Location: Fruit and Tree Nut ResearchTitle: Localization, characterization and candidate gene discovery for genes controlling dormancy, chilling requirement, bloom time, and heat requirement in Prunus species. Author
Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 12/11/2009
Publication Date: 1/13/2010
Citation: Fan, S., Olukolu, B., Bielenberg, D., Holland, D., Zhebentyayeva, T., Okie, W.R., Reighard, G., Abbott, A. 2010. Localization, characterization and candidate gene discovery for genes controlling dormancy, chilling requirement, bloom time, and heat requirement in Prunus species [abstract]. Plant and Animal Genome XVIII Conference. p. W260. Interpretive Summary: Most fruit trees need cold weather during the winter to prepare them for growth in the spring. This also allows them to stay dormant until appropriate temperatures come along. The biochemical triggers for spring growth are unknown. Study of the molecular genetics of peach and apricot allow identification of specific regions of the DNA that are associated with the mechanisms that keep track of the amount of cold experienced by the tree. An understanding of these important mechanisms in the plant will allow better manipulation of these traits to bring about better adaptation of the trees.
Technical Abstract: Perennial fruiting trees require sustained exposure to low, near freezing, temperatures before vigorous floral and vegetative bud break is possible after the resumption of warm temperatures in the spring. The depth of dormancy, duration of chilling required (the chilling requirement, CR) blooming date (BD) and heat requirement to break buds (HR) are determined by the climatic adaptation of the particular cultivar, thus limiting its geographic distribution. This limitation is particularly evident when attempting to introduce superior cultivars to regions with very warm winter temperatures. The physiological mechanisms for these important life history characters are partially understood; however, the genetic pathways central to physiology remain poorly characterized, and although breeding programs deliberately manipulate these characters, robust closely associated markers to the traits have not been available in the past. In this regard, we have developed a comprehensive mapping program directed at characterization of QTL controlling these characters. We used segregating populations of apricot (100 F1 individuals, Newe Ya'ar Research Center, ARO) and peach (378 F2 individuals, Clemson University) to discover discret genomic loci that regulate CR, BD and HR. We used the extensive genomic/genetic resources available for Prunus to successfully combine our apricot and peach genetic data and identify major QTL with strong effects that are conserved between species, as well as QTL that are unique to each species. In addition, we have investigated the use of association mapping in both species to further define the QTLs and mined the resultant genomic regions for candidate genes. Here, we present the results of these efforts and discuss the implications of these results to our fundamental understanding of the genetics of these traits and the application of this knowledge for manipulation of these characters in marker assisted breeding programs.