Expression patterns of DEMETER-like DNA demethylases homologs hint at potential involvement in grapevine dormancy release

Abstract

Climate change represents an undeniable threat to traditional viticulture in many areas of the world. Although an increase of average surface temperatures is expected in the future, late frost occurrences are predicted to be an actual challenge, being budburst the critical stage during which cold hardiness levels dramatically decrease and frost vulnerability is at its maximum. Genomic DNA methylation is known as an important mechanism for gene expression regulation. A sub-group of epigenetic regulators named DEMETER-like DNA demethylases (DMLs) has been shown to be involved in budbreak regulation in Populus trichocarpa. In this study, buds of two Vitis cultivars, Fleurtai (Friulano × Kozma 20-3) and UD 31-103 (Merlot × Kozma 20-3), characterized by different levels of resistance to winter freezing temperatures, were sampled during the 2019/2020 winter season. Cold hardiness dynamics were monitored with differential thermal analysis (DTA) at regular intervals. Expression levels of two putative grapevine DEMETER homologs were investigated during natural dormancy conditions. Results show dissimilar deacclimation rates in the two varieties. As observed in other woody species, putative grapevine DEMETERs show downregulation and upregulation trends hinting at a potential involvement in grapevine dormancy release.