Improving freeze tolerance of Vitis under a changing climate

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Cold hardiness research is critical for high-value crops such as wine grapes (Vitis spp.) with the threat of climate change. Perennial woody plants are stationary in nature and have evolved mechanisms to overwinter. During dormancy, plants gain and lose cold tolerance and it is highly dynamic in nature with many physical, physiological and metabolic changes. Cold hardiness follows a predictable seasonal pattern which includes cold acclimation in late fall, a period of maximum hardiness in winter, and cold deacclimation in the spring prior to bud break. Both genotype and environmental conditions impact dormancy and cold hardiness responses. The acclimation phase has been well studied in some plants, but cold hardiness and its mechanisms are not well understood for the deacclimation phase in woody plants such as Vitis spp. During the deacclimation phase, plants can gain back hardiness (reacclimation), an even less understood phenomenon. Therefore, a research program is required to understand the underlying mechanisms of how acclimation, deacclimation and reacclimation capacity are affected by changes in environmental conditions and in different Vitis genotypes. Furthermore, there is a gap of knowledge concerning the plant hormone abscisic acid, potential signaling and hormonal pathways during deacclimation and reacclimation and associated changes in cold hardiness related metabolites such as specific dehydrin proteins and carbohydrates. Therefore, the long-term objective of my research program is to gain a comprehensive understanding of the mechanisms of cold hardiness and associated molecular, physiological and metabolic changes in Vitis during different phases of dormancy. The goal is to improve grapevine cold tolerance and resiliency to the effects of climate change to ensure sustainability in fruit and wine production. This may be accomplished by treating plants with growth regulators and through identification of potential cold-hardiness-related markers that may be used for "best in class" cultivar, clonal and rootstock selection. A first step of achieving this long-term goal is to gain insights into potential signaling and hormonal pathways involved in cold deacclimation and reacclimation as well as corresponding cold hardiness metabolites. Therefore, the short-term objectives are: 1) Follow and analyze the expression of targeted genes during deacclimation/reacclimation of different Vitis genotypes. 2) Compare treatment effects of exogenous applications of ABA analogs, including a known cold hardiness enhancer and an ABA antagonist, on dormancy and cold tolerance of different Vitis genotypes. 3) Elucidate relationships between cold hardiness changes during deacclimation and reacclimation phases and molecular and biochemical changes of different Vitis genotypes treated with ABA analogs known as a cold hardiness enhancer as well as an ABA antagonist.