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To achieve the high-value utilization of squid skin obtained from squid processing, this study utilized an enzymatic approach to prepare protein peptides. The enzymatic hydrolysis parameters were optimized using single factor and response surface tests, with the concentration of peptide and trichloroacetic acid-nitrogen soluble index (TCA-NSI) serving as evaluation criteria. The amino acid composition, molecular weight distribution, peptide sequence, antioxidant activity, and in vitro simulated digestive properties of the prepared protein peptides were also thoroughly characterized. The results showed that the optimal conditions for enzymatic hydrolysis were as follows: Enzymatic temperature of 43.50 ℃, enzymatic time of 100 minutes, enzymatic pH of 7.50, trypsin to alkaline protease ratio of 2:1, and enzyme dosage of 4000 U/g. Under these specified conditions, the TCA-NSI achieved a value of 89.02%±0.66%. The prepared protein peptides exhibited a well-balanced amino acid composition, with an essential amino acid index (EAAI) value of 0.90. Furthermore, the prepared protein peptides encompassed a total of 43 polypeptide sequences, with 38 of these segments exhibiting molecular weights below 1800 Da. The IC50 values for scavenging DPPH radical, ABTS+ radical, and hydroxyl radical were determined to be 0.61, 0.28 and 1.95 mg/mL, respectively. Notably, the antioxidant activity remained favorable even after undergoing simulated gastrointestinal digestion in vitro. These findings serve to establish a solid theoretical basis for the advancement and exploitation of byproducts derived from squid processing, as well as their subsequent value-added utilization.

Abstract Background Platinum-drugs based chemotherapy in clinic increases the potency of tumor cells to produce M2 macrophages, thus leading to poor anti-metastatic activity and immunosuppression. Lysosome metabolism is critical for cancer cell migration and invasion, but how it promotes antitumor immunity in tumours and macrophages is poorly understood and the underlying mechanisms are elusive. The present study aimed to explore a synergistic strategy to dismantle the immunosuppressive microenvironment of tumours and metallodrugs discovery by using the herent metabolic plasticity. Methods Naphplatin was prepared by coordinating an active alkaline moiety to cisplatin, which can regulate the lysosomal functions. Colorectal carcinoma cells were selected to perform the in vivo biological assays. Blood, tumour and spleen tissues were collected and analyzed by flow cytometry to further explore the relationship between anti-tumour activity and immune cells. Transformations of bone marrow derived macrophage (BMDM) and M2-BMDM to the M1 phenotype was confirmed after treatment with naphplatin. The key mechanisms of lysosome-mediated mucolipin-1(Mcoln1) and mitogen-activated protein kinase (MAPK) activation in M2 macrophage polarization have been unveiled. RNA sequencing (RNA-seq) was used to further explore the key mechanism underlying high-mobility group box 1(HMGB1)-mediated Cathepsin L(CTSL)-lysosome function blockade. Results We demonstrated that naphplatin induces divergent lysosomal metabolic programs and reprograms macrophages in tumor cells to terminate the vicious tumour-associated macrophages (TAMs)-MDSCs-Treg triangle. Mechanistically, macrophages treated with naphplatin cause lysosome metabolic activation by triggering Ca2+ release via Mcoln1, which induces the activation of p38 and nuclear factor-κB (NF-κB) and finally results in polarizing M2 macrophages. In contrast, HMGB1-mediated lysosome metabolic blockade in cancer cells is strongly linked to antitumor effects by promoting cytoplasmic translocation of HMGB1. Conclusions This study reveals the crucial strategies of macrophage-based metallodrugs discovery that are able to treat both immunologically “hot” and “cold” cancers. Different from traditional platinum-based antitumour drugs by inhibition of DNAs, we also deliver a strong antitumour strategy by targeting lysosome to induce divergent metabolic programs in macrophages and tumours for cancer immunotherapy.

Previous studies have shown a negative correlation between chilling accumulation (CA) and heat requirements (HRs) in peaches (Prunus persica (L.) Batsch), consistent with findings in other plants in spring events. However, there is a lack of comparative research on the CA–HR relationship in peach varieties with different chilling requirements (CRs), and the specific impact of CA on HR reduction remains poorly described. To address this, we investigated the effects of CA on the days and HR for flowering in 54 peach varieties of differing CRs. Scanning electron microscopy was used to observe the effects of CA on the phenology of floral organ development in a selected peach variety. Our results indicate that, in general, peaches exhibit a reduced HR and accelerated flowering as the CA increases, but that the strength and trend of the CA–HR relationship is influenced by the CR and the variety. Low-CR varieties showed less sensitivity to CA increments, requiring higher relative increases in CA to significantly lower the HR, whereas high-CR varieties appeared to be more sensitive, with even modest changes leading to substantial reductions in HR. However, variations from this generality exist, even within varieties displaying the same rCA (the ratio of CA to CR). Additionally, we provide a summary of the relationship between the rCA and drHR in peaches of differing CRs, and identify several varieties exhibiting a strong response in the CA–HR relationship. This study also highlights the impact of CA on flower bud development, revealing slower progression under lower CA levels and accelerated growth with an increased CA. In particular, we identified the critical period of the enlargement and initiation of green scales as indicative of successful pollen grain formation. Finally, we present a schematic of the CA–HR relationship for flowering in peaches.

To construct a heterotrophic axenic system of Chlorella sorokiniana FZU60, the symbiotic bacteria were isolated and identified, and the effects of eight common antibiotics (cefotaxime, kanamycin, neomycin, ampicillin, streptomycin, tetracycline, chloramphenicol, and erythromycin) on the cell growth of symbiotic bacteria and C. sorokiniana FZU60 were investigated. Results showed that the main symbiotic bacteria were Bacillus (78.76%) and Methylobacterium (3.14%). Besides, 10 mg/L cefotaxime, 10 mg/L tetracycline, 100 mg/L kanamycin, and 100 mg/L erythromycin showed excellent inhibitory effect on these two symbiotic bacteria but no obvious effect on the cell growth of C. sorokiniana FZU60. Based on the above-mentioned results, the inhibition effect of different antibiotic combinations on symbiotic bacteria of C. sorokiniana FZU60 was further investigated. It was found that the heterotrophic axenic system could be successfully constructed by using the combination of 10 mg/L cefotaxime, 10 mg/L tetracycline, and 100 mg/L kanamycin. Moreover, C. sorokiniana FZU60 could maintain stable and axenic growth after three generations. The experimental results would provide theoretical reference and experimental basis for the preparation of axenic microalgal seed for high-cell-density heterotrophic cultivation of C. sorokiniana.

Abstract Background Chlorella sorokiniana FZU60 is a promising lutein producing microalga. A mixotrophy/photoautotrophy two-stage strategy can achieve high biomass concentration at stage 1 and high lutein content at stage 2, leading to excellent lutein production efficiency in C. sorokiniana FZU60. However, the underlying molecular mechanisms are still unclear, restraining the further improvement of lutein production. Results In this study, physiological and biochemical analysis revealed that photochemical parameters (Fv/Fm and NPQ) and photosynthetic pigments contents increased during the shift from mixotrophy to photoautotrophy, indicating that photosynthesis and photoprotection enhanced. Furthermore, transcriptomic analysis revealed that the glyoxylate cycle and TCA cycle were suppressed after the shift to photoautotrophy, leading to a decreased cell growth rate. However, the gene expression levels of photosynthesis, CO2 fixation, autophagy, and lutein biosynthesis were upregulated at the photoautotrophy stage, demonstrating that microalgal cells could obtain more precursor to synthesize lutein for enhancing photosynthesis and reducing reactive oxygen species. Conclusions The findings help to elucidate the molecular mechanisms for high lutein production efficiency of C. sorokiniana FZU60 under the mixotrophy/photoautotrophy strategy, identify key functional genes responsible for lutein biosynthesis, and shed light on further improvement of lutein production by genetic or metabolic engineering in future studies.

Plant plasma membrane H+-ATPase is a transport protein that is generally located on the plasma membrane and generates energy by hydrolyzing adenosine triphosphate (ATP) to pump hydrogen ions (H+) in the cytoplasm out of the cell against a concentration gradient. The plasma membrane H+-ATPases in plants are encoded by a multigene family and potentially play a fundamental role in regulating plant responses to various abiotic stresses, thus contributing to plant adaptation under adverse conditions. To understand the characteristics of the plasma membrane H+-ATPase family in peach (Prunus persica), this study analyzed the plasma membrane H+-ATPase family genes in peach. The results showed that there were 27 members of the plasma membrane H+-ATPase family in peach with amino acid sequences ranging from 943 to 1327. Subcellular localization showed that 23 of the 27 members were located on the cell membrane, and the phylogenetic tree analysis indicated that peach plasma membrane H+-ATPase members were divided into five groups. There were four genes with tandem repeat relationships, and six plasma membrane H+-ATPase genes were differentially expressed after 5 days of flooding and under non-flooding conditions based on the RNA-seq and RT-qPCR analyses. This study also investigated the characteristics and possible functions of the plasma membrane H+-ATPase family members in peach. The results provide theoretical support for further studies on their biological functions in peach.

BackgroundIn nursing homes, elder neglect has come to the forefront. Currently, few studies have examined the impact of personal and organizational factors of geriatric nursing assistants on elder neglect. From the perspective of geriatric nursing assistants, this study aims to explore the current situation and influencing factors of elder neglect in Chinese nursing homes.MethodsA convenience sampling method was used to recruit 412 geriatric nursing assistants from 50 nursing homes in China. Participants were surveyed using a demographic questionnaire, the Elder Neglect Scale for Geriatric Nursing Assistants, the General Self-Efficacy Scale (GSES), and the Proactive Personality Scale (PPS). Spearman correlation analysis and multiple linear regression were used to analyze the factors influencing elder neglect.ResultsGeriatric nursing assistants scored a median of 74 out of 85 on the Elder Neglect Scale. Multiple linear regression analyses showed that the main personal factors influencing geriatric nursing assistants’ elder neglect were general self-efficacy (β = 0.312), proactive personality (β = 0.180), and advanced qualification (β = 0.084), while the main organizational factors included monthly salary ≤ 1,900 RMB (β = −0.256), no regular training after induction (β = −0.253), and the number of days off per month (3–4 days off β = 0.192, ≥ 5 days off β = 0.101).ConclusionAlthough geriatric nursing assistants are at low levels of elder neglect, it remains a cause for concern. Among the personal factors, geriatric nursing assistants who possessed proactive personalities, high self-efficacy and advanced qualifications, exhibited low levels of elder neglect. Among the organizational factors, those who possessed a high number of days off per month portrayed low levels of elder neglect. Conversely, those who received low monthly salaries and no regular training after induction portrayed high levels of elder neglect. To reduce the risk of elder neglect, nursing homes should give due consideration to candidates’ self-efficacy and proactive personality traits when recruiting, and focus on fostering these personality traits in their employees during their work. In addition, strengthening regular training for geriatric nursing assistants, optimizing the salary structure, and arranging rest days in a reasonable manner are also necessary measures.

Background: Numerous studies have shown that polymorphisms in the diabetes susceptibility gene, insulin-like growth factor 2mRNA–binding protein 2 (IGF2BP2), are associated with the occurrence and development of various malignant tumors; however, their correlation with the onset of diffuse large B-cell lymphoma (DLBCL) is still unknown. Therefore, this study aimed to explore whether IGF2BP2 polymorphisms increase the risk of developing DLBCL. Methods: This study included 295 DLBCL patients and 331 healthy individuals. Peripheral blood was collected, and polymerase chain reaction-ligase detection reaction (PCR-LDR) was used to detect IGF2BP2 gene polymorphisms. Logistic regression was used to assess the association between IGF2BP2 polymorphism and the risk of DLBCL, adjusted for age, sex, and body mass index (BMI). P

The brain-computer interfaces (BCIs) based on steady-state visual evoked potential (SSVEP) have been extensively explored due to their advantages in terms of high communication speed and smaller calibration time. The visual stimuli in the low- and medium-frequency ranges are adopted in most of the existing studies for eliciting SSVEPs. However, there is a need to further improve the comfort of these systems. The high-frequency visual stimuli have been used to build BCI systems and are generally considered to significantly improve the visual comfort, but their performance is relatively low. The distinguishability of 16-class SSVEPs encoded by the three frequency ranges, i.e., 31-34.75 Hz with an interval of 0.25 Hz, 31-38.5 Hz with an interval of 0.5 Hz, 31-46 Hz with an interval of 1 Hz, is explored in this study. We compare classification accuracy and information transfer rate (ITR) of the corresponding BCI system. According to the optimized frequency range, this study builds an online 16-target high frequency SSVEP-BCI and verifies the feasibility of the proposed system based on 21 healthy subjects. The BCI based on visual stimuli with the narrowest frequency range, i.e., 31-34.5 Hz, have the highest ITR. Therefore, the narrowest frequency range is adopted to build an online BCI system. An averaged ITR obtained from the online experiment is 153.79 ±6.39 bits/min. These findings contribute to the development of more efficient and comfortable SSVEP-based BCIs.

Steady-state visual evoked potential (SSVEP)-based brain-computer interfaces (BCIs) have received significant attention owing to their high information transfer rate (ITR) and low training requirements. Previous SSVEP-based BCIs mostly adopt the stationary visual flickers where only a few studies have explored the effect of moving visual flickers on the SSVEP-BCI. In this study, a novel stimulus encoding method based on the simultaneous modulation of luminance and motion was proposed. We adopted the sampled sinusoidal stimulation method to encode the frequencies and phases of stimulus targets. In addition to luminance modulation, at the same time, visual flickers also moved horizontally towards right and left at different frequencies (i.e., 0, 0.2, 0.4, and 0.6 Hz) following a sinusoidal function. Accordingly, a nine-target SSVEP-BCI was built to evaluate the influence of motion modulation on the BCI performance. Filter bank canonical correlation analysis (FBCCA) approach was adopted to identify the stimulus targets. Offline experimental results of 17 subjects revealed that the system performance decreased with the increase of superimposed horizontal periodic motion frequency. Our online experimental results showed that the subjects achieved 85.00 ± 6.77 % and 83.15 ± 9.88 % accuracy for the superimposed horizontal periodic motion frequencies of 0 and 0.2 Hz, respectively. These results verified the feasibility of the proposed systems. In addition, the system with 0.2 Hz horizontal motion frequency provided the best visual experience for subjects. These results indicated that moving visual stimulus can provide an alternative option for SSVEP-BCIs. Furthermore, the proposed paradigm is expected to develop a more comfortable BCI system.

Background/objective Bone marrow biopsy, the gold standard for the diagnosis of multiple myeloma (MM), has main limitation of the invasiveness. Here, we explored the diagnostic and prognostic values of circulating miR-1246 in patients with MM.Material and methods Ninety MM patients and 30 healthy donors (control group) were recruited in this study. The expression of miR-1246 in the peripheral blood samples was detected using qPCR. The receiver operating characteristic (ROC) curve was used to assess the diagnostic value of miR-1246 in MM. The Kaplan–Meier survival analyze was performed to evaluate the prognostic value of miR-1246.Results The expression level of serum miR-1246 from newly diagnosed MM patients was significantly higher than that of the control group. Circulating miR-1246 level was decreased after treatment in remission patients, but remained high levels in relapsed patients (P

The flavour and mouthfeel of peaches are crucial qualities of peach germplasm resources that significantly influence consumer preferences. In this study, we utilized 212 peach germplasm resources from the Nanjing Peach Resource Repository, National Fruit Germplasm facility, Jiangsu Academy of Agricultural Sciences as materials for sensory analysis, electronic nose analysis, and composition analysis via high-performance liquid chromatography (HPLC). In the sensory analysis, we divided 212 peach germplasms into three clusters based on hierarchical cluster analysis (d = 5). No.27, No.151, and No.46 emerged as the most representative of these clusters. The electronic nose was used to conduct an evaluation of the aroma profiles of the 212 peach germplasms, revealing that the primary distinguishing factors of peach aroma can be attributed to three sensors: W1S (methane), W1W (terpenes and organosulfur compounds), and W5S (hydrocarbons and aromatic compounds). The primary differences in the aromatic substances were characterized by sensors W2W (aromatic compounds, sulphur, and chlorine compounds) and W1C (aromatic benzene). The HPLC analysis indicated that the persistence of peach sensory characteristics was positively correlated with acids and sourness and negatively correlated with sweetness and the ratio of sugar to acids. The overall impression of the 212 peach germplasms revealed a negative correlation with acids, while a positive correlation was observed between the overall impression and the ratio of sugar to acids. Therefore, this study substantially contributes to the preliminary screening of the analysed specific characteristics of peach germplasms such as No.27, No.46, No.151, and No.211. These selections may provide valuable information for the potential creation of superior germplasm resources.

Abstract Co-production of multiple compounds is an efficient approach to enhance the economic feasibility of microalgae-based metabolites production. In this study, Chlorella sorokiniana FZU60 was cultivated under different bioprocess strategies to enhance the co-production of lutein and protein. Results showed that both lutein and protein content (7.72 and 538.06 mg/g, respectively) were highest at the onset of nitrogen deficiency under batch cultivation. Semi-batch III strategy, with 75% microalgal culture replacement by fresh medium, obtained similar content, productivity, and yield of lutein and protein as batch cultivation, demonstrating that it can be used for stable and continuous production. Fed-batch II strategy, feeding with 1/3 modified BG11 medium, achieved super-high lutein and protein yield (28.81 and 1592.77 mg/L, respectively), thus can be used for high-output production. Besides, two-stage strategy, combining light intensity shift and semi-batch cultivation, gained extremely high lutein and protein productivity (15.31 and 1080.41 mg/L/day, respectively), thereby is a good option for high-efficiency production. Moreover, the fed-batch II and two-stage strategy achieved high-quality lutein and protein, thus are promising for the co-production of lutein and protein in C. sorokiniana FZU60 for commercial application.

Lutein is a high-value carotenoid with many human health benefits. Lycopene β- and ε-cyclases (LCYB and LCYE, respectively) catalyze the cyclization of lycopene into distinct downstream branches, one of which is the lutein biosynthesis pathway, via α-carotene. Hence, LCYB and LCYE are key enzymes in lutein biosynthesis. In this study, the coding genes of two lycopene cyclases (CsLCYB and CsLCYE) of a lutein-enriched marine green microalga, Chlorella sorokiniana FZU60, were isolated and identified. A sequence analysis and computational modeling of CsLCYB and CsLCYE were performed using bioinformatics to identify the key structural domains. Further, a phylogenetic analysis revealed that CsLCYB and CsLCYE were homogeneous to the proteins of other green microalgae. Subcellular localization tests in Nicotiana benthamiana showed that CsLCYB and CsLCYE localized in chloroplasts. A pigment complementation assay in Escherichia coli revealed that CsLCYB could efficiently β-cyclize both ends of lycopene to produce β-carotene. On the other hand, CsLCYE possessed a strong ε-monocyclase activity for the production of δ-carotene and a weak ε-bicyclic activity for the production of ε-carotene. In addition, CsLCYE was able to catalyze lycopene into β-monocyclic γ-carotene and ultimately produced α-carotene with a β-ring and an ε-ring via γ-carotene or δ-carotene. Moreover, the co-expression of CsLCYB and CsLCYE in E. coli revealed that α-carotene was a major product, which might lead to the production of a high level of lutein in C. sorokiniana FZU60. The findings provide a theoretical foundation for performing metabolic engineering to improve lutein biosynthesis and accumulation in C. sorokiniana FZU60.

The effects of different fruit load treatments during peach growth and development on the internal and external quality of peach fruit were studied. At 47 days after full bloom, the plant materials were divided into four treatments: about 100%, 75%, 50% and 25% of fruit were retained. The results showed that as the fruit load was reduced during fruit growth and development, the fruit weight, size, soluble solid contents (SSC), total sugar content, sugar/acid ratio and color quality increased, while the flesh firmness, index of absorbance difference (IAD) and total acid content decreased. Compared with the control treatment in which the fruit were not thinned, the weight of individual mature fruit increased by 24.52%, 39.73% and 51.68% under three fruit thinning treatments (in which about 75%, 50% and 25% of the fruit were left on the tree). SSC increased by 30.78%, 37.63% and 49.69%; total sugar content increased by 13.58%, 22.33% and 31.42%; and the sugar-acid ratio increased by 13.25%, 13.59% and 19.47%, respectively, under the three conditions. In addition, the longitudinal, transverse and lateral diameters of fruit increased to varying degrees when the fruit load was reduced. Furthermore, the fruit firmness and IAD value of fruit skins decreased, and fruit ripening was advanced when the fruit load was reduced. The results showed that fruit quality and flavor were improved significantly by fruit thinning.

As the most abundant phenolic acid in peach fruit, chlorogenic acid (CGA) is an important entry point for the development of natural dietary supplements and functional foods. However, the metabolic and regulation mechanisms underlying its accumulation in peach fruits remain unclear. In this study, we evaluated the composition and content of CGAs in mature fruits of 205 peach cultivars. In peach fruits, three forms of CGA (52.57%), neochlorogenic acid (NCGA, 47.13%), and cryptochlorogenic acid (CCGA, 0.30%) were identified. During the growth and development of peach fruits, the content of CGAs generally showed a trend of rising first and then decreasing. Notably, the contents of quinic acid, shikimic acid, p-coumaroyl quinic acid, and caffeoyl shikimic acid all showed similar dynamic patterns to that of CGA, which might provide the precursor material basis for the accumulation of CGA in the later stage. Moreover, CGA, lignin, and anthocyanins might have a certain correlation and these compounds work together to maintain a dynamic balance. By the comparative transcriptome analysis, 8 structural genes (Pp4CL, PpCYP98A, and PpHCT) and 15 regulatory genes (PpMYB, PpWRKY, PpERF, PpbHLH, and PpWD40) were initially screened as candidate genes of CGA biosynthesis. Our findings preliminarily analyzed the metabolic and molecular regulation mechanisms of CGA biosynthesis in peach fruit, which provided a theoretical basis for developing high-CGA content peaches in future breeding programs.

ABSTRACT The toxic dinoflagellate Karenia mikimotoi is a harmful algal bloom-forming species in coastal areas around the world. It produces ichthyotoxins and hemolytic toxins, with deleterious effects on marine ecosystems. In this study, the bacterium Pseudoalteromonas sp. FDHY-MZ2, with high algicidal efficiency against K. mikimotoi, was isolated from a bloom event. Based on the results, it completely lysed K. mikimotoi cells within 24 h 0.5% (vol/vol), with the algicidal activity of the supernatant of the bacterium culture. Algal cell wall fragmentation occurred, leading to cell death. There was a marked decline in various photochemical traits. When treated with the supernatant, cellulase, pheophorbide a oxygenase (PAO) and cyclin B genes were significantly increased, suggesting induced cell wall deterioration, chloroplast degradation and cell cycle regulation of K. mikimotoi cells. In addition, the expression levels of reactive oxygen species (ROS) scavenging gene was significantly inhibited, indicating that the ROS removal system was damaged. The bacterial culture was dried to obtain the spray-dried powder, which showed algicidal activity rates of 92.2 and 100% against a laboratory K. mikimotoi culture and a field microcosm of Karlodinium sp. bloom within 24 h with the addition of 0.04% mass fraction powder. Our results demonstrate that FDHY-MZ2 is a suitable strain for K. mikimotoi and Karlodinium sp. blooms management. In addition, this study provides a new strategy for the anthropogenic control of harmful algal bloom-forming species in situ. IMPORTANCE K. mikimotoi is a noxious algal bloom-forming species that cause damaging of the aquaculture industry and great financial losses. Bacterium with algicidal activity is an ideal agency to inhibit the growth of harmful algae. In this approach application, the bacterium with high algicidal activity is required and the final management material is ideal for easy-to-use. The algicidal characteristics are also needed to understand the effects of the bacterium for managing strategy exploration. In this study, we isolated a novel algicidal bacterium with extremely high lysis efficiency for K. mikimotoi. The algicidal characteristics of the bacterium as well as the chemical and molecular response of K. mikimotoi with the strain challenge were examined. Finally, the algicidal powder was explored for application. The results demonstrate that FDHY-MZ2 is suitable for K. mikimotoi and Karlodinium sp. blooms controlling, and this study provides a new strategy for algicidal bacterium application.

Peach (Prunus persica (L.) Batsch) is a highly desirable fruit that is consumed around the world. However, the peach fruit is highly perishable after harvest, a characteristic that limits the distribution and supply to the market and causes heavy economic losses. Thus, peach fruit softening and senescence after harvest urgently need to be addressed. In the current study, transcriptomic analysis was performed to identify candidate genes associated with peach fruit softening and senescence, comparing peach fruit from cultivars with different flesh textures, namely melting and stony hard (SH) flesh textures during storage at room temperature. The mitogen-activated protein kinase signaling pathway-plant and plant hormone signal transduction pathways were associated with peach fruit softening and senescence according to the Venn diagram analysis and weighted gene co-expression network analysis. The expression levels of seven genes, including Prupe.1G034300, Prupe.2G176900, Prupe.3G024700, Prupe.3G098100, Prupe.6G226100, Prupe.7G234800, and Prupe.7G247500, were higher in melting peach fruit than in SH peach fruit during storage. Furthermore, the SH peach fruit softened rapidly after 1-naphthylacetic acid treatment, during which the levels of expression of these seven genes, determined by a quantitative reverse transcription polymerase chain reaction, were strongly induced and upregulated. Thus, these seven genes may play essential roles in regulating peach fruit softening and senescence.

Platinum (Pt) drugs have developed rapidly in clinical applications because of their broad and highly effective antitumor effects. In recent years, with the rapid development of immunotherapy, Pt-based antitumor agents have gained new challenges and opportunities. Since the discovery of their pharmacological effects in immunotherapy and tumor microenvironment regulation, research into Pt drugs has progressed to multi-ligand and multi-functional Pt precursors and their own shortcomings have been further highlighted. With the development of antitumor immunotherapy and the rise of combination therapy, the development of Pt-based drugs has started to move in the direction of multi-targeting, nanocarrier modification, immunotherapy and photodynamic therapy. In this paper, we first overview the recent applications of Pt-based drugs in antitumor inorganic chemistry, with a focus on summarizing the application of Pt-based drugs and their precursors in the anticancer immune response. The paper also provides a reasonable outlook on the future development of Pt-based drugs from the chemical and immunological perspectives, relying on the existing content and problems of Pt-based drug development. On the basis of the gathered information, joint multidisciplinary programs on implementing comprehensive immune analyses for the future development of novel anticancer metal compounds should be initiated.

Peach (Prunus persica) fruit emit more than 100 volatile organic compounds. Among these volatiles, γ-decalactone is the key compound that contributes to peach aroma. The final step in lactones biosynthesis is catalyzed by alcohol acyltransferases (AATs). In this study, five AAT genes were isolated in the peach genome, and the ways that these genes contribute toward the peach aroma were studied. The sequence analysis of the five AATs showed PpAAT4 and PpAAT5 are truncated genes, missing important residues such as HXXXD. The expressions of PpAATs were investigated to identify the roles in creating the peach aroma. The results indicated that only PpAAT1 is highly expressed during γ-decalactone formation. A functional survey of the five PpAATs, using the oleaginous yeast expression system, suggested that only PpAAT1 significantly increased the γ-decalactone content, whereas the other four PpAATs did not significantly alter the γ-decalactone content. Enzyme assays on PpAATs heterologously expressed and purified from Escherichia coli indicated that only PpAAT1 could catalyze the formation of γ-decalactone. All results indicated that PpAAT1 is a more efficient enzyme than the other four PpAATs during the γ-decalactone biosynthesis process in peach fruit. The results from this study should help improve peach fruit aroma.

Auxin is an important endogenous plant hormone that is usually present as indole-3-acetic acid (IAA). The flavin monooxygenase YUCCA is the rate-limiting enzyme of IAA biosynthesis and plays an important regulatory role in plant growth and development. To further investigate the function of the YUCCA gene family in weeping peach trees, members of the YUCCA gene family were identified via bioinformatics analysis. The gene structure and conserved domains of the weeping peach YUCCA genes were investigated, and phylogenetic analysis and gene annotation were carried out. Fourteen PpYUCCAs were identified in the weeping peach variety ‘Hongchuizhi’ and were found to be randomly located on five different chromosomes. Moreover, the prediction of subcellular localization showed that most of the YUCCA proteins were localized in the cytoplasm. Based on our transcriptome analysis, only nine PpYUCCAs, including PpYUCCA1, PpYUCCA3/4/5/6, PpYUCCA9, and PpYUCCA12/13/14, were expressed in the weeping peach branches, which could result in the accumulation of auxin. PpYUCCA6/12 may play a critical role in the appearance of the weeping trait, as indicated by the higher expression levels found in the Hongchuizhi variety compared with the Xiahui 6 variety. The results of this study provide a foundation for further research on the biological functions of PpYUCCAs in weeping peach trees.

Aroma profiling peach flowers can improve the landscape and ecological value of the surrounding environment. In order to preliminarily explore and screen the flower aromas of peach germplasms, the floral aroma profiles of 50 peach germplasms were analyzed by electronic nose detection. The clustering results from ten sensors showed that it was possible to identify each peach blossom aroma type. ‘Gansutao2’ was separately classified as cluster I; ‘Yuntaishanshantao’, ‘Dazhuanggansutao’, and ‘Zhouxingshantao’ as cluster II; ‘Xinjiangpantao’ and ‘Xinjianghuangrou’ as cluster III; and the remaining germplasms as cluster IV. The flower aromas of clusters I, II, and III were different from that of cluster IV and were mainly highlighted by the significant differences in the response values of the three main sensors, which were W1S (methane), W1W (hydrogen sulfide), and W5S (nitrogen oxides). The principal component analysis and significance analysis of the sensor response values showed that ‘Hua3’, ‘Hongfenjiaren’, and ‘Yuntaishanshantao’ had special flower aromas. The response values of these three varieties produced by the W1S, W1W, and W5S sensors and two aromatic sensors, W2W (aromatic components and organic sulfides) and W3S (methane-aliph), were significantly different from most of the other germplasms. The ‘Yuntaishanshantao’ response values produced by the five sensors’ were low, which showed that it had a light aroma, while the ‘Hongfenjiaren’ and ‘Hua3’ values were high, which showed that they had strong aromas. The results from this study provided basic data that could be used to screen peach germplasms with obvious floral aromas, cultivate new varieties with strong aromas, and aid the development and utilization of peach floral aroma substances.

To investigate the peach fruit flesh types (soft-melting, hard-melting, stonyhard and non-melting) and harvest maturity level suitable for near-freezing temperature storage (NFTS), eight peach cultivars that had four flesh types were used as test materials. Changes in fruit respiration intensity and ethylene release rates, as well as the differences in quality indexes, such as soluble solids content (SSC), firmness, color difference, pigment content, soluble sugar and organic acid component content, of three fruit maturity levels (70%, 80% and 90% maturity) under NFTS conditions were analyzed and compared. The fruit quality indexes of peach having different maturity levels and flesh types changed little during NFTS. The SSC and total sugar content of hard-melting and stonyhard peach fruit were higher than those of other flesh types during NFTS. Those fruit maintained greater firmness at the end of the storage period. The differences in respiration intensity and ethylene release rate were small, but for fruit coloring, hard-melting fruit performed better than stonyhard fruit. The 80%, compared with the 90%, maturity stage maintained more fruit moisture, had less fruit mass loss and maintained a greater edible firmness. It effectively impeded the fruit senescence process and was the most suitable maturity for NFTS. Thus, the hard-melting peach maintained the highest commercial value and desirable storage characteristics under NFTS conditions, and its 80% maturity level was the most suitable for NFTS.

Amino acids play an interesting and important role in the metabolism of peaches. The objectives of this study were to investigate and compare amino acid profiles in peaches at harvest for future research about the resistance effects, nutritional value of amino acids in peaches and to produce high-quality peach wine. In the study, 10 peaches and nectarines, including white, yellow and red flesh varieties, were selected for amino acid concentration and composition by high performance liquid chromatography (HPLC). Results showed sugar levels in nectarines were higher than in peaches in this study. High concentrations of total acids were found in “Tropic Prince”, “Yixianhong”, “NJN76” and “Hongrou1”. Malic acids had the highest concentrations, compared toquinic and citric acid concentrations. Total amino acids in yellow and white flesh varieties were over 1100 µg/g FW, while red flesh varieties had total amino acids below 750 µg/g FW. Asn was the highest concentration compared to other amino acids, with the high concentration of Asn in “Tropical Prince’ (3279.15 µg/g FW) and the lowest concentration in “Touxinhong” (559.60 µg/g FW). “Jinxia”, “Yuhua3” and “Chengxiang” had better amino acid scores compared with others, in particularly the lowest value in the red flesh varieties. Finally, according to PCA and the heatmaps, amino acids in “Chengxiang”had evident differences to other varieties, which showed the different amino acid concentrations and composition. Overall, the results of this study highlighted three yellow flesh and one white flesh varieties that had satisfactory concentrations and components of amino acid values. In addition, amino acids were the precursors of aroma compounds, so these differences between varieties werea new way to screen the potential varieties for producing high quality peach wines with the anticipated specific characteristics.

In this study, the carotenoid profiles and content in 132 cultivars of yellow-flesh peach having different fruit developmental periods (short, middle, and long), fruit surface indumenta (glabrous and pubescent skin), and flesh colors (yellow, golden, and orange) were investigated. We simultaneously analyzed and compared the levels of five carotenoids (lutein, zeaxanthin, β-cryptoxanthin, α-carotene, and β-carotene) through high-performance liquid chromatography. Large differences in carotenoid content among germplasms were observed, with coefficients of variation ranging from 21.24% to 67.78%. The carotenoid content, from high to low, was as follows: β-carotene > zeaxanthin > α-carotene > β-cryptoxanthin > lutein. We screened several varieties with high carotenoid content, including zeaxanthin in ‘Ruiguang2’, β-cryptoxanthin in ‘NJN76’ and ‘TX4F244C’, and β-carotene and total carotenoids in ‘Jintong7’, ‘77-26-7’, and ‘77-20-5’. A longer fruit developmental period was associated with greater β-carotene accumulation but lowered the zeaxanthin and β-cryptoxanthin accumulation. The zeaxanthin, β-carotene, and total carotenoid concentrations significantly increased as the flesh color deepened, but the lutein and α-carotene levels remained similar among the three flesh colors. The classification index of the indumenta significantly affected the β-carotene and total carotenoid content (p < 0.05) and was higher in pubescent than glabrous skin.

Peach flesh colors and aromas impact greatly on consumer behaviors and these two traits are closely associated in white- and yellow-fleshed peaches. However, current understanding of their aromas is rather limited and confined to the concentration differences of some volatiles. Therefore, this study aims to compare the overall aromas of the white-fleshed peach ‘Hu Jing Mi Lu’ (HJML) and yellow-fleshed peach ‘Jin Yuan’ (JY), two fresh cultivars with intense aromas and industrial influence by applications such as HS-SPME/GC-MS analysis, odor activity value evaluations, and odor note analysis. The significant contributions of 26 odor-active compounds to their aromas were revealed. Among which, 15 compounds showed no concentration differences and contributed to the fruity, floral, sweet, etc., odors in both HJML and JY; (E)-2-nonenal, 1-pentanol, and styrene showed significantly higher concentrations in HJML and conveyed much stronger fusel-like and balsamic odors; likewise, (Z)-3-hexenyl acetate, octanal, nonanal, and 3,5-octadien-2-one showed significantly higher concentrations in JY and conveyed much stronger banana, citrus-like, and honey odors; besides, benzyl alcohol, 1-heptanol, 1-octen-3-ol, and 3-octanone with woody, earthy, mushroom, and lavender odors were exclusively detected in HJML. Overall, apart from the common and stronger specific odors in either the white- or yellow-fleshed peach cultivar, the white-fleshed peach was endowed with a unique aroma.

Abstract Background Peach (Prunus persica) is an important fruit crop that generally softens rapidly after harvest resulting in a short shelf-life. By contrast, stony hard (SH) peach fruit does not soften and hardly produces ethylene. To explore the candidate genes responsible for the SH phenotype, a high-density genetic map was constructed by restriction-site associated DNA sequencing technology. Results In the present study, the linkage map consisted of 1310 single nucleotide polymorphism markers, spanning 454.2 cM, with an average marker distance of 0.347 cM. The single nucleotide polymorphisms were able to anchor eight linkage groups to their corresponding chromosomes. Based on this high-density integrated peach linkage map and two years of fruit phenotyping, two potential quantitative trait loci for the SH trait were identified and positioned on the genetic map. Additionally, Prupe.6G150900.1, a key gene in abscisic acid (ABA) biosynthesis, displayed a differential expression profile identical to the ABA accumulation pattern: mRNA transcripts were maintained at a high level during storage of SH peaches but occurred at low levels in melting fruit. Conclusion Thus Prupe.6G150900.1 might play a crucial role in the SH phenotype of peach in which ABA negatively regulates ethylene production. Also, this high-density linkage map of peach will contribute to the mapping of important fruit traits and quantitative trait loci identification.

Peach is a putrescible fruit thus drastically restricting its postharvest storage life. In recent years, the application of 1-methylcyclopropene (1-MCP) and nitric oxide (NO) in postharvest fruit quality control has received considerable attention and investigative efforts due to the advantages of using relatively low concentrations and short-time treatment duration. In the present study, the effects of various 1-MCP and NO treatments on peach fruit (Prunus persica L. cv. Xiahui-8) stored at 25 °C were evaluated and compared. Results indicated that the combination treatment with both chemical agents (MN) was most effective in postponing peach ripening and preserving fruit quality, followed by 1-MCP and NO treatment alone. We also demonstrated that NO could delay fruit senescence mainly by stimulating antioxidant enzymes, while 1-MCP overly outperformed NO in the treatment of ‘Xiahui-8′ peach in slowing down respiration rate, inhibiting ethylene production, maintaining high firmness and reducing ROS content. NO treatment showed a greater influence on phenolic compounds than 1-MCP especially anthocyanins, flavanones and flavones according to LC/MS analysis. The phenolic change in MN group were highly associated to NO treatment. Through this study we provide informative physiological, biochemical and molecular evidence for the beneficial effects of the combined 1-MCP and NO treatment on peach fruit based on a functional synergy between these two chemical agents.

The aim of our study was to assess differences in the expression of genes involved in fruit softening and ethylene biosynthetic pathways under different temperature storage conditions. Different peach cultivars of ‘Xiacui’ and ‘Yumyeong’, which are stonyhard, ‘Yinhualu’, which is soft-melting, ‘Hujing Milu’, which is hard-melting, and ‘Baby Gold 6’, which is non-melting at 80% ripening, were collected as test materials. The results showed that only slight ethylene production was detected after harvesting of ‘Yumyeong’ and ‘Xiacui’ under either a room temperature (25 °C) or low temperature (4 °C). The fruit firmness of stonyhard cultivars was retained at a high level under room temperature over time, whereas a low temperature induced ‘Yumyeong’ fruit to soften. Quantitative real-time PCR results indicated that the PpACS1 gene was highly expressed in soft-melting, hard-melting and non-melting cultivars; however, expression was extremely low in stonyhard peaches. PpACS2 or PpACS3, however, was not detected in all five cultivars. Interestingly, cold treatment significantly decreased firmness along with endo-PG expression obviously up-regulated in ‘Yumyeong’, but not in ‘Xiacui’ peaches. In conclusion, this study revealed that fruit softening of peaches with different flesh textures was closely related to ethylene biosynthesis during the storage period, which was controlled via regulating relevant gene expression levels under different storage temperatures.

Marine microalgae are regarded as potential feedstock because of their multiple valuable compounds, including lipids, pigments, carbohydrates, and proteins. Some of these compounds exhibit attractive bioactivities, such as carotenoids, ω-3 polyunsaturated fatty acids, polysaccharides, and peptides. However, the production cost of bioactive compounds is quite high, due to the low contents in marine microalgae. Comprehensive utilization of marine microalgae for multiple compounds production instead of the sole product can be an efficient way to increase the economic feasibility of bioactive compounds production and improve the production efficiency. This paper discusses the metabolic network of marine microalgal compounds, and indicates their interaction in biosynthesis pathways. Furthermore, potential applications of co-production of multiple compounds under various cultivation conditions by shifting metabolic flux are discussed, and cultivation strategies based on environmental and/or nutrient conditions are proposed to improve the co-production. Moreover, biorefinery techniques for the integral use of microalgal biomass are summarized. These techniques include the co-extraction of multiple bioactive compounds from marine microalgae by conventional methods, super/subcritical fluids, and ionic liquids, as well as direct utilization and biochemical or thermochemical conversion of microalgal residues. Overall, this review sheds light on the potential of the comprehensive utilization of marine microalgae for improving bioeconomy in practical industrial application.

The MYB transcription factor superfamily is one of the largest superfamilies modulating various biological processes in plants. Over the past few decades, many MYB superfamily genes have been identified and characterized in some plant species. However, genes belonging to the MYB superfamily in peach (Prunus persica) have not been comprehensively identified and characterized although the genome sequences of peach were released several years ago. In total, this study yielded a set of 256 MYB superfamily genes that was divided into five subfamilies: the R2R3-MYB (2R-MYB), R1R2R3-MYB (3R-MYB), MYB-related (1R-MYB), 4R-MYB, and Atypical-MYB subfamilies. These subfamilies contained 128, 4, 109, 1, and 14 members, respectively. The 128 R2R3-MYB subfamily genes in peach were further clustered into 35 groups, and the 109 MYB-related subfamily genes were further clustered into 6 groups: the CCA1-like, CPC-like, TBP-like, I-box-binding-like, R-R-type, and Peach-specific groups. The motif compositions and exon/intron structures within each group within the R2R3-MYB or MYB-related subfamily in peach were highly conserved. The logo sequences of the R2 and R3 repeats of R2R3-MYB subfamily members were highly conserved with those in these repeats of several other plant species. Except for 48 novel peach-specific MYB genes, the remaining 208 out of 256 MYB genes in peach were conserved with the corresponding 198 MYB genes in A. thaliana. Additionally, the 256 MYB genes unevenly distributed on chromosomes 1 to 8 of the peach genome. Eighty-one orthologous pairs of peach/A. thaliana MYB genes were identified among 256 MYB genes in peach and 198 MYB genes in A. thaliana in this study. In addition, 146 pairs of paralogous MYB genes were identified on the eight chromosomes of peach. The expression levels of some of the 51 MYB genes selected for qRT-PCR analysis decreased or increased with red-fleshed fruit development, while the expression patterns of some genes followed no clear rules over the five developmental stages of fruits. This study laid the foundation for further functional analysis of MYB superfamily genes in peach and enriched the knowledge of MYB superfamily genes in plant species.

The basic helix-loop-helix (bHLH) transcription factor family is a superfamily found in all eukaryotes that plays important roles in regulating growth and development. Over the past several decades, many bHLH superfamily genes have been identified and characterized in herbaceous and woody plants. However, the genes belonging to the bHLH superfamily in peach (Prunus persica) have not yet been comprehensively identified and characterized. Here, we identified 95 members of the bHLH superfamily in the peach genome, and these genes were classified into 19 subfamilies based on a phylogenetic comparison with bHLH proteins from Arabidopsis. The members within each subfamily were highly conserved according to the analysis of motif compositions and exon/intron organizations. The 95 bHLH genes were unevenly distributed on chromosomes 1 to 8 of the peach genome. We identified 57 pairs of bHLH members that were orthologous between peach and Arabidopsis. Additionally, 48 pairs of paralogous bHLH genes were identified on the eight chromosomes of the peach genome. Coupled with relative expression analysis of bHLH genes in red-fleshed peach fruit at five developmental stages, we identified several bHLH genes that might be involved in fruit development and anthocyanin biosynthesis. This study provides insight into the molecular mechanisms through which these genes are involved in the regulation of biological and biochemical processes in peach and lays the foundation for further studies on these genes.

Harvest maturity is closely related to peach fruit quality and has a very important effect on the fresh fruit market. Unfortunately, at present, it is difficult to determine the maturity level of peach fruits by artificial methods. The objectives of this study were to develop quadratic polynomial regression models using near-infrared spectroscopy that could determine the peel color difference, fruit firmness, soluble solids content (SSC), soluble sugar, organic acid components, and their relationships with the absorbance of chlorophyll (index of absorbance difference, IAD) in late maturing 'Xiahui 8' peach and 'Xiaguang' nectarine fruits. The analysis was based on data for fruits at veraison, fruits at harvesting maturity, and all fruits. The results showed that firmness has the highest correlation coefficient with IAD. Prediction models for fruit maturity were established between firmness and the IAD of the two cultivars using the quadratic polynomial regression method. Further variance analysis on the one degree term and quadratic term of each equation showed that every partial regression coefficient reached a significant or extremely significant level. No significant difference was observed between estimated and observed values after regression prediction. The regression equations seem to fit well. Other peach and nectarine varieties were used to test the feasibility of maturity prediction by this method, and it was found that maturity was successfully predicted in all the samples. The result indicated that the IAD can be used as an index to predict peach fruit maturity.

Microalgae are considered as excellent candidates for bioactive compounds, yet microalgal residues remaining after the extraction of one or two compounds are usually discarded, which is not economical. This study demonstrates the alkaline extraction of proteins from Chlorella pyrenoidosa residue after lipid and pigment extractions, and their functional properties. Single-factor experiments and response surface methodology were used to obtain the optimal conditions for protein extraction. Based on our results, a maximum protein yield of 722.70 mg/g, was obtained under the following extraction conditions: sodium hydroxide concentration 7.90%, extraction temperature 70.00 °C, extraction time 34.80 min, and microalgal residue concentration 8.20 mg/mL. The molecular weight of microalgal residue protein isolate (MRPI) was mainly distributed at the regions of 0.18−0.50 kDa, 0.50−1.50 kDa, and 1.50−5.00 kDa. The essential amino acid content was greater than the values recommended by FAO/WHO standards; a high essential amino acid index value (1.49) was another good indication that MRPI is suitable for human consumption. Moreover, MRPI exhibited excellent emulsifying properties and antioxidant activity, which suggests it may be useful as an emulsifying agent and antioxidant. These findings could improve the extraction methods of functional protein from microalgal residue and add value to microalgae-based bioactive compound production processes.

MicroRNAs (miRNAs) are a group of non-coding RNAs that have functions in post-transcriptional gene regulation in plants. Although the most important economic component of peach trees (Prunus persica) is the fruit, not much is known about miRNAs in this organ. In this study, miRNAs and their targets were identified and characterized from libraries of small RNAs of peach fruit through Solexa based-sequencing and bioinformatics approaches. A total of 557 known peach miRNAs belonging to 34 miRNA families were identified, and some of these miRNAs were found to be highly conserved in at least four other plant species. Using the most current criteria for miRNA annotation, 275 putative novel miRNAs were predicted, and the sequencing frequencies of these novel miRNAs were less than those of the conserved miRNAs. In total, 3959 and 1614 target genes for 349 known and 193 novel miRNAs, respectively, were predicted with the criteria that a single target gene can be targeted by different miRNAs and that a single miRNA can also have a large number of target genes. Three targets were even found to be targeted by 13 novel miRNAs that contained the same complete miRNA sequence at different locations and had different scaffolds. The proteins predicted to be targeted by the miRNAs identified in this study encompass a wide range of transcription factors and are involved in many biological processes and pathways, including development, metabolism, stress responses and signal transduction. A total of 115 and 101 target genes were identified to be cleaved by 60 known miRNAs and 27 novel miRNAs through degradome sequencing, respectively. These miRNAs induce cleavage of their targets precisely at the position between nucleotides 10 and 11 of the miRNA sequences from the 5' to the 3' end. Thirty conserved miRNAs and 19 novel miRNAs exhibited differential expression profiles in the peach, and the expression patterns of some miRNAs appeared to be tissue- or developmental stage-specific. The findings of this study provide an important basis for the analysis of miRNAs, their targets and the functions of these targets in peach fruit.

The PII signaling protein is a key protein for controlling nitrogen assimilatory reactions in most organisms, but little information is reported on PII proteins of green microalga Haematococcus pluvialis. Since H. pluvialis cells can produce a large amount of astaxanthin upon nitrogen starvation, its PII protein may represent an important factor on elevated production of Haematococcus astaxanthin. This study identified and isolated the coding gene (HpGLB1) from this microalga. The full-length of HpGLB1 was 1222 bp, including 621 bp coding sequence (CDS), 103 bp 5′ untranslated region (5′ UTR), and 498 bp 3′ untranslated region (3′ UTR). The CDS could encode a protein with 206 amino acids (HpPII). Its calculated molecular weight (Mw) was 22.4 kDa and the theoretical isoelectric point was 9.53. When H. pluvialis cells were exposed to nitrogen starvation, the HpGLB1 expression was increased 2.46 times in 48 h, concomitant with the raise of astaxanthin content. This study also used phylogenetic analysis to prove that HpPII was homogeneous to the PII proteins of other green microalgae. The results formed a fundamental basis for the future study on HpPII, for its potential physiological function in Haematococcus astaxanthin biosysthesis.

Shikimic acid/quinic acid hydroxy cinnamyl transferase (HCT) is one of the key enzymes in the phenylpropanoid pathway. However, the role of the HCT gene in chlorogenic acid (CGA) biosynthesis in peach fruit remains unclear. For this, we identified the accumulation pattern of CGA in four peach cultivars, cloned and characterized 11 PpHCT gene members, and further analyzed the expression patterns of these PpHCT genes during fruit development. The contents of CGAs in the four peach cultivars all exhibited a trend of increasing and then decreasing during the fruit growth and development. Moreover, the contents of CGAs in the peel and flesh were tissue-specific. Gene structure analysis indicated that the PpHCT genes were highly conserved, containing two exons and one intron. The protein structure analysis demonstrated that the PpHCT proteins contained two conserved motifs (HXXXD, DFGWG) and a transferase domain (PF02458), which belonged to the BAHD acyltransferase family. The cis-acting element analysis suggested that the promoters of PpHCT genes contained many light-related, hormonerelated, stress-related, tissue-specific, and circadian-related elements, and they could participate in a variety of biological processes. Phylogenetic analysis showed that the HCT proteins of peach were closely related to the HCT proteins of plum and had a close evolutionary relationship. The qRT-PCR analysis indicated that the expression levels of PpHCT1 and PpHCT2 showed an opposite trend to the accumulation of CGA, whereas the expression levels of PpHCT4, PpHCT5, PpHCT7, PpHCT8, and PpHCT11 demonstrated the same trend as CGA accumulation. It was worth noting that only PpHCT4 and PpHCT5 were highly expressed in the two high-CGA cultivars but showed low levels of expression in the two low-CGA cultivars. Therefore, it was hypothesized that these two genes might be key genes to the synthesis of CGA in peach fruit. Those findings provide a theoretical basis for further study on the biological functions of the HCT gene and help to reveal the molecular mechanism of CGA. [ABSTRACT FROM AUTHOR]