Transcriptomic analysis and volatile profiling reveals the regulatory mechanism of flavor volatiles in fresh-cut potatoes

ABSTRACT The potato (Solanum tuberosum L.) is one of the most edible vegetables worldwide. The cutting process disrupts the internal structure of several volatile substances that prompt flavor changes in fresh-cut potatoes. Understanding the composition of volatiles along with their biosynthesis mechanism is important to preserve original potato flavor during processing technology. This study characterized the volatile profiles and gene expression of fresh cut potato shreds at 0 hour (CK) and after 4 hours of storage (CK4). According to volatile profiling, alkanes were found to be the most abundant volatiles, followed by alcohols, aldehydes, esters, furans, and quinone. The abundance level of these volatiles was reduced many folds in CK4 potato shreds except for specific alkenes such as hexane, 1,3-hexadiene, and 1,6-octadiene. The transcriptome analysis revealed 5961 differentially regulated genes. An array of differential genes had functional annotations with biological responses to wounding, alcohol, water deprivation, and the molecular activity of acetyltransferase. In addition, most of these genes had pathway enrichment into the biosynthesis of secondary metabolites, alpha-linolenic acid metabolism, fatty acid biosynthesis, degradation, elongation, and metabolism. In particular, the many-fold differential regulation of the hydroperoxide pathway encoding genes probably yielded different volatile profiles that cause flavor disorders even after storage of fresh cut potato shreds for a few hours. Our results determined major flavor volatiles in fresh cut potato and identified important genes associated with the regulation of flavor volatiles in potato shreds. Our results will facilitate development of optimal management practices for preserving fresh-cut potatoes quality.


Background
Potatoes are one of the most widely consumed vegetables in the world.China is one of the largest producers and consumers of potatoes globally, with more than 90 million tons produced in 2020. [1]otato consumption has been increasing in recent years due to their versatility, nutritional value, and affordability. [2]Potatoes are an excellent source of carbohydrates, vitamins, and minerals.They are rich in dietary fiber, vitamin C, potassium, and vitamin B. [3] Potatoes also contain phytochemicals, such as flavonoids, carotenoids, and phenolic acids, which have antioxidant properties and may reduce the risk of chronic diseases. [4]otatoes can be consumed in a number of ways depending on the cooking methods and preferences in various cultures. [5]Fresh-cut potatoes, such as potato chips, are popular snack foods in China, and the quality of these products is critical for the success of the food industry. [6]However, the flavor of fresh-cut potatoes often changes rapidly, leading to an undesirable taste and aroma, and causing significant economic losses. [7,8]Therefore, understanding the factors affecting flavor change in fresh-cut potatoes is essential to improving the quality and shelf life of potato food products.
Food flavor is produced through the synthesis of fragrant substances during metabolic processes in plants and animals, which can be changed through cooking or processing. [9,10]uman perception of taste is influenced by psychological and cultural factors. [11]While taste buds perceive soluble nonvolatile compounds in food, the majority of flavor comes from volatile aromatic compounds that stimulate olfactory receptors in the nose. [12]This complex sensation of flavor is not an innate characteristic of a compound but rather a subjective evaluation by the individual. [13]Therefore, the same compound can be perceived differently by different people or even by the same person at different times.Identifying the components that determine food flavor can be quite challenging due to its subjective nature.The flavor of fresh-cut potatoes is influenced by various factors, such as cultivar, processing method, storage conditions, microbial activity, and presence and level of volatile compounds. [7,14,15]The cultivar of potato used can affect the flavor and texture of the finished product. [14]The processing method, such as slicing or frying, can also impact the flavor of fresh cut potatoes.Storage conditions, such as temperature and humidity, can affect the rate of flavor change in fresh-cut potatoes. [16]Microbial activity can also contribute to flavor changes in fresh-cut potatoes, as microorganisms can produce volatile compounds that alter the aroma and taste of the product. [17]Enzymatic and non-enzymatic browning can also contribute to flavor change in fresh-cut potatoes.Enzymatic browning occurs when enzymes, such as polyphenol oxidase and peroxidase, oxidize phenolic compounds in the potato to form brown pigments. [18]Nonenzymatic browning occurs when reducing sugars react with amino acids in a process known as the Maillard reaction, leading to the formation of brown pigments and flavor compounds. [19]Minimizing browning during processing and storage is crucial for maintaining the quality of fresh-cut potatoes.
Volatile compounds undergo further modifications during the cooking process.As many as 159 volatile components have been identified in raw potatoes, while 182 were found in boiled potatoes and 392 in baked potatoes. [20]Cutting and slicing of raw potatoes causes membrane disruption, which in turn promotes the oxidation of fatty acids by the lipoxygenases found in the raw potato. [21][23][24] Lipid oxidation results in the production of a lot of volatile compounds, including 1-pentanol, 2-octenal, 2,4-heptadienal, heptanal, 2-pentylfuran, and 2,6-nonadienal.Some of these volatiles have been studied for their association with potato flavor, for example, 2-pentylfuran is significantly associated with sweetness and off-flavor; 1-pentanol is highly linked with rancidness, flavor intensity, and savory, while 2-octenal produces rancidness in potato flavor.
[27][28][29] However, the previous studies on flavor change in fresh-cut potatoes were focused on the effects of cooking methods, storage conditions, and cultivars choice. [15,30,31]So far, no study has been conducted to unravel the regulatory mechanism of flavor volatiles in potatoes.In this study, we investigated transcriptome of a fresh-cut potato (after 0 and 4 hours of storage) and used headspace gas chromatography/mass spectrometry (HS-GC/MS) for the quantification of volatiles.The results provide useful insights about regulatory mechanism of flavor volatiles.

Plant material
Feiwuruita potato tubers were obtained from the Jilin Academy of Agricultural Sciences (voucher number: TS7710aD).The plant material has been formally identified by Prof Wenhua Wang.No permission is required to study potato samples.Potato tubers with no obvious disease on the skin, neat appearance and smooth surface were selected for the analysis of volatile components.The headspace gas chromatography/mass spectrometry (HS-GC/MS) was used for the quantification of volatiles at two time points: 1) immediately after cutting (CK) and 2) after four hours of storage (CK4).

Sample preparation
Six grams of potato shreds were added to 25 ml of pure water.Water was drained after 5 seconds, and filter paper was used to dry the shreds.Three grams of potato shreds were taken, and 100 μl/ml N, N-dimethylformamide (DMF) was added to 25 mL of transparent headspace bottle with a polytetrafluoroethylene (PTFE) silicone rubber bottle pad.DMF was used as an internal reference marker.

Headspace analysis
A Hewlett Packard Headspace HP7694E machine was used for headspace analysis with the following conditions: The headspace loop and transfer line temperatures were set to 135°C and 155°C, respectively; the vial was pressurized for 1 minute, the loop was filled for 12 seconds, the loop equilibrium time was 3 seconds, and the inject time was 6 seconds.Once the volatile compounds reached equilibrium, the headspace vapor was extracted from the vial with a gas-tight syringe and immediately transferred into the GC-MS.

Gas chromatography-mass spectrometry analysis
Gas chromatograph Agilent model 7890B coupled with an Agilent model 5977A mass spectrometry detector was used for Gas chromatography-Mass spectrometry Analysis.Chromatographic separations were performed on a HP-INNOWax capillary column measuring 60 m in length, 0.25 mm in diameter, and 0.5 µm in particle size.Helium was used as carrier gas.The GC oven temperature was programmed to begin at 40°C for 1 minute, followed by an increase to 190°C at a heating rate of 3°C/ min, and finally ramped up at 10°C/min up to 250°C, where it was held for 3 minutes.The ionization energy was 70 eV, while the mass analyzer was programmed to scan from 30 amu to 550 amu.Volatile compounds were identified by matching computer-generated data with the National Institute of Standards and Technology (NIST) library and by comparing the retention indices (RI) with those previously reported in the literature.

RNA extraction, sequencing and analysis
Ten grams of shreds of potato tubers after immediate peeling and after 4 hours of storage at room temperature were collected for total RNA extraction using the CTAB method. [32]The quality of RNA was assessed by gel electrophoresis.The RNA concentration was measured by the Qubit 2.0 fluorescent meter.RNA sequencing was performed by the Illumina HiSeq platform.Low quality reads were filtered out.High quality reads were mapped to the potato reference genome (http://spuddb.uga.edu/).The Fragments Per Kilobase of transcript sequence per Millions of base pairs sequenced (FPKM) value of each gene was computed.DEGseq [33] was used for differential gene or transcriptional analysis.Expression of DEGs with adjusted P < .05corrected by the Benjamini and Hochberg's approach was considered significant. [34]The functional and pathway enrichment analyses for DEGs were carried out with GOATOOLS [35] and KOBAS software, [36] respectively (P-value ≤.05).

Real-time quantitative PCR analysis
Genes were randomly selected for validation of RNA-seq results.Primer Premier 5 software was used for designing the primers for selected genes (Supplementary Table S1).Exocyst complex component sec3 gene (F: CGCTCACTTCGGTGATCATA, R: GCTTTTGCATTCTGGAGGTT) was used for internal control.Universal SYBRgreen Master (Rox) (Roche, Mannheim, Germany) was used to conduct qRT-PCR.Manufacturer's instructions were followed to carry out the reaction.The qRT-PCR data analysis was based on three biological replicates each with three technical replicates run for target and control genes.

Volatile profiles during different time intervals in fresh-cut potatoes
Volatile substances are key determinants that regulate the quality of fresh and processed potatoes.In particular, the composition and concentration of certain volatile compounds alter the profiles of flavor, aroma, and nutrient contents.This study analyzed profiles of volatiles and transcripts in freshcut potato shreds at 0 hour (hereafter CK) (Figure 1a) and after 4 hours of storage (CK4) (Figure 1b).The uniform-sized potato shreds were utilized to perform subsequent analyses (Figure 1).A total of 22 volatile compounds were detected in CK, whereas 24 volatile compounds were detected in CK4 (Figure 2, Supplementary Table S2).The majority of volatiles belonged to different species of alkane, followed by alcohol, aldehyde, furan, ester, and quinone at both time intervals.An aldehyde compound N, N-dimethylformamide had the highest concentration in potato shreds at both time intervals, followed by the furan compound 2-pentylfuran (Figure 3).The higher abundance of these substances probably has an influence on the quality of potato foods.Among different compounds of alkanes, 2,6,10,14-tetramethylpentadecane, 2,6,10-trimethylpentadecane, phytane, hexadecane, and heneicosane were dominant in potato shreds at both time intervals.However, hexane, 1,3-hexadiene, and 1,6-octadiene were specifically identified in CK4 (Figure 3b).
In addition, the ester compound n-hydroxybenzoate methyl ester was only identified in CK (Figure 3a), while 2,4,4-trimethylpentane-1,3-diyl bis (2-methylpropanoate) was noticed in CK4 (Figure 3b).These differences in volatile composition after the cutting process most likely can cause changes in potato color, flavor, and aroma.The alcoholic volatiles such as 1-octene-3-ol and 1-pentanol were identified at both time intervals.But, the cis-3-nonen-1-ol was identified only in CK   (Figure 3a).One species of quinone named 2,6-di-tert-butyl-p-benzoquinone was the other volatile compound identified in potato shreds at both time intervals.
Comparative analysis revealed significant differences in the concentration of certain volatiles at both time intervals.For instance, the alkane compound 2-methylheptadecane had significantly higher abundance in CK4 (Figure 4).In contrast, alcoholic volatile 1-pentanol had a significantly higher abundance in CK (Figure 5a).Moreover, the majority of alkane volatile compounds, including 2, 6, 10, 14, tetramethylpentadecane, hexadecane, heneicosane, and phytane, had higher abundance levels in CK than CK4 (Figure 4).The 1-Octen-3-ol and N,N-dimethylformamide were other volatile substances that had shown higher abundance in CK.The 2-pentylfuran however, had higher abundance in CK4 (Figure 5c), while the quinone named 2,6-di-tert-butyl-p-benzoquinone had higher abundance in CK (Figure 5d).In brief, volatile profiling at different time intervals suggested that cutting processes cause changes in compositions and concentrations of alkenes, aldehydes, esters, furans, and alcohols.Interestingly, most of the volatile components belong to alkenes, aldehydes, and alcohols, which were reduced after 4 hours of fresh cut potatoes.Thus, it can ultimately lead to various profiles of aroma and flavor during boiling, roasting, baking, and frying potato processing technology.

Overview of transcriptome sequencing at different time intervals in fresh-cut potatoes
Transcriptome sequencing with triplicate samples of CK and CK4 to explore regulatory genes associated with the volatile substances of fresh-cut potatoes.The brief details of deep Illumina pairend RNA sequencing for each library can be seen in Table 1.In brief, our sequencing yielded almost 47,935,176 raw reads in each library of CK.The mean of raw reads was 52,477,682 in CK4.After strict quality checks and filtrations, a mean of 6.93 and 7.57 clean bases were retained for subsequent analysis in CK and CK4, respectively.The mapping statistics revealed that nearly 89% of clean reads were mapped to the reference Solanum tuberosum genome.Specifically, 85% of the total mapped reads were uniquely mapped, and nearly 4% were multi-mapped in each sequencing library for both time intervals.The total GC content percentage was 42.9 in CK and 43 in CK.The Q30% was higher than 93 in our sequencing.The overall quality assessment of the transcriptome data showed highquality transcripts for subsequent analysis.
The expression of each gene was first calculated based on the Fragments Per Kilobase of Transcript per Million Fragments Mapped (FPKM).Then, comparative transcriptome analysis was performed to identify the differential genes during different time intervals in fresh-cut potato shreds.The screening criteria were log2 (fold change) >1 or < −1 and statistical significance (p value < 0.05).The comparative analysis showed a total of 5961 DEGs in CK and CK4 (Figure 6a, Supplementary Table S3).Of which, 4550 genes were up-regulated and 1411 genes were down-regulated in CK4 compared with CK.All up and down-regulated DEGs of CK4 had many fold change differences from CK.In particular, the upregulated DEGs had a distinct expression distribution compared to the down-regulated DEGs at both  time intervals.The heatmap further revealed an obvious separation and clustering among biological samples of CK and CK4 (Figure 6b).These results revealed that the cutting process induced large-scale changes in transcript profiling that facilitate the biosynthesis of various aromatic volatile components in potato shreds at both time intervals.
Interestingly, GO enrichment categorized an array of DEGs into biological responses to wounding, alcohol, and water deprivation.At the molecular level, an array of genes had functional annotations for o-acetyltransferase activity along with carbohydrate binding, transcription regulatory region DNA binding, and signal receptor binding (Figure 7, Supplementary Table S4).Further pathway enrichment analysis identified that these functional genes were annotated into key pathways such as biosynthesis of secondary metabolites, alpha-linolenic acid metabolism, fatty acid biosynthesis, degradation, elongation, and metabolism, MAPK signaling pathway-plant, plant hormone signal transduction, phenylpropanoid biosynthesis metabolic pathways, and plant-pathogen interaction (Figure 8, Supplementary Table S5).These results highlighted that the cutting process altered the expression of many genes involved in various functions and pathways.Their differential regulation will most likely yield various flavor and aroma volatile profiles in CK and CK4 potato shreds.

Dynamic changes in major substrates and genes associated with volatile components at different time intervals in fresh-cut potatoes
The vast majority of volatiles detected belonged to the major classes of alkene, alcohol, ester, and aldehyde.Our results therefore identified 42 core DEGs specifically linked to these volatile components (Figure 9, Supplementary Table S6).[39] In brief, the fatty acyl encoding genes, such as acyl carrier proteins (ACPs), fatty acid elongase (FAE), fatty acid reductase (FAR), and fatty acid desaturase (FAD), play an important role in producing precursors of aromatic volatile substances.Our targeted analysis identified that 12 genes related to precursors of aromatic volatile substances showed significantly higher expression in CK4.However, genes such as Soltu.DM.01G043150-FAR3,Soltu.DM.02G029960-FAE3,Soltu.DM.06G003120-FAD, and Soltu.DM.11G004020-ACP had shown many folds higher expression in CK4 than CK.The differential regulation of these genes probably contributes to the difference in composition and concentration of volatiles detected at both time intervals in fresh-cut potato shreds.In the alcohol volatile biosynthesis pathway, eight genes encoding alcohol dehydrogenase (ADH), such as Soltu.DM.01G033170-ADH,Soltu.DM.03G011790-ADH,Soltu.DM.04G025720-ADH,Soltu.DM.08G030190-ADH,Soltu.DM.11G002020-ADH,Soltu.DM.11G002040-ADH, Soltu.DM.11G002250-ADH had higher fold change difference among CK4 and CK.The dynamic changes in these regulatory genes may alter the amounts of 1-octene-3-ol, 1-pentanol, and cis-3-nonen-1-ol at both time intervals in fresh-cut potato shreds.The significant differential expression of one gene annotated with the aldehyde dehydrogenase family (ALDH) and five genes encoding aldehyde reductase-like proteins (ALR) may influence the biosynthesis of N, N-dimethylformamide in response to the cutting process in potatoes.For volatile esters associated genes, six genes encoding carboxylesterase (CXE) showed many fold higher regulation in CK4 than CK, which ultimately can yield various ester volatiles at both time intervals in fresh-cut potato shreds.In particular, the higher regulation of Soltu.DM.02G025660-CXE15 probably promotes the abundance of 2,4,4-trimethylpentane-1,3-diyl bis (2-methylpropanoate) only in CK4 potato shreds.Our targeted analysis for alkanes-encoding genes identified that eight eceriferum (CER) genes along with two mid-chain alkane hydroxylase (MAH) genes had significant expression differences in the comparison of CK4 and CK.In particular, the many fold higher regulation of Soltu.DM.10G008360-CER1 and Soltu.DM.04G023490-MAH1 in CK4 may facilitate a significantly higher level of 2-methylheptadecane, hexane, 1,3-hexadiene, and 1,6-octadiene during the early stages of the cutting process.Lower expression of Soltu.DM.10G026560-MAH1 along with Soltu.DM.05G004550-CER9 and Soltu.DM.08G005580-CER9 in CK4 most likely reduced the contents of 2,6,10,14- tetramethylpentadecane, hexadecane, heneicosane, and phytane.The differential abundance of these volatiles can yield flavor disorders in potatoes even before further processing.In brief, the mechanism of cutting generated dynamic changes in the expression of genes annotated for volatile species of alcohols, aldehydes, esters, and alkanes.It ultimately altered the composition and abundance levels of aromatic volatiles at both time intervals.Finally, deteriorate the quality characteristics, including aroma, flavor, and appearance of fresh-cut potato shreds.However, further research with advanced genomic and biochemical analysis could be critical to understanding the quality control mechanism of fresh-cut potatoes.

Quantitative real-time PCR validation
To confirm our transcriptome results, 15 flavor encoding genes were randomly selected to perform a qRT-PCR analysis.These genes showed a significant differential expression among CK and CK4 potato shreds.All gene expression trends investigated by qRT-PCR had significantly higher regulation in CK4 (Figure 10a).Remarkably, the Pearson correlation coefficient revealed that the gene expression data yields from RNA-seq and qRT-PCR had similar profiles (R2 > 0.8) (Figure 10b).Thus, these results confirm the accuracy of our transcriptome analysis performed in fresh-cut potato shreds at different time intervals.

Discussion
The taste of food is potentially altered through cooking or processing. [20]Ultimately, human perception of taste or flavor is impacted by a range of psychological and cultural aspects. [40,41]The majority of flavor is believed to be produced by volatile aromatic compounds released in the mouth and carried to the olfactory receptors. [12,42]This means that the same flavor compound can be perceived differently by different individuals or by the same person at different times. [43,44]he flavor of fresh-cut potatoes is influenced by various factors, such as cultivar, processing method, storage conditions, microbial activity, and the presence and level of volatile  compounds. [7,14,15,45,46]Raw potatoes have a distinct aroma that can be detected during preparation when the volatile compounds are released from the cut or damaged surface of potato tubers. [14,47]owever, method of potato cooking (baking, steaming, boiling, roasting, or frying) influences the type and intensity of flavor produced. [24]For example, baked potatoes have a dominant quantitative presence of compounds derived from lipids and the Maillard reaction/sugar degradation. [48]For a particular interest, this study identified the major volatile compounds in fresh-cut potato shreds at two time points and further discussed their biosynthesis mechanism.
We studied volatile compounds in fresh-cut potato shreds at two time points, i.e., immediately after cutting (CK) and after four hours of storage (CK4).In CK, 22 volatile compounds were detected, while 24 volatile compounds were detected in CK4.The majority of these volatiles belonged to different types of alkanes, followed by alcohol, aldehyde, furan, ester, and quinone in both time intervals.Aldehydes are an important class of volatiles known for flavor in various foods. [49]Aldehydes are biosynthesized either by transamination followed by decarboxylation and reduction of amino acids or by lipoxidation of plant fatty acids. [50]One aldehyde compound, N, N-dimethylformamide, had the highest concentration in potato shreds at both time intervals, followed by the furan compound 2-pentylfuran.Furans are also produced by lipoxidation reactions. [51]2-pentylfuran is associated with off-flavor and fruity aroma in potatoes. [24,52,53]The abundance of these volatiles suggests their significant role in determining the quality of potato foods.Alkanes are another class of volatiles biosynthesized during lipid metabolic reactions.Among the different alkane compounds, 2,6,10,14tetramethylpentadecane, 2,6,10-trimethylpentadecane, phytane, hexadecane, and heneicosane were dominant in potato shreds at both time intervals.Cutting and slicing of raw potatoes causes cell membrane disruption, which in turn promotes the oxidation of fatty acids by the lipoxygenases found in the raw potato. [21,54][23][24] Interestingly, we found some of the volatiles such as 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, 1,3-hexadiene, 1,6-octadiene and hexane) were only present in CK4, while levels of 2-ethyl-3-methyl-1-pentene and 2-octenal were higher in CK4 than CK.
Most of the flavor and aroma volatile components in vegetables and fruits are the result of fatty acid metabolism, which is regulated by lipoxygenase (LOX) genes. [54]Lipoxygenase-initiated reactions convert unsaturated fatty acids to aldehydes and saturated fatty acids to corresponding aldehydes, alcohols, esters, and hydrocarbons. [50]Other genes affecting the level and presence of volatiles include acyl carrier proteins (ACPs), fatty acid elongase (FAE) [55] , fatty acid reductase (FAR), and fatty acid desaturase (FAD). [56]Differential gene expression analysis in our study identified that 12 genes related to the fatty acid metabolism pathway showed significantly higher expression in CK4.Four of these genes (Soltu.DM.01G043150-FAR3,Soltu.DM.02G029960-FAE3,Soltu.DM.06G003120-FAD, and Soltu.DM.11G004020-ACP) had shown many folds higher expression in CK4 than CK.The differential regulation of these genes probably contributes to the difference in composition and concentration of volatiles detected at both time intervals in fresh-cut potato shreds.[59][60] Differential expression of alcohol dehydrogenase (ADH) genes in CK and CK4 suggests the effect of varying levels of alcohol (1-octene-3-ol, 1-pentanol, and cis-3-nonen-1-ol) on the flavor of the fresh-cut potato shreds.][63][64] The significant differential expression of aldehyde biosynthesis related genes (aldehyde dehydrogenase family (ALDH) and aldehyde reductase-like protein (ALR)) may regulate the biosynthesis of N,N-dimethylformamide and consequently affect the flavor of fresh-cut potatoes.
Esters are the main volatiles responsible for the fruity aroma of fruits and vegetables. [65]These substances are synthesized by esterification of alcohols and carboxylic acids. [59][71][72] The up-regulation of carboxylesterase (CXE) genes in CK4 suggests the role of esters (N-hydroxybenzoate methyl ester and 2,4,4-trimethylpentane-1,3-diyl bis(2-methylpropanoate)) in changing the flavor of fresh-cut potatoes.The formation of hydrocarbons in potato is associated with oxidative off-flavor. [73]The up-regulation of genes (Soltu.DM.10G008360-CER1 and Soltu.DM.04G023490-MAH1) related to hydrocarbons in CK4 and the higher level of some hydrocarbons in CK4 suggest the involvement of these genes in the regulation of flavor change in fresh-cut potatoes.

Conclusion
In this study, volatile analysis determined that alkenes, alcohols, esters, aldehydes, and furans are the predominant volatiles present in fresh-cut potato shreds.However, the cutting process imbalanced the profiles of several aromatic volatile compounds in potatoes.The abundance of many alkenes and alcoholic substances was reduced even after a few hours of storage.Similarly, many fatty acyl-coding genes involved in the regulation of volatile precursors showed significant differential regulation.Importantly, the many folds differential regulation of Soltu.DM.10G008360-CER1,Soltu.DM.08G005580-CER9, and Soltu.DM.04G023490-MAH1 most likely facilitates differential level of hexane, 1,3-hexadiene, and 1,6-octadiene in storage potato shreds.In addition, differential regulation of Soltu.DM.11G002250-ADH,Soltu.DM.01G038420-ALR, and Soltu.DM.02G025660-CXE15 can alter the composition of several alcohols, aldehydes, and esters, respectively.The disruption of these hydroperoxide annotated genes probably contributes to potato quality disorders, including flavor changes in response to potato cutting.Our study will be vital to improving the quality traits of freshcut potatoes, including flavor, aroma, appearance, and texture.

Figure 1 .
Figure 1.Phenotypic appearance of fresh-cut potato shreds utilized in this study (a) at 0 hour (CK) (b after 4 hours of storage (CK4).

Figure 2 .
Figure 2. The distribution of volatile compounds into different groups for CK and CK4 potato shreds.

Figure 3 .
Figure 3.The abundance levels of all volatile compounds identified in CK (a) and CK4 (b) potato shreds.(Six grams of potato shreds were used in each time interval).The underlined volatile compounds were specific to time interval.They were present only in one of the time points (CK or CK4).

Figure 4 .
Figure 4.The percentage of various alkenes identified in the comparison of CK and CK4 potato shreds.Here data is mean ± SE in each CK and CK4 (n = 3) and * represents significant difference at p < .05.

Figure 5 .
Figure 5.The percentage of various volatiles identified in the comparison of CK and CK4 potato shreds (A) alcohols (B) aldehydes (C) furan (D) quinone.Here data is mean ± SE in each CK and CK4 (n = 3) and * represents significant difference at p < .05.

Figure 6 .
Figure 6.The profiles of differentially expressed genes identified in CK and CK4 potato shreds (a) statistics for differential genes (b) expression profiles of differential genes among three biological repeats of CK and CK4 potato shreds.

Figure 7 .
Figure 7. GO enrichment analysis for DEGs identified in comparison of CK and CK4 potato shreds.

Figure 8 .
Figure 8. Pathway enrichment for DEGs identified in comparison of CK and CK4 potato shreds.

Figure 9 .
Figure 9. Gene regulatory network of various flavor volatiles in fresh-cut potato shreds at different time intervals (a) Simplest diagram of the fatty acid-derived volatile pathway, ACP: acyl carrier proteins; FAS: fatty acid synthases; FAR: fatty acid reductase; FAE: fatty acid elongation; FAD: fatty acid desaturase; LOX: lipoxygenase; HPL: hydroperoxide lyase; ADH, alcohol dehydrogenase; AAT, alcohol acyltransferase; CER: eceriferum; and MAH: mid-chain alkane hydroxylase (b) Expression profiles of flavor volatiles related genes in three biological repeats of CK and CK4 potato shreds.

Figure 10 .
Figure 10.The qRT-PCR validation of flavor related genes in fresh-cut potato shreds at different time intervals (a) qRT-PCR relative expression levels among CK and CK4 potato shreds (b) Pearson's correlation of RNA-seq and qRT-PCR data.

Table 1 .
Summary of RNA sequencing for each biological replicate of CK and CK4 potato shreds.