Early epigenetic changes are involved in bud dormancy release in grapevine

Plant phenological development is deeply influenced by changes in temperature, with budbreak dates occurring earlier as the mean global temperature increases. As a result, spring frost damage risk is increasing in many areas of the world. In grapevine, early dormancy release may also result in the advancement of all subsequent developmental stages, including ripening and harvest, thus challenging traditional wine production schedules in important wine-making regions. Understanding the molecular regulation of dormancy release in buds is essential to direct breeding efforts to produce late-budbreak varieties better suited to the new climatic scenarios. Recent evidence collected in field-grown grapevines implies that DNA demethylation is involved in dormancy regulation. To further describe these aspects, potted plants of ‘Cabernet Sauvignon’ were kept in controlled conditions to induce dormancy, chilling requirement fulfilment and dormancy release. Buds were regularly sampled for transcriptomic analyses to assess the major biological processes taking place from cold acclimation to deacclimation. RNA-seq revealed a wide range of significant changes concerning epigenetic regulation taking place exclusively during deacclimation. Genes affected by these changes, up to 18 days before budbreak, included homologs of DNA demethylases ROS1 (Repressor of Silencing 1) and DME (DEMETER). Evidence of demethylated regions within gene promoters was detected with BS-seq, including several developmental and growth-related targets characterized by an increased expression during forcing conditions. While dedicated studies are required to validate these preliminary observations, these results reinforce the possibility of a role for active DNA demethylation in dormancy progression and release in grapevine.

Valeria De Rosa won the ISHS Young Minds Award for the best oral presentation at the XVI EUCARPIA Symposium on Fruit Breeding and Genetics in Germany in September 2023.

Valeria De Rosa, Dipartimento di Scienze Agroalimentari, Ambientali e Animali (Di4A), University of Udine, Via delle Scienze 206, 33100 Udine, Italy, e-mail: valeria.derosa@uniud.it

The article is available in Chronica Horticulturae