Polypeptide with fruit and vegetable fresh-keeping function, derivative thereof and application thereof

Abstract

The application relates to the field of postharvest preservation of fruits and vegetables, and particularly discloses a polypeptide and a derivative thereof with fruit and vegetable preservation functions and applications. The polypeptide comprises the following two kinds: DP1, the amino acid sequence of which is VTLLDLIKDVEM; and DP2, the amino acid sequence of which is SRKNVTAYGSLG. Research shows that the polypeptide can interact with a key receptor protein in a plant ethylene signal pathway, thereby inhibiting ethylene signal transmission and delaying the fruit and vegetable ripening and aging process. The polypeptide or the derivative thereof is applied to the surface of fruits and vegetables in a spraying or soaking mode, and can significantly reduce the fruit peel browning and rotting rate and prolong the shelf life of the fruits and vegetables under normal temperature or cold chain storage conditions. The polypeptide has the advantages of small molecular weight, good stability, high safety, convenient use and the like, and is suitable for postharvest preservation of various fruits and vegetables such as tomatoes, mangoes and the like.

Description

Technical Field

[0001] This invention relates to the field of postharvest preservation technology for fruits and vegetables, specifically to polypeptides and their derivatives with fruit and vegetable preservation functions and their applications. Background Technology

[0002] Fruits and vegetables are highly susceptible to quality deterioration during postharvest storage and transportation, including accelerated ripening, softening, browning, and rotting, resulting in significant economic losses. Ethylene, an important endogenous gaseous hormone in plants, plays a crucial regulatory role in the ripening and senescence of fruits and vegetables. Particularly in climacteric fruits and vegetables such as tomatoes, mangoes, bananas, and apples, the activation of ethylene signals significantly accelerates fruit coloring and senescence. Therefore, effectively regulating ethylene activity and delaying fruit and vegetable ripening has always been a key research focus in the field of postharvest preservation.

[0003] Existing fruit and vegetable preservation technologies mainly include low-temperature storage, modified atmosphere storage, and chemical preservative treatment. While low-temperature storage and modified atmosphere storage can delay fruit and vegetable ripening to some extent, they suffer from high energy consumption, high equipment costs, and limited applicability. Chemical preservatives, such as 1-methylcyclopropene (1-MCP), work by inhibiting ethylene receptors' sensing of ethylene. Although they have shown some effectiveness in practical applications, they still have drawbacks such as a single target, limited processing conditions, and concerns from some consumers regarding their safety and residues. Furthermore, these methods primarily focus on blocking ethylene production or sensing, with limited regulation of the intracellular transduction of ethylene signals.

[0004] In recent years, with the deepening of research on the ethylene signaling pathway in plants, people have gradually realized that the transmission of ethylene signals not only depends on the ethylene receptor itself, but also involves the interaction between the receptor and downstream signal transduction proteins. However, there are still few regulatory strategies targeting the protein interaction level in the ethylene signaling pathway, and there is a lack of fruit and vegetable preservation technologies that can precisely regulate the ethylene signal transduction process while being safe and operable (KLEIN S, FIEBIG A, NEUWALD D, et al. Influence of the ethylene-related signal-inhibitingoctapeptide NOP-1 on postharvest ripening and quality of 'Golden Delicious' apples [J]. J Sci Food Agric, 2019, 99(8): 3903-3909.).

[0005] Therefore, there is an urgent need to develop a new fruit and vegetable preservation technology with a clear mechanism of action, high safety, and easy application, in order to overcome the shortcomings of existing preservation methods and provide a new technical approach for post-harvest preservation of fruits and vegetables. Summary of the Invention

[0006] To address the problems of unclear mechanisms of action, single regulatory targets, and limited safety and applicability in existing postharvest preservation technologies for fruits and vegetables, the present invention aims to provide polypeptides and their derivatives with fruit and vegetable preservation functions. These polypeptides, derived from plant endogenous proteins, can delay fruit and vegetable ripening and senescence by regulating ethylene signaling processes, thereby effectively reducing the incidence of postharvest rot and quality deterioration, and extending the shelf life of fruits and vegetables.

[0007] A further objective of this invention is to provide a novel preservation technology with a clear mechanism of action, simple usage, and applicability to a variety of fruits and vegetables, in order to compensate for the shortcomings of existing fruit and vegetable preservation methods in terms of ethylene signal transduction and regulation.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution.

[0009] This invention provides a polypeptide with fruit and vegetable preservation function, named DP1, whose amino acid sequence is shown in SEQ ID NO.1.

[0010] The present invention also provides a polypeptide with fruit and vegetable preservation function, named DP2, whose amino acid sequence is shown in SEQ ID NO.2.

[0011] Furthermore, DP1 or DP2 can bind to the GAF domain ETR1-GAF of the plant ethylene receptor ETR1, and block the downstream transmission of ethylene signals by inhibiting the interaction between the ethylene signal transduction protein EIN2 and the ethylene receptor ETR1, thereby delaying the ripening and senescence of fruits and vegetables.

[0012] The present invention also provides a polypeptide derivative with fruit and vegetable preservation function. The polypeptide derivative is obtained by modifying the above-mentioned DP1 or DP2 with end groups. The end group modification is selected from: N-terminal acetylation, C-terminal amidation, or a combination thereof.

[0013] The present invention also provides a polypeptide derivative with fruit and vegetable preservation function. The polypeptide derivative is obtained by modifying the above-mentioned DP1 or DP2 to improve stability. The modification is selected from: PEGylation, fatty acidation, cyclization or N-methylation.

[0014] This invention also provides a polypeptide derivative with fruit and vegetable preservation function. The polypeptide derivative is obtained by solid-phase synthesis method, which involves conservative substitution of 1-3 amino acid sites in DP1 or DP2. The conservative substitution is carried out according to the following amino acid sets, and amino acids in the same set can be substituted for each other: (i) hydrophobic aliphatic: V, I, L, M; (ii) acidic: D, E; (iii) basic: K, R, H; (iv) polar and uncharged: S, T, N, Q; (v) aromatic: F, Y, W; (vi) small volume: A, G.

[0015] The present invention also provides the application of the above-mentioned polypeptides or polypeptide derivatives with fruit and vegetable preservation functions in postharvest preservation of fruits and vegetables, for delaying the ripening and aging process of fruits and vegetables.

[0016] Furthermore, the fruits and vegetables are climacteric fruits and vegetables, including one or more of tomatoes, mangoes, bananas, apples, and kiwis.

[0017] Furthermore, peptides or peptide derivatives are applied to the surface of fruits and vegetables by spraying or soaking.

[0018] Furthermore, the concentration of the polypeptide or polypeptide derivative is 100 μmol / L to 400 μmol / L.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The polypeptide with fruit and vegetable preservation function provided by this invention is derived from plant endogenous protein. It has a small molecular weight, simple structure, good safety and biocompatibility, and is suitable for post-harvest preservation of fruits and vegetables.

[0021] The polypeptides or polypeptide derivatives with fruit and vegetable preservation function provided by this invention achieve precise control of the fruit and vegetable ripening process by regulating the ethylene signal transduction process rather than simply inhibiting ethylene production or sensing. The mechanism of action is clear and is different from existing chemical preservatives and physical preservation methods.

[0022] The polypeptides or polypeptide derivatives with fruit and vegetable preservation function provided by this invention can be applied to the surface of fruits and vegetables by spraying or soaking. The application method is simple and suitable for room temperature or cold chain storage conditions, and has good prospects for practical application.

[0023] Experimental results show that the polypeptides or polypeptide derivatives with fruit and vegetable preservation functions provided by this invention can significantly delay the aging process of fruits and vegetables, reduce the incidence of browning and rot of fruit peels, and effectively extend the shelf life of fruits and vegetables. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the mechanism of action of the polypeptide with fruit and vegetable preservation function in regulating ethylene signal transduction provided by the present invention.

[0025] Figure 2 Elution curves of the GAF domain protein (ETR1-GAF) of the ethylene receptor ETR1 obtained by affinity chromatography and molecular sieve chromatography.

[0026] Figure 3 SDS-PAGE results of expression and purification of ETR1-GAF and the C-terminal fragment of EIN2 (EIN2-C) (a: ETR1-GAF; b: EIN2-C).

[0027] Figure 4 The image shows the heteronuclear single quantum coherence (HSQC) spectrum of the interaction between EIN2-C and the ethylene acceptor ETR1-GAF.

[0028] Figure 5 This is an enlarged view of the region where significant chemical shift perturbation (CSP) occurs in the interaction region between EIN2-C and the ethylene acceptor ETR1-GAF.

[0029] Figure 6 The distribution of chemical shift perturbations (CSPs) of each residue in EIN2-C after the addition of ETR1-GAF.

[0030] Figure 7 This is a schematic diagram showing the binding kinetics of the interaction between the polypeptide DP1, which has fruit and vegetable preservation function, and the ethylene receptor ETR1-GAF protein.

[0031] Figure 8 This is a schematic diagram showing the binding kinetics of the interaction between the polypeptide DP2, which has fruit and vegetable preservation function, and the ethylene receptor ETR1-GAF protein.

[0032] Figure 9 This is a schematic diagram illustrating the preservation effect of polypeptides DP1 and DP2, which have fruit and vegetable preservation functions, on tomatoes.

[0033] Figure 10 This is a schematic diagram illustrating the preservation effect of polypeptides DP1 and DP2, which have fruit and vegetable preservation functions, on mangoes. Detailed Implementation

[0034] The present invention will be further illustrated below with specific examples, but the implementation and protection scope of the present invention are not limited thereto.

[0035] Example 1: Expression and purification of ETR1-GAF protein and EIN2-C

[0036] To verify the interaction between the polypeptide with fruit and vegetable preservation function provided by the present invention and the ethylene receptor ETR1 and its downstream signal transduction protein EIN2, this embodiment expresses and purifies the GAF domain (ETR1-GAF) protein of the ethylene receptor ETR1 and the C-terminal fragment (EIN2-C) of EIN2, respectively.

[0037] The amino acid sequence (residues 1-307) corresponding to the GAF domain of the Arabidopsis thaliana ethylene receptor ETR1 was selected and cloned into an expression vector (pPICZA) with a tag sequence to construct the ETR1-GAF recombinant expression vector. This vector was transformed into a Pichia pastoris expression host for amplification and expression. The transformed engineered bacteria were cultured under induction conditions to promote the expression of the ETR1-GAF protein. After culture, the bacterial cells were collected and disrupted to obtain a crude extract. Membrane protein components were obtained by ultracentrifugation and dissolved in a buffer system containing surfactant (50 mM Tris-HCl, 200 mM NaCl, 0.01 g / mL Fos-choline-1).

[0038] The dissolved protein solution was purified sequentially by affinity chromatography to remove impurities, yielding enriched ETR1-GAF protein. Further purification was then performed using molecular sieve chromatography, and monomeric and dimer forms of ETR1-GAF protein were separated based on elution peak shapes. The dimer form of ETR1-GAF protein was selected for subsequent interaction studies with EIN2-C and peptides with fruit and vegetable preservation functions.

[0039] Figure 2 The elution curves of ETR1-GAF protein obtained by affinity chromatography and molecular sieve chromatography are shown, with an elution peak appearing at 8.5-14 mL.

[0040] Figure 3 Figure 'a' shows the SDS-PAGE results of ETR1-GAF expression and purification. M represents the standard molecular weight marker. Lane 1 corresponds to a fraction with an elution volume of 8.5-9.0 mL by molecular sieve chromatography; lane 2 corresponds to a fraction with an elution volume of 9.0-9.5 mL; lane 3 corresponds to a fraction with an elution volume of 9.5-10.0 mL; lane 4 corresponds to a fraction with an elution volume of 10.0-10.5 mL; lane 5 corresponds to a fraction with an elution volume of 10.5-11.0 mL; lane 6 corresponds to a fraction with an elution volume of 11.0-11.5 mL; lane 7 corresponds to a fraction with an elution volume of 11.5-12.0 mL; lane 8 corresponds to a fraction with an elution volume of 12.0-12.5 mL; lane 9 corresponds to a fraction with an elution volume of 12.5-13.0 mL; lane 10 corresponds to a fraction with an elution volume of 13.0-13.5 mL; and lane 11 corresponds to a fraction with an elution volume of 13.5-14.0 mL.

[0041] SDS-PAGE analysis showed that the obtained ETR1-GAF protein had good purity and homogeneity, meeting the requirements for subsequent experiments.

[0042] Concurrently, the amino acid sequence corresponding to the C-terminal fragment of the Arabidopsis thaliana ethylene signal transduction protein EIN2 was selected, and its coding sequence was cloned into a prokaryotic expression vector (PETM44) to construct the EIN2-C recombinant expression vector. This vector was transformed into *E. coli* expression hosts, and expression was performed under induction conditions. After culture, the bacterial cells were collected and disrupted to obtain a crude extract containing EIN2-C. The EIN2-C protein was initially purified by affinity chromatography, and further purified using molecular sieve chromatography to obtain a homogeneous EIN2-C protein.

[0043] Figure 3 Figure b shows the SDS-PAGE results of EIN2-C expression and purification. M represents the standard molecular weight marker. SDS-PAGE analysis shows that the EIN2-C protein has high purity and is suitable for subsequent interaction analysis.

[0044] Using the above method, ETR1-GAF protein and EIN2-C protein were successfully obtained for subsequent nuclear magnetic resonance analysis and biolayer interference binding experiments, providing an experimental basis for the study of the mechanism of action of the peptide with fruit and vegetable preservation function provided by this invention.

[0045] Example 2: Delineation of the interaction region between EIN2-C and the ethylene receptor ETR1-GAF

[0046] To identify the key regions in the ethylene signaling protein EIN2 involved in its interaction with the ethylene receptor ETR1, this study analyzed the interaction between EIN2-C and ETR1-GAF proteins. The interaction process between EIN2-C and ETR1-GAF was monitored using solution-state NMR. The results showed that in the presence of ETR1-GAF, the signals corresponding to certain amino acid residues in EIN2-C underwent significant changes, suggesting a direct interaction between EIN2-C and ETR1-GAF.

[0047] Figure 4-6 The interaction region between EIN2-C and the ethylene receptor ETR1-GAF is shown.

[0048] Figure 4 The results of heteronuclear single quantum coherence (HSQC) spectrum of the interaction between EIN2-C and the ethylene acceptor ETR1-GAF are shown. Figure 5This image shows a magnified view of the region where significant chemical shift perturbation (CSP) occurs in the interaction region between EIN2-C and the ethylene acceptor ETR1-GAF. All four images in the figure are... Figure 4 The image shows a magnified view of the corresponding horizontal and vertical coordinate regions. The image reveals several relatively concentrated signal variation regions within EIN2-C, indicating that its integration with ETR1-GAF involves multiple segments.

[0049] Figure 6 The distribution of chemical shift perturbations (CSPs) of each residue in EIN2-C after the addition of ETR1-GAF is shown. The distribution of EIN2-C residues that undergo significant chemical shift perturbations after the addition of ETR1-GAF is marked, thereby defining several key peptide regions that interact with ETR1-GAF, providing a basis for screening peptides such as DP1 and DP2 with fruit and vegetable preservation functions.

[0050] Based on the above results, several peptides closely related to the interaction of ETR1-GAF were selected from EIN2-C as candidate polypeptides with fruit and vegetable preservation functions, including DP1 and DP2 as described in subsequent examples.

[0051] Example 3: Verification of the interaction between the fruit and vegetable preservation peptide DP1 and the ethylene receptor ETR1-GAF protein.

[0052] To verify whether the polypeptide DP1 with fruit and vegetable preservation function provided by this invention can interact with the plant ethylene receptor ETR1, this embodiment uses biolayer interference technology to detect the binding behavior between DP1 and the ETR1-GAF protein. DP1 can be obtained according to its amino acid sequence using conventional polypeptide synthesis methods (such as solid-phase synthesis methods).

[0053] The recombinantly expressed and purified ETR1-GAF protein was immobilized on the surface of the Anti-Penta-HIS (HIS1K) biosensor. After establishing a stable baseline in a buffer system (buffer: 50 mM Tris-HCl, 200 mM NaCl, 0.0005 g / mL Fos-choline-14), DP1 peptides with fruit and vegetable preservation functions at concentrations of 5.25, 15.7, 47.2, 141.7, and 425 μM were sequentially added to the reaction system, and the changes in the sensor response signal over time were monitored in real time.

[0054] Experimental results showed that DP1 exhibited a significant concentration-dependent binding characteristic with the immobilized ETR1-GAF protein, and the biolayer interference response signal gradually increased with increasing DP1 concentration. During the dissociation phase, after replacing the reaction system with a buffer solution free of DP1, the sensor signal gradually decreased, indicating a reversible interaction between DP1 and the ETR1-GAF protein. Using a Ni-NTA sensor, ETR1-GAF immobilization at 25℃, and a buffer solution containing Tris, NaCl, and the surfactant Fos-choline-14, and employing a 1:1 binding model, global fitting of the experimental data yielded an apparent dissociation constant (KD) of 81.71 ± 0.96 μM between DP1 and the ETR1-GAF protein through biolayer interference.

[0055] Figure 7 The binding kinetics of the interaction between the fruit and vegetable preservation peptide DP1 and the ethylene receptor ETR1-GAF protein are shown. The binding and dissociation curves between DP1 and the ETR1-GAF protein immobilized on the surface of the HIS1K biosensor at different concentrations are displayed by biolayer interferometry (BLI). The apparent dissociation constant (KD) of the interaction between the two is obtained by global fitting, which is used to illustrate that there is a reversible, concentration-dependent specific binding between DP1 and the ethylene receptor.

[0056] The above results indicate that the polypeptide DP1 with fruit and vegetable preservation function provided by the present invention can directly bind to the GAF domain of the ethylene receptor ETR1, but its binding affinity is relatively weak, which provides experimental support for its role in regulating ethylene signaling during postharvest preservation of fruits and vegetables.

[0057] Example 4: Verification of the interaction between the fruit and vegetable preservation peptide DP2 and the ethylene receptor ETR1-GAF protein.

[0058] To further verify the binding characteristics of different peptides with fruit and vegetable preservation functions to the ethylene receptor ETR1, this embodiment uses the same biolayer interference method as in Example 2 to detect the interaction between the fruit and vegetable preservation peptide DP2 and the ETR1-GAF protein. DP2 can be obtained according to its amino acid sequence using conventional peptide synthesis methods (such as solid-phase synthesis).

[0059] After immobilizing the ETR1-GAF protein on the surface of the HIS1K biosensor, DP2 peptide solutions with concentrations of 14.8, 44.4, 133, 400, and 1200 μM were added sequentially, and the changes in the sensor response signal over time were recorded in real time.

[0060] Experimental results showed that DP2 and ETR1-GAF protein exhibited a significant concentration-dependent binding behavior, with the response signal rapidly increasing and stabilizing during the binding phase. During the dissociation phase, replacing the reaction system with a buffer solution lacking DP2 resulted in a smaller decrease in the sensor signal, indicating a relatively stable interaction between DP2 and ETR1-GAF protein. Global fitting analysis of the experimental data was performed under the following conditions: Ni-NTA sensor, ETR1-GAF immobilization at 25℃, buffer solution containing Tris, NaCl, and the surfactant Fos-choline-14, and using a 1:1 binding model. Biolayer interferometry yielded an apparent dissociation constant (KD) of 16.38 ± 0.23 μM between DP2 and ETR1-GAF protein.

[0061] Figure 8 The binding kinetics of the interaction between the polypeptide DP2, which has fruit and vegetable preservation function, and the ethylene receptor ETR1-GAF protein are shown.

[0062] Figure 8 Also based on biological layer interferometry (BLI), the binding and dissociation behavior of DP2 with ETR1-GAF protein under different concentration conditions was shown, and the corresponding KD fitting results were given to illustrate that DP2 and ethylene receptor have high binding affinity and relatively stable interaction characteristics.

[0063] Compared with the experimental results of DP1 in Example 3, the apparent dissociation constant between DP2 and the ETR1-GAF protein was significantly reduced, indicating that it has higher binding affinity and more stable binding properties. These results suggest that DP2 is more conducive to forming a stable interaction with the ethylene receptor ETR1, providing experimental evidence for its more significant ethylene signaling regulation effect during postharvest preservation of fruits and vegetables.

[0064] Figure 1 The diagram illustrates the mechanism of action of the polypeptide with fruit and vegetable preservation function regulating ethylene signal transduction provided by the present invention. TM1-TM3 are the three transmembrane domains of ETR1, DHp and CA are collectively referred to as the histidine kinase domain, and RD is the receiver domain.

[0065] Figure 1 In the ethylene signaling pathway, the polypeptides DP1 and DP2 provided by this invention, which have the function of preserving fruits and vegetables, interact with the GAF domain of the ethylene receptor ETR1, weakening the binding of ETR1 to EIN2, thereby regulating the downstream transmission of ethylene signals, hindering ethylene signal transduction, and thus delaying the ripening and senescence of fruits and vegetables.

[0066] Since DP1 or DP2 are peptides in EIN2-C that are closely related to the interaction with ETR1-GAF, the binding of DP1 or DP2 to ETR1-GAF will hinder the interaction between ETR1-GAF and EIN2-C. Their binding will competitively inhibit the interaction between EIN2 and the receptor, thereby blocking signal transduction.

[0067] Example 5: The Preservation Effect of Polypeptides with Fruit and Vegetable Preservation Function on Tomatoes

[0068] Prepare the buffer solution (50mM Tris-HCl, 300mM NaCl, 0.0015g / mL Fos-choline-14).

[0069] Fresh, unripe tomatoes of uniform maturity, size, and without mechanical damage or lesions were selected as experimental materials. The tomatoes were washed with clean water and then surface-sterilized, and allowed to air dry. The polypeptide DP1, which has fruit and vegetable preservation function provided by this invention, was dissolved in buffer solution to prepare concentrations of 100 and 200 μM, and DP2 was dissolved in buffer solution to prepare concentrations of 200 and 400 μM. These solutions were applied evenly to the surface of the tomato fruits using a spraying method, ensuring complete coverage of the peel. The control group was sprayed only with the same volume of buffer solution without the polypeptide.

[0070] After treatment, tomatoes were stored at room temperature (24-26℃) under the same environmental conditions, and changes in appearance were recorded and photographed at the same time points during storage. By comparing the changes in skin color, reddening process, and overall ripening status of tomatoes in different treatment groups during storage, the effects of peptides with fruit and vegetable preservation functions on the ripening and senescence process of tomatoes were evaluated.

[0071] Experimental results are as follows Figure 9 As shown in the figure, the appearance changes of tomatoes during room temperature storage were compared between the control group and tomatoes treated with different peptides with fruit and vegetable preservation functions and different concentrations, including the process of the peel color changing from green to orange-red and then to red, to illustrate that the peptides with fruit and vegetable preservation functions provided by the present invention can delay the ripening and aging process of tomatoes.

[0072] The control group tomatoes rapidly changed color from green to orange-red and eventually reached full ripeness during storage, exhibiting a faster ripening process. Tomatoes treated with peptides possessing fruit and vegetable preservation functions showed a significantly slower skin color change and a significantly slower ripening rate compared to the control group. Furthermore, different peptides with fruit and vegetable preservation functions and different treatment concentrations showed varying effects on inhibiting the ripening process of tomatoes.

[0073] Compared to the DP1 treatment group, the DP2 treatment group showed that tomatoes retained more green or yellowish-green areas within the same storage time, demonstrating a more significant effect in delaying ripening. Furthermore, the inhibitory effect on tomato color change and ripening was further enhanced with increasing DP2 concentration. The DP2 treatment group exhibited a more significant preservation effect at higher concentrations; under these conditions, the tomatoes maintained a relatively intact appearance during the later stages of storage, without showing obvious softening or overripeness.

[0074] The above results indicate that the polypeptide with fruit and vegetable preservation function provided by the present invention can effectively delay the ripening process of tomatoes. Among them, DP2, as the preferred embodiment, shows a more significant preservation effect at higher treatment concentrations, indicating that it has good application potential in the field of postharvest preservation of fruits and vegetables.

[0075] Example 6: The Preservative Effect of Polypeptides with Fruit and Vegetable Preservation Function on Mangoes

[0076] Prepare the buffer solution (50mM Tris-HCl, 300mM NaCl, 0.0015g / mL Fos-choline-14).

[0077] To further verify the preservation effect of the polypeptide with fruit and vegetable preservation function provided by the present invention in different climacteric fruits, mango was used as a representative object to verify the application effect of the polypeptide with fruit and vegetable preservation function in the postharvest storage process.

[0078] Fresh mangoes with uniform maturity, size, and no mechanical damage or obvious lesions were selected as experimental materials. Before the experiment, the mangoes were cleaned and air-dried. The mangoes were then randomly divided into a control group and a peptide treatment group. The peptide treatment group included DP1 and DP2 treatment groups, each dissolved in buffer solution at concentrations of 100 and 200 μM.

[0079] The peptides DP1 and DP2, which have fruit and vegetable preservation functions, were dissolved in buffer solution and applied evenly to the surface of mango peel by spraying to form a continuous coating layer. The control group mangoes were treated with the same volume of buffer solution without the peptides. After treatment, the mangoes in each group were stored at room temperature.

[0080] During storage, the appearance of mangoes in each treatment group was recorded at predetermined time points, and the formation of black spots on the peel surface was observed and analyzed. The percentage of black spots on the peel surface relative to the total peel area was used as an indicator of the degree of decay. When no identifiable black spots were detected on the peel surface, the decay rate was not recorded at the corresponding time point.

[0081] Experimental results are as follows Figure 10As shown in the figure, the formation of black spots on the peel and the decay process of mangoes treated with different concentrations of DP1 and DP2 during the storage process are illustrated. The figure may include quantitative statistical results of the proportion of black spot area or decay rate at each time point, which are used to illustrate that the polypeptide with fruit and vegetable preservation function provided by the present invention can effectively delay the occurrence of decay and reduce the coverage of black spots on the peel in the post-harvest storage of mangoes, and has a good preservation effect.

[0082] Compared to the control group, mangoes treated with peptides possessing fruit and vegetable preservation functions showed a generally delayed onset of black spots on the peel and a slower rate of decay during storage. Specifically, the DP2 treatment group exhibited a certain preservation effect under different concentrations, with the effect becoming more pronounced as the concentration increased. At higher concentrations, DP2-treated mangoes maintained a lower degree of black spot coverage in the later stages of storage, and the overall decay process was significantly slower than that of the low-concentration DP2 and DP1 treatment groups.

[0083] In comparison, although DP1 also slowed down the decay process of mangoes to some extent, under the same conditions, its inhibitory effect on the formation of black spots on the peel was weaker than that of DP2, and some fruits still showed obvious decay in the later stages of storage.

[0084] The above results indicate that the polypeptide DP2 with fruit and vegetable preservation function provided by the present invention has a good preservation effect during the post-harvest storage of mangoes, and its preservation effect has obvious concentration-dependent characteristics, making it suitable for post-harvest preservation treatment of fruits and vegetables.

Claims

1. A polypeptide with fruit and vegetable preservation function, characterized in that, It was named DP1, and its amino acid sequence is shown in SEQ ID NO.

1.

2. A polypeptide with fruit and vegetable preservation function, characterized in that, It was named DP2, and its amino acid sequence is shown in SEQ ID NO.

2.

3. The polypeptide according to claim 1 or 2, characterized in that, The DP1 or DP2 can bind to the GAF domain ETR1-GAF of the plant ethylene receptor ETR1.

4. A polypeptide derivative with fruit and vegetable preservation function, characterized in that, The polypeptide derivative is obtained by modifying the polypeptide of claim 1 or 2 with terminal groups, wherein the terminal group modification is selected from: N-terminal acetylation, C-terminal amidation, or a combination thereof.

5. A polypeptide derivative with fruit and vegetable preservation function, characterized in that, The polypeptide derivative is obtained by modifying the polypeptide of claim 1 or 2 to improve its stability, wherein the modification is selected from: PEGylation, fatty acidation, cyclization or N-methylation.

6. The application of the polypeptide according to any one of claims 1-2 or the polypeptide derivative according to any one of claims 4-5 in postharvest preservation of fruits and vegetables, characterized in that, The polypeptide or polypeptide derivative is used to delay the ripening and aging process of fruits and vegetables; the fruits and vegetables are one or more of tomatoes and mangoes.

7. The application according to claim 6, characterized in that, The polypeptide or polypeptide derivative is applied to the surface of fruits and vegetables by spraying or soaking.

8. The application according to claim 7, characterized in that, The concentration of the polypeptide or polypeptide derivative is 100 μmol / L to 400 μmol / L.

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