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Abstract

Bud dormancy is an adaptive strategy for the survival of drought, high temperature, low temperature, and freeze-dehydration stress. Dormancy is not a static state, but rather a dynamic phase of plant development that impacts the geographical range, yields and management strategies of many woody species, including grapevines (Vitis). In temperate woody plant buds, the major stages of bud dormancy have been described relative to the environmental and physiological processes regulating growth. These stages include: paradormancy (correlative inhibition, summer dormancy), when growth is regulated by physiological factors originating outside the bud; endodormancy (rest, vegetative maturity), when inhibition of growth originates within the bud meristem and chilling is required before growth can resume; and ecodormancy (quiescence, imposed dormancy, or winter dormancy), when one or more environmental factors are inadequate to support growth. Bud endodormancy is induced in the overwintering woody plant by a decreasing photoperiod and/or low temperature naturally occurring in the autumn. In Vitis species, the environmental regulation of bud endodormancy varies between genotypes. Some genotypes become dormant in response to decreasing photoperiod and others require low temperature or both environmental cues to induce endodormancy. The timing of endodormancy induction and release influences the economic production of grapes, the most valuable temperate fruit crop in the United States and the world. In cold winter regions, late induction of grape bud endodormancy, as well as early release from endodormancy, may contribute to freeze-dehydration injury to the buds resulting in crop losses and high production costs. To develop an understanding of the coordination of the environmental and genetic mechanisms regulating bud endodormancy this project will use a Vitis genetic system with differences in endodormancy induction, transcriptomic, proteomic and metabolomic profiling, and integrated bioinformatics tools to transform separate ""omic"" data sets into cohesive and useful biological knowledge. Short (SD) or long (LD) photoperiods will be used to induce endodormancy or maintain paradormancy in photoperiod responsive and non-responsive Vitis genotypes. Temporal studies in age matched buds during endodormancy and paradormancy development will be used to separate bud maturation responses from endodormancy regulation. Transcriptomic analysis will identify differentially expressed genes between the treatments and across the temporal states. Comparison of these results with abiotic stress studies in Vitis will enhance the ability to detect signal transduction mechanisms regulating environmental responses. Identification of differentially expressed proteins will enhance the understanding of pathways involved in bud maturation and response to environmental conditions, as well as the differences between the two processes. Metabolomic analysis will provide metabolite and hormone profiling of grape buds during development and endododormancy induction in a more comprehensive manner than has been previously conducted. All data will be archived in public repositories and in databases (http://vitis-dormancy.sdstate.org) that allow users to search for specific genes of interest based on sequence information or annotation, or perform flexible on-line analysis. The separate data sets will be integrated through a pathway database that can output systems biology markup language (SBML) and BioPAX compatible information that links the metabolic networks to the regulatory networks and the protein interaction networks. This comprehensive analysis will improve our understanding of cellular processes that occur in the bud meristem during maturation and those regulating endodormancy and paradormancy development. The information can be further used to develop markers for breeding and mapping initiatives, target cultural practices for dormancy management in existing cultivars, and provide insights in dormancy regulation that can be explored in other plant organs and species exhibiting dormancy cycles.

All data will be available through public databases:
http://www.plexdb.org/plex.php?database=Grape
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=geo
http://metnet3.vrac.iastate.edu/
http://www.ebi.ac.uk/pride

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