A method for improving the flavor quality of gean fruit by spraying methyl jasmonate

Abstract

This invention belongs to the field of fruit tree cultivation technology, specifically relating to a method for spraying methyl jasmonate (MeJA) to improve the flavor quality of Prunus cerasifera (European plum). This method uses Prunus cerasifera fruit as the target, spraying a MeJA solution during key stages of fruit development. Using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), qualitative and quantitative analyses are performed on the volatile substances of the fruit during key developmental stages—including the coloring and swelling stage (S1), the hard-ripening stage (S2), and the full-ripening stage (S3)—to clarify the effect of MeJA treatment on the aroma components and content of Prunus cerasifera (European plum). This invention, through exogenous spraying of MeJA, achieves targeted regulation of aroma metabolism in Prunus cerasifera (European plum) fruit, significantly optimizing aroma composition, reducing the relative content of unpleasant odor substances, and promoting the accumulation of characteristic fruit aroma substances. This invention provides a simple and effective technical solution for improving the aroma quality of Prunus cerasifera (European plum) fruit, and has good application prospects.

Description

Technical Field

[0001] This invention belongs to the field of fruit tree cultivation technology, specifically relating to a method for spraying methyl jasmonate to improve the flavor and quality of European plum fruit. Background Technology

[0002] The aroma of European plum (Cerasus humilis) fruit, as a crucial component of its flavor quality, directly influences consumers' sensory experience and market acceptance, and can also exert positive physiological and psychological effects on consumers through its pleasant scent. However, the overall aroma characteristics of the fruit are not determined by a single compound, but rather by a complex system composed of various volatile organic compounds (VOCs), including terpenes, esters, alcohols, aldehydes, and acids. Terpenes, esters, and some aldehydes typically impart pleasant floral and fruity aromas to the fruit; alcohols often exhibit grassy notes; and acids, heterocyclic compounds, and nitrogen- and sulfur-containing compounds are often accompanied by unpleasant odors such as sourness, astringency, fishiness, and bitterness. Therefore, the key to improving the aroma quality of the fruit lies not only in increasing the total amount of volatile substances, but also in optimizing the aroma composition, i.e., "removing the grassy smell and enhancing the aroma" while suppressing unpleasant odor components.

[0003] Methyl jasmonate (MeJA), an endogenous plant hormone belonging to the jasmonic acid family, has been proven to broadly regulate plant growth and development, stress responses, and secondary metabolic processes. Existing research indicates that MeJA treatment can promote the accumulation of flavor compounds such as flavonoids, total phenols, and anthocyanins, showing potential in regulating fruit aroma formation. However, current research on the application of MeJA mainly focuses on promoting coloring or increasing antioxidant content. For its application to European plum fruit, specifically targeting the combination of application timing, concentration, and frequency to "increase floral and fruity aromas, reduce acidity, astringency, and fishiness, and optimize aroma composition," no publicly available standardized technical solution has yet been established. Therefore, developing a safe, efficient, and easy-to-operate MeJA application method that can significantly improve the aroma quality of European plum fruit is of great significance for enhancing the commercial characteristics and added value of the industry. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for improving the flavor and quality of Prunus cerasifera fruit. The method involves spraying the entire plant with methyl jasmonate solution before the coloring and swelling stage of the Prunus cerasifera fruit, spraying twice before the coloring and swelling stage with a 10-day interval, and spraying once during the coloring and swelling stage to the ripening stage, for a total of three sprayings.

[0005] Furthermore, the final concentration of the methyl jasmonate solution is 20 mg / L.

[0006] Furthermore, spray the entire plant of the European plum on a sunny morning between 8:00 and 10:00.

[0007] Furthermore, an electric sprayer was used to spray the entire plant.

[0008] The present invention has the following beneficial effects:

[0009] 1. The method of this invention regulates the aroma metabolism of Prunus armeniaca fruit by spraying the entire plant with a 20 mg / L MeJA solution. Compared with the water control, Prunus armeniaca fruit treated with this method significantly promotes the accumulation of characteristic aroma compounds. During the coloring and swelling stage, MeJA treatment increases the volatile metabolites controlling the fruit's aroma and sweetness, such as 2-dodecenal, 5-methylhexanoic acid, and α,2,6,6-tetramethyl-1-cyclohexen-1-propanol. During the hard-ripening stage, MeJA treatment increases the volatile metabolites controlling the fruit's floral and sweet aroma, such as hexyl 2-furanoate and α,2,6,6-tetramethyl-1-cyclohexen-1-propanol. During the full-ripe stage, MeJA treatment increases the volatile metabolites controlling the fruit's aroma and floral aroma, such as 2,6,6-trimethyl-1-cyclohexen-1-carboxaldehyde, homolyl ester, and methyl nonanoate.

[0010] 2. The method of this invention significantly improves the aroma quality of *Prunus armeniaca* fruit by spraying the entire plant with a 20 mg / L MeJA solution. Compared with the water control, during the coloring and swelling stage, MeJA treatment reduced the sour, fishy, ​​and oily odors produced by volatile metabolites such as 4,5-dimethylthiazole, (2-bromoethyl)ethylene oxide, and 2-methyl-3-heptanone; during the hard-ripening stage, MeJA treatment reduced the smoky and burnt odors produced by volatile metabolites such as 2,4-dimethylphenol, 2-ethylphenol, and 6-methylquinoline; and during the fully ripening stage, MeJA treatment reduced the metallic, camphor, and minty odors produced by volatile metabolites such as carvyl propionate and cyclohexanol. This invention provides a new technical means for improving the aroma quality of *Prunus armeniaca* fruit and provides a reference for subsequent research on the effects of MeJA on fruit quality.

[0011] 3. The method of this invention focuses on inhibiting the synthesis and metabolism of unpleasant odor substances. This strategy avoids the energy consumption and metabolic burden that may result from excessive stimulation of secondary metabolism, making it a more energy-efficient and effective way to regulate aroma quality.

[0012] 4. As an endogenous hormone, MeJA leaves no exogenous residues on the fruit after treatment, ensuring high safety and meeting the requirements for green and high-quality fruit production.

[0013] 5. The method of this invention has a clear application time, is simple to operate, and is easy to master. It can be directly integrated into existing field management practices without increasing labor and material costs. As an endogenous plant hormone, MeJA has no pesticide residue risk, is safe for fruit trees and the environment, is suitable for green and high-quality fruit production, and has good prospects for industrialization and promotion. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 In the figure, A is the OPLS-DA scatter plot of metabolomics data for the MeJA spray treatment and the water control (CK). The horizontal axis represents Component 1 (12.6% explanatory power), and the vertical axis represents Component 2 (21.7% explanatory power). Different colors and symbols represent different treatment groups (CK-S1, CK-S2, and CK-S3 are the water control group; MeJA-S1, MeJA-S2, and MeJA-S3 are the MeJA treatment group). B is the permutation test plot, where the red dots represent R... 2 Y (the model's explanatory power for categorical variables), the blue triangle represents Q. 2 (Model predictive ability), with the horizontal axis representing similarity. The original model's R-value... 2 Y=0.983, Q 2 =0.861, all significantly higher than all permuted models, and Q 2 A negative intercept on the regression line indicates that the OPLS-DA model is not overfitting and its discriminative ability is reliable. C represents the permutation test frequency histogram, and the horizontal axis represents the R-squared value of the permuted model. 2 X, R 2 Y and Q 2 The vertical axis represents the value, and the vertical axis represents the frequency of occurrence of the corresponding value. The R-squared value of the original model is... 2 X=0.843, R 2 Y=0.983, Q 2 =0.861, all significantly higher than all permuted models (p<0.005, 200 permutations). D is a histogram of model fitting parameters, where R0.861 2 X=0.126 represents the model's explanatory power for the metabolomics independent variables, R0 2 Y=0.803 represents the model's explanatory power for the grouped dependent variable, Q 2 =0.532 indicates the model's predictive power.

[0016] Figure 2 Heatmaps showing the differences in aroma components in Prunus cerasifera fruit under MeJA treatment at three key developmental stages (S1, S2, and S3). Detailed Implementation

[0017] Various exemplary embodiments of the present invention are now described in detail. Unless otherwise specified, the methods used in the embodiments are conventional methods, and the reagents used are commercially available reagents or reagents prepared using conventional methods. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0018] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0019] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0020] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0021] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0022] Example 1: Aroma characteristics analysis of Prunus cerasifera fruit after MeJA treatment

[0023] To study the aroma characteristics of Prunus cerasifera fruit after MeJA treatment, volatile components of MeJA-treated Prunus cerasifera samples were extracted using the SH-SPME method and analyzed by GC-MS.

[0024] The specific method is as follows:

[0025] I. Experimental Materials

[0026] 1. Determining the spraying time. Based on the growth and development process of the European plum fruit, spraying should be carried out on a sunny morning between 8:00 and 10:00 before the fruit coloring and expansion stage and before the hardening stage. At this time, the temperature and humidity are moderate, which is conducive to the absorption of MeJA solution on the surface of leaves and fruit.

[0027] 2. Preparation of MeJA (purchased from Solarbio, model IM5630) solution. Prepare a MeJA solution with a final concentration of 20 mg / L. Taking 10 L of solution as an example, accurately weigh 200 mg of MeJA powder, add a small amount (10-20 ml) of anhydrous ethanol, stir thoroughly to dissolve, and then dilute to 10 L with distilled water. Prepare immediately before use.

[0028] 3. Whole-plant spraying with MeJA solution. Load the prepared MeJA solution into an electric sprayer and spray evenly over the entire Prunus cerasifera plant, ensuring small, even droplets form on the leaves and fruit surface without dripping. During spraying, adjust the nozzle angle to ensure even coverage of the fruit and leaves.

[0029] 4. Harvesting. Harvest the fruit after it has reached full ripeness. Select healthy fruit that is uniform in size, free from pests, diseases, and mechanical damage to ensure the representativeness and accuracy of the experimental results.

[0030] 5. Sample processing. The collected fruits were transported back to the laboratory in ice boxes, washed with distilled water and dried, then divided into 3 equal portions and flash-frozen in liquid nitrogen at -80 ℃ for storage until analysis.

[0031] II. Handling Methods

[0032] 1. HS-SPME Extraction Conditions: Under constant temperature of 60℃, shake for 5 min, insert a 120µm DVB / CWR / PDMS extraction tip into the sample headspace vial, perform headspace extraction for 15 min, followed by resolution at 250℃ for 5 min, and then perform GC-MS separation and identification. Before sampling, the extraction tip was aged at 250℃ for 5 min in a Fiber Conditioning Station. Note: New extraction tips were aged in a Fiber Conditioning Station for 2 h before extraction. Furthermore, an SPME Arrow was used, whose sensitivity is up to 10 times that of traditional SPME fiber tips.

[0033] 2. Chromatographic conditions: DB-5MS capillary column (30m × 0.25mm × 0.25μm, Agilent J & W Scientific, Folsom, CA, USA), carrier gas was high-purity helium (purity not less than 99.999%), constant flow rate was 1.2mL / min, injection port temperature was 250℃, and solvent delay was 3.5min. Temperature program: 40℃ held for 3.5min, increased to 100℃ at 10℃ / min, then increased to 180℃ at 7℃ / min, and finally increased to 280℃ at 25℃ / min, held for 5min.

[0034] 3. Mass spectrometry conditions: Electron impact ion source (EI), ion source temperature 230℃, quadrupole temperature 150℃, mass spectrometer interface temperature 280℃, electron energy 70eV, scanning mode selected ion detection mode (SIM), qualitative and quantitative ion precise scanning (GB23200.8-2016).

[0035] III. Data Analysis

[0036] The GC-MS detection platform of Maiwei Metabolism (Wuhan) Biotechnology Co., Ltd. was used, and the software Analyst 1.6.3 (Chong J, 2018) was employed for qualitative and quantitative mass spectrometry analysis, including baseline filtering, peak identification, integration, retention time correction, peak alignment, and mass spectrometry fragmentation analysis. Unsupervised principal component analysis (PCA) and supervised orthogonal partial least squares discriminant analysis (OPLS-DA) were used to perform multivariate statistical analysis on overall metabolites among groups and metabolites within groups.

[0037] IV. Aroma Characteristic Analysis

[0038] Using the control group as a reference, differentially expressed metabolites were screened using the criteria of VIP≥1, P-value>0.05, and |Log2FC|≥1. The characteristics of each key stage of *Prunus armeniaca* are shown in Tables 1-3. During the coloring and swelling stage, MeJA treatment significantly increased volatile metabolites with fruity aroma, such as 2-dodecenal, 5-methylhexanoic acid, and α,2,6,6-tetramethyl-1-cyclohexen-1-propanol, while decreasing volatile metabolites with sour, fishy, ​​and oily odors, such as 4,5-dimethylthiazole, (2-bromoethyl)ethylene oxide, and 2-methyl-3-heptanone. During the ripening stage, MeJA treatment increased volatile metabolites with fruity floral and sweet aromas, such as 2-hexyl furfurylate and α,2,6,6-tetramethyl-1-cyclohexen-1-propanol, while decreasing volatile metabolites with smoky and burnt odors, such as 2,4-dimethylphenol, 2-ethylphenol, and 6-methylquinoline. At full ripeness, MeJA treatment increased volatile metabolites such as 2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde, homolyl ester, and methyl nonanoate, which have fruity and floral aromas, while decreasing volatile metabolites such as carvyl propionate and cyclohexanol, which have metallic, camphor-like, and pungent odors.

[0039] Table 1. Aroma compounds of Prunus cerasifera fruit during the coloring and swelling stage after MeJA treatment.

[0040]

[0041] Table 1 (Continued) - Aroma compounds of Prunus cerasifera fruit during coloring and swelling stage after MeJA treatment

[0042]

[0043] Table 1 (Continued) - Aroma compounds of Prunus cerasifera fruit during coloring and swelling stage after MeJA treatment

[0044]

[0045] Note: a represents the increase in volatile metabolites after MeJA treatment; b represents the decrease in volatile metabolites after MeJA treatment. The unit of concentration is μg·ml. ﹣1 The descriptions in Tables 2 and 3 are the same.

[0046] Table 2. Aroma compounds of Prunus cerasifera fruit at ripening stage after MeJA treatment.

[0047]

[0048] Table 2 (Continued) Aroma compounds of Prunus cerasifera fruit at the ripening stage after MeJA treatment

[0049]

[0050] Table 3. Aroma compounds of fully ripe Prunus cerasifera fruit after MeJA treatment.

[0051]

[0052] Example 2: Aroma Component Difference Analysis

[0053] To assess the impact of MeJA treatment on plant metabolomics, orthogonal partial least squares discriminant analysis (OPLS-DA) was used to compare samples from the MeJA-treated group and the water control group. Figure 1 As shown in the OPLS-DA score plot, the MeJA treatment group and the control group exhibited a clear separation in their metabolic profiles, indicating that MeJA treatment significantly altered the metabolic composition of the plants. Simultaneously, some separation also existed between samples at different time points within the MeJA group, suggesting a time-dynamic metabolic response. The model evaluation parameter was R0. 2 Y=0.983, Q 2 =0.861, indicating that the model has a good fit and strong predictive ability. Further robustness of the model was verified through a permutation test (200 random permutations), and the results showed that the R-value of the original model was... 2 Y and Q 2 The values ​​were all significantly higher than those of the random permutation model, confirming that the model did not overfit and that the grouping was statistically significant. MeJA treatment can induce significant and reproducible changes in the metabolomic profile of plants, and these changes differ at different treatment time points, indicating its potential application value in regulating plant metabolism.

[0054] To further analyze the contribution of different aroma components in MeJA-treated fruits, based on the data analysis structure of this embodiment, volatile differential metabolites at three key developmental stages of Prunus cerasifera fruit were screened using the criteria of VIP≥1, P-value>0.05, and |Log2FC|≥1. Specifically, during the coloring and swelling stage, 69 differential aroma substances were screened, including 12 terpenes, 12 esters, 11 heterocyclic compounds, 11 alcohols, 2 ketones, 4 aldehydes, 2 hydrocarbons, 5 acids, 3 phenols, 3 aromatic hydrocarbons, 3 ethers, and 1 halogenated hydrocarbon. Figure 2 As shown in A and Table 1, compared to the CK group, the content of 18 volatile metabolites increased, while the content of 51 volatile metabolites decreased. During the hard-ripening period, 48 differential aroma compounds were screened, including 8 terpenes, 7 esters, 7 heterocyclic compounds, 6 alcohols, 4 ketones, 3 aldehydes, 4 hydrocarbons, 1 acid, 5 phenols, 4 aromatic hydrocarbons, 1 nitrogen-containing compound, and 1 ether. Figure 2 As shown in B and Table 2, compared to the CK group, the content of 8 volatile metabolites increased, while the content of 40 volatile metabolites decreased. Twenty-one differential aroma compounds were screened at full maturity, including 2 terpenes, 13 esters, 1 heterocyclic compound, 2 alcohols, 1 acid, and 1 phenol. Figure 2 As can be seen from Table C and Table 3, compared with the CK group, the content of 6 volatile metabolites increased and the content of 15 volatile metabolites decreased.

[0055] MeJA treatment induces significant and reproducible metabolomic changes in Prunus cerasifera fruit, with these changes exhibiting differential regulatory characteristics at different developmental stages. During the coloring and expansion stage and the hard-ripening stage, MeJA primarily enhances aroma and reduces astringency by upregulating the synthesis of characteristic fruit aroma compounds such as esters and aldehydes, while inhibiting the accumulation of some acids and heterocyclic compounds that produce unpleasant odors. At full ripeness, MeJA further optimizes the overall aroma quality of the fruit by significantly reducing the content of some alcohols, phenols, and heterocyclic compounds that produce pungent odors. This invention achieves aroma regulation in Prunus cerasifera fruit by spraying MeJA during key developmental stages. Compared to the water control, MeJA treatment significantly increases the content of esters and aldehydes that impart fruity and sweet aromas, while effectively reducing the relative content of acids, alcohols, phenols, and heterocyclic compounds that produce sour, astringent, fishy, ​​and pungent odors, thereby significantly improving the aroma quality and flavor characteristics of Prunus cerasifera fruit.

[0056] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for improving the flavor quality of European plum fruit, characterized in that, Spray the entire plant with methyl jasmonate solution before the coloring and swelling period of the plum fruit. Spray twice before the coloring and swelling period, with an interval of 10 days. Spray once during the coloring and swelling period to the hardening stage, for a total of 3 sprays.

2. The method according to claim 1, characterized in that, The final concentration of the methyl jasmonate solution is 20 mg / L.

3. The method according to claim 1, characterized in that, Spray the entire plant of the European plum on a sunny morning between 8:00 and 10:

00.

4. The method according to claim 1, characterized in that, Use an electric sprayer to spray the entire plant.

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