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Article

Natural Variation in the AAT1 Promoter Is Responsible for the Disparity in Ester Aroma Between Actinidia chinensis and Actinidia eriantha

by
Qing Cao
1,2,†,
Zhenyu Huang
3,4,†,
Jinyin Chen
1,† and
Zengyu Gan
1,*
1
Jiangxi Provincial Key Laboratory for Postharvest Storage and Preservation of Fruits and Vegetables, Jiangxi Agricultural University, Nanchang 330045, China
2
School of Hydraulic and Ecological Engineering, Nanchang Institute of Technology, Nanchang 330099, China
3
National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops, Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou 450009, China
4
Zhongyuan Research Center, Chinese Academy of Agricultural Sciences, Xinxiang 453500, China
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Agronomy 2024, 14(12), 2965; https://doi.org/10.3390/agronomy14122965
Submission received: 22 November 2024 / Revised: 9 December 2024 / Accepted: 10 December 2024 / Published: 12 December 2024
(This article belongs to the Section Horticultural and Floricultural Crops)
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Abstract

:
To understand ester compound biosynthesis in kiwifruit, two Actinidia species with distinct characteristics were compared. The firmness of Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits gradually decreased as the fruit ripened after harvest, whereas the total soluble solids increased continuously, reaching a peak on the 8th day. The Ganlv-1 fruit ester content was significantly lower than in the Donghong fruits at the optimal eating stage, and the alcohol acyltransferase (AAT) activity in the Ganlv-1 fruits was significantly lower than in the Donghong fruits. The gene expression levels of AAT1 and AAT17 in the Donghong fruits were significantly higher than in the Ganlv-1 fruits, with a particularly remarkable difference observed for AAT1, which exhibited a 36-fold higher expression in the Donghong fruits when compared with the fully ripened Ganlv-1 fruits. A transient overexpression of the AAT1 gene in the kiwifruit led to a significant increase in ester content. Interestingly, a natural variation was observed in the promoter sequence of AAT1 between the Donghong and Ganlv-1 cultivars. Furthermore, separate analyses of the respective promoter activities revealed significantly higher activity levels in the Donghong fruits than in the Ganlv-1 fruits. In conclusion, a natural variation in the AAT1 promoter is primarily responsible for the disparity in AAT1 gene expression between the Donghong and Ganlv-1 fruits, resulting in a divergent accumulation of ester aroma compounds during the postharvest ripening stages.

1. Introduction

Kiwifruit, a dioecious deciduous climbing perennial plant, is widely cultivated as an economical fruit crop in temperate regions due to its flavor and high nutritional content, which makes it highly favored by consumers [1]. Kiwifruit is native to China, where 52 of 54 species of the genus Actinidia are naturally distributed [2]. Currently, the primarily cultivated kiwifruits include Actinidia chinensis, Actinidia deliciosa, Actinidia arguta, and Actinidia eriantha [1].
Aroma refers to the volatile compounds that can be perceived through olfaction and gustation and is an essential indicator of fruit flavor quality [3]. Fruits possess distinct aroma profiles that contribute to their diverse flavor characteristics. The aroma profiles are associated with the unique “aroma fingerprint” or “aroma characteristic spectrum” of each fruit, serving as a crucial parameter for evaluating fruit quality [4]. With the advancement of headspace solid-phase microextraction gas chromatography and mass spectrometry (HS-SPME/GC-MS) techniques, volatile aroma compounds have been isolated and identified from various fruits, such as citrus [5], apple [6], pear [7], and kiwifruit [8]. Notably, the types and compositions of fruit aroma constituents vary significantly across different cultivars [7,9,10,11,12]. The aroma profile of kiwifruit is diverse, with over 300 volatile compounds, predominantly including aldehydes, ketones, esters, acids, alcohols, and hydrocarbons [13]. Esters are the primary aroma compounds present in Actinidia chinensis during fruit postharvest ripening; however, they do not dominate in Actinidia eriantha [14,15,16].
Fatty acid metabolism is the primary pathway of kiwifruit aroma biosynthesis. Fatty acids in fruits are catalyzed by fatty acid desaturases to produce unsaturated fatty acids such as linoleic acid and linolenic acid [17]. Through the action of lipoxygenase (LOX), linoleic and linolenic acids are decomposed into hydroperoxides which are subsequently catalyzed by hydroperoxide lyase (HPL) to generate the corresponding aldehydes and oxygenated compounds [17,18]. Subsequently, specific alcohols are synthesized using alcohol dehydrogenase (ADH) [18]; alcohol and alkyl-coenzyme A then undergo catalysis by alcohol acyltransferases (AAT) to form their respective ester compounds [19]. The rate-limiting enzyme in the ester biosynthesis pathway is AAT. During fruit ripening, significant quantities of volatile ester aroma compounds are generated. There is a strong positive correlation between AAT activity and the ester compound content in fruits. As the concentration of AAT enzymes increases, the ester component levels also gradually increases [20].
The AAT protein is encoded by members of the polygenic family. Currently, AAT genes have been isolated and cloned from fruits, such as pears [21] and strawberries [22,23], with these AAT genes belonging to the BAHD family. Certain members of the AAT gene family positively correlate with AAT enzyme activity and play a role in the regulation of ester aroma formation. Previous studies have reported significant positive correlations between the expression of SAAT, FcAAT1, and FaAAT2 in strawberries [22,23], MdAAT1/2 in apples [24,25], and PpAAT1 in peaches [26], with the ester aroma content in these fruits. Thirty AAT genes have been identified in the Actinidia EST database, 12 of which are potential candidate genes for ester aroma formation [27]. The expression of AAT1 and AAT17 genes is upregulated with kiwifruit ripening, and is induced by ethylene, indicating that AAT1 and AAT17 may serve as the pivotal genes involved in ester aroma biosynthesis in kiwifruit [28].
Donghong (Actinidia chinensis) is one of the primary kiwifruit cultivars, whereas Ganlv-1 (Actinidia eriantha) is a new variety which has been developed in recent years. However, limited research is available regarding the ester aroma components in both varieties. The objective of this study was to compare the characteristics of the ester aroma components of the Donghong and Ganlv-1 cultivars during postharvest ripening. To elucidate the disparities in ester aroma formation during fruit ripening, we quantified the relative expression levels of genes involved in ester aroma biosynthesis, and compared the promoter activities of key differentially expressed genes. This study elucidated the underlying factors contributing to the disparity in ester aroma formation during the ripening process of distinct kiwifruit species, thereby facilitating a comprehensive understanding and the effective management of postharvest quality control measures for kiwifruit.

2. Materials and Methods

2.1. Material Collection

Two kiwifruit varieties, Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha), were harvested from a kiwifruit germplasm resource nursery in Fengxin County, Jiangxi Province, China, which exhibits a warm climate and sandy soil. All fruits were collected during the commercial harvesting period (Donghong, total soluble solids (TSS) 6.5~7.0%; Ganlv-1, TSS 7.0–7.5%) and transported to the laboratory for analysis. Next, uniform-sized fruits free from physical damage were selected and stored at room temperature (20 ± 1 °C) for 10 d until the fruits were completely softened. Each kiwifruit variety consisted of 200 fruits, with all experiments repeated in triplicate. Samples were collected every two days, and the fruits from each kiwifruit variety were subjected to washing and peeling procedures. The pulp (excluding the seeds) was collected for subsequent analysis.

2.2. Fruit Firmness and the TSS

Fruit firmness and the TSS were determined using an established methodology [29]. After removing the 1-mm-thick peel, the firmness of both sides of each fruit was measured using a fruit texture analyzer (TMS-Touch, FTC, Tinton Falls, NJ, USA) equipped with a 7.9 mm probe. Fifteen fruits were measured in each trial, and the results were denoted as N. The TSS were determined using a refractometer (PL-1, ATAGO, Kyoto, Japan). The juice was extracted from each fruit and collected by squeezing it from both ends. Subsequently, three drops of juice were extracted using an eye dropper and placed onto a refractometer to determine the TSS. This process was repeated for the nine bioreplicate samples per treatment at each sampling point.

2.3. Extraction and Determination of Esters

Approximately 0.5 g of kiwifruit sample was ground into a fine powder and placed into a 20 mL headspace vial containing 0.4 g mL−1 saturated NaCl solution (HPLC grade, purity ≥99%, Solarbio, Beijing, China), and 20 μL (10 μg/mL) of the internal standard solution (3-Hexanone) (HPLC grade, purity ≥99%, Sigma-Aldrich, St. Louis, MO, USA) was added. The vial was immediately sealed with a PTFE/silicone rubber spacer (Agilent Technologies, Santa Clara, CA, USA). The headspace vial was placed into a magnetic stirrer and equilibrated at 60 °C for 5 min. This was followed by adsorption and extraction using a 120 µm DVB/CARWR/PDMS SPME Arrow (Agilent, Palo Alto, CA, USA) extractor at 60 °C for 15 min. The VOCs were identified and quantified using an Agilent 8890 gas chromatography system coupled with a 7000E mass spectrometer (Agilent Technologies Inc., Santa Clara, CA, USA), which was equipped with a DB-5MS capillary column measuring 30 m × 0.25 mm × 0.25 μm (Agilent, Palo Alto, CA, USA). High-purity helium (minimum purity of 99.999%; Jiangzhu, Nanchang, China) was used as the carrier gas and maintained at a constant flow rate of 1.2 mL/min. The inlet temperature was set at 250 °C with no shunt injection, and a solvent delay of 3.5 min was applied. Next, a programmed temperature ramp approach was applied. The temperature was initially maintained at 40 °C for 3.5 min, and a 10 °C/min ramp rate was programmed up to 100 °C. This was followed by an increase of 7 °C/min up to 180 °C, and a final rapid increase of 25 °C/min up to 280 °C, with a holding period of 5 min. The mass spectrometry employed an electron bombardment ion source (Agilent, Palo Alto, CA, USA), with the ion source temperature set at 230 °C, the quaternary bar temperature at 150 °C, and the mass spectrum interface temperature at 280 °C. The identification of the ester compounds was further confirmed by comparing their electron ionization mass spectrometry results with those of the NIST-2017 mass spectrometry library, and the retention time of the standard. Three independent biological replicates were used for each experiment. The results are expressed as μg kg−1.

2.4. Determination of AAT Content

The samples (1 g) were thoroughly pulverized into a fine powder using liquid nitrogen. Subsequently, 9 mL of phosphate buffer (pH 7.2–7.4) was added, and the mixture was vigorously homogenized. Then, the resulting solution was centrifuged at 3000 rpm for 20 min at 4 °C, and the supernatant was collected for further utilization. The AAT content was detected using an ELISA kit (Jining, Shanghai, China); the absorbance was measured at 450 nm. The enzyme content of the samples were determined using a standard curve. The standard concentrations were 4800, 2400, 1200, 600, 300, and 0 pg/mL. The equation for the standard curve is Y = 2817.7 X-230.02 with an R2 value of 0.9927, where Y represents the enzyme content, and X represents the light absorption value. Each sample was analyzed in triplicate. The results are expressed as ng mg−1.

2.5. RNA Extraction and Gene Expression Analysis

Total RNA was extracted from the kiwifruit pulp using a Plant RNA Kit (Tiangen, Beijing, China) according to the manufacturer’s protocol. Subsequently, the integrity of the extracted RNA was assessed using 1% agarose gel electrophoresis, while its concentration and purity were determined using a BioDrop ultramicrospectrophotometer (Bio-Rad, Hercules, CA, USA) to ensure that the RNA was of a reliable quality. First strand cDNA was synthesized using a reverse transcription kit (Tiangen, Beijing, China). qRT-PCR was performed using a CFX196 Touch fluorescence quantitative PCR instrument (Bio-Rad, Hercules, CA, USA) [30]. The relative gene expression was quantified as −2△△t, and three biological replicates were performed. The gene-specific primer sequences listed in Table S1 were used, with Actin serving as the internal reference.

2.6. AAT1 Transient Overexpression in Kiwifruit

The open reading frame (ORF) fragment of the AAT1 gene was amplified from the kiwifruit cDNA using gene-specific primers (Table S2). The PCR product was cloned into the PBI121 vector to generate the AAT1-OE vector, which was subsequently transformed into an Agrobacterium tumefaciens strain GV3101. A resuspension of Agrobacterium tumefaciens was obtained from a previous study [30]. Subsequently, the resuspended solution was incubated at 28 °C for 3 h; this was followed by aspiration of approximately 200 μL using a syringe, and slowly injected into the central column of the kiwifruit. Each treatment involved the injection of 15 fruits and was repeated three times. After 3 days, samples from the mid-column of the fruits were collected for subsequent analysis of the gene expression and the ester content.

2.7. Analysis of AAT1 Promoter Activity

We selected primers from the 5’ upstream region of the AAT1 translation initiation site (ATG) in the kiwifruit. The sequence was amplified from the DNA of the Donghong and the Ganlv-1 fruits using specific primers and validated by sequencing. The promoter sequences were amplified and cloned into pCAMBIA-1391 (without a promoter) to generate the recombinant plasmids (proAcAAT1-GUS and proAcAAT1-GUS). Agrobacterium strains containing proAcAAT1-GUS, proAcAAT1-GUS, or pCAMBIA-1391 (empty vector) were individually infiltrated into tobacco leaves. After three days, GUS staining was performed using a GUS staining detection kit (Huayueyang, Beijing, China). The GUS activity was quantified according to established protocols [30].

2.8. Statistical Analysis

GraphPad Prism 8.0 software was utilized for drawing and data analysis, with the data presented as mean ± standard deviation (SD). Statistical analysis was performed using SPSS 20.0, with significance set at p < 0.05 using Duncan’s multiple range test.

3. Results

3.1. Volatile Esters in Ripe Actinidia chinensis and Actinidia eriantha

Volatile esters in different kiwifruit species were investigated using the Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits (Figure 1A,B). Throughout the postharvest storage, the firmness of both fruits gradually decreased, whereas the TSS content steadily increased. Both firmness and soluble solid content reached their minimum and maximum values on the 8th day after harvest (Figure 1C,D). Therefore, the 8th day after harvest is the optimal period for consuming Donghong and Ganlv-1 kiwifruits.
We observed ester compounds in the Donghong and Ganlv-1 fruits on the 8th day post-harvest, and noted a significantly higher total ester aroma content in the Donghong fruits than in the Ganlv-1 fruits (Figure 2A). Among the 16 detected ester compounds (with the exception of benzoic acid methyl ester, methyl salicylate, hexanoic acid butyl ester, and butanoic acid propyl ester), the levels were significantly higher in the Donghong fruits than they were in the Ganlv-1 fruits (Table 1). Additionally, we investigated changes in AAT activity during fruit ripening in both varieties. The findings revealed an increase in AAT activity throughout ripening in both types of fruit; however, AAT activity was consistently higher in the Donghong fruits than in the Ganlv-1 fruits over the entire storage period (Figure 2B).

3.2. Changes in the Expression of AATs in Ripe Actinidia chinensis and Actinidia eriantha

The expression levels of the two genes, AAT1 and AAT17, which encode the key enzyme AAT in kiwifruit ester aroma biosynthesis, were determined in ripe Donghong and Ganlv-1 cultivars, respectively. The results revealed a significant upregulation in the expression levels of both AAT1 and AAT17 in the Donghong fruits compared with levels in the Ganlv-1 fruits (Figure 3). Specifically, the expression of AAT1 in the Donghong fruits was 36-fold higher compared with the Ganlv-1 fruits (Figure 3A), whereas the expression of AAT17 in the Donghong fruits was only 1.6-fold higher compared with the Ganlv-1 fruits (Figure 3B). Consequently, it can be inferred that the AAT1 gene is a pivotal candidate responsible for the disparity in ester aroma between the Donghong and Ganlv-1 cultivars.

3.3. Overexpression of the AAT1 Gene Alters Volatile Ester Content

To further investigate the effect of AAT1 on ester aroma accumulation, we constructed an overexpression vector for AAT1 and transformed it into Agrobacterium tumefaciens GV3101. The recombinant plasmid 35S-AAT1 was subsequently injected into the Donghong fruits on the day of harvesting, and the relative expression level of AAT1 was assessed by qRT-PCR after 3 days to evaluate the effect of transient overexpression. The results demonstrated a significant upregulation in the transcription levels of AAT1 in fruits overexpressing AAT1 compared with those in the control group (Figure 4A). Consistent with the elevated expression level of AAT1, there was a notable increase in the total ester content in fruits overexpressing AAT1 compared with the control group (Figure 4B), suggesting that AAT1 plays a pivotal role in ester biosynthesis in kiwifruit.

3.4. Analysis of AAT1 Promoter Activity Differences Between Actinidia chinensis and Actinidia eriantha

The upstream 1097 bp sequence of AAT1 was separately isolated from the Donghong and the Ganlv-1 fruits to investigate the genetic mechanism underlying the transcriptional regulation of AAT1. The findings revealed that the AAT1 promoter sequence in the Ganlv-1 fruits (proAeAAT1) exhibited numerous natural variations compared with the AAT1 promoter sequence isolated from the Donghong fruits (proAcAAT1) (Figure S1). Natural variations in the AAT1 promoter may alter its promoter activity. To evaluate the activity of AAT1 gene promoters in the Donghong and the Ganlv-1 fruits, we transiently expressed the fusion constructs, proAeAAT1-GUS and proAcAAT1-GUS, in tobacco leaves to examine their promoter activity (Figure 5A). The GUS activity driven by proAcAAT1 was significantly higher than the activity driven by proAeAAT1 (Figure 5B), indicating a weaker transcriptional activity of AAT1 in the Ganlv-1 fruit cells than in the Donghong fruit cells.

4. Discussion

Aromas enhance the sensory qualities of horticultural products. The types and concentrations of volatile components influence the sensory properties of fruit aroma [10,31]. Kiwifruit contain a high concentration of volatile components which significantly contribute to its distinctive aroma when fully ripe [13,14,28]. However, studies analyzing the proportions of these compounds in different kiwifruit species are limited. Kiwifruit species exhibit varying aromatic profiles [32,33]. Certain species, such as Actinidia arguta and Actinidia eriantha, possess a high content of terpenes, and the levels of terpenoids increase during fruit ripening. Actinidia chinensis and Actinidia deliciosa possess a low content of terpenoids [15,27]. Esters are associated with sweet, honey, floral, and fruity aromas, and they are the primary volatile compounds in ripe Actinidia chinensis and Actinidia deliciosa [32,34,35]. As the fruit ripens, its flavor profile transitions from grassy and green, to fruity, and is characterized by increased levels of esters and reduced levels of aldehydes [36]. In the present study, the concentration of esters was significantly higher in the ripened Donghong (Actinidia chinensis) fruit than in the Ganlv-1 (Actinidia eriantha) fruit. These findings are consistent with those of previous studies.
The AAT enzyme plays a crucial role in the bioanabolic metabolism of esters. It not only serves as the terminal enzyme, but also exhibits the utmost significance in this metabolic pathway [19,20]. Treatment of strawberry and apple fruits with 1-MCP, results in a significant reduction in the levels of aromatic substances and the activity of the AAT enzyme [23,37]. In this study, the AAT enzyme content in the Donghong fruits was significantly higher than in the Ganlv-1 fruits throughout the postharvest ripening stage; this corresponds to the disparity in ester content between the two cultivars, indicating a pivotal role of AAT in kiwifruit volatile ester biosynthesis.
The identification of the AAT gene is a crucial milestone in advancing our understanding of ester biosynthesis in fruits. PsAATL exhibits the most pronounced variation in expression in the LOX pathway during pear fruit ripening, concomitant with the accumulation of volatile esters [7]. The involvement of MdAAT1 and MdAAT2 in ester biosynthesis has been demonstrated as crucial in apples [6,38]. In this study, we analyzed the expression of two genes, AAT1 and AAT17, which were previously believed to be pivotal in kiwifruit ester biosynthesis [28]. Our findings revealed a significantly higher expression level of AAT1 in the Donghong fruits than in the Ganlv-1 fruits, corresponding to their ester aroma content. Notably, AAT1 has also been identified as playing a crucial role in various other species, such as MdAAT1 in apples [38], PpAAT1 in peaches [26], FaAAT1 in strawberries [23], VpAAT1 in mountain papaya [39], and SlAAT1 in tomatoes [40]. Notably, transgenic tomatoes with suppressed SlAAT1 expression, exhibited almost negligible ester production, further emphasizing the vital role of AAT1 in fruit volatile ester biosynthesis [40]. AAT17 expression was 1.6-fold higher in the Donghong fruits, and this is a relatively minor difference compared with AAT1. Correspondingly, there was no discernible distinction between the Donghong and the Ganlv-1 fruits regarding certain ester compounds, such as benzoic acid methyl ester; it is plausible that AAT17 is implicated in the biosynthesis of benzoic acid methyl ester.
Several factors influence gene transcription. Promoters play a pivotal role in initiating gene transcription and regulating gene expression, both temporally and spatially. Previous studies have demonstrated that natural variations in cis-elements within promoters can result in phenotypic variations [41]. The natural variation observed in the TPS gene promoter serves as a key determinant of the disparity in terpene accumulation between Actinidia arguta and Actinidia chinensis [15]. In the present study, natural variations in the AAT1 promoter were observed in the Donghong and Ganlv-1 fruits, resulting in a significant disparity in promoter activity. This discrepancy may serve as the primary factor contributing to the substantial difference in the transcription levels of the AAT1 gene between the Donghong and Ganlv-1 fruits, consequently leading to variations in ester accumulation during postharvest ripening.

5. Conclusions

In this study, the aroma components of volatile esters in Donghong and Ganlv-1 fruits during postharvest ripening were analyzed. Our findings revealed a significantly higher ester content in the Donghong fruits than in the Ganlv-1 fruits, along with a corresponding increase in the AAT enzyme content. Moreover, the expression level of the AAT1 gene was notably higher in the Donghong fruits than in the Ganlv-1 fruits. Notably, the overexpression of AAT1 resulted in a significant increase in kiwifruit ester content. Finally, we discovered natural variations in the AAT1 promoter sequence between the Donghong and Ganlv-1 fruits, which may account for their differential transcription levels. Further research is required to gain a more comprehensive understanding of the precise regulatory mechanisms underlying the variations in ester component formation during postharvest ripening in different kiwifruit species.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/agronomy14122965/s1, Figure S1: Comparative analysis of AAT1 gene promoter sequence in the Donghong and Ganlv-1 fruits; Table S1: Primers were used for qRT-PCR analysis; Table S2: Primers were used for vector construction.

Author Contributions

Conceptualization, Q.C. and Z.H.; methodology, Q.C. and Z.H.; software, Q.C.; formal analysis, Q.C.; investigation, Q.C.; resources, Z.G.; data curation, Z.G.; writing, original draft preparation, Q.C.; writing, review and editing, Z.G. and J.C.; visualization, J.C.; supervision, J.C. and Z.H.; project administration, Z.G. and J.C.; funding acquisition, Z.G. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Natural Science Foundation of China (32060704, 32302627), the Major discipline academic and technical leaders training program of Jiangxi Province, China-young talents project (20243BCE51082), and the Natural Science Foundation of Jiangxi Province of China (20232BAB205040).

Data Availability Statement

The original contributions presented in this study are included in the article/Supplementary Materials. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Fan, J.B.; Zhong, C.H. Fruit scientific research in New China in the past 70 years: Kiwifruit. J. Fruit Sci. 2019, 36, 1352–1359. [Google Scholar] [CrossRef]
  2. Li, X.W.; Li, J.Q.; Soejarto, D.D. New synonyms in Actinidiaceae from China. Acta Phytotax Sin. 2007, 45, 633–660. [Google Scholar] [CrossRef]
  3. Dudareva, N.; Klempien, A.; Muhlemann, J.K.; Kaplan, I. Biosynthesis, function and metabolic engineering of plant volatile organic compounds. New Phytol. 2013, 198, 16–32. [Google Scholar] [CrossRef] [PubMed]
  4. El Hadi, M.A.M.; Zhang, F.J.; Wu, F.F.; Zhou, C.H.; Tao, J. Advances in fruit aroma volatile research. Molecules 2013, 18, 8200–8229. [Google Scholar] [CrossRef]
  5. Ye, Y.H.; Zheng, S.Y.; Wang, Y.X. Analysis of aroma components changes in Gannan navel orange at different growth stages by HS-SPME-GC-MS, OAV, and multivariate analysis. Food Res. Int. 2024, 175, 113622. [Google Scholar] [CrossRef]
  6. Li, R.; Yan, D.; Tan, C.Y.; Li, C.; Song, M.J.; Zhao, Q.Q.; Yang, Y.M.; Yin, W.J.; Liu, Z.D.; Ren, X.L.; et al. Transcriptome and metabolomics integrated analysis reveals MdMYB94 associated with esters biosynthesis in apple (Malus domestica). J. Agric. Food Chem. 2023, 71, 7904–7920. [Google Scholar] [CrossRef]
  7. Liu, Y.; Wen, H.; Yang, X.P.; Wu, C.Y.; Ming, J.Q.; Zhang, H.Y.; Chen, J.J.; Wang, J.B.; Xu, J. Metabolome and transcriptome profiling revealed the enhanced synthesis of volatile esters in Korla pear. BMC Plant Biol. 2023, 23, 264. [Google Scholar] [CrossRef]
  8. Garcia, C.V.; Stevenson, R.J.; Atkinson, R.G.; Winz, R.A.; Quek, S.Y. Changes in the bound aroma profiles of ‘Hayward’ and ‘Hort16A’ kiwifruit (Actinidia spp.) during ripening and GC-olfactometry analysis. Food Chem. 2013, 137, 45–54. [Google Scholar] [CrossRef]
  9. Xiao, Z.B.; Chen, L.N.; Niu, Y.W.; Zhu, J.C.; Zhang, J.; Deng, J.M. Evaluation of the interaction between esters and sulfur compounds in pineapple using feller’s additive model, OAV, and odor activity coefficient. Food Anal. Method 2021, 14, 1714–1729. [Google Scholar] [CrossRef]
  10. Xu, S.J.; He, W.Y.; Yan, J.T.; Zhang, R.G.; Wang, P.; Tian, H.L.; Zhan, P. Volatomics-assisted characterization of aroma and off-flavor contributors in fresh and thermally treated kiwifruit juice. Food Res. Int. 2023, 167, 112656. [Google Scholar] [CrossRef]
  11. Ye, L.Q.; Yang, C.X.; Li, W.D.; Hao, J.B.; Sun, M.; Zhang, J.R.; Zhang, Z.S. Evaluation of volatile compounds from Chinese dwarf cherry (Cerasus humilis (Bge.) Sok.) germplasms by headspace solid-phase microextraction and gas chromatography-mass spectrometry. Food Chem. 2017, 217, 389–397. [Google Scholar] [CrossRef] [PubMed]
  12. Zhang, H.P.; Xie, Y.X.; Liu, C.H.; Chen, S.L.; Hu, S.S.; Xie, Z.Z.; Deng, X.X.; Xu, J. Comprehensive comparative analysis of volatile compounds in citrus fruits of different species. Food Chem. 2017, 230, 316–326. [Google Scholar] [CrossRef] [PubMed]
  13. Young, H.; Paterson, V.J. Characterisation of bound flavour components in kiwifruit. J. Sci. Food Agric. 2010, 68, 257–260. [Google Scholar] [CrossRef]
  14. Chai, J.X.; Liao, B.A.; Li, R.; Liu, Z.D. Changes in taste and volatile compounds and ethylene production determined the eating window of ‘Xuxiang’ and ‘Cuixiang’ kiwifruit cultivars. Postharvest Biol. Technol. 2022, 194, 112093. [Google Scholar] [CrossRef]
  15. Nieuwenhuizen, N.J.; Chen, X.Y.; Wang, M.Y.; Matich, A.J.; Perez, R.L.; Allan, A.C.; Green, S.A.; Atkinson, R.G. Natural variation in monoterpene synthesis in kiwifruit: Transcriptional regulation of terpene synthases by NAC and ETHYLENE-INSENSITIVE3-like transcription factors. Plant Physiol. 2015, 167, 1243–1258. [Google Scholar] [CrossRef]
  16. Yang, H.Y.; Li, J.Z.; Li, X.H.; Wu, R.; Zhang, X.L.; Fan, X.G.; Li, G.T.; Gong, H.S.; Yin, X.R.; Zhang, A.D. The mechanism of gibberellins treatment suppressing kiwifruit postharvest ripening processes by transcriptome analysis. Postharvest. Biol. Technol. 2023, 198, 112223. [Google Scholar] [CrossRef]
  17. Stolterfoht, H.; Rinnofner, C.; Winkler, M.; Pichler, H. Recombinant lipoxygenases (LOX) and hydroperoxide lyases (HPL) for the synthesis of green leaf volatiles. J. Agric. Food Chem. 2019, 2019, 13367–13392. [Google Scholar] [CrossRef]
  18. Qin, G.H.; Qi, X.X.; Qi, Y.J.; Gao, Z.H.; Yi, X.K.; Pan, H.F.; Xu, Y.L. Identification and expression patterns of alcohol dehydrogenase genes involving in ester volatile biosynthesis in pear fruit. J. Integr. Agric. 2017, 16, 1742–1750. [Google Scholar] [CrossRef]
  19. Schwab, E.; Davidovich-Rikanati, R.; Lewinsohn, E. Biosynthesis of plant-derived flavor compounds. Plant J. 2008, 54, 712–732. [Google Scholar] [CrossRef]
  20. Beekwilder, J. Functional characterization of enzymes forming volatile esters from strawberry and banana. Plant Physiol. 2004, 135, 1865–1878. [Google Scholar] [CrossRef]
  21. Liu, C.; Qiao, X.; Li, Q.; Zeng, W.; Wei, S.; Wang, X.; Chen, Y.; Wu, X.; Wu, J.; Yin, H.; et al. Genome-wide comparative analysis of the BAHD superfamily in seven Rosaceae species and expression analysis in pear (Pyrus bretschneideri). BMC Plant Biol. 2020, 20, 14. [Google Scholar] [CrossRef] [PubMed]
  22. Cumplido-Laso, G.; Medina-Puche, L.; Moyano, E.; Hoffmann, T.; Sinz, Q.; Ring, L.; Studart-Wittkowski, C.; Luis Caballero, J.; Schwab, W.; Munoz-Blanco, J.; et al. The fruit ripening-related gene FaAAT2 encodes an acyl transferase involved in strawberry aroma biogenesis. J. Exp. Bot. 2012, 63, 4275–4290. [Google Scholar] [CrossRef] [PubMed]
  23. Gonzalez, M.; Gaete-Eastman, C.; Valdenegro, M.; Figueroa, C.R.; Fuentes, L.; Herrera, R.; Alejandra Moya-Leon, M. Aroma development during ripening of Fragaria chiloensis fruit and participation of an alcohol acyltransferase (FcAAT1) gene. J. Agric. Food Chem. 2009, 57, 9123–9132. [Google Scholar] [CrossRef] [PubMed]
  24. Li, D.; Shen, J.; Wu, T.; Xu, Y.; Zong, X.; Li, D.; Shu, H. Overexpression of the apple alcohol acyltransferase gene alters the profile of volatile blends in transgenic tobacco leaves. Physiol. Plantarum. 2008, 134, 394–402. [Google Scholar] [CrossRef]
  25. Souleyre, E.J.F.; Chagne, D.; Chen, X.; Tomes, S.; Turner, R.M.; Wang, M.Y.; Maddumage, R.; Hunt, M.B.; Winz, R.A.; Wiedow, C.; et al. The AAT1 locus is critical for the biosynthesis of esters contributing to “ripe apple” flavour in “Royal Gala” and “Granny Smith” apples. Plant J. 2014, 78, 903–915. [Google Scholar] [CrossRef]
  26. Cao, X.; Wei, C.; Duan, W.; Gao, Y.; Kuang, J.; Liu, M.; Chen, K.; Klee, H.; Zhang, B. Transcriptional and epigenetic analysis reveals that NAC transcription factors regulate fruit flavor ester biosynthesis. Plant J. 2021, 106, 785–800. [Google Scholar] [CrossRef]
  27. Crowhurst, R.N.; Gleave, A.P.; MacRae, E.A.; Ampomah-Dwamena, C.; Atkinson, R.G.; Beuning, L.L.; Bulley, S.M.; Chagne, D.; Marsh, K.B.; Matich, A.J.; et al. Analysis of expressed sequence tags from Actinidia: Applications of a cross species EST database for gene discovery in the areas of flavor, health, color and ripening. BMC Genom. 2008, 9, 351. [Google Scholar] [CrossRef]
  28. Kim, J.; Lee, J.G.; Lim, S.; Lee, E.J. A comparison of physicochemical and ripening characteristics of golden-fleshed ‘Haegeum’ and green-fleshed ‘Hayward’ kiwifruit during storage at 0 °C and ripening at 25 °C. Postharvest Biol. Technol. 2023, 196, 112166. [Google Scholar] [CrossRef]
  29. Gan, Z.; Shan, N.; Fei, L.; Wan, C.; Chen, J. Isolation of the 9-cis-epoxycarotenoid dioxygenase (NCED) gene from kiwifruit and its effects on postharvest softening and ripening. Sci. Hortic. 2020, 261, 109020. [Google Scholar] [CrossRef]
  30. Gan, Z.; Yuan, X.; Shan, N.; Wan, C.; Chen, C.; Zhu, L.; Xu, Y.; Kai, W.; Zhai, X.; Chen, J. AcERF1B and AcERF073 positively regulate indole-3-acetic acid degradation by activating AcGH3.1 transcription during postharvest kiwifruit ripening. J. Agric. Food Chem. 2021, 69, 13859–13870. [Google Scholar] [CrossRef]
  31. Zhang, A.D.; Zhang, Q.Y.; Li, J.H.; Gong, H.S.; Fan, X.G.; Yang, Y.Q.; Liu, X.F.; Yin, X.R. Transcriptome co-expression network analysis identifies key genes and regulators of ripening kiwifruit ester biosynthesis. BMC Plant Biol. 2020, 20, 103. [Google Scholar] [CrossRef] [PubMed]
  32. Souleyre, E.J.F.; Nieuwenhuizen, N.J.; Wang, M.Y.; Winz, R.A.; Matich, A.J.; Ileperuma, N.R.; Tang, H.; Baldwin, S.J.; Wang, T.C.; List, B.W.; et al. Alcohol acyl transferase genes at a high-flavor intensity locus contribute to ester biosynthesis in kiwifruit. Plant Physiol. 2022, 190, 1100–1116. [Google Scholar] [CrossRef] [PubMed]
  33. Yuan, X.Y.; Zheng, H.; Fan, J.T.; Liu, F.X.; Li, J.T.; Zhong, C.H.; Zhang, Q. Comparative study on physicochemical and nutritional qualities of kiwifruit varieties. Foods 2023, 12, 108. [Google Scholar] [CrossRef]
  34. Shi, Y.L.; Wang, M.Q.; Dong, Z.B.; Zhu, Y.; Shi, J.; Ma, W.J.; Lin, Z.; Lv, H.P. Volatile components and key odorants of Chinese yellow tea (Camellia sinensis). LWT 2021, 146, 111512. [Google Scholar] [CrossRef]
  35. Wang, Q.; An, X.X.; Xiang, M.L.; Chen, X.; Luo, Z.Y.; Fu, Y.Q.; Chen, M.; Chen, J.Y. Effects of 1-MCP on the physiological attributes, volatile components and ester-biosynthesis-related gene expression during storage of ‘jinyan’ kiwifruit. Horticulturae 2021, 7, 381. [Google Scholar] [CrossRef]
  36. Du, D.D.; Xu, M.; Wang, J.; Gu, S.; Zhu, L.Y.; Hong, X.Z. Tracing internal quality and aroma of a red-fleshed kiwifruit during ripening by means of GC-MS and E-nose. RSC Adv. 2019, 9, 21164–21174. [Google Scholar] [CrossRef]
  37. Li, D.P.; Xu, Y.F.; Xu, G.M.; Gu, L.K.; Li, D.Q.; Shu, H.R. Molecular cloning and expression of a gene encoding alcohol acyltransferase (MdAAT2) from apple (cv. Golden Delicious). Phytochemistry 2006, 67, 658–667. [Google Scholar] [CrossRef]
  38. Li, L.X.; Fang, Y.; Li, D.; Zhu, Z.H.; Zhang, Y.; Tang, Z.Y.; Li, T.; Chen, X.S.; Feng, S.Q. Transcription factors MdMYC2 and MdMYB85 interact with ester aroma synthesis gene MdAAT1 in apple. Plant Physiol. 2023, 193, 2442–2458. [Google Scholar] [CrossRef]
  39. Balbontin, C.; Gaete-Eastman, C.; Fuentes, L.; Figueroa, C.R.; Herrera, R.; Manriquez, D.; Latche, A.; Pech, J.C.; Alejandra Moya-Leon, M. VpAAT1, a gene encoding an alcohol acyltransferase, is involved in ester biosynthesis during ripening of mountain papaya fruit. J. Agric. Food Chem. 2010, 58, 5114–5121. [Google Scholar] [CrossRef]
  40. Goulet, C.; Kamiyoshihara, Y.; Lam, N.B.; Richard, T.; Taylor, M.G.; Tieman, D.M.; Klee, H.J. Divergence in the enzymatic activities of a tomato and solanum pennellii alcohol acyltransferase impacts fruit volatile ester composition. Mol. Plant 2014, 8, 153–162. [Google Scholar] [CrossRef]
  41. Zheng, X.; Li, Y.; Ma, C.; Chen, B.; Sun, Z.; Tian, Y.; Wang, C. A mutation in the promoter of the arabinogalactan protein 7-like gene PcAGP7-1 affects cell morphogenesis and brassinolide content in pear (Pyrus communis L.) stems. Plant J. 2022, 109, 47–63. [Google Scholar] [CrossRef] [PubMed]
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Figure 1. Fruit ripening characteristics of the Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits. The photographs depict the Donghong (A) and Ganlv-1 (B) fruits. Changes in firmness (C) and the total soluble solid (TSS) content (D) of the Donghong and Ganlv-1 fruits during postharvest storage.
Figure 1. Fruit ripening characteristics of the Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits. The photographs depict the Donghong (A) and Ganlv-1 (B) fruits. Changes in firmness (C) and the total soluble solid (TSS) content (D) of the Donghong and Ganlv-1 fruits during postharvest storage.
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Figure 2. (A) Total ester content in ripe Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits. (B) Changes of AAT enzyme content in the Donghong and Ganlv-1 fruits during postharvest storage. Data represent mean ± SD of at least three biological replicates. ** indicates that in the Duncan’s multiple range test, there is a significant difference between the Donghong and Ganlv-1 fruits (p < 0.01).
Figure 2. (A) Total ester content in ripe Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits. (B) Changes of AAT enzyme content in the Donghong and Ganlv-1 fruits during postharvest storage. Data represent mean ± SD of at least three biological replicates. ** indicates that in the Duncan’s multiple range test, there is a significant difference between the Donghong and Ganlv-1 fruits (p < 0.01).
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Figure 3. Relative expression of AAT1 (A) and AAT17 (B) in ripe Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits. Data represents mean ± SD of at least three biological replicates. Different letters indicate that the expression level of the same gene is significantly different in the Donghong and Ganlv-1 fruits (p < 0.05).
Figure 3. Relative expression of AAT1 (A) and AAT17 (B) in ripe Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits. Data represents mean ± SD of at least three biological replicates. Different letters indicate that the expression level of the same gene is significantly different in the Donghong and Ganlv-1 fruits (p < 0.05).
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Figure 4. Transient overexpression of AAT1 in kiwifruit. (A) Relative expression of AAT1 in control and AAT1-overexpression kiwifruit. (B) The total ester content in control and AAT1-overexpression kiwifruit. Data represent mean ± SD of at least three biological replicates. Different letters indicated significant differences between the control and the AAT1-OE groups (p < 0.05).
Figure 4. Transient overexpression of AAT1 in kiwifruit. (A) Relative expression of AAT1 in control and AAT1-overexpression kiwifruit. (B) The total ester content in control and AAT1-overexpression kiwifruit. Data represent mean ± SD of at least three biological replicates. Different letters indicated significant differences between the control and the AAT1-OE groups (p < 0.05).
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Figure 5. Analysis of AAT1 promoter activity in the Donghong and Ganlv-1 fruits. (A) Diagram of cloning AAT1 promoter to pCAMBIA1391 vector (no promoter vector). (B) Transient GUS activity analysis of proAeAAT1 and proAcAAT1 in tobacco leaves. Tobacco leaves were transfected with proAeAAT1-GUS, proAcAAT1-GUS, and pCAMBIA1391 vector fusions. Data represent mean ± SD of at least three biological replicates. Bar with different letters showed significant differences at p < 0.05.
Figure 5. Analysis of AAT1 promoter activity in the Donghong and Ganlv-1 fruits. (A) Diagram of cloning AAT1 promoter to pCAMBIA1391 vector (no promoter vector). (B) Transient GUS activity analysis of proAeAAT1 and proAcAAT1 in tobacco leaves. Tobacco leaves were transfected with proAeAAT1-GUS, proAcAAT1-GUS, and pCAMBIA1391 vector fusions. Data represent mean ± SD of at least three biological replicates. Bar with different letters showed significant differences at p < 0.05.
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Table 1. Volatile ester compounds in ripe Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits.
Table 1. Volatile ester compounds in ripe Donghong (Actinidia chinensis) and Ganlv-1 (Actinidia eriantha) fruits.
CompoundsDonghong (μg kg−1) 1Ganlv-1 (μg kg−1)
Benzoic acid, methyl ester4136.01 ± 406.39 a4262.66 ± 544.86 a
2-Butenoic acid, 3-methyl-, methyl ester1740.43 ± 318.42 a421.64 ± 63.74 b
Hexanoic acid, methyl ester63.02 ± 5.08 a23.68 ± 0.42 b
Butanoic acid, 2-pentenyl ester, (Z)-749.87 ± 83.03 a514.14 ± 47.57 b
Methyl salicylate417.93 ± 62.92 b1170.67 ± 88.61 a
Octanoic acid, methyl ester10.65 ± 2.91 a2.86 ± 0.41 b
2(3H)-Furanone, 5-butyldihydro-291.12 ± 36.68 a188.24 ± 17.53 b
Butanoic acid, ethyl ester3137.28 ± 132.80 a13.72 ± 1.95 b
Formic acid, 2-phenylethyl ester482.59 ± 85.48 a80.68 ± 9.47 b
Hexanoic acid, butyl ester80.44 ± 13.85 a70.44 ± 1.68 a
Hexanoic acid, ethyl ester692.09 ± 88.16 a25.78 ± 0.91 b
1-Ethylpropyl acetate575.46 ± 20.33 a1.38 ± 0.51 b
Benzeneacetic acid, methyl ester128.66 ± 24.76 a22.86 ± 1.36 b
Octanoic acid, ethyl ester97.54 ± 15.46 a46.31 ± 1.14 b
Butanoic acid, propyl ester49.84 ± 6.00 b70.47 ± 7.80 a
Pentanoic acid, ethyl ester96.69 ± 10.94 a0.48 ± 0.09 b
1 Different letters indicate that the same compound is significantly different in the Donghong and Ganlv-1 fruits.
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MDPI and ACS Style

Cao, Q.; Huang, Z.; Chen, J.; Gan, Z. Natural Variation in the AAT1 Promoter Is Responsible for the Disparity in Ester Aroma Between Actinidia chinensis and Actinidia eriantha. Agronomy 2024, 14, 2965. https://doi.org/10.3390/agronomy14122965

AMA Style

Cao Q, Huang Z, Chen J, Gan Z. Natural Variation in the AAT1 Promoter Is Responsible for the Disparity in Ester Aroma Between Actinidia chinensis and Actinidia eriantha. Agronomy. 2024; 14(12):2965. https://doi.org/10.3390/agronomy14122965

Chicago/Turabian Style

Cao, Qing, Zhenyu Huang, Jinyin Chen, and Zengyu Gan. 2024. "Natural Variation in the AAT1 Promoter Is Responsible for the Disparity in Ester Aroma Between Actinidia chinensis and Actinidia eriantha" Agronomy 14, no. 12: 2965. https://doi.org/10.3390/agronomy14122965

APA Style

Cao, Q., Huang, Z., Chen, J., & Gan, Z. (2024). Natural Variation in the AAT1 Promoter Is Responsible for the Disparity in Ester Aroma Between Actinidia chinensis and Actinidia eriantha. Agronomy, 14(12), 2965. https://doi.org/10.3390/agronomy14122965

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