1. Jean-Michel Boursiquot (Keynote Speaker) - Chenin Blanc knowledge
During this conference, I will focus on presenting Chenin under its various facets in order to contribute to the improvement of the global knowledge of this variety, with the aim to control better and optimize its culture and the quality of its products. I will begin with a historical and genetic study on the origin of this variety. Then, I will discuss its development, its importance, its distribution and the synonyms used to name it. After having defined its ampelographic characteristics, I will present its agronomic and technological aptitudes: phenology, physiology, adaptation to the soil, rootstocks, clones, sensitivity to pests and diseases, emphasizing the different factors influencing the characteristics and quality of its wines. To conclude, I will highlight the key points to optimize its management as well as the possible future development and the positioning perspectives of this variety.
Moderators : André Deyrieux & Etienne Goulet
2. Virginie Grondain - Chenin Blanc repository in Montreuil Bellay
Chenin is an emblematic wine grape cultivar from Loire Valley and other regions in the world. The safeguarding of this variety and its diversity is an important objective for these vineyards, for heritage and for the ajustment to future climate change.
In order to gather the genetic and phenotypic diversity, a new Chenin repository is being created at Montreuil-Bellay Experimental Estate (French Vine and Wine Institute – IFV, Maine-et-Loire, France). This collection is based on the previous historical one (307 accessions) and on new international surveys conducted by the IFV and its partners.
Since 2016, 350 accessions have been selected in 34 old parcels in Loire Valley and 14 accessions were taken from an old collection in the Aveyron district. These accessions were added to the 307 accessions previously present in the former repository at Montreuil-Bellay. Plants free of virus were grafted and planted in the new Chenin repository, that is 473 different accessions.
In 2019, surveys were extended to South Africa, resulting in 97 plants selected in about 20 old parcels located in vineyards around Stellenbosch. After virus status checking, the healthy plant material will enrich the new repository at Montreuil-Bellay, leadind to more than 500 different accessions of Chenin.
This new collection of Chenin cultivar, hosting a unique diversity, will be enlarged in the future depending on potential new findings in France or abroad. These genetic resources could be used for further selection works by studying the agronomical characteristics and behaviour of Chenin blanc.
3. Dr Johan Burger - The Pinotage old vine story - lessons learnt for future genetics research in Chenin Blanc.
In many parts of the world there is a newfound interest in old vines and vineyards, and the exceptional wines produced from them. These wines are generally accepted as having more depth and complexity than young-vineyard wines, thus often the term “old vine” are used on wine labels as an indication of a superior, high-quality wine.
In South Africa, two of the most prominent cultivars used for the production of old-vine wines are Chenin blanc and Pinotage. However, there is only anecdotal evidence that these wines are truly of a higher standard. This study is the first genetic research into the so-called “old-vine” wine character, aiming to determine any significant differences in gene expression in leaves and berries of young (7-yrs) and old (>40-yrs) clonal Pinotage vines, at the time of harvest. Genome sequencing, as well as RNA-seq, allowed for the identification of 925 genes differentially expressed between young and old Pinotage vines. Many of these genes are involved in metabolic pathways active during fruit ripening, and a general trend was observed towards delayed berry ripening in old vines. Berries of these vines also had a lower sugar concentration and higher titratable acids at the time of harvest, compared to young-vine berries.
Collectively, these results suggest that berries of old Pinotage vines take longer to ripen, possibly allowing for the accumulation of volatile aromas that influence berry flavour. The obvious question that arises is if similar trends exist in a classical white cultivar like Chenin blanc, especially since chemical and sensory analyses of young- and old-vine Chenin blanc wines have been done before.
Comparing these results to those obtained from a such differential gene expression study in young and old clonal Chenin blanc vines could potentially tie genotype and phenotype together in a unique way for grapevine research.