Ripening agents can accelerate the ripening of fruits and maintain a similar appearance to naturally ripe fruits, but the fruit flavor and quality will be changed compared to naturally ripe fruits. To find an efficient detection method to distinguish whether crab apples were artificial ripened, the naturally ripe and artificially ripe fruits were detected and analyzed using the electronic nose (e-nose) technique in this study. The fruit quality indexes of samples were determined by the traditional method as a reference. Significant differences were found between naturally ripe and artificially ripe fruits based on the analysis of soluble sugar content, titratable acidity content, sugar–acid ratio, soluble protein content, and soluble solids content. In addition, principal component analysis (PCA), linear discriminant analysis (LDA), support vector machine (SVM), and random forest (RF) analyses were performed on the electrical signals generated by the electronic nose sensor, respectively. The results showed that the RF is the best recognition algorithm for distinguishing which crab apples were naturally ripe or artificially ripe; the average recognition accuracy is 98.3%. On the other hand, the prediction models between the e-nose response data and fruit quality indexes were constructed by partial least squares regression (PLSR), which showed that the feature value of e-nose response curves extracted by wavelet transform was highly correlated with the quality indexes of fruits, the determination coefficients (R²) of regression models were higher than 0.91. The results demonstrated that the detection technology with an electronic nose could be used to test whether the fruit of the crab apple was artificially ripe, which is an economical and efficient method.

Flowers are imperative reproductive organs and play a key role in the propagation of offspring, along with the generation of several metabolic products in flowering plants. In Juglans mandshurica, the number and development of flowers directly affect the fruit yield and subsequently its commercial value. However, owing to the lack of genetic information, there are few studies on the reproductive biology of Juglans mandshurica, and the molecular regulatory mechanisms underlying the development of female and male inflorescence remain unclear. In this study, phytohormones and transcriptomic sequencing analyses at the three stages of female and male inflorescence growth were performed to understand the regulatory functions underlying flower development. Gibberellin is the most dominant phytohormone that regulates flower development. In total, 14,579 and 7188 differentially expressed genes were identified after analyzing the development of male and female flowers, respectively, wherein, 3241 were commonly expressed. Enrichment analysis for significantly enriched pathways suggested the roles of MAPK signaling, phytohormone signal transduction, and sugar metabolism. Genes involved in floral organ transition and flowering were obtained and analyzed; these mainly belonged to the M-type MADS-box gene family. Three flowering-related genes (SOC1/AGL20, ANT, and SVP) strongly interacted with transcription factors in the co-expression network. Two key CO genes (CO3 and CO1) were identified in the photoperiod pathway. We also identified two GA20xs genes, one SVP gene, and five AGL genes (AGL8, AGL9, AGL15, AGL19, and AGL42) that contributed to flower development. The findings are expected to provide a genetic basis for the studies on the regulatory networks and reproductive biology in inflorescence development for J. mandshurica.

Cerasus humilis, a small shrub of the Cerasus genus within the Rosaceae family, is native to China and renowned for its highly nutritious and medicinal fruits, robust root system, and remarkable drought resistance. This study primarily employed association transcriptome and metabolome analyses to assess changes in abscisic acid (ABA) levels and identify key regulatory genes in C. humilis subjected to varying degrees of drought stress. Notably, we observed distinct alterations in transcription factors across different drought intensities. Specifically, our transcriptome data indicated noteworthy shifts in GATA, MYB, MYC, WRKY, C2H2, and bHLH transcription factor families. Furthermore, combined transcriptomic and metabolomic investigations demonstrated significant enrichment of metabolic pathways, such as ‘Carbon metabolism’, ‘Biosynthesis of amino acids’, ‘Biosynthesis of cofactors’, ‘Phenylpropanoid biosynthesis’, ‘Starch and sucrose metabolism’, and ‘Plant hormone signal transduction’ under moderate (Mod) or severe (Sev) drought conditions. A total of 11 candidate genes involved in ABA biosynthesis and signaling pathways were identified. The down-regulated genes included secoisolariciresinol dehydrogenase-like and PYL2. Conversely, genes including FAD-dependent urate hydroxylase-like, cytochrome P450 97B2, carotenoid cleavage dioxygenase 4 (CCD4), SnRK2.2, ABI 5-like protein 5, PP2C 51, and SnRK2.3, were up-regulated under Mod or Sev drought stress. This study lays the genetic foundation for ABA biosynthesis to enhance drought tolerance and provides genetic resources for plant genetic engineering and breeding efforts.

Canker is a destructive fungal disease that adversely affects plant growth, triggering leaf drop, branch dieback and even plant death. For the blueberry industry, fungal canker reduces blueberry yield and quality. In this study, diseased branches of the ‘Bluegold’ blueberry cultivar collected from open-field plantations in Jilin Province, China, were used to isolate and identify the pathogen, characterize its biological properties, and investigate the physiological and metabolomic responses of blueberry shoots to pathogen infection. Based on morphological characteristics and internal transcribed spacer sequence analysis, the pathogen was preliminarily identified as Diaporthe eres. Biological characterization showed that the optimal temperature and pH for mycelial growth of the isolate were 25 °C and 6, respectively, while light conditions had no significant effect on fungal growth. Pathogenicity results demonstrated that infection by the isolate significantly induced the accumulation of superoxide anions (O₂^.−) and hydrogen peroxide (H₂O₂) in blueberry new shoots, which led to lipid peroxidation and subsequently resulted in significant increases in malondialdehyde content and relative electrical conductivity. Concurrently, the plant’s antioxidant enzyme system was disrupted, and the activities of peroxidase and superoxide dismutase remained significantly elevated throughout the infection period, while catalase activity exhibited an initial increase followed by a gradual decline. Metabolomic analysis identified 541 differentially accumulated metabolites, with key metabolites including ferulic acid, quercetin and kaempferol showing marked abundance changes. These were primarily enriched in pathways closely associated with plant resistance, such as phenylpropanoid biosynthesis and flavonoid biosynthesis. Combined analysis of physiological and metabolomic data showed that reactive oxygen species accumulation and antioxidant enzyme responses were accompanied by significant enrichment of phenylpropanoid and flavonoid metabolism, indicating coordinated antioxidant regulation and secondary metabolic reprogramming in blueberry shoots following pathogen infection. Overall, this study preliminarily identified a D. eres isolate associated with blueberry canker in Jilin Province, and systematically characterized the physiological and metabolic responses of blueberry to pathogen infection, providing a theoretical basis for understanding blueberry—Diaporthe interactions and for developing effective disease management strategies.

Fragaria pentaphylla, a unique wild strawberry species in China, is rich in various fruit colors and a valuable resource for studying color genes. Fruits of different colors from F. pentaphylla were selected as the experimental material. Liquid chromatography-mass spectrometry (LC-MS) and high-throughput RNA sequencing (RNA-seq) were employed to identify key genes responsible for the development of different fruit colors. Metabolite analysis revealed that 3249 metabolites were detected, including nine differential metabolites related to anthocyanin synthesis and five biological pathways. Additionally, an analysis combining transcriptome and metabolome data showed that the structural genes FpDFR, FpCHS, FpCHI, and FpUFGT were upregulated in red fruit, with significantly higher expression levels compared to pink and white fruits, actively promoting anthocyanin production in red fruit. Conversely, genes FpANR and FpLAR were upregulated in white fruit, enhancing catechin synthesis and inhibiting anthocyanin formation. The gene FpPAL was upregulated in pink fruit. Transcription factors FpbHLH18, FpMYB1, FpMYB24, and FpMYB114 collaborate with structural genes to enhance the synthesis of anthocyanins in red fruit. The findings improve our understanding of the molecular mechanisms that control anthocyanin production in F. pentaphylla. The identified key candidate genes may be utilized in the molecular breeding of strawberries.