Physiological and transcriptomic characterization of cold acclimation in endodormant grapevine under different temperature regimes

It is essential for the survival of grapevines in cool climate viticultural regions that vines properly acclimate in the late fall and early winter and develop freezing tolerance. Climate change-associated abnormities in temperature during the dormant season, including oscillations between extreme cold and prolonged warmth, impacts cold acclimation and threatens the sustainability of the grape and wine industry. We conducted two experiments in controlled environment to investigate the impacts of different temperature regimes on cold acclimation ability in endodormant grapevine buds through a combination of freezing tolerance based physiological and RNA-seq based transcriptomic monitoring. Results show that the freezing tolerance of buds was not altered from field levels when exposed to stable temperatures ranging from 2 {degrees}C to 22 {degrees}C but was enhanced when exposed to temperature cycling (7{+/-}5 {degrees}C). We also characterized the transcriptomic response of endodormant buds to high and low temperatures and the potential genetic control for the maintenance of endodormancy. Several pathways that were previously reported to be responsive or functional during cold acclimation, such as the ICE-CBF-COR cascade, were not observed to play a role in the enhancement of freezing tolerance or the sensing of different temperatures, indicating our current understanding of the genetic control of cold acclimation remains a challenge when generalizing across plant species and phenological stages.