From sensory quality and aroma chemistry to novel traits in MAS grape vine breeding – The case of polyfunctional thiols

Abstract

In the context of global crises such as climate change, biodiversity loss and pollution, it is necessary to reconsider current agricultural practices. Breeding new grape varieties that are resistant to pests can make viticulture more sustainable by reducing the need for pesticides and their impact on biodiversity and pollution. As a traditional product with well-established styles, acceptance of new wine varieties depends heavily on sensory quality. Including wine sensory quality as a trait for marker-assisted selection (MAS) in a grapevine breeding programme would make grapevine breeding faster and more efficient. [1]. In the current multidisciplinary project, two segregating F1 populations of ‘Calardis Musqué’ x ‘Villard Blanc’ crosses, including a total of 150 selected individual genotypes, were characterised by a high-density genetic map using a ‘genotyping by sequencing’ approach [2]. Individual wines were vinified over multiple vintages and extensively characterised by sensory and chemical analysis. Sensory analysis shows a high overall reproducibility of a measure called Total Quality Score (TQS) for the whole system “Growing – Harvesting – Winemaking – Sensory Analysis” over all vintages. TQS was strongly positively correlated with the descriptive sensory attributes ‘floral’, ‘fruity’ and ‘tropical fruit’. To understand the underlying molecular basis, the concentration of highly aroma-active varietal volatile thiols in the experimental wines was analysed by means of HPLC-MS-MS using a modified method according to Capone et al. (2015) [3]. When the results of aroma compound analysis in the wines were linked to sensory data, the varietal thiol 4-sulfanyl-4-methyl-pentan-2-one (4-MSP) showed significantly higher values for the group of best wines. At the same time, 3-sulfanylhexanol (3-SH) and its actetate ester 3-sulfanylhexanol acetate (3-SHA) did not directly correlate significantly with sensory quality. The concentration of three polyfunctional thiols (3-SH, 3-SHA and 4-MSP) in wines was used as phenotypic data, which was then combined with genetic information to identify stable quantitative trait loci (QTLs) associated with variation in wine quality. This approach revealed six stable QTL’s for these compounds (2 for 3-SH, 1 for 3-SHA, and 3 for 4-MSP) throughout the genome. The results of this study will help to enable the selection of thiol producing genotypes by MAS in future breeding programs.

References

1. Töpfer, R., & Trapp, O. (2022). A cool climate perspective on grapevine breeding: climate change and sustainability are driving forces for changing varieties in a traditional market. Theoretical and Applied Genetics, 135(11), 3947-3960.
2. Frenzke L, Röckel F, Wenke T, Schwander F, Grützmann K, Naumann J, Zakrzewski F, Heinekamp T, Maglione M, Wenke A, Kögler A, Zyprian E, Dahl A, Förster F, Töpfer R, Wanke S. (2024). Genotyping-by-sequencing-based high-resolution mapping reveals a single candidate gene for the grapevine veraison locus Ver1. Plant Physiology, Plant Physiology 196 (1), 244–260
3. Capone, D.L., Ristic, R., Pardon, K.H. and Jeffery, D.W. (2015) Simple quantitative determination of potent thiols at ultratrace levels in wine by derivatization and high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) analysis. Analytical Chemistry 87, 1226–1231.