Perennial plants use bud dormancy as a strategy to survive stressful environments, such as cold temperatures during winter. This strategy is dependent on the ability of the dormant bud to track the length of winter, avoiding early spring budbreak. With sufficient exposure to low, non-freezing temperatures (chilling requirement), grapevine buds transition between early (endodormant) and late winter (ecodormant) states. In a recent study published in AoBP, Kovaleski et al. aimed to uncover the relationship between fulfilment of the chilling requirement and the effects of various temperatures on loss of cold hardiness (deacclimation).

Deacclimation kinetics of Vitis species — Cold hardiness of grapevine buds in the field is ~U shaped (A). If forced, buds lose hardiness (red arrows, A). Deacclimation rates are genotype specific, differ according to temperature of exposure (B) and dormancy level, described as deacclimation potential (C). Early bud phenology follows same kinetics as deacclimation (D). Image credit: Kovaleski *et al*.

The relationship between chilling requirement and temperature as it affects the rate of deacclimation was examined for dormant cuttings of Vitis vinifera, V. aestivalis, V. amurensis and V. riparia. The results of the study demonstrate that as winter progresses, the sensitivity of grapevine buds to temperature increases, and highlights a link between dormancy state and loss of winter hardiness. The kinetics of this process also describe early bud phenology. With these results, it will be possible to model the response of buds to current and future climate conditions. This work is particularly important in predicting potential losses due to Midwinter warming events that are expected to become more frequent under climate change.

Researcher highlight

Al Kovaleski graduated with an Agronomic Engineering degree from the Federal University of Rio Grande do Sul, Brazil in 2011 followed by a Master’s degree in Horticultural Sciences from University of Florida, USA in 2014. He obtained his PhD in Horticultural Biology at Cornell University, under the guidance of Dr. Bruce Reisch and Dr. Jason Londo. Al is currently a postdoctoral researcher with Dr. Jason Londo at USDA – Agricultural Research Service – Grape Genetics Research Unit.

Al studies bud development and off-season physiology of woody perennials. He makes use of modelling approaches along with transcriptomics to help unravel the complexity of climate effects on fruit crops and natural forests.