Research On Auxin Inhibiting The Browning Of Fresh-cut Potato

The market demand of fresh-cut potato in China is huge,and browning is the main factor affecting its quality and shelf life.It is urgent to find a convenient,safe and effective browning inhibitor for processing and preservation of fresh-cut potato.In this study,transcriptome sequencing analysis(RNA-Seq)was carried out on the Kexin No.4 and Kexin No.13 potatoes with significant differences in browning degree after fresh cutting,and the expression of genes related to auxin signal pathway and the change of endogenous auxin content in the potatoes of Kexin No.4 and Kexin No.13 after cutting were measured.The mechanism of endogenous auxin signal regulating the browning of fresh cutting potatoes was preliminarily revealed.After that,the main potato variety Netherlands 15 in shandong province was used as the experimental material,screened the best conditions of exogenous auxin treatment to inhibit browning of fresh-cut potatoes,and preliminarily explored the mechanism of exogenous auxin treatment in inhibiting browning of fresh-cut potato by measuring the key enzyme activity of browning,browning substrate and antioxidant capacity.The specific research results are as follows:(1)Through the observation of the browning degree of two potato varieties(Kexin No.4and Kexin No.13)after fresh cutting,it was found that the potatoes of Kexin No.4 had a significant browning 8 hours after cutting,and the potatoes of Kexin No.13 had a good color1 day after cutting,indicating that the potatoes of Kexin No.4 were more prone to browning.The mechanism of inhibiting browning of fresh-cut potato was analyzed from the perspective of transcriptomics by determining the tuber samples of Kexin No.4 and Kexin No.13.One hundred and twenty-one differentially expressed genes were screened and GO enrichment analysis was carried out on these differentially expressed genes,and six significantly enriched metabolic pathways were screened out.The "hormone response" pathway was one of the three most significantly enriched pathways,then selected the auxin response gene St RES with the highest differential expression multiple as subsequent research object.In addition,used Realtime Quantitative polymerase chain reaction(Real-time PCR)to detect the expression of the auxin synthesis gene St SYN1-8 and the auxin response gene St RES in potato,found that the expression of St SYN1,St SYN2 and St RES in Kexin No.13 was significantly up-regulated compared with that in Kexin No.4 on the 3 day after cutting,among them,the expression of St SYN1 was up-regulated by 277,and that of St RES was up regulated by 17,.while the downregulation of St SYN3,St SYN4,St SYN5,St SYN6,St SYN7 and St SYN8 was significant.Surmised that St SYN1,St SYN2 and St RES may be involved in regulating the browning of fresh-cut potato.(2)By measuring the endogenous auxin content of Kexin No.4 and Kexin No.13 potato after cutting,it was found that the auxin content of both of them increased,but the auxin content of Kexin No.13 potato with slower browning increased faster.The browning of Kexin No.4 potato was aggravated after inhibiting the synthesis of endogenous auxin by auxin synthesis inhibitor.These results suggest that the synthesis of endogenous auxin may be involved in the regulation of browning of fresh-cut potatoes.The results of transcriptome analysis,real-time PCR and endogenous auxin content determination indicated that endogenous auxin signal may be involved in the regulation of browning of fresh-cut potatoes by regulating the expression of auxin synthesis genes St SYN1,St SYN2 and auxin response genes St RES;and exogenous auxin treatment may inhibit Browning of fresh-cut potatoes.(3)The exogenous auxin treatment with appropriate concentration can significantly inhibit the browning of fresh-cut potato and potato slurry.The best treatment conditions are:5 mg/L,soaking for 40 seconds,placing for 48 hours after soaking,then fresh cutting.Under the storage condition of 4?,fresh-cut potato treated with exogenous auxin were browned 10 hours later than the control and water treatment.At room temperature,the control and water treated potato slurry browning occurred in 20 minutes,and the exogenous auxin treated potato slurry browning began in 40 minutes.Through the determination of physiological indexes,it was further found that exogenous auxin treatment could significantly inhibit the activity of polyphenol oxidase(PPO),reduce the content of tyrosine and total phenol,and increase the free radical inhibition rate of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS).However,which aspect of PPO activity,tyrosine content,total phenol content and ABTS free radical inhibition rate is the main factor that auxin affects potato browning still needs further verification.