Location: Grape Genetics ResearchTitle: Variation in the chilling requirement and bud burst rate of wild Vitis species Author
Submitted to: Environmental and Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2013
Publication Date: 1/10/2014
Citation: Londo, J.P., Johnson, L.M. 2014. Variation in the chilling requirement and bud burst rate of wild Vitis species. Environmental and Experimental Botany. 160: 138-147. Interpretive Summary: Cultivated grapevine (Vitis vinifera) is one of the most important agricultural fruit crops in the world. Climate change predictions indicate that suitable vineyard habitats may begin to shift as temperatures warm. To meet the environmental demands of varied climate, grapevine breeders will have to draw on wild grapevine species for adaptive traits, particularly in regard to abiotic stress resistance. Cool temperatures in winter are important for grapevine production because grapevines are a perennial species and require a dormancy period to be ready for growth in the spring. Specific amounts of cold temperature are necessary to satisfy the dormancy period and grapevines that do not receive enough will not synchronously burst in the spring. This leads to disruptions in the flowering and fruiting patterns of grapevine and is detrimental to harvesting in the fall. In this study, we characterized both the amount of chilling required by grapevines and the maximal bud burst rate following cold temperatures. We examined 27 different grapevine varieties, representing 9 different grapevine species. Using statistics (survival analysis), we tested if different quantities of cold temperature was sufficient to break dormancy. We also examined the maximal bud burst rate, measured by the number of days needed for grapevine buds to grow. We identified different categories of grapevine based on their responses to cold temperatures: low, moderate, and high chill species. When compared with geographic distribution of the species and genotypes in this study, patterns between northern and southern populations suggest that chilling requirement and bud burst rate are adaptive traits. Grapevine breeders can now use this information to make informed decisions about the most appropriate species and varieties to use in breeding programs.
Technical Abstract: Cultivated grapevine (Vitis vinifera) is one of the most important agricultural fruit crops in the world. In the United States, grapevines are often grown in environments very different than the Mediterranean climate from where the cultivated species was domesticated. Predictions of changing climatic conditions also indicate that suitable vineyard habitats may begin to shift. To meet the environmental demands of varied climate, grapevine breeders will have to draw on wild grapevine species for adaptive traits, particularly in regard to abiotic stress resistance. One particular suite of traits that are important for grape growth regardless of environment are traits related to dormancy and cold tolerance. In warm cultivation regions, cold temperatures are important for satisfying the dormancy requirements of grapevine and priming dormant buds for growth and production in the coming year. Without sufficient winter cooling, grape buds do not synchronously burst in the spring, resulting in disruptions in flowering and fruiting. In cold cultivation regions, the duration of winter is not a concern; however, protection from spring frosts is essential and delayed bud burst phenotypes are an important strategy for protecting young green tissue. In this study, we characterized both the chilling requirement and maximal bud burst rate phenotypes in wild grapevine species. Using survival analysis, we examined the effect of varied lengths of low temperature on bud burst in 27 different genotypes of grapevine, including seven wild grapevine species, three cultivated grape varieties, and four hybrid varieties. Results of our two year study demonstrate a wide range in both intraspecific and interspecific variation in these traits. Trends within the data allow us to categorize low, moderate, and high chill species. Correlated with these categories are fast, moderate, and slow maximal bud burst phenotypes. When compared with geographic distribution of species and genotypes, patterns between northern and southern populations suggest that chilling requirement and bud burst rate are adaptive traits. Potential interactions between these adaptive phenotypes and a changing climate are discussed. This information is essential for making informed decisions about the future of grapevine breeding.