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Article

Quality Characteristics and Color Formation Mechanism of Low Chilling Requirement Sweet Cherry (Prunus avium L.) Cultivars in Southeast China

by
Yue Xu
1,2,†,
Yonglin Jing
1,†,
Yanfei Guo
1 and
Wangshu Zhang
1,3,*
1
School of Biological and Chemical Engineering, Ningbo Tech University, Ningbo 315100, China
2
College of Horticulture Science, Zhejiang A & F University, Hangzhou 311300, China
3
National & Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Horticulturae 2025, 11(3), 269; https://doi.org/10.3390/horticulturae11030269
Submission received: 2 January 2025 / Revised: 6 February 2025 / Accepted: 17 February 2025 / Published: 3 March 2025
(This article belongs to the Section Developmental Physiology, Biochemistry, and Molecular Biology)
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Versions Notes

Abstract

:
Sweet cherry (Prunus avium L.), renowned for its vibrant color and distinctive flavor, enjoys widespread popularity and is planted in temperate climates. This study investigated four short-chilling requirement cultivars in southeast China, which is known as a subtropical climate region, and determined several key fruit qualities, such as color, size, weight, and nutrient attributes (e.g., vitamin C, soluble sugar, organic acid, protein, gibberellin, and brassinolide) at four maturities due to the climate’s effect on the fruit color and the main color substance: anthocyanin accumulation. Therefore, the color index (a*, b*, and L*) and anthocyanin content were determined, and the anthocyanin-related gene expression was quantitative and analyzed using WGCNA. The results showed that the red variety, ‘Jiangnanhong’, exhibited the highest fruit weight and diameter as well as the greatest concentration of cyanidin-3-rutinoside (C3R). Conversely, the yellow variety, ‘Chaoyang 1’, demonstrated higher L* and b* values along with a greater vitamin C content. The research confirmed that C3R is the predominant anthocyanin present in sweet cherries during ripening. Additionally, three genes—LOC110744862, LOC110749842, and LOC110753376—were identified as playing crucial roles in anthocyanin biosynthesis. Anthocyanins significantly influence both the visual appeal and nutritional quality of the fruit. These results provide a theoretical foundation for understanding the differences among sweet cherry varieties in southeast China.

1. Introduction

Sweet cherry is mainly eaten as fresh fruit, and its consumption is directly related to ripeness and fruit quality [1]. At the same time, fruit color, protein content, endogenous hormones, anthocyanins, and a variety of phenolic substances constitute the fruit quality of sweet cherry [2]. Vitamin C (VC) plays an important physiological role in the human body, and it is an important antioxidant that reduces the risk of cancer and cardiovascular disease [3]. Studies have shown that the VC content in sweet cherries is higher than in apricots, nectarines, peaches, and plums [4], which may also provide important biological protection functions to reduce oxidative damage to body cells [5]. Plant endogenous hormones are involved in key processes such as plant growth, development, and signal response. Both gibberellin (GA) and brassinolide (BR) can improve the fruit set percentage, prevent falling flowers and fruit, increase stress resistance, etc. [6,7]. However, there are few studies on BR in sweet cherries.
The flavor of fleshy fruits is mainly determined by the dynamic balance between sugars and acids [8]. The soluble glucose, sucrose, and fructose not only act as signal molecules to initiate the signal transduction cascade but also play an important role in plant growth and fruit quality [9]. Natural organic acids are widely found in fruits and medicinal plants, which play an important role in antioxidant, antibacterial, and anti-inflammatory effects on human health [10]. The common organic acids in fruits are mainly divided into aliphatic organic acids, including citric acid, tartaric acid, malic acid, etc. Aromatic organic compounds include salicylic acid and caffeic acid [11].
Anthocyanin is a class of water-soluble natural pigment in plants that widely presents in nature and belongs to a subgroup of flavonoids [12]. The mechanisms of anthocyanin biosynthesis have been elucidated in a variety of plant species, such as apple, pear, sweet cherry, eggplant, tomato, etc. [13,14,15]. Anthocyanins, as one of the important qualities of sweet cherries, play a decisive role in the appearance and color of sweet cherry fruit [16]. The color of the sweet cherry fruit ranges from dark red to yellow because of the variety and content of anthocyanins. In the market, sweet cherry species are mainly divided into red sweet cherry and yellow sweet cherry. The biosynthesis of anthocyanin compounds is maintained at high levels when red sweet cherries turn red, but the regulatory mechanism of anthocyanin transport and accumulation is still unclear [17].
Sweet cherries (Prunus avium L.), belonging to the Rosaceae family, originated on the border between Asia and Europe. Due to its unique taste and rich nutritional value, it is an important and valuable orchard species in temperate climates [18,19]. Sweet cherries were first introduced to Yantai City, Shandong Province, China, in the 1870s. In recent years, growers have attempted to introduce the crop to southeastern China in order to consume the fresh quality and increase income. Although the southeastern area of China is relatively economically developed, it belongs to the subtropical climate region, where the lack of chill requirement and rapid within-spring warming lead to blossom without bearing fruit [20,21,22]. With the advancement of breeding technology, a number of low-chill-hour varieties, such as ‘Royal Lee’ and ‘Summit’, have been bred that can be cultivated in low chilling accumulation areas. These varieties usually have a chill requirement of less than 500 h and are cultivated in rain shelters. The quality of sweet cherry fruits can also meet consumer expectations. Meanwhile, the low chilling temperature accumulation and the rapid within-spring warming in southeast China affect the quality of sweet cherry fruit, such as the fruit’s apparent characteristics and nutritional content accumulation, especially the fruit color.
In this research, we selected four low-chilling requirements for sweet cherry varieties, two with red fruit and two with yellow fruit, to investigate the fruit quality-related attributes, especially those focused on the fruit color formation mechanism with an in-depth analysis of the expression of three key genes involved in the formation and metabolism of anthocyanin, which is the major pigment substance. This study aims to provide theoretical support for enhancing sweet cherry fruit quality and molecular breeding efforts.

2. Materials and Methods

2.1. Plant Materials

The material red sweet cherry fruits from ‘Jiangnanhong’, ‘5-106’, and ‘Changfeng 1’ and yellow fruits from ‘Chaoyang 1’ were harvested from a commercial orchard in Yuyao County, Ningbo City, China (121°16′ E, 30°1′ N; elevation 6 m). The annual average temperature in Ningbo in the past 8 years has been between 16.5 and 18.5 °C, the average precipitation was about 1800 mm, and the maximum annual average sunshine duration was 1800 h. The trees were grafted onto ‘Gisela 6’ rootstock and planted under rain-shelter conditions in March 2016, and the planting interval was 4 × 4 m. Crop management is according to the report of Huimin Zhang [23]. The phenological periods of plants can be affected by temperature and precipitation, the phenological periods of the four cultivars are described in Table 1. Fruit were harvested in early April 2022 at 4 commercial maturity stages: 40 days after full bloom (DAF) (S1), 44 DAF (S2), 48 DAF (S3), and 52 DAF (S4). Furthermore, fruits that were free of pests, diseases, and mechanical damage and roughly the same size were immediately transported back to the laboratory under cold storage.

2.2. Fruit Color, Weight and Size

Fruit color parameters were measured using a spectrometer (Konica Minolta, Chiyoda, Japan), according to the CIELAB one-color system to analyze L*, a* and b* parameters. L* is the lightness of the color, ranging from black (L* = 0) to white (L* = 100). The a* negative and positive represent green and red, and b* negative and positive are for blue and yellow, respectively. The single fruit weight of each variety was weighed by an electronic balance with a 1% sensitivity. Fruit size was measured by vernier calipers. Fruit shape index = fruit longitudinal diameter/fruit transverse diameter. Each measurement of color, weight and size were performed using a completely randomized design. Data are means from 20 fruits as replicates.

2.3. Total Soluble Solids, VC and Total Protein Content, Gibberellin and Brassinolide

The total soluble solids (TSS) content was determined in the juice at 20 °C by using a portable reflectometer (PAL-1, ATAGO Corporation, Tokyo, Japan), and the results were presented as °Brix. The VC content and total protein content were measured using the corresponding kit (Jiancheng Bio. Inc., Nanjing, China). Gibberellin (GA) and brassinolide (BR) were determined using corresponding plant hormone kits (Jingmei Bio., Shenzhen, China). We took 0.2 g samples according to the protocol and determined them under the microplate reader (SpectraMax i3x, Molecular Devices Corporation, Sunnyvale, CA, USA).

2.4. Contents of Soluble Sugar and Organic Acid

Tissues from 10 fruits were ground into liquid nitrogen, and the resulting powder (2.0 g) was transferred to a test tube and dissolved in 20 mL of deionized water. The mixture was then incubated at −80 °C for 30 min. After filtration, the supernatant was collected, and deionized water was added to adjust the final volume to 25 mL. The diluted supernatant was subsequently passed through a 0.45 μm filter for the determination of soluble sugars and organic acids content.
The fructose, glucose, and mannitol contents were measured according to the procedure described by Wu et al. [24] with minor modifications. A quantitative analysis of sugar content was performed using a high-performance liquid chromatography (HPLC) system (Model e2695, Waters Corporation, Milford, MA, USA) equipped with an InertSustain NH2 column (5 μm, 4.6 × 250 mm, GL Sciences Inc., Shinjuku-ku, Tokyo, Japan) and a refractive index detector (Model 2414, Waters Corporation, Milford, MA, USA). For each sample, 20 μL of the diluted supernatant was injected into the HPLC system for analysis. The column temperature was set at 30 °C, and the mobile phase consisted of acetonitrile/water (80:20, v/v) at a flow rate of 1.0 mL/min.
The organic acids content was measured using an HPLC system as described above, which was equipped with a ZORBAX SB-Aq C18 column (5 μm, 4.6 × 250 mm, Shimadzu Inc., Kyoto, Japan) following the method of Fan et al. [25]. HPLC analysis was conducted using 20 μL of the diluted supernatant. The mobile phase consisted of phosphate buffer (25 mM, pH 2.4) at a flow rate of 0.5 mL/min at 30 °C. Organic acids were detected at a wavelength of 210 nm using a photodiode array detector. Soluble sugars and organic acids were identified and quantified by comparing retention times and peak areas with those of standard substances. The standard substances were HPLC-grade reagents purchased from Sangon Biotech (Shanghai) Co., Ltd. (Shanghai, China), and the results were expressed as mg/g fresh weight.

2.5. Extraction and Analysis of Anthocyanin Components

Anthocyanin content was determined using the method described by Wei et al. [26] with minor modification. The supernatant fluid was condensed by rotary steaming and filtered through a 0.45 μm membrane for the identification and analysis of anthocyanin. The anthocyanin content was measured by the TripleTOFTM 5600 LC-MS/MS (AB SCIEX, Framingham, MA, USA) at 520 nm. Anthocyanin compound standards purified at HPLC grade, including cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside chloride and pelargonidin-3-glucoside chloride, were purchased from Sigma Aldrich Chemical Co., Ltd. (St. Louis, MO, USA).

2.6. Real-Time Quantitative PCR Analysis of Gene Expression

The total RNA was extracted by the polysaccharide polyphenol reagent kit (Takara Cat.9769, Takara Bio., Dalian, China). Using total RNA as the template, reverse transcription experiments were performed using a NovoScript® Plus All-in-one 1st Strand cDNA Synthesis SuperMix kit (Novoprotein Cat.E047, Novoprotein, Suzhou, China). Specific primer pairs and reference gene (β-Actin) are shown in Supplementary Table S1. qRT-PCR analysis was also performed by a kit according to protocol (Vazyme biotech Co., Ltd., Vazyme, Nanjing, China). The following reactions were performed using a real-time PCR instrument (ABI Q6 Flex) and standard procedure: 95 °C, 1 min; 95 °C 15 s; 60 °C 1 min (45 cycles of the above steps). Each plate was repeated three times in independent runs for all reference and selected genes. The real-time data were analyzed by CFX ManagerTM 3.0 software to obtain amplification and melting curves, which were transformed to analyze the data results by the 2−ΔΔCt method. Three biological replicates and three technical replicates were performed for each sample.

2.7. Analysis of WGCNA

Using gene expression information, WGCNA was constructed by the R language package (R version 4.2.2), and 12 modules were obtained. According to the gene expression and module eigen value, the correlation between gene and module was evaluated to identify the correlation result between the gene and module.

2.8. Statistical Analysis

Statistical analysis and curve fitting were performed by using SPSS 19.0 software (SPSS Inc., Chicago, IL, USA). Significant differences were calculated by using a one-way analysis of variance (ANOVA) followed by Duncan’s multiple range test at the 5% level (p < 0.05). The analyzed data are shown in all the figures with lowercase letters (a, b, c, etc.) between the different treatments. Correlation analysis uses Origin 21.0 software (OriginLab Inc., Northampton, MA, USA) to represent correlation coefficients.

3. Results

3.1. Fruits Shape

The changes in the single fruit weight, fruit shape index, and transverse and longitudinal diameter of sweet cherry fruit are shown in Figure 1. The single fruit weight of all four varieties showed an increasing trend during ripening, with ‘Jiangnanhong’ being the largest, while no significant change was observed in S3 and S4 (p < 0.05). The single fruit weight of ‘Chaoyang 1’ reached its maximum in S3, whereas other varieties reached the their maximum in S4 (Figure 1A). The variation trend of the longitudinal and transverse diameter was similar to that of single fruit weight, increasing first and then stabilizing, and the difference was significant in the S3 and S4 periods compared with the S1 period. The transverse diameter of ‘Jiangnanhong’ fruit was larger than that of other varieties. With regard to the longitudinal diameter, ‘Chaoyang 1’ fruit was significantly smaller than the other varieties in S3 and S4 (Figure 1C,D). The fruit shape index of ‘Jiangnanhong’ and ‘Changfeng 1’ sweet cherry remained stable throughout the four stages of maturity, with values ranging from 0.9 to 1.0, indicating a round fruit shape. In contrast, the fruit shape index of ‘5-106’ and ‘Chaoyang 1’ showed significant differences at S1 and S2 compared to S4, with values greater than 1.0 at S1 and S2 but less than 1.0 at S4, suggesting a change in fruit shape from elongated to round (Figure 1B).

3.2. Fruits Color

The L* value of the four sweet cherry varieties exhibited a gradual decrease during ripening (Table 2). The L* values ranged from 22.10 to 72.44 with ‘Jiangnanhong’ having the lowest L* value across all maturities and ‘Chaoyang 1’ having the highest. This indicates that ‘Jiangnanhong’ had the darkest fruit color, while ‘Chaoyang 1’ had the brightest. Significant differences in L* values were observed among all varieties with the greatest variation in ‘Changfeng 1’ and the least in ‘Chaoyang 1’. For ‘Jiangnanhong’ and ‘Changfeng 1’, the a* values initially increased and then decreased, reaching a maximum of 40.74 at ‘Jiangnanhong’ S2 and 44.06 at ‘Changfeng 1’ S3, respectively. In contrast, for ‘5-106’ and ‘Chaoyang 1’, the a* values increased gradually during ripening, peaking at 42.89 and 14.75 at S4, respectively. These observations suggest that ‘Jiangnanhong’ fruits were dark red, ‘5-106’ and ‘Changfeng 1’ fruits were red, while ‘Chaoyang 1’ maintained a consistently low level of redness, significantly differing from the other varieties. The b* values of ‘Jiangnanhong’, ‘5-106’, and ‘Changfeng 1’ decreased during maturation and varied significantly between maturities, ranging from 2.72 to 34.44. Conversely, the b* values of ‘Chaoyang 1’ remained relatively stable between 39 and 40, indicating a yellowish fruit color.

3.3. Fruits Quality

The total soluble solids (TSS), total protein content, VC, GA, and BR of sweet cherry fruit were also determined in this study. TSS exhibited a continuous increase throughout the ripening process of sweet cherry fruit, which increased significantly in ‘Jiangnanhong’ (p < 0.05) and reached the highest level of 18.30% among the four varieties in S4 (Figure 2A). Fructose and glucose were identified as the predominant soluble sugars with mannitol also present in significant amounts. The glucose and fructose contents of ‘Jiangnanhong’, ‘Chaoyang 1’, and ‘5-106’ exhibited a positive correlation with maturity, whereas ‘Changfeng 1’ displayed a negative correlation. Mannitol increased continuously in ‘Chaoyang 1’ and ‘5-106’ but showed the opposite in ‘Jiangnanhong’ and ‘Changfeng 1’. Among the varieties, ‘Jiangnanhong’ exhibited the highest content of the three sugar components, while ‘5-106’ had the lowest (Figure 2B–D). Meanwhile, malic acid, citric acid, and quinic acid were the three types of organic acids with the highest content detected, and malic acid was the main component of organic acids. With malic acid content ranging from 310.18 to 415.45 mg·100 g−1, the content of ‘Jiangnanhong’ at S4 increased by 23.5% compared with S1, while that of ‘Chaoyang 1’ and ‘5-106’ at S4 decreased by 12.4% and 15.5%, respectively, compared with S1 (Figure 2E–G). The total protein content of ‘Jiangnanhong’ was the highest, ranging from 46.71 to 59.27 mg·g−1. The lowest total protein content was found in ‘5-106’, ranging from 20.86 to 23.23 mg·g−1 (Figure 2H). The VC content of both ‘Jiangnanhong’ and ‘5-106’ showed an increasing trend, while that of ‘Changfeng 1’ exhibited a pattern of initially declining and then rising (Figure 2I). Compared with S1, the variety with the greatest difference in gibberellin content during S4 was ‘5-106’ with a decrease of 34.24% in content. Conversely, the smallest difference was observed in ‘Chaoyang 1’, which showed a reduction of 10.55% (Figure 2J). The brassinolide (BR) content in ‘Jiangnanhong’ at different maturities was the lowest, ranging from 0.25 to 0.32 μg·kg−1. The BR content in ‘5-106’ reached a maximum of 0.48 μg·kg−1 in ‘5-106’ at S4 (Figure 2K).

3.4. Determination of Anthocyanin Components

The anthocyanin content at each maturity stage of sweet cherry was identified (Table 3). The results showed that three anthocyanins were detected in southern sweet cherries: cyanidin-3-O-glucoside (C3G), cyanidin-3-O-rutinoside chloride (C3R) and pelargonidin-3-glucoside chloride (P3G), with their proportions declining in that order. The C3R content of four varieties increased with the increase in maturity, and significant differences were observed among different stages of maturity. Among all the maturities, ‘Jiangnanhong’ reached a maximum of 3909.32 µg/g at the red cherry stage (‘Jiangnanhong’ S4), while it only reached a maximum of 6.25 µg/g in yellow cherries (‘Chaoyang 1’ S3). The C3G content increased with the maturity, except for ‘Chaoyang 1’, where it initially increased and then decreased. The C3G content varied significantly among different maturities except for ‘Chaoyang 1’. Across all varieties, the C3G content ranged from 0.74 to 13.54 μg·g−1 with ‘Jiangnanhong’ having the highest content and ‘Chaoyang 1’ the lowest. P3G was only detected in trace amounts in ‘Jiangnanhong’ and ‘Changfeng 1’.
The biosynthesis of anthocyanins is closely linked to the expression of F3′H, DFR, ANS and UFGT genes. All of the anthocyanin genes (including F3′H, DFR, ANS and UFGT) were significantly upregulated in each variety during ripening. The expression of genes related to anthocyanin biosynthesis was analyzed using real-time quantitative PCR. As shown in Figure 3, the relative expression level of F3′H in ‘Jiangnanhong’, ‘5-106’ and ‘Changfeng 1’ was, respectively, 10-fold, 4-fold and 2-fold higher than that in ‘Chaoyang 1’ at S4 (Figure 3A). Furthermore, the relative expression level of DFR in ‘Jiangnanhong’ was increased by 7-fold compared to that of ‘Chaoyang 1’ (Figure 3B). The relative expression level of ANS in ‘Chaoyang 1’ was the lowest compared to those of ‘Jiangnanhong’, ‘5-106’ and ‘Changfeng 1’ (Figure 3C). As for UFGT, the relative expression level in ‘Jiangnanhong’ exhibited a significantly greater difference compared to those of ‘Chaoyang 1’, ‘5-106’ and ‘Changfeng 1’ with an 800-fold increase relative to ‘Chaoyang 1’ (Figure 3D).

3.5. Differential Transcription Factor of Sweet Cherry Fruit

The anthocyanin anabolism of sweet cherry is regulated by structural genes and transcription factors. We identified three families of transcription factors to explore their effects on anthocyanin synthesis in two cultivars, ‘Jiangnanhong’ (red fruits) and ‘Chaoyang 1’ (yellow fruits) (Figure 4A–C). Among them, the MYB superfamily was the largest, including 42 MYB transcription factors. The second largest family was the bHLH family with 31 members, which was followed by the WD40 family with 15 members. Among all the detected MYB transcription factors, 32 genes were commonly expressed in S1 and S2 of both ‘Jiangnanhong’ and ‘Chaoyang 1’, while 6 MYB transcription factors genes were specifically expressed in S1 and S2, and 4 MYB transcription factors genes were expressed in S3 and S4, respectively.
The differential expression trend of bHLH transcription factors in ‘Jiangnanhong’ and ‘Chaoyang 1’ was similar to that of MYB transcription factors. Four bHLH transcription factors genes were specifically expressed in S3 and S4, while three MYB transcription factors genes were expressed across all four ripening stages, respectively. Other bHLH transcription factors were significantly expressed at S1 and S2 in both ‘Jiangnanhong’ and ‘Chaoyang 1’, but the expression was even more significant in ‘Jiangnanhong’. The WD40 transcription factors were significantly expressed at S1 and S2 in ‘Jiangnanhong’ with three WD40 transcription factors also showing significant expression at S4. Additionally, the WD40 transcription factors were predominantly expressed in S1 and S2 of ‘Chaoyang 1’, but their expression levels were lower than those in ‘Jiangnanhong’.

3.6. Screening Key Candidate Genes Based on WGCNA

In our study, the related genes affecting the fruit anthocyanin biosynthesis of different sweet cherry fruit types were further identified through WGCNA analysis. Based on the correlation coefficient between 24 samples, the co-expression modules of all samples were constructed, resulting in 12 modules (Figure 5A). Correlation analysis between the gene expression module and C3R content revealed that the yellow module was significantly correlated (r2 = 0.85), containing 173 genes, including a MYB transcription factor gene (Gene ID = LOC110744862) and a bHLH transcription factor gene (Gene ID = LOC110749842) (Figure 5B). Analysis of the enrichment of C3G metabolism-related showed that the red module, which contains 102 genes, was highly correlated with C3G contents (r2 = 0.77), identifying a bHLH transcription factor gene (Gene ID = LOC110753376).

4. Discussion

4.1. Difference in Fruit Quality Between Red and Yellow Cultivars

Sweet cherries are divided into red and yellow groups based on the appearance of fruit color: the red fruit group always show bright red, dark red, black red and so on, while the yellow ones show a slight red tint in the yellow [27,28]. In this research, the red varieties ‘Jiangnanhong’ and ‘5-106’ showed bright red and dark red, while the yellow variety exhibited a yellow background with a translucent red color, which is consistent with Jin et al. [28]. Results showed that the fruit size of red varieties was significantly larger than that of yellow varieties, similar to previous studies [14]. As for the different varieties, the color of sweet cherry fruit is primarily determined by the type and content of anthocyanins [16]. However, the main anthocyanin components in both red and yellow cultivars were the same, and UFGT played an important role in anthocyanin synthesis [29], which was consistent with the study of Wei et al. [30]. Consistent with this study, the main anthocyanin component in red and yellow varieties is C3R. Previous studies have suggested that anthocyanin biosynthesis might lead to a reduction in other processes in plants because it competes directly for assimilated carbon [31]. The anthocyanin content of red and yellow sweet cherry varieties increased, but only the soluble sugar content of ‘Changfeng 1’ decreased slightly. We speculated that during fruit ripening, a large amount of organic acid accumulated in the fruit, and anthocyanin synthesis did not affect the production of soluble sugar.
Multiple pathways are involved in vitamin C synthesis, the most important of which is the pathway starting from glucose [32]. The ‘Chaoyang 1’ yellow variety was consistent with Smirnoff’s report [32]. The vitamin C content in red varieties ‘Jiangnanhong’, ‘5-106’, and ‘Changfeng 1’ increased gradually, but this trend was inconsistent with the change in glucose content. In red varieties, there may be another pathway for vitamin C synthesis that is independent of glucose.

4.2. Quality Indexes During the Development of Sweet Cherry Fruit

In this study, the experimental materials were selected from different cultivars of sweet cherry at different maturity stages [33]. Sweet cherry growth and development follows a double ‘S’ curve. According to its developmental characteristics, it is mainly divided into three stages. The first stage is mainly characterized by cell division and elongation, during which the fruit remains predominantly green. The second stage is the endocarp hardening stage, leading to the formation of the fruit stone and the development of fruit color. The third stage is the exponential growth period due to cell enlargement, during which there are significant physiological and biochemical changes, such as sugar, organic acid, and color [34,35]. From the late color-turning stage to the commercial maturity stage, as the fruit expands, the fruit shape index was less than 1 for all cultivars, except ‘5-106’, which aligns with the general growth pattern of sweet cherries, potentially indicating a unique growth attribute of this cultivar that requires further exploration. Additionally, our results on appearance color showed that the L* value in the red cultivar decreases continuously, the a* value increases initially and then decreases, and the b* value decreases continuously. These findings are consistent with previous studies [36].
In terms of internal nutritional quality, no significant differences were observed in total protein content and vitamin C content across different maturities. Regarding endogenous hormones, gibberellin (GA) promotes cell division, cell enlargement, and fruit development, while it can also inhibit anthocyanin synthesis through the DELLA protein pathway [37,38,39,40]. In this study, the GA content in the fruit continuously decreased as maturity progressed, coinciding with a significant increase in anthocyanin content, which aligns with previous findings. Anthocyanins serve as a critical indicator of the intrinsic quality in sweet cherry fruits and play crucial roles in protecting plants from UV radiation and oxidative stress as well as enhancing the nutritional value and sensory attributes of fruits. The significant increase in anthocyanin content observed in this study suggests a potential mechanism for improving fruit quality through regulatory pathways. The inverse relationship between GA content and anthocyanin accumulation further supports the notion that hormonal regulation plays a pivotal role in determining the coloration and overall quality of sweet cherry fruits.
The content of C3R in red sweet cherry increased sharply with the increase in maturity [30], and it also increased significantly in yellow sweet cherry cultivars. Anthocyanins are one of the important indicators of the internal quality of sweet cherry fruit, and the content of C3R is the main anthocyanin in sweet cherry, which was consistent with Liu et al. [41]. The content of C3R increased sharply with the increase in maturity in red sweet cherry varieties, but it only slightly increased in yellow varieties, which was consistent with the study of Wei et al. [14]. The reason for this is that the anthocyanin metabolism pathway is regulated by genes, and the gene expression profiles vary among different varieties.

4.3. PaMYB, PabHLH and PaWD40 Candidate Involved in Fruit Quality

Fruit quality is defined by its external and internal features, and fruit color is an effective indicator of both. The fruit peel pigment content determines the color of the fruit and can be influenced by a variety of factors [42]. A large accumulation of anthocyanins occurs in the peel and pulp tissue during the ripening process of sweet cherry fruit, which is favored by consumers because of its red flesh, unique taste and rich nutritional composition. Anthocyanins not only directly affect the appearance and quality of the fruit but also have a variety of beneficial effects on human health due to its anti-oxidation and anti-carcinogenic functions [43]. Anthocyanins are a class of natural water-soluble pigments belonging to flavonoids, which impart various colors like red, blue and purple to plant tissues and reproductive organs [44]. The synthesis of anthocyanins is mainly regulated by two types of genes: one encoding the key enzymes of anthocyanin synthesis, and the other being regulatory genes such as MYB, bHLH, NAC and other transcription factors. The synthesis of anthocyanins in plants is mainly regulated by the MYB-bHLH-WD40 (MBW) transcriptional regulatory complex, which is formed by the interaction of MYB TF, bHLH TF and WD40 [45,46]. In Arabidopsis, AtMYB90 can interact with TTG1 (WD40) and different bHLH partners (TT8, GL3 or EGL3) to regulate anthocyanin biosynthesis genes, and the sequence variation in the AtMYB90 gene is the reason for the natural variation in anthocyanin accumulation [47,48]. However, FaMYB1 inhibits anthocyanin synthesis by interacting with bHLH proteins (JAF13 and AN1) in the MBW activation complex in strawberry [49]. The interaction of PpMYBC2-L1 and PpMYBC2-L3 with MYC1 inhibits the MBW complex protein in grape [50]. Similarly, in lily, LvMYB3 inhibits the synthesis of anthocyanins by competing with the activator LvMYB7 to bind bHLH proteins [51]. In addition, there are many other TFs that regulate anthocyanin accumulation. MdNAC42, MdbZIP44 and MdERF78, found in apple, can interact with MYB TFs and then participate in the regulatory network of anthocyanin accumulation [52,53,54]. PaMYB, PabHLH and PaWD40 candidates were screened by WGCNA analysis in this study. It is speculated that these candidate genes regulate anthocyanin synthesis in sweet cherry by forming protein complexes or interacting with other TFs, but their detailed mechanism needs further study.

5. Conclusions

In this study, we found that the fruit quality of four short chilling-required varieties of sweet cherry in southeast China is similar to that of the traditional sweet cherry varieties grown in temperate climate areas. The red variety ‘Jiangnanhong’ had the highest fruit weight and diameter with a higher content of C3R, C3G, malic acid and total protein. The yellow variety ‘Chaoyang 1’ had higher quinic acid and VC content, while the content of C3R, C3G, and citric acid were the lowest. In addition, it was determined in this research that the main anthocyanin content in sweet cherry fruits during the ripening period is C3R. Genes LOC110744862, LOC110749842 and LOC110753376, which participate in anthocyanin biosynthesis, were finally screened. Anthocyanins play an important role in the fruit appearance and nutritional quality. Therefore, it is speculated that they are involved in the formation of fruit anthocyanin biosynthesis traits of sweet cherries, but their mechanism needs further study.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/horticulturae11030269/s1, Table S1: Primers used for qRT-PCR.

Author Contributions

Methodology, Y.X.; Writing—original draft preparation, Y.X. and Y.J.; Writing—review and editing, Y.J. and Y.G.; Supervision and project administration, W.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Ningbo Science and Technology Planning project (2019B10024).

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors on requests.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Irfan, A.S.; Liu, X.J.; Jiu, S.T.; Matthew, W.; Zhang, C.X. Plant growth regulators modify fruit set, fruit quality, and return bloom in sweet cherry. HortScience 2021, 56, 922–931. [Google Scholar]
  2. Eda, H.; Mehmet, S.A. The effect of different electrolyzed water treatments on the quality and sensory attributes of sweet cherry during passive atmosphere packaging storage. Postharvest Biol. Technol. 2015, 102, 32–41. [Google Scholar]
  3. Byers, T.; Perry, G. Dietary carotenes, vitamin C, and vitamin E as protective antioxidants in human cancers. Annu. Rev. Nutr. 1992, 12, 139–159. [Google Scholar] [CrossRef]
  4. Leong, S.Y.; Oey, I. Effects of processing on anthocyanins, carotenoids and vitamin C in summer fruits and vegetables. Food Chem. 2012, 133, 1577–1587. [Google Scholar] [CrossRef]
  5. Leong, S.Y.; Burritt, D.J.; Hocquel, A.; Penberthy, A.; Oey, I. The relationship between the anthocyanin and vitamin C contents of red-fleshed sweet cherries and the ability of fruit digests to reduce hydrogen peroxide-induced dxidative stress in Caco-2 cells. Food Chem. 2017, 227, 404–412. [Google Scholar] [CrossRef] [PubMed]
  6. Wang, L.; Zhang, C.X.; Huang, J.C.; Zhu, L.N.; Yu, X.M.; Li, J.F.; Ma, C. Hydrogen cyanamide improves endodormancy release and blooming associated with endogenous hormones in ‘Summit’ sweet cherry trees. N. Z. J. Crop Hortic. Sci. 2017, 45, 14–18. [Google Scholar] [CrossRef]
  7. Lv, J.H.; Dong, T.Y.; Zhang, Y.P.; Ku, Y.; Zheng, T.; Jia, H.F.; Fang, J.G. Metabolomic profiling of brassinolide and abscisic acid in response to high-temperature stress. Plant Cell Rep. 2022, 41, 935–946. [Google Scholar] [CrossRef]
  8. Colaric, M.; Veberic, R.; Stampar, F.; Hudina, M. Evaluation of peach and nectarine fruit quality and correlations between sensory and chemical attributes. J. Sci. Food Agric. 2005, 85, 2611–2616. [Google Scholar] [CrossRef]
  9. Cho, Y.H.; Yoo, S.D. Signaling role of fructose mediated by FINS1/FBP in Arabidopsis thaliana. PLoS Genet. 2011, 7, e1001263. [Google Scholar] [CrossRef]
  10. Adamczak, A.; Ożarowski, M.; Karpiński, T.M. Antibacterial activity of some flavonoids and organic acids widely distributed in plants. J. Clin. Med. 2019, 9, 109. [Google Scholar] [CrossRef]
  11. Liu, R.; Wang, Y.; Qin, G.; Tian, S. Molecular basis of 1-methylcyclopropene regulating organic acid metabolism in apple fruit during storage. Postharvest Biol. Technol. 2016, 117, 57–63. [Google Scholar] [CrossRef]
  12. He, J.; Giusti, M.M. Anthocyanins: Natural colorants with health-promoting properties. Annu. Rev. Food Sci. Technol. 2010, 1, 163–187. [Google Scholar] [CrossRef] [PubMed]
  13. Liu, H.M.; Liu, Z.J.; Wu, Y.; Zheng, L.M.; Zhang, G.F. Regulatory mechanisms of anthocyanin biosynthesis in apple and pear. Int. J. Mol. Sci. 2021, 22, 8441. [Google Scholar] [CrossRef] [PubMed]
  14. Wei, H.R.; Chen, X.; Zong, X.J.; Shu, H.R.; Gao, D.S.; Liu, Q.Z. Comparative transcriptome analysis of genes involved in anthocyanin biosynthesis in the red and yellow fruits of sweet cherry (Prunus avium L.). PLoS ONE 2015, 10, e0121164. [Google Scholar] [CrossRef]
  15. Li, L.Z.; He, Y.J.; Ge, H.Y.; Liu, Y.; Chen, H.Y. Functional characterization of SmMYB86, a negative regulator of anthocyanin biosynthesis in eggplant (Solanum melongena L.). Plant Sci. 2020, 302, 110696. [Google Scholar] [CrossRef]
  16. Gonzalez-Gomez, D.; Lozano, M.; Fernandez-Leon, M.F.; Bernalte, M.J.; Ayuso, M.C.; Rodriguez, A.B. Sweet cherry phytochemicals: Identification and characterization by HPLC-DAD/ESI-MS in six sweet-cherry cultivars grown in Valle del Jerte (Spain). J. Food Compos. Anal. 2010, 23, 533–539. [Google Scholar] [CrossRef]
  17. Qi, X.L.; Liu, C.L.; Song, L.L.; Dong, Y.X.; Chen, L.; Li, M. A sweet cherry glutathione S-transferase gene, PavGST1, plays a central role in fruit skin coloration. Cells 2022, 11, 1170. [Google Scholar] [CrossRef]
  18. Antonio, M.; Federica, I.; Petronia, C.; Loredana, F.C.; Pasqualina, W.; Amodio, F. Metabolic characterization and antioxidant activity in sweet cherry (Prunus avium L.) campania accessions: Metabolic characterization of sweet cherry accessions. Food Chem. 2018, 240, 559–566. [Google Scholar]
  19. Karagiannis, E.; Sarrou, E.; Michailidis, M.; Tanou, G.; Ganopoulos, I.; Bazakos, C.; Kazantzis, K.; Martens, S.; Xanthopoulou, A.; Molassiotis, A. Fruit quality trait discovery and metabolic profiling in sweet cherry genebank collection in Greece. Food Chem. 2021, 342, 128315. [Google Scholar] [CrossRef]
  20. Erez, A. Chemical control of budbreak. HortScience 1987, 22, 1240–1243. [Google Scholar] [CrossRef]
  21. Oukabli, A.; Mahhou, A. Dormancy in sweet cherry (Prunus avium L.) under Mediterranean climatic conditions. Biotechnol. Agron. Soc. Environ. 2007, 11, 133–139. [Google Scholar]
  22. Wang, L.; Zhang, L.; Ma, C.; Xu, W.; Liu, Z.; Zhang, C.; Mat-Thew, W.D.; Wang, S. Plmpact of chilling accumulation and hydrogen cyanamide on floral organ development of sweet cherry in a warm region. J. Integr. Agric. 2016, 15, 2529–2538. [Google Scholar] [CrossRef]
  23. Zhang, H.M.; Yan, H.G.; Li, Q.; Lin, H.; Wen, X.P. Identification of VOCs in essential oils extracted using ultrasound- and microwave-assisted methods from sweet cherry flower. Sci. Rep. 2021, 11, 1167. [Google Scholar] [CrossRef]
  24. Wu, Z.F.; Tu, M.M.; Yang, X.P.; Xu, J.H.; Yu, Z.F. Effect of cutting and storage temperature on sucrose and organic acids metabolism in postharvest melon fruit. Postharvest Biol. Technol. 2020, 161, 111081. [Google Scholar] [CrossRef]
  25. Fan, Y.T.; Li, C.Y.; Zhu, J.; Sun, L.; Huang, R.; Guo, M.; Ge, Y.H. Organic acids metabolism and GABA shunt involved in maintaining quality of Malus domestica by methyl jasmonate treatment. Food Res. Int. 2022, 160, 111741. [Google Scholar] [CrossRef] [PubMed]
  26. Wei, H.R.; Yi, X.B.; Tan, Y.; Zong, X.J.; Wang, J.W.; Xu, L.; Liu, Q.Z. Determination of anthocyanins in the peel of sweet cherry by ultra performance liquid chromatography-tandem mass spectrometry. Chromatography 2015, 33, 577–582. [Google Scholar] [CrossRef]
  27. Esti, M.; Cinquanta, L.; Sinesio, F.; Moneta, E.; Matteo, M.D. Physicochemical and sensory fruit characteristics of two sweet cherry cultivars after cool storage. Food Chem. 2002, 76, 399–405. [Google Scholar] [CrossRef]
  28. Jin, W.M.; Wang, H.; Li, M.F.; Wang, J.; Yang, Y.; Zhang, X.M.; Yan, G.H.; Zhang, H.; Liu, J.S.; Zhang, K.C. The R2R3 MYB transcription factor PavMYB10.1 involves in anthocyanin biosynthesis and determines fruit skin colour in sweet cherry (Prunus avium L.). Plant Biotechnol. J. 2016, 14, 2120–2133. [Google Scholar] [CrossRef] [PubMed]
  29. Montefiori, M.; Espley, R.V.; Stevenson, D.; Cooney, J.; Datson, P.M.; Saiz, A.; Allan, A.C. Identification and characterisation of F3GT1 and F3GGT1, two glycosyltransferases responsible for anthocyanin biosynthesis in red-fleshed kiwifruit (Actinidia chinensis). Plant J. 2011, 65, 106–118. [Google Scholar] [CrossRef]
  30. Wei, H.R.; Tan, Y.; Zong, X.J.; Zhu, D.Z.; Chen, X.; Xu, L.; Liu, Q.Z. Relationship between anthocyanin accumulation and the activities of anthocyanin biosynthesis enzymes in different color of sweet cherry fruits. Plant Physiol. J. 2017, 53, 429–436. [Google Scholar]
  31. García-Macías, P.; Ordidge, M.; Vysini, E.; Waroonphan, S.; Battey, N.H.; Gordon, M.H.; Wagstaffe, A. Changes in the flavonoid and phenolic acid contents and antioxidant activity of red leaf lettuce (Lollo Rosso) due to cultivation under plastic films varying in ultraviolet transparency. J. Agric. Food Chem. 2007, 55, 10168–10172. [Google Scholar] [CrossRef] [PubMed]
  32. Smirnoff, N. Botanical briefing: The function and metabolism of ascorbic acid in plants. Ann. Bot. 1996, 78, 661–669. [Google Scholar] [CrossRef]
  33. Zhang, C.X.; Whiting, M. Plant growth regulators improve sweet cherry fruit quality without reducing endocarp growth. Sci. Hortic. 2013, 150, 73–79. [Google Scholar] [CrossRef]
  34. Chen, C.; Chen, H.; Yang, W.; Li, J.; Tang, W.; Gong, R. Transcriptomic and Metabolomic Analysis of Quality Changes during Sweet Cherry Fruit Development and Mining of Related Genes. Int. J. Mol. Sci. 2022, 23, 7402. [Google Scholar] [CrossRef] [PubMed]
  35. Tang, W.; Chen, C.; Zhang, Y.; Chu, Y.; Yang, W.; Cui, Y.; Kou, G.; Chen, H.; Song, H.; Gong, R. Effect of Low-Light Stress on Sugar and Acid Accumulation during Fruit Development and Ripening of Sweet Cherry. Horticulturae 2023, 9, 654. [Google Scholar] [CrossRef]
  36. Piotr, C.; Ireneusz, O.; Pawel, F. Sweet cherry skin colour measurement as an non-destructive indicator of fruit maturity. Food Technol. 2019, 13, 157–166. [Google Scholar]
  37. Jeong, S.T.; Goto-Yamamoto, N.; Kobayashi, S.; Esaka, M. Effects of plant hormones and shading on the accumulation of anthocyanins and the expression of anthocyanin biosynthetic genes in grape berry skins. Plant Sci. 2004, 167, 247–252. [Google Scholar] [CrossRef]
  38. Kumar, R.; Khurana, A.; Sharma, A.K. Role of plant hormones and their interplay in development and ripening of fleshy fruits. J. Exp. Bot. 2014, 65, 4561–4571. [Google Scholar] [CrossRef]
  39. Jiang, C.F.; Gao, X.H.; Liao, L.L.; Harberd, N.P.; Fu, X.D. Phosphate starvation root architecture and anthocyanin accumulation responses are modulated by the gibberellin-DELLA signaling pathway in Arabidopsis. Plant Physiol. 2007, 145, 1460–1470. [Google Scholar] [CrossRef]
  40. Xie, Y.; Tan, H.J.; Ma, Z.X.; Huang, J.R. DELLA proteins promote anthocyanin biosynthesis via sequestering MYBL2 and JAZ suppressors of the MYB/bHLH/WD40 complex in Arabidopsis thaliana. Mol. Plant 2016, 9, 711–721. [Google Scholar] [CrossRef]
  41. Liu, Y.; Liu, X.Y.; Zhong, F.; Tian, R.R.; Zhang, K.C.; Zhang, X.M.; Li, T.H. Comparative study of phenolic compounds and antioxidant activity in different species of cherries. J. Food Sci. 2011, 76, 633–638. [Google Scholar] [CrossRef] [PubMed]
  42. Muhammad, N.; Luo, Z.; Zhao, X.; Yang, M.; Liu, Z.; Liu, M. Transcriptome-wide expression analysis of MYB gene family leads to functional characterization of flavonoid biosynthesis in fruit coloration of Ziziphus Mill. Front. Plant Sci. 2023, 14, 1171288. [Google Scholar] [CrossRef] [PubMed]
  43. Wu, Z.Q.; Li, X.S.; Zeng, Y.Y.; Cai, D.B.; Teng, Z.J.; Wu, Q.X.; Sun, J.X.; Bai, W.B. Color stability enhancement and antioxidation improvement of Sanhua plum wine under circulating ultrasound. Foods 2022, 11, 2435. [Google Scholar] [CrossRef]
  44. Song, J.H.; Guo, C.K.; Shi, M. Anthocyanin biosynthesis and transcriptional regulation in plant. Mol. Plant Breed. 2021, 19, 3612–3620. [Google Scholar]
  45. Chen, D.Z.; Chen, H.D.; Dai, G.Q.; Zhang, H.M.; Liu, Y.; Shen, W.J.; Zhu, B.; Cui, C.; Tan, C. Genome-wide identification of R2R3-MYB gene family and association with anthocyanin biosynthesis in Brassica species. BMC Genom. 2022, 23, 441. [Google Scholar] [CrossRef]
  46. Wang, L.; Deng, R.; Bai, Y.; Wu, H.; Li, C.; Wu, Q.; Zhao, H. Tartary Buckwheat R2R3-MYB Gene FtMYB3 Negatively Regulates Anthocyanin and Proanthocyanin Biosynthesis. Int. J. Mol. Sci. 2022, 23, 2775. [Google Scholar] [CrossRef]
  47. Gonzalez, A.; Zhao, M.Z.; Leavitt, J.M.; Lloyd, A.M. Regulation of the anthocyanin biosynthetic pathway by the TTG1/bHLH/Myb transcriptional complex in Arabidopsis seedlings. Plant J. 2008, 53, 814–827. [Google Scholar] [CrossRef]
  48. Bac-Molenaar, J.A.; Fradin, E.F.; Rienstra, J.A.; Lloyd, A.M. GWAS mapping of anthocyanin accumulation reveals balancing selection of MYB90 in Arabidopsis thaliana. PLoS ONE 2015, 10, e0143212. [Google Scholar] [CrossRef]
  49. Aharoni, A.; De Vos, C.H.; Wein, M.; Sun, Z.; Greco, R.; Kroon, A.; Mol, J.N.; O’Connell, A.P. The strawberry FaMYB1 transcription factor suppresses anthocyanin and flavonol accumulation in transgenic tobacco. Plant J. 2001, 28, 319–332. [Google Scholar] [CrossRef]
  50. Cavallini, E.; Matus, J.T.; Finezzo, L.; Zenoni, S.; Loyola, R.; Guzzo, F.; Schlechter, R.; Ageorges, A.; Arce-Johnson, P.; Tornielli, G.B. The phenylpropanoid pathway is controlled at different branches by a set of R2R3-MYB C2 repressors in Grapevine. Plant Physiol. 2015, 167, 1448–1470. [Google Scholar] [CrossRef]
  51. Wang, Q.; Jing, L.; Xu, Y.; Zheng, W.; Zhang, W. Transcriptomic Analysis of Anthocyanin and Carotenoid Biosynthesis in Red and Yellow Fruits of Sweet Cherry (Prunus avium L.) during Ripening. Horticulturae 2023, 9, 516. [Google Scholar] [CrossRef]
  52. An, J.P.; Yao, J.F.; Xu, R.R.; You, C.X.; Wang, X.F.; Hao, Y.J. Apple bZIP transcription factor MdbZIP44 regulates abscisic acid-promoted anthocyanin accumulation. Plant Cell Environ. 2018, 41, 2678–2692. [Google Scholar] [CrossRef] [PubMed]
  53. Zhang, S.Y.; Chen, Y.X.; Zhao, L.L.; Li, C.Q.; Yu, J.Y.; Li, T.T.; Yang, W.Y.; Zhang, S.G.; Su, H.Y.; Wang, l. A novel NAC transcription factor, MdNAC42, regulates anthocyanin accumulation in red-fleshed apple by interacting with MdMYB10. Tree Physiol. 2020, 40, 413–423. [Google Scholar] [CrossRef] [PubMed]
  54. Fang, X.; Zhang, L.Z.; Wang, L.J. The transcription factor MdERF78 is involved in ALA-induced anthocyanin accumulation in apples. Front. Plant Sci. 2022, 13, 915197. [Google Scholar] [CrossRef]
Horticulturae 11 00269 g001
Figure 1. Variation in weight of single fruit (A), fruit shape index (B), transverse diameter (C) and longitudinal diameter (D) of sweet cherry. Values are mean ± standard error (SE) of three biological replicates (n = 3). Means followed by different lowercase superscripts are significantly different at p < 0.05.
Figure 1. Variation in weight of single fruit (A), fruit shape index (B), transverse diameter (C) and longitudinal diameter (D) of sweet cherry. Values are mean ± standard error (SE) of three biological replicates (n = 3). Means followed by different lowercase superscripts are significantly different at p < 0.05.
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Figure 2. Variation in TSS (A), glucose (B), mannitol (C), fructopyranose (D), malic acid (E), quinic acid (F), citric acid (G), total protein content (H), VC content (I), GA content (J), and BR content (K) in sweet cherry. Values are means ± standard error (SE) of three biological replicates (n = 3). Means followed by different lowercase superscripts are significantly different at p < 0.05.
Figure 2. Variation in TSS (A), glucose (B), mannitol (C), fructopyranose (D), malic acid (E), quinic acid (F), citric acid (G), total protein content (H), VC content (I), GA content (J), and BR content (K) in sweet cherry. Values are means ± standard error (SE) of three biological replicates (n = 3). Means followed by different lowercase superscripts are significantly different at p < 0.05.
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Figure 3. Expression analysis of the structural genes related to anthocyanin biosynthesis in sweet cherry using qRT-PCR. Values are mean ± standard error (SE) of three biological replicates (n = 3). Means followed by different lowercase superscripts are significantly different at p < 0.05. (A) Expression analysis of the F3′H gene. (B) Expression analysis of the DFR gene. (C) Expression analysis of the ANS gene. (D) Expression analysis of the UFGT gene.
Figure 3. Expression analysis of the structural genes related to anthocyanin biosynthesis in sweet cherry using qRT-PCR. Values are mean ± standard error (SE) of three biological replicates (n = 3). Means followed by different lowercase superscripts are significantly different at p < 0.05. (A) Expression analysis of the F3′H gene. (B) Expression analysis of the DFR gene. (C) Expression analysis of the ANS gene. (D) Expression analysis of the UFGT gene.
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Figure 4. Differential expression analysis of transcription factors. (A) MYB transcription factors. (B) bHLH transcription factors. (C) WD40 transcription factors.
Figure 4. Differential expression analysis of transcription factors. (A) MYB transcription factors. (B) bHLH transcription factors. (C) WD40 transcription factors.
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Figure 5. WGCNA analysis of different developmental stages and varieties of sweet cherry. (A) Cluster diagram of co-expression modules. Different colors correspond to different co-expression modules. (B) Relationships between modules and traits. The values in the cells in which the rows and columns cross represent the correlation coefficient between modules and phenotypes, and the numbers in brackets are p values.
Figure 5. WGCNA analysis of different developmental stages and varieties of sweet cherry. (A) Cluster diagram of co-expression modules. Different colors correspond to different co-expression modules. (B) Relationships between modules and traits. The values in the cells in which the rows and columns cross represent the correlation coefficient between modules and phenotypes, and the numbers in brackets are p values.
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Table 1. Phenological periods of four sweet cherry varieties (2022).
Table 1. Phenological periods of four sweet cherry varieties (2022).
CultivarSprouting
(MM/DD)		Initial Flowering
(MM/DD)		Full Flowering
(MM/DD)		Final Flowering
(MM/DD)		Spring Fruiting
(MM/DD)		Spring Foliage Color
(MM/DD)		Ripening
Jiangnanhong2/143/103/254/054/084/155/07
5-1062/153/083/194/014/124/125/07
Chaoyang 12/153/103/204/104/044/145/08
Changfeng 12/163/123/213/314/054/165/10
Table 2. Color parameters of sweet cherry fruits at different maturity levels.
Table 2. Color parameters of sweet cherry fruits at different maturity levels.
CultivarColor ParameterS1S2S3S4
JiangnanhongL*48.50 ± 3.68 a36.63 ± 3.24 b27.31 ± 2.17 c22.10 ± 2.12 d
a*36.98 ± 3.21 b40.74 ± 2.01 a30.94 ± 3.17 c13.97 ± 2.21 d
b*24.33 ± 2.18 a20.07 ± 2.01 b11.88 ± 1.43 c2.72 ± 1.31 d
5-106L*64.35 ± 3.65 a51.95 ± 1.37 b45.63 ± 1.60 c36.86 ± 3.30 d
a*21.20 ± 5.62 c39.59 ± 1.25 b42.61 ± 1.35 a42.89 ± 2.06 a
b*34.44 ± 3.31 a26.43 ± 0.30 b22.77 ± 1.86 bc21.05 ± 2.66 c
Chaoyang 1L*72.44 ± 0.77 a69.17 ± 2.14 b62.07 ± 2.55 bc58.89 ± 1.44 c
a*3.73 ± 0.84 c7.31 ± 0.98 b13.82 ± 1.68 a14.75 ± 1.02 a
b*39.29 ± 1.60 a39.22 ± 1.48 a39.68 ± 1.65 a39.73 ± 0.85 a
Changfeng 1L*71.67 ± 2.67 a56.76 ± 3.52 b40.77 ± 1.78 c30.03 ± 2.67 d
a*24.61 ± 1.48 d32.14 ± 2.86 c44.06 ± 2.40 a36.84 ± 2.21 b
b*31.74 ± 2.97 a27.18 ± 2.94 b23.82 ± 1.85 c14.59 ± 1.46 d
Note: S1, S2, S3, and S4 refer to different maturity levels. L* represents the lightness value, a* represents the red–green value, and b* represents the yellow–blue value. Values are the means ± standard error (SE) of three biological replicates (n = 3). Means followed by different lowercase superscripts are significantly different at p < 0.05.
Table 3. Anthocyanin content of sweet cherry.
Table 3. Anthocyanin content of sweet cherry.
CultivarMaturityCyanidin-3-O-Rutinoside (μg·g−1 FW)Cyanidin-3-O-Glucoside (μg·g−1 FW)Pelargonidin 3-Glucoside (μg·g−1 FW)
JiangnanhongS1111.07 ± 5.17 d1.13 ± 0.04 dud
S2837.70 ± 15.12 c1.70 ± 0.02 cud
S31424.16 ± 7.56 b4.29 ± 0.05 b0.09 ± 0.01 b
S43909.32 ± 112.67 a13.54 ± 0.28 a0.23 ± 0.01 a
5-106S119.64 ± 1.22 d0.83 ± 0.09 dud
S2185.10 ± 19.25 c1.16 ± 0.07 cud
S3239.80 ± 34.48 b1.46 ± 0.05 bud
S4354.08 ± 32.94 a1.67 ± 0.03 aud
Chaoyang 1S11.35 ± 0.23 c0.94 ± 0.03 abud
S21.44 ± 0.12 c1.07 ± 0.16 aud
S36.25 ± 0.44 b0.74 ± 0.11 bud
S47.63 ± 0.44 a0.83 ± 0.06 bud
Changfeng 1S1182.20 ± 7.04 d1.22 ± 0.09 dud
S2367.59 ± 8.39 c1.61 ± 0.08 cud
S3798.92 ± 36.69 b1.96 ± 0.03 bud
S41247.53 ± 18.65 a2.14 ± 0.02 a0.11 ± 0.01 a
Note: ud, the substance was not detected. Values are mean ± standard error (SE) of three biological replicates (n = 3). Means followed by different lowercase superscripts are significantly different at p < 0.05.
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Xu, Y.; Jing, Y.; Guo, Y.; Zhang, W. Quality Characteristics and Color Formation Mechanism of Low Chilling Requirement Sweet Cherry (Prunus avium L.) Cultivars in Southeast China. Horticulturae 2025, 11, 269. https://doi.org/10.3390/horticulturae11030269

AMA Style

Xu Y, Jing Y, Guo Y, Zhang W. Quality Characteristics and Color Formation Mechanism of Low Chilling Requirement Sweet Cherry (Prunus avium L.) Cultivars in Southeast China. Horticulturae. 2025; 11(3):269. https://doi.org/10.3390/horticulturae11030269

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Xu, Yue, Yonglin Jing, Yanfei Guo, and Wangshu Zhang. 2025. "Quality Characteristics and Color Formation Mechanism of Low Chilling Requirement Sweet Cherry (Prunus avium L.) Cultivars in Southeast China" Horticulturae 11, no. 3: 269. https://doi.org/10.3390/horticulturae11030269

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Xu, Y., Jing, Y., Guo, Y., & Zhang, W. (2025). Quality Characteristics and Color Formation Mechanism of Low Chilling Requirement Sweet Cherry (Prunus avium L.) Cultivars in Southeast China. Horticulturae, 11(3), 269. https://doi.org/10.3390/horticulturae11030269

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