Study On The Synthetic Pathway Of Anthocyanin In Pericarp Of Passion Fruit Based On Transcriptome Analysis

Passion fruit is grown in most parts of the world,its pulp is rich in nutrients,often processed into juice for consumption,but the use of the peel is less,resulting in a waste of resources.This study mainly studies passion fruit peel from the transcriptome level,aiming to lay a foundation for revealing the molecular mechanism and regulatory mechanism of passion fruit anthocyanin biosynthesis.In this study,four samples of purple-bark passion fruit and yellow-bark passion fruit were studied at ripe and non-ripe stage,and firstly,a response surface method was used to investigate the optimal conditions for the extraction of anthocyanins from passion fruit peel,and the anthocyanins of four samples were extracted by this condition.Secondly,the transcriptome was sequenced by Illumina-Hiseq technology,and the original data were filtered by quality control,and Clean Reads was compared to the passion fruit reference genome.The expression of the aligned genes is then quantified and then used with DESeq2 in|log₂Fold Change|≥1 and the FDR<0.05 criteria were used to screen for differentially expressed genes.Differentially expressed genes were genetically annotated with KEGG,GO and KOG,respectively,and gene function and metabolic pathways were analyzed.Further identification of hub genes which may be associated with anthocyanin synthesis by WGCNA analysis.Finally,part of the hub gene was verified using RT-q PCR.The above-mentioned study has yielded the following findings:（1）The optimal conditions for extracting were found to be an ethanol concentration of78%,an extraction time of 73 min,ultrasonic power of 345 W,and a material-liquid ratio of1:45.The results obtained under these conditions were favorable.The anthocyanin contents of ripe peel（TPR）,non-ripe peel（TPU）,yellow peel ripe peel（TYR）and non-ripe peel（TYU）were 3.329 mg/g,1.073 mg/g,0.897 mg/g and 0.877 mg/g,respectively.（2）The transcriptome of 12 samples was sequenced using Illumina-Hiseq technology,and559 million raw reads were obtained,535 million filtered Clean Reads,with an average length of 150 bp,and the Clean Base of each sample was above 6 G,and the alignment rate of each sample was higher than 73%.（3）The results of differentially expressed genes obtained by DESeq2 screening showed that there were 7528 differentially expressed genes in TPR＿vs＿TYR comparison,of which3504 gene expression was upregulated and 4024 gene expression was down-regulated.TPU＿vs＿TPR comparison,a total of 3976 differentially expressed genes were detected,of which 1894 genes were up-regulated and 2082 gene expression was down-regulated.TPU＿vs＿TYU comparison,a total of 5039 differentially expressed genes were detected,of which 2272 genes were upregulated and 2767 were down-regulated.Differentially expressed genes were annotated and found to have the most differentially expressed genes on KOG database annotations.（4）WGCNA analysis was performed on differentially expressed genes,the genes were clustered into 10 modules,combined with anthocyanin content,the two modules with the highest positive and negative correlation with anthocyanin content were further analyzed,and the gene co-expression network diagram was constructed,and the 10 hub genes with the highest score by the MCC algorithm of the two modules were screened respectively.The five hub genes with the highest MCC algorithm scores in the two modules were verified by real-time PCR,and the results were in line with the expected experimental assumptions.The above study fills a gap in the transcriptome research of anthocyanin synthesis in passion fruit pericarp,lays the foundation for the subsequent selection of specific transcription factors to study the transcriptional regulation mechanism of anthocyanin biosynthesis,and also provides data reference for the in-depth exploitation of anthocyanins.Color is an important indicator to evaluate the appearance quality of horticultural crops,so our study not only made full use of the passion fruit peel to develop anthocyanin resources,but also to further improve its appearance quality.