Abstract
This study investigated the optimal strategies for improving sugar biosynthesis in mango fruits. Randomized block design was used for experimental treatments. The mango cultivar “Renong-1” was sprayed with five green plant growth regulators, including solutions of SBP (sucrose-based polymers, a new highly efficient and eco-friendly plant growth regulator), SPM (sucrose + potassium dihydrogen phosphate + microelement fertilizer), TPM (taurine + potassium dihydrogen phosphate + microelement fertilize), PFA (potassium fulvic acid), and SOP (seaweed oligosaccharide peptide) at different fruit development stages. Indicators, such as soluble solid content, soluble sugar and starch contents, and activities of 11 enzymes associated with sugar metabolism in physiologically mature and in full ripening fruits were evaluated. The results showed that SBP solution diluted 100-fold exerted the strongest effect on the soluble sugar content and sweetness value of “Renong-1” mango fruits. Based on the linear regression analysis, a significant negative correlation was observed between the activity of acid invertase and the perceived sweetness of physiologically mature fruits, while the activities of other enzymes were significantly negatively correlated with the perceived sweetness of full ripening fruits. According to multiple regression (by lars function in R) and other comprehensive analysis, A1B3 (spraying SBP solution one time in the young fruit stage) was selected as the optimal treatment combination for enhancing “Renong-1” mango perceived sweetness, followed by A1B2 (spraying SBP solution for the first time in the young fruit stage and the second time at medium maturity) as the alternative treatment combination.
1. Introduction
As a well-known tropical and subtropical fruit, the mango fruit (Mangifera indica L., Anacardiaceae) is known as the “king of tropical fruits” and is one of the top five tropical fruits in the world (bananas, pineapples, litchi fruits, mangoes, and longans). Its high sugar, acid, vitamin, and dietary fiber contents, coupled with low amounts of protein, fat, and minerals, make it the most preferred fruit among people. The cultivated area of mangoes in 2022 was nearly 381,000 ha, and the production was about 3.8 million tons of the world []. China is the second largest country in mango production and is rich in mango germplasm (about 900 accessions) [], but only a few varieties with a strong, sweet texture are popularized. Most varieties with appealing appearances exhibit limited sweetness, thereby reducing their values to be used as the primary commercial varieties. To a certain extent, the selection and breeding of new mango varieties with the excellent germplasm resources has also been restricted.
Sugar, the most significant source of chemical energy as well as the end product of photosynthesis, is a key indicator of fruit quality, and the perceived sweetness largely depends on the type and proportion of sugars in a fruit []. Much research has given attention to sugar metabolism in fruits, such as peaches [], strawberries [], apples [], tomatoes [], and other horticultural crops []. In the case of mango, the content and proportion of soluble sugars—such as sucrose (S), fructose (F), and glucose (G)—in mango fruits considerably contribute to sweetness, flavor, quality, and commercial value [,].
Among the methods for improving sugar accumulation, using various nontoxic plant growth regulators to explore potential technologies to improve mango sugar biosynthesis and thus increase the sweetness value is an effective and green strategy []. The common fruit sweeteners available in markets include citrus sweeteners, sweetening liquids, and phytoalexins among others [,,,], which contain phosphorus, calcium, and various trace elements. However, such sweeteners function by nourishing the tree or as plant stimulants, and their safety in fruits and the ecological environment is difficult to investigate. Furthermore, the effect of the sweeteners on different fruits varies, and no study has identified effective sweeteners for mangoes.
The nontoxic plant growth regulators used in this study as sweeteners, including sucrose-based polymers (SBP), potassium fulvic acid, taurine, and seaweed oligosaccharide peptide [], are well-known green and nontoxic compounds. Taurine is a green biogenic compound that has been patented for its sweetening effect on fruits []. Researchers have conducted several studies to increase the sweetening effect of SBP on fruits. For instance, aqueous foliar sprays of SBP during the fruit-bearing stage can effectively increase sucrose synthase (SS) and sucrose phosphate synthase (SPS) activities in longan (Dimocarpus longan Lour.) leaves, in turn promoting sugar accumulation during the fruit-ripening stage [,,,]. In addition, the sweetening effect of SBP has been observed in Sanyuehong litchi (Litchi chinensis Sonn.), netted melon (Cucumis melo L.), sweet orange (Citrus sinensis L. Osbeck), pawpaw (Carica papaya L.), and cherry tomato (Solanum lycopersicum (L.) var. cerasiforme Mill.) [,]. Potassium fulvic acid is a highly effective macromolecular organic compound characterized by its low molecular weight and easy absorption and utilization by crops to promote crop growth and to increase chlorophyll, vitamin C, and sugar contents. Moreover, the acid enhances resistance to cold, drought, and diseases in plants [,], making it the most active organic compound among soil humic acids [,,].
The mango cultivar “Renong-1” has high quality and yield; however, it has a low sugar content and low sweetness. Thus, this study aimed to screen a highly efficient and nontoxic plant growth regulator formulation and establish an effective supporting technology system for improving sugar biosynthesis and sweetness values of mango fruits. The results of this study could provide crucial insights for improving the quality of mangoes through the application of eco-friendly plant growth regulators and technological support systems. Furthermore, it could lay the groundwork for developing superior mango varieties that satisfy consumer preferences, utilizing the rich mango germplasm resources in China.
2. Materials and Methods
2.1. Chemicals and Reagents
All chemicals and reagents for soluble sugar extraction and high-performance liquid chromatography (HPLC) analysis were of the highest available purity. Chromatographically pure acetonitrile and ethyl alcohol were respectively from Thermo Fisher Scientific Company (Waltham, MA, USA) and Shanghai Anpel Experimental Technology Co., Ltd., Shanghai, China. For reference standards, sucrose (57-50-1), glucose (50-99-7), and fructose (57-48-7) were purchased from Shanghai Anpel Experimental Technology Co., Ltd., Shanghai, China). Also used were potassium dihydrogen phosphate (7778-77-0, Shanghai Anpel Experimental Technology Co., Ltd., Shanghai, China), microelement fertilizer (Anyang City Xi Mandi fertilizer Co., Ltd., Anyang, China), Taurine (107-35-7, Shanghai Anpel Experimental Technology Co., Ltd., Shanghai, China), and potassium fulvic acid (Anyang City Xi Mandi fertilizer Co., Ltd., Anyang, China). Water was purified using a Milli-Q deionization unit (Millipore, Bedford, MA, USA).
2.2. Mango Variety and Treatment
“Renong-1” mango fruits were collected from a mango orchard at the South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang city, Guangdong province, China (20°18′ N, 101°18′ E). “Renong-1” is a conventional excellent high-yielding variety independently cultivated by the mango research group at the institute, although it has the disadvantages of low sugar content and low sweet taste.
Field trials were conducted from April to July 2022, where the natural conditions were generally 20–35 °C and 75–100% relativity humidity. Five solutions—SBP, sucrose-potassium dihydrogen phosphate-microelement fertilizer mixture solution, taurine-potassium dihydrogen phosphate-microelement fertilizer mixture solution, potassium fulvic acid solution, and a seaweed oligosaccharide peptide solution—were applied at different fruit growth stages. A total of 63 well-grown “Renong-1” mango trees with consistent growth at the blooming stage were selected and tagged. The trees were divided into 21 groups of 3; 20 groups were sprayed by the 5 solutions at different fruit development stages using a spray gun, and 1 group was blank processed as a control (CK) (Table 1).
Table 1.
The 20 types of spraying treatments used in this study.
SBP was supplied by the School of Environmental and Life Sciences, Nanning Normal of University, Nanning, China and is a new environmentally friendly efficient plant growth regulator. Sucrose crystals were pre-irradiated by γ-rays of 60 Co and turned into an activated form. Then, the activated sucrose was polymerized directly with another monomer (e.g., acrylic acid) to yield SBP.
Based on our prior experiments, the SBP solution (A1) was prepared by diluting the original SBP liquid 100-fold with water. SPM solution (A2) was prepared by mixing 5000 ppm S, 0.4% potassium dihydrogen phosphate, and 500 ppm microelement fertilizer (i.e., 50 g S, 40 g potassium dihydrogen phosphate, 5 g microelement fertilizer, and 10 L water). TPM solution (A3) was prepared by mixing 500 ppm taurine, 0.4% potassium dihydrogen phosphate, and 500 ppm microelement fertilizer (i.e., 5 g taurine, 40 g potassium dihydrogen phosphate, 5 g microelement fertilizer, and 10 L water). PFA solution (A4) was prepared by mixing 20 g potassium fulvic acid and 10 L water. SOP solution (A5) was prepared by mixing 8.3 mL seaweed oligosaccharide peptide solution and 10 L water.
Sampling method: At the physiological maturity stage (about 125 days after flowering), five fruits which were well-shaped, disease-free, and of uniform size and maturity were picked from Renong-1 mango trees from each of five directions (east, south, west, north, and middle). More than half of the harvested fruits were subjected to post-ripening treatment at room temperature (25 °C) until they became edible (i.e., reached the full ripening stage). For both stages, 10 fruits were ground, weighed, extracted, and used to quantify their contents of S, G, and F as well as enzyme activities. The tests were repeated three times, and the average value was calculated.
2.3. Determination of Total Soluble Solid Content
The total soluble solid content of fruit pulps was determined using a digital portable refractometer (PAL-1; Atago Co., Ltd., Tokyo, Japan).
2.4. Determination of Soluble Sugar Contents
The contents of S, F, and G were determined using HPLC coupled with mass spectrometry (HPLC-MS) equipped with an auto sampler, an ultraviolet detector (LC-20A, Shimadzu Inc., Kyoto, Japan), and integration software (v1.5.2). The column was 250 mm × 4.6 mm, i.d., 5 μm ZORBAX SB-C18 (PerkinElmer Inc., Waltham, MA USA, the same below). Briefly, 1 g of fruit pulp was extracted with 85% alcohol and centrifuged, and the supernatant was evaporated in a water bath at 85 °C and then dissolved in 4 mL of water. Afterward, 1 mL of the resulting solution was filtered through a 0.4 μm membrane filter for subsequent liquid-phase analysis under the following chromatographic conditions: mobile phase consisted of acetonitrile and water (72:28, v/v), chromatographic column was an amino column, flow rate was 1.0 mL/min, column temperature was set to 27 °C, injection volume was 10 μL, and the run time was 15 min. The soluble sugar content was calculated with reference to the peak areas of the samples and the corresponding standard curves of the sugars.
2.5. Determination of Total Sugar Content and Calculation of Perceived Sweetness
Total sugar (TS) content was calculated by summing the contents of F, G, and S.
Perceived sweetness was calculated according to the method of Yao et al. [] as follows: S = 1.00, F = 1.75, and G = 0.75. Therefore, SV = S content × 1.00 + F content × 1.75 + G content × 0.75.
2.6. Determination of Starch Content
Starch content was determined using a micro method test kit (Suzhou Comin Biotechnology Co., Ltd., Suzhou, China), where the experimental procedures were performed according to the manufacturer’s instructions.
2.7. Determination of Activities of Enzymes Associated with Sugar Metabolism
The activities of enzymes associated with sugar metabolism were determined using assay kits. The activities of ADP-glucose pyrophosphorylase (AGP), sucrose synthase (SS), protein kinase (PK), phosphoglucomutase (PGM), α-amylase (α-amy), β-amylase (β-amy), debranching enzyme (DBE), isoamylase (ISA), invertase (INV), acid invertase (AI), and sucrose phosphate synthase (SPS) were measured independently using an AGP assay kit, SS assay kit, PK assay kit, PGM assay kit, α-amylase assay kit, β-amylase test kit, starch DBE test kit, ISA test kit, INV test kit, AI test kit, and SPS assay kit (Enzyme-linked Biotechnology Co., Ltd., Shanghai, China), respectively, according to the manufacturer’s instructions.
2.8. Statistical Analysis
The analysis of soluble sugar contents and processing of data obtained via HPLC-MS were performed using the built-in Analyst 1.5.2 (AB SCIEX, Foster City, CA, USA).
Statistical analysis of the data was performed using MS Excel 2010 (Microsoft Corp., Redmond, WA, USA) and IBM SPSS Statistics 22.0 (IBM Corp., Armonk, NY, USA). Multiple regression analyses were conducted using the LASSO (least absolute shrinkage and selection operator) model, implemented in R (v3.6.1) with the Lars package, and the results were further visually presented with the Igraph package.
3. Results
3.1. Sugar Contents Under Different Treatments of ’Renong-1’ Mango Fruits at the Physiologically Maturity Stage
The contents of TSS, S, G, F, TS, and SV in “Renong-1” mango fruits at physiologically maturity stage were illustrated in Figure 1, and the significance test of difference is indicated in Table 2 and Table 3.
Figure 1.
Variations in indicators of mango fruit quality at physiological maturity under different treatments. TSS, total soluble solids; S, sucrose; G, glucose; F, fructose; TS, total sugar; SV, sweetness value.
Table 2.
The contents of sucrose (S), glucose (G), fructose (F) and starch in physiologically mature “Renong-1” mango fruits under different treatments.
Table 3.
The contents of total soluble solid (TSS) and total sugar (TS), and perceived sweetness (SV) of physiologically maturity “Renong-1” mango fruits under different treatments.
The results revealed that for the physiologically maturity mango, treatment groups with SBP enhanced the accumulation of soluble sugars, TS and SV. It is noteworthy that A1B2 (SBP sprayed in the young fruit and medium maturity stages) brought the remarkable-highest TS and SV. A3B1 (TPM sprayed in the young fruit, medium maturity, and pre-harvest stages) obtained the highest S contents of that was significantly higher (p < 0.05) than the rest treatment. A1B2 and A4B3 (PFA sprayed at young fruit stage) treatment groups had the second highest S content and were significantly higher (p < 0.05) than those of the other 18 treatment groups. A2B2 (SPM sprayed at young fruit and medium maturity stages) significantly increased the G, F, and TS contents and SV values. Unexpectedly, the starch content and TSS of the control group did not differ significantly from those of the 20 treated groups.
3.2. Sugar Contents of Full Ripening “Renong-1” Mango Fruits Under Different Treatments
The contents of TSS, S, G, F, TS, and SV in “Renong-1” mango fruits at the post-ripening stage were illustrated in Figure 2, and the significance test of difference is indicated in the Table 4 and Table 5.
Figure 2.
Variations in indicators of full ripening mango fruit quality under different treatments. TSS, total soluble solids; S, sucrose; G, glucose; F, fructose; TS, total sugar; SV, sweetness value.
Table 4.
The contents of sucrose (S), glucose (G), fructose (F), and starch in fully ripened “Renong-1” mango fruits under different treatments.
Table 5.
Total soluble solid (TSS) and total sugar (TS) contents and perceived sweetness (SV) of fully ripened “Renong-1” mango fruits under different treatments.
For the fully ripened mango, A1B3 (SBP sprayed in the young fruit stage) affected the improvement of the G content; meanwhile, TS content and SV were the brightest. The TS content of 100 g of fresh mango flesh in the A1B3 treatment group was 18,708.05 mg; and the SV was 17.3% in weight, which was 7.7% higher than that of the control group (9.6%) (Table 5). Furthermore, the TS content and SV of the A1B2 (SBP sprayed in the young fruit and medium maturity stages) were considerably higher than those of the other treatment groups but lower than those of the A1B3 treatment group (Table 5). In terms of S content, A1B1 (SBP sprayed in the young fruit, medium maturity, and pre-harvest stages) was observably more than any others, which reached to 6341.98 mg per 100 g of fresh mango flesh after spraying. Similarities to the physiologically maturity mango were found in the following points: F content was the highest in the A2B2 treatment group, although the effect of the treatment was insignificant; overall, most treatments with SBP solutions exerted strong effects on S, G, F, and TS contents, SV; the starch content and TSS of full ripening fruits differed considerably, but almost no significant differences were observed among all groups.
3.3. The Activities of Enzymes Associated with Sugar Metabolism in Physiologically Maturity and Full Ripening Fruits Under Different Treatments
The activities of enzymes associated with sugar metabolism (AGP, SS, PK, PGM, α-amy, β-amy, DBE, ISA, INV, AI, and SPS) in physiologically mature and fully ripened “Renong-1” mangoes under different treatments are presented in Table 6 and Table 7.
Table 6.
Activities of enzymes associated with sugar metabolism in physiologically mature “Renong-1” mango fruits under different treatments.
Table 7.
Activities of enzymes associated with sugar metabolism in fully ripened “Renong-1” mango fruits under different treatments.
To identify the key enzymes that serve as the basis for selecting optimal treatment combinations, a multiple linear regression analysis was conducted. The effects of 13 variables (TSS, starch, AGP, SS, PK, DBE, PGM, α-amy, β-amy, ISA, INV, AI, and SPS) on SV, F, G, and S were estimated, and the results are described by the following two equations.
Sweetness = 297.0 × TSS + 0.0 × Starch + 0.0 × AGP + 0.0 × SS − 842.5 × PK + 792.9 × DBE + 0.0 × PGM + 924.3 × α-Amylase + 0.0 × β-Amylase + 334.9 × Isoamylase + 1262.3 × INV − 1064.4 × AI − 821.5 × SPS
Sweetness = 0.0 × TSS − 75.0 × Starch + 1649.7 × AGP + 3367.2 × SS − 2067.0 × PK +1812.0 × DBE − 0.4 × PGM − 2774.1 × α-Amylase − 2923.6 × β-Amylase − 528.8 × Isoamylase + 2480.1 × INV − 2981.8 × AI − 4621.4 × SPS
In Equation (1), the model derived from statistical data for fruit samples at the green-ripening stage demonstrated that the degree of influence on SV decreased in the order of INV > AI > α-amy > PK > SPS > DBE > ISA > TSS, with PK, AI, and SPS exerting significant negative effects (Figure 3A).
Figure 3.
Schematic representation of enzymes associated with the sugar metabolism and sweetness values of “’Renong-1” mango fruits. (A) Statistic data from physiologically mature fruits; (B) statistic data from fully ripened fruits.
In Equation (2), the model derived from statistical data for fruit samples at the fully ripe stage revealed that the degree of influence on SV decreased in the order of SPS > SS > AI > β-amylase > α-amylase > INV > PK > DBE > AGP > isoamylase > starch > PGM, with SPS, AI, β-amylase, α-amylase, PK, isoamylase, starch, and PGM exerting significant negative effects (Figure 3B).
It should be noted that at the green-ripening stage, four enzymes (AGP, SS, PGM, and β-Amylase) are determined to have no effect on SV, in contrast to the fully ripe stage, where none are decided. Additionally, the coefficient of each enzyme in Equation (2) is larger than that in Equation (1).
3.4. Selection of the Optimal Treatment Combination
To determine the optimal treatment combination in the view of sweetness, both TS content and SV indicators were evaluated. At the physiologically mature stage, A1B2 and A2B2 treatment groups whose TS and SV values were significantly greater than that of the control group were selected; similarly, at the fully ripened stage, treatment combinations of A1B2 and A1B3 were selected. Considering that A2B2 treatment showed higher values of TS and SV only in the early stage but not in the fully ripened stage, it should be discarded (Table 4 and Table 5). Overall, A1B3 was selected as the optimal treatment combination for its best effects on enhancing mango perceived sweetness, followed by A1B2 as the alternative treatment.
4. Discussion
4.1. Section of Testing Factors Associated with Sweetness
The taste texture of fruit is a mixture trait comprising a series of aspects, including pulp hardness, texture, smell, sweetness, sourness, and so on, with each affected by various factors. In the case of sweetness, it is well known that many compounds, such as soluble sugars, acids, and alcohols, are involved, again with each containing numerous components []. Obviously, it is impossible to test so many chemicals and their contents with a few experiments implemented in one study, whereas picking out those most important factors for examination is reasonable. There, we here checked that the contents of sugars (S, F, and G), TSS and starch were in line with previous studies.
On the other hand, soluble sugar accumulation is closely associated with the activities of enzymes involved in sugar metabolism []. Moreover, plant growth regulators influence fruit development and ripening, as well as sugar accumulation and metabolism in fruits, by affecting these sugar-associated enzymes []. Consequently, the activities of AGP, SS, PK, PGM, α-amylase, β-amylase, DBE, ISA, INV, AI, and SPS were selected for examination, referencing numerous previous studies.
4.2. Effects of Different Plant Growth Regulators on Sweetness
The results of this study indicated that TS content and SV value of “Renong-1” mango fruits were not significantly affected after spraying with SOP or PFA; however, S content was increased substantially by TPM, and G and F contents were increased considerably by SPM. The SBP exerted the strongest effect on the sugar content, with significant increases observed in TS content and SV when compared to the control group, particularly at the full ripening stage (Figure 2 and Figure 3, Table 2, Table 3, Table 4, Table 5 and Table 6).
Seaweed oligosaccharide peptide (SOP) and potassium fulvic acid (PFA) are both nutrients and regulators [,]. They did not improve the sugar content in this study, possibly because they functioned merely as nutrients, and the dosage used was too small to nourish a large tree. Similar to SOP and PFA, SPM and TPM consist of a mixture solution containing sucrose/taurine, potassium dihydrogen phosphate, and microelement fertilizers, which are richer in nutrients and can therefore increase certain sugar contents. Unlike the first four mixtures, SBP is limited in nutrients but has significantly higher contents of various sugars, suggesting it functions as a stimulant. During the SBP production process, sucrose crystals were pre-irradiated with γ-rays, thereby making it possible to obtain activators that may affect sugar metabolism. Nevertheless, the efficiency of SBP in the present study is consistent with that of previous studies [,].
It should be noted that compared to the CK group, no tested growth regulators were able to enhance starch content or TSS content at either tested stage (Figure 2 and Figure 3, Table 2, Table 3, Table 4, Table 5 and Table 6), indicating that these indices are not relevant for selecting the optimal treatment. Given that TS was enhanced at the full ripening stage, it can be inferred that more sugar-like compounds were present before fruit harvest. Thus, if starch was not affected, it suggests that other polysaccharides, such as fibers, must have increased. Therefore, further studies are recommended to analyze other quality compounds.
4.3. Effects of Activity of Different Enzymes on Sweetness
As mentioned previously, plant growth regulators influence sugar accumulation through enzymes []. Consequently, monitoring the relationship between enzyme activity and sweetness can provide insights into the underlying mechanisms []. Compared to other mathematical models, the LASSO (least absolute shrinkage and selection operator) is less accurate (p-values are not provided) but simpler and more concise, with the coefficients of insignificant variables being directly expressed as zero, whereas significant variables (either positive or negative) are screened out. Upon utilizing this model, we observe that nearly every enzyme (with the exception of α-amylase) maintains its effect trend (positive or negative) on SV from the fruit’s green-ripening stage to the fully ripened stages, while the absolute values of their coefficients gradually increase. The results indicate that these enzymes are closely related to sugar accumulation during mango fruit development, and therefore, some of them could potentially be used as markers to determine which plant growth regulators are more effective. To document this issue, it is necessary to dynamically monitor enzyme activity and sugar content from the young fruit stage through to harvest and full ripeness in future studies.
5. Conclusions
At the present study, a randomized block design was employed to investigate the effects of various plant growth regulators on sugar biosynthesis during fruit development and ripening stages. Key physiological and biochemical indicators, including enzyme activities related to sugar metabolism, are comprehensively analyzed to identify optimal treatment combinations. In summary, the SBP solution sprayed once in the young fruit stage had the optimal sweetening effect on “Renong-1” mango fruits, with significant effects being observed on increasing sugars, i.e., S, G, and F contents. It is hope that the application of SBP will benefit for the field of fruit physiology study and sustainable agriculture production in the near future.
Author Contributions
L.L.: funding acquisition, conceptualization, data curation, software, writing—original draft, visualization. X.M.: investigation. S.W.: project administration, supervision, validation. C.X.: investigation, data curation, formal analysis. H.W.: investigation. Y.W.: investigation, resources, methodology. B.Z.: conceptualization, supervision. Y.H.: resources. Q.L. and W.X.: data curation, formal analysis. W.L.: conceptualization, project administration, writing—review and editing. All authors have read and agreed to the published version of the manuscript.
Funding
This work was supported by the Hainan Province Natural Science Foundation of China (322MS117), Guangxi Minzu University Research Funding Project (2022KJQD18), Guangxi Natural Science Foundation (2023GXNSFBA026292, 2025GXNSFAA069329), the Open Project of Guangxi Key Laboratory of Biology for Mango (GKLBMO2305).
Data Availability Statement
The raw data supporting the conclusions of this article will be made available by the authors on request.
Conflicts of Interest
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.
Abbreviations
| Abbreviation | Full title |
| SBP | Sucrose-based polymer solution |
| SPM | Sucrose–potassium dihydrogen phosphate–microelement fertilizer mixture solution |
| TPM | Taurine–potassium dihydrogen phosphate–microelement fertilizer solution |
| PFA | Potassium fulvic acid solution, |
| SOP | Seaweed oligosaccharide peptide solution |
| AGP | ADP-glucose pyrophosphorylase |
| PK | Protein kinase |
| α-amy | α-amylase |
| DBE | Debranching enzyme |
| INV | Invertase |
| SPS | Sucrose phosphate synthase |
| TSS | Total soluble solids |
| TS | Total sugar |
| S | Sucrose |
| G | Glucose |
| F | Fructose |
| SS | Sucrose synthase |
| PGM | Phosphoglucomutase |
| β-amy | β-amylase |
| ISA | Isoamylase |
| AI | Acid invertase |
| SV | Perceived sweetness |
References
- FAO. 2022. Available online: https://www.fao.org/faostat/zh/#data/QCL (accessed on 20 December 2024).
- Huang, G.D.; Chen, Y.S.; Su, M.H.; Luo, S.X.; Li, R.W.; Wang, Y.R. Protection, Utilization status quo and development path of mango germplasm resources in Guangxi. Agric. Res. Appl. 2024, 37, 56–60. [Google Scholar]
- Wei, C.B.; Wu, H.X.; Ma, W.H.; Wang, S.B.; Sun, G.M. Sucrose metabolism in Irwin mango (Mangifera indica L.) during maturation. Southwest China J. Agric. Sci. 2008, 21, 972–974. [Google Scholar] [CrossRef]
- Feng, B.S.; Liu, L.X.; Sun, J.; Len, P.; Wang, L.; Guo, Y.Y.; Min, D.D.; Liu, Y.G. Combined metabolome and transcriptome analyses of quality components and related molecular regulatory mechanisms during the ripening of Huangjin Peach. Sci. Hortic. 2024, 327, 112787. [Google Scholar] [CrossRef]
- Langer, S.E.; Hirsc, H.M.; Burges, P.L.; Martínez, G.A.; Civello, P.M.; Marina, M.; Villarreal, N.M. Biochemical and molecular traits underlying the quality preservation and defence enhancement by heat treatment in harvest-ripe strawberries. Sci. Hortic. 2024, 333, 113287. [Google Scholar] [CrossRef]
- Wang, J.H.; Li, F.J.; Sun, W.W.; Ali, M.; Li, B.G.; Zhang, X.Y.; Li, X.A.; Zhang, X.H. Role of sugar and energy metabolism in apple flesh browning during cold storage. Sci. Hortic. 2024, 326, 112758. [Google Scholar] [CrossRef]
- Ali, A.; Viviana, C.; Piero, S.; Jacopo, M.; Antonio, F.; Giacomo, C. Quality and physiological evaluation of tomato subjected to different supplemental lighting systems. Sci. Hortic. 2024, 323, 112469. [Google Scholar] [CrossRef]
- Shah, I.H.; Wu, J.H.; Li, X.Y.; Hameed, M.K.; Manzoor, M.A.; Li, P.L.; Zhang, Y.D.; Niu, Q.L.; Chang, L.Y. Exploring the role of nitrogen and potassium in photosynthesis implications for sugar: Accumulation and translocation in horticultural crops. Sci. Hortic. 2024, 327, 112832. [Google Scholar] [CrossRef]
- Wang, Y.Z.; Zhang, D.P. A Study on the relationships between acid invertase sucrose synthase and sucrose metabolism in ‘Red Fuji’ apple fruit. Acta Hortic. Sin. 2001, 28, 259–261. [Google Scholar] [CrossRef]
- Lv, Y.M.; Zhang, D.P. Accumulation of sugar during fruit development. Plant Physiol. J. 2000, 36, 258–265. Available online: https://www.docin.com/p-722078630.html (accessed on 1 August 2012).
- Yamada, K.; Fujita, E.; Nishimura, S.I. High performance polymer supports for enzyme-assisted synthesis of glycoconjugates. Carbohydr. Res. 1997, 305, 443–461. [Google Scholar] [CrossRef]
- Yan, S.G.; Zheng, Z.W.; Jiang, K.P.; Sun, D.G.; Yang, M.C. Application effect of citrus sweetener on fruit trees. South China Fruits 1999, 28, 23. [Google Scholar]
- Niu, J.X.; Feng, N.N. Application of “Jinkuizi” sweetening liquid and biological phosphate and potassium fertilizer on grape. North. Hortic. 2002, 5, 56–57. [Google Scholar] [CrossRef]
- Li, Z.D.; Xiong, Y.M.; Ning, H.G. The effect of ripening and sweetening experiment of mandarin. Fujian Fruits 1997, 1, 15–16. [Google Scholar]
- He, W.Z. Several key factors of orange bentonite in coloration and sweetening. Nong Jia Zhi You 2017, 11, 60. (In Chinese) [Google Scholar]
- Pang, C.P.; Ye, L.; Ma, J.; Lu, T.; Yang, Z.Y.; Qi, M.F. Effect of trehalose on photosynthesis of tomato seedling leaves under high temperature. Jiangsu Agric. Sci. 2017, 21, 143–146. [Google Scholar] [CrossRef]
- Hao, L.H.; He, P.Q.; Liu, C.Y.; Chen, K.S.; Li, G.Y. Physiological effects of taurine on the growth of wheat (Triticum aestivum L.) seedlings. J. Plant Physiol. Mol. Biol. 2004, 30, 595–598. [Google Scholar] [CrossRef]
- He, Y.Z.; Lv, M.Q.; Yao, P.J.; Wei, Y.A. Study on the fresh-keeping of mango treated by sucrose-based polymer at room temperature. China Fruits 2004, 4, 5–7. [Google Scholar] [CrossRef]
- Walker, A.J.; Ho, L.C.; Baker, D.A. Carbon translocation in the tomato: Path ways of carbon metabolism in fruit. Ann. Bot. 1978, 42, 901–909. [Google Scholar] [CrossRef]
- Hubrard, N.L.; Pharr, D.M.; Huber, S.C. Sucrose metabolism in ripening musk melon fruit as affected by leaf area. J. Amer. Soc. Hort. Sci. 1990, 115, 798–802. [Google Scholar] [CrossRef]
- Huber, S.C. Role of sucrose-phosphate synthetase in partitioning of carbon in leaves. Plant Physiol. 1983, 71, 818–821. [Google Scholar] [CrossRef]
- He, Y.Z.; Yao, P.J.; Zhang, H.B.; Wei, Y.F.; Chen, W.Y.; Wu, R.D. Effects of sucrose-based polymers on the quality of 3 kinds of fruits. J. Anhui Agric. Sci. 2008, 36, 12157–12158. [Google Scholar] [CrossRef]
- Ye, Y.; He, Y.Z.; Huang, Y.; Lv, M.Q. Effects of sucrose-based polymers on enzyme activities related to sucrose metabolism of cherry tomato during storage. Hubei Agric. Sci. 2008, 47, 947–950. Available online: https://d.wanfangdata.com.cn/periodical/hbnykx200808031 (accessed on 7 November 2008).
- Sun, L.; Ma, Z.J.; Xiao, Y. Application of fulvic acid in agriculture. Hei Long Jiang Sci. 2013, 4, 40–41. [Google Scholar] [CrossRef]
- Qiu, M.K.; Hui, Z.L.; Huang, X.P.; Wu, J.F. Influences of fulvic acid on drought resistance of aeroponic potato seedlings. Agric. Res. Arid Areas 2013, 31, 155–161. [Google Scholar] [CrossRef]
- Bai, Z.P. The application and development prospect of humic acid in pesticides. Biol. Disaster Sci. 2012, 35, 149–152. [Google Scholar] [CrossRef]
- Sun, M.G.; Du, M.F.; Zhang, Z.H. Preliminary study of high water-soluble fulvic acid fertilizer effect. Nitrogenous Fertil. Technol. 2017, 38, 44–48. [Google Scholar]
- Gao, W.L.; Li, M.; Yang, J.; Feng, H.J.; Zhang, S.P.; Zheng, C.L. Effects of different application amounts of potassium fulvate on yield and quality of tomato and soil physical and chemical properties. Agric. Sci. Technol. 2017, 18, 2392–2400. [Google Scholar]
- Yao, G.F.; Zhang, S.L.; Cao, Y.F.; Liu, J.; Wu, J.; Yuan, J.; Zhang, H.P.; Xiao, C.C. Characteristics of components and contents of soluble sugars in pear fruits from different species. Sci. Agric. Sin. 2010, 43, 4229–4237. [Google Scholar] [CrossRef]
- Zhang, S.L.; Chen, K.S. Molecular Physiology of Fruit Quality Development and Regulation; Agricultural Press: Beijing, China, 2007. [Google Scholar]
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