# Comprehensive Analysis of Malate Accumulation in Peaches in Response to Cold Stress Based on Transcriptomics

## TL;DR

This study investigates how cold storage affects malate levels in peaches, finding that vacuolar transport and specific genes help maintain sourness during cold storage.

## Contribution

The study provides a novel molecular framework for understanding cold-induced malate accumulation in peaches through transcriptomic analysis.

## Key findings

- Low temperature storage maintains higher malate content and delays fruit firmness decline.
- Proton pump and transporter genes are upregulated under cold storage, correlating with malate accumulation.
- Transcription factors PpTST1 and PpMYB62 are regulated by cold storage, influencing malate levels.

## Abstract

Malate is the predominant organic acid in peach, contributing significantly to fruit sourness and overall organoleptic quality. However, comprehensive understanding of the molecular mechanisms underlying malate accumulation in response to different storage conditions remains limited. In this study, “Hujingmilu” peach was subjected to room temperature (RT, 25°C), low temperature (LT, 4°C), and LT followed by shelf life (LT‐SL, 25°C) treatments to investigate transcriptional regulation mechanisms underlying malate accumulation, with emphasis on biosynthesis, vacuolar storage, and transcription factor regulation. Results demonstrated that LT storage delayed the decline in fruit firmness and maintained higher malate content compared to RT and LT‐SL. Transcriptomic profiling indicated that the expression patterns of malate biosynthetic genes (PpPEPC1/2, PpNAD‐MDH1/2, PpNADP‐ME1) showed limited alignment with malate accumulation. In contrast, genes implicated in proton pump and malate transporter, such as PpAtpvA1/2/3/4/5, PpVp2, and PptDT1, were significantly upregulated under LT conditions, consistent with the observed malate accumulation. Furthermore, LT storage repressed the malate transcriptional repressor PpTST1 while inducing the candidate regulatory gene PpMYB62. These findings provided a comprehensive molecular framework for understanding malate modulation under varying storage conditions.

This study explored malate‐accumulation mechanisms in “Hujingmilu” peaches under different storage conditions. Low temperature (LT) delayed firmness decline and maintained higher malate. Transcriptomics showed malate biosynthetic genes weakly correlate with malate levels, while proton pump and transporter genes were up‐regulated under LT. LT also affects transcription factors (TFs) such as PpTST1 and PpMYB62. Findings indicated that the vacuolar storage and transport system, along with specific TFs, plays crucial roles in the cold‐induced malate accumulation.