Developmental stage-specific effects of high temperature on aroma accumulation in ‘Marselan’ grapes from the Helan Mountain region

Abstract

The aroma of wine grapes is influenced by a complex metabolic network, with terroir factors, especially high temperatures, playing a critical role during berry development. This study explores how natural terroir conditions affect aroma accumulation in ‘Marselan’ grapes and the underlying molecular mechanisms.

We constructed the Marselan Terroir-Temporal Metabolic Network (MTTMN) dataset, which includes climate, soil, and vine growth data from five vineyards, as well as physicochemical, metabolomic, and transcriptomic data from ‘Marselan’ berries at various developmental stages. A total of 46 sample sets, each with three biological replicates, were collected. Targeted metabolomics (GC-MS, LC-MS) quantified 115 volatile metabolites, 43 aroma precursors, and 11 hormones. Transcriptomic data were generated through next-generation sequencing, yielding 890.5 Gb of clean data.

Cluster tree and t-SNE analyses revealed stage-specific accumulation patterns of genes and metabolites, leading to the reclassification of samples into six key developmental stages. Early stages (flowering, setting, green berry) were found to significantly impact aroma compound accumulation, with metabolites like β-damascenone and linalool being key for wine aroma quality. Co-regulation and TO-GCN analyses constructed a regulatory network of aroma metabolism, in which 6 structural genes and 31 candidate transcription factors associated with norisoprenoids were identified.

We found that vineyards with higher temperatures during the green berry stage had higher norisoprenoid levels. Heat treatments at the green berry and mature stages (38°C day, 30°C night) showed that high temperatures promoted β-damascenone and vitispirane synthesis before veraison, but inhibited accumulation after veraison. Transcriptomic analysis confirmed this stage-specific effect. We identified heat-responsive genes in the norisoprenoid regulatory network and validated two key genes, VvZEP4 and VvTAS1, along with three WRKY transcription factors involved in norisoprenoid regulation under high temperatures.

This study provides insights into the molecular mechanisms regulating aroma metabolism in response to terroir, particularly high temperatures, offering guidance for adaptive viticulture strategies amidst climate change.