Analysis of Important Volatile Organic Compounds and Genes Produced by Aroma of Pepper Fruit by HS-SPME-GC/MS and RNA Sequencing

Pepper is an important condiment, and its aroma affects its commercial value. In this study, transcriptome sequencing and combined headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) were used to analyze the differentially expressed genes and volatile organic compounds in spicy and non-spicy pepper fruits. Compared with non-spicy fruits, there were 27 up-regulated volatile organic compounds (VOCs) and 3353 up-regulated genes (Up-DEGs) in spicy fruits. The results of KEGG enrichment analysis of the Up-DEGs combined with differential VOCs analysis showed that fatty acid biosynthesis and terpenoid biosynthesis may be the main metabolic pathways for aroma differences between non-spicy and spicy pepper fruits. The expression levels of the fatty acid biosynthesis-related genes FAD, LOX1, LOX5, HPL, and ADH and the key terpene synthesis gene TPS in spicy pepper fruits were significantly higher than those in non-spicy pepper fruits. The differential expression of these genes may be the reason for the different aroma. The results can provide reference for the development and utilization of high-aroma pepper germplasm resources and the breeding of new varieties.

Automated summary

Transcriptome sequencing and HS-SPME-GC-MS analysis were used to study the differentially expressed genes and volatile organic compounds (VOCs) in spicy and non-spicy pepper fruits. The results showed that fatty acid biosynthesis and terpenoid biosynthesis may be the main metabolic pathways for aroma differences between these two types of fruits. The differential expression of genes related to fatty acid biosynthesis and key terpene synthesis genes may contribute to the different aroma. The findings provide references for the development of high-aroma pepper germplasm resources and breeding of new varieties.