# Variation in Fruit Quality and Aroma Biosynthesis of ‘Summer Black’ Grape in Southern China

## TL;DR

This study examines how regional differences in southern China affect the quality and aroma of 'Summer Black' grapes, identifying key compounds and genes involved in aroma formation.

## Contribution

The study identifies eight consistently detected aroma compounds and 15 genes linked to phenylpropanoid biosynthesis in grape aroma formation.

## Key findings

- Samples from CD-2 had the highest soluble solid content and TSS/TA ratio.
- Eight aroma compounds were consistently detected across all regions, with phenethyl alcohol showing the most variation.
- Transcriptome analysis identified 15 differentially expressed genes related to aroma biosynthesis, including PAO significantly correlated with phenethyl alcohol content.

## Abstract

Objectives: The aroma profile is a key determinant of fruit quality. Methods: In this study, mature ‘Summer Black’ grape berries were collected from 36 major producing areas in southern China to evaluate regional differences in fruit quality, volatile compounds were analyzed by via GC-MS, and a representative volatile profile was established. Furthermore, transcriptome sequencing was employed to identify key genes involved in the phenylpropanoid biosynthesis pathway related to aroma formation. Results: The results showed the following: (1) Samples from CD-2 exhibited the highest soluble solid content and the largest TSS/TA ratio. (2) A total of 20 volatile compounds were selected as indicators for the aroma fingerprint. MS-1 samples contained the most diverse aroma compounds (19 types), while CS-2 had the fewest (12 types). (3) Eight aroma compounds were consistently detected across all regions: hexanal, trans-2-hexenal, n-hexanol, β-citronellol, geraniol, nerol, benzyl alcohol, and phenethyl alcohol. Among these, hexanal and trans-2-hexenal were the most abundant; phenylethyl alcohol exhibited the most significant variation in percentage content across all samples, and was determined to be the representative and dominant volatile compound in ‘Summer Black’ grapes. (4) A transcriptome analysis of six representative regions identified 15 differentially expressed genes associated with phenylpropanoid biosynthesis and metabolism. Among them, PAO (Vitvi04g01467) was significantly correlated with phenethyl alcohol content. Conclusions: These findings provide a basis for evaluating the aroma quality of ‘Summer Black’ grapes and offer insights for regional cultivation selection.