concentrations of exogenous rac-GR24 (GR24) are used to treat the strawberry plants. It was found that GR24 effectively inhibited the sprouting of strawberry stolons, while promoting the growth of the stems and leaves. Among the treatments, the most effective concentration was found to be 5 μmol/L GR24. This treatment resulted in a decrease in the glucose content in the strawberry crowns and also caused changes in the contents of two endogenous phytohormones, gibberellic acid (GA3) and trans-zeatin riboside (tZR). Transcriptome data further suggested that exogenous GR24 may inhibit strawberry plant tillering by affecting various phytohormone signaling pathways and the sugar metabolism pathway. In 5 μmol/L GR24-treated plants, the expression level of type-B response regulator (B-ARR) was down-regulated and the expression level of CYTOKININ RESPONSE 1 (CRE1), histidine-containing phosphotransfer protein (AHP), and type-A response regulator (A-ARR) were up-regulated, suggesting the inhibition of the cytokinin (CTK) signaling pathway. The down-regulation of auxin (AUX) and auxin response factor (ARF), as well as the up-regulation of auxin/indole-3-acetic acid (AUX/IAA), led to the inhibition of the indole-3-acetic acid (IAA) signaling pathway. Additionally, the up-regulation of pyrabactin resistance 1/ pyrabactin resistance 1-like (PYR/PYL), non-fermenting 1-related protein kinase 2 (SnRK2), and ABRE binding factors (ABF) and the down-regulation of protein phosphatase 2C (PP2C) were observed in the up-regulated abscisic acid (ABA) signaling pathways. In the sugar metabolism pathway, the up-regulation of invertase (INV), hexokinase (HK), and fructokinase (FRK) and the down-regulation of trehalase (TREH) and beta-amylase (BMY) led to a decreased glucose synthesis and an increased glucose consumption. Therefore, GR24 can effectively inhibit strawberry plant tillering through these pathways, making it an effective reagent for tillering inhibition.

GR24, a synthetic strigolactone analogue, plays a crucial role in a wide range of life processes. Studying the effects of the pre-harvest application of GR24 on strawberry ripening and fruit quality provides a scientific basis for the application of GR24 in horticultural crop production. GR24 solutions at concentrations of 0, 0.5, 1 and 2 µmol/L were applied to strawberries at the de-greening stage. The results showed that pre-harvest treatment with 1 µmol/L GR24 increased fruit weight and size; promoted fruit softening; increased the content of sugars, total flavonoids, total phenolics, and anthocyanins, and increased antioxidant activity. These results proved that GR24 effectively accelerated fruit ripening and improved fruit quality. In addition, to gain more insight into the biological mechanism of GR24 in fruit ripening, we conducted a combined transcriptomic and metabolomic analysis. It was found that the differences were related to sugar and flavonoid biosynthesis, particularly in the later stage of fruit ripening. qRT-PCR analysis revealed that GR24 increased gene expression activity and metabolite accumulation in the anthocyanin and sugar biosynthetic pathway, thereby promoting strawberry color and flavor.

Ethylene at least partly regulates some aspects during non-climacteric ripening in strawberry. However, the ethylene signaling pathway genes in the strawberry fruit have not been comprehensively and systematically analyzed. In the present study, 15 FaETRs and 14 FaEIN3/EINs were identified in the octoploid strawberry genome. Subcellular localization analysis predicted that FaETRs and FaEIN3/EINs are respectively localized to the endoplasmic reticulum and the nucleus. The phylogenetic trees showed that FaETRs were classified into two subgroups, while FaEIN3/EINs were divided into three clades, which was supported by gene structure and conserved motif analysis. FaETRs and FaEIN3/EINs could interact with several components, such as CTR1, RTE1, EIN2 and ERF1B, in the ethylene signaling pathway by protein–protein interaction network analysis. Transcriptomic data showed that FaETRs were mainly expressed at the early stage of fruit development in three strawberry cultivars. Additionally, a couple of FaETRs (FaETR2 and FaETR13) and FaEINs (FaEIN2 and FaEIN7) could be induced by 1 μM ABA and inhibited by 100 μM nordihydroguaiaretic acid (NDGA, an ABA biosynthesis blocker). These findings suggested that the FaETR- and FaEIN3/EIN-mediated ethylene signaling pathway might play a role in strawberry fruit ripening.

Red pears are appreciated for their abundant nutritional benefits and visually striking red hue, rendering them a favored option among consumers and stimulating substantial market demand. The present study employs the flesh of a red pear as the explant, subjecting the flesh callus to varying sugar sources, MS concentrations, light qualities, and temperatures to investigate the alterations in secondary metabolites, including anthocyanins, within the callus. It was found that sucrose can induce more anthocyanins, and its related metabolites and genes also increase as the sucrose and MS concentrations increase. Under the conditions of red-blue light and a temperature of 15 °C, it can further induce the production of more anthocyanins and secondary metabolites and can also upregulate the synthesis of anthocyanin-related genes. As such, this investigation serves to elucidate the factors that contribute to anthocyanin accumulation in red pears, thereby providing a theoretical foundation for understanding the mechanisms underlying color change.

Strawberry is a worldwide demanded edible fruit with high economic and nutritional value; however, a very short storage life largely limits its supply and marketing. In this study, strawberries were treated using sodium selenite with different concentrations (6, 12, 18, and 24 mg/L), and the postharvest fruit quality and resistance to Botrytis cinerea were substantially assessed. Among all concentrations, 12 mg/L Se was the most effective treatment, which maintained fruit skin brightness, reduced natural decay incidence, severity, and weight loss, increased the Se content in fruit, and thus maintained the postharvest fruit quality of the strawberry. Furthermore, strawberries treated with 12 mg/L Se had lower flavonoid, phenolic, anthocyanins, proanthocyanidins, H2O2, and O2− contents compared to the control and, correspondingly, lower antioxidant capacity; moreover, 12 mg/L Se treatment decreased the decay incidence and severity caused by the infection of B. cinerea. Collectively, our findings may provide a reference for developing safe and environmentally friendly alternative methods to sustain quality and manage gray mold in postharvest strawberries as well as other horticultural crops.

There are few reports on the reproductive biology of celery, which produces small flowers in a long flowering period. Anther development was analyzed by paraffin sectioning and related genes were examined by transcriptome sequencing and qPCR. The development process was divided into nine stages based on the significant changes in the cell and tissue morphologies. These stages included: archesporial stage, sporogenous cell stage, microspore mother cell stage, dyad and tetrad stage, mononuclear microspore stage, late uninucleate microspore stage, binuclear cell stage, mature pollen stage, and dehiscence stage. A total of 1074 differentially expressed genes were identified by transcriptome sequencing in the early flower bud, middle flower bud, and early flowering period. Functional annotation indicated that these genes were involved in physiological and biochemical processes such as ribosomes metabolism, sugar metabolism, and amino acid metabolism. Transcription factors such as C2H2, AP2/ERF, bZIP, WRKY, and MYB played key regulatory roles in anther development and had different regulatory capabilities at various stages. The expression patterns based on qPCR and transcriptome data of the selected transcription factor genes showed consistency, suggesting that these genes played an important role in different flower development stages. These results provide a theoretical basis for molecular breeding of new celery varieties with pollen abortion. Furthermore, they have enriched research on the reproductive biology of celery and the Apiaceae family.