Functional Identification of a C-repeat Binding Factor Transcriptional Activator from Blueberry Associated with Cold Acclimation and Freezing Tolerance

Abstract

<jats:p>Highbush blueberry (<jats:italic>Vaccinium corymbosum</jats:italic>) is susceptible to winter freezing injury and frost damage in the spring. As part of an ongoing project to understand the process of cold acclimation, we isolated a C-repeat binding factor (<jats:italic>CBF</jats:italic>) transcriptional activator gene-coding region from the highbush blueberry cultivar Bluecrop. Expression of the highbush blueberry <jats:italic>CBF</jats:italic> gene was compared in floral buds of the cold-tolerant northern highbush cultivar Bluecrop and the more cold-sensitive southern rabbiteye (<jats:italic>V. virgatum</jats:italic>) blueberry cultivar Tifblue. Relative gene expression was higher in ‘Bluecrop’ than in ‘Tifblue’. Expression in both cultivars was highest at the earliest time point in the fall (coincident with the first stage of cold acclimation), declined during the later fall and winter, and, in ‘Bluecrop’, increased again as buds deacclimated, when temperatures tend to fluctuate. To confirm the putative identity of the gene as a member of the <jats:italic>CBF</jats:italic> gene family, and to determine if expression in a heterologous system could enhance freezing tolerance, the blueberry gene coding sequence was overexpressed in transgenic <jats:italic>Arabidopsis thaliana</jats:italic> under the control of the cauliflower mosaic virus 35S promoter. Transgenic plants expressing the putative blueberry <jats:italic>CBF</jats:italic> gene exhibited induced expression of the <jats:italic>A. thaliana</jats:italic> cold-regulated (<jats:italic>COR</jats:italic>) genes <jats:italic>COR78</jats:italic> and <jats:italic>COR6.6</jats:italic>, under non-inducing conditions (i.e., 23 °C); however, expression of two other <jats:italic>COR</jats:italic> genes was unaffected. Transgenic plants also exhibited enhanced freezing tolerance under non-acclimated conditions, but not to the level of acclimated control plants. Thus, the expression pattern in floral buds and the ability of the isolated gene to turn on a subset of <jats:italic>COR</jats:italic> genes and increase freezing tolerance in a heterologous system suggest it is a functional member of the <jats:italic>CBF</jats:italic> gene family in blueberry.</jats:p>

Ectopic expression of a novel peach (Prunus persica) CBF transcription factor in apple (Malus × domestica) results in short-day induced dormancy and increased cold hardiness

“…Overexpression of Arabidopsis CBF genes in other species such as poplar (Benedict et al 2006) and potato (Pino et al 2008), as well as the ectopic expression of CBF genes from other species in Arabidopsis (Welling and Palva 2008;Polashock et al 2010;Kitashiba et al 2004) has resulted in increased levels of freezing tolerance. In these studies, freezing tolerance was generally improved by 2-3°C.…”

“…The role of CBF in cold response and acclimation has been well documented in both herbaceous (Thomashow et al 2001) and woody plants (Welling and Palva 2006). In relation to woody plants, CBF transcription factors have been isolated and shown to be cold-responsive in birch (Betula pendula) (Welling and Palva 2008), poplar (Benedict et al 2006), eucalyptus (Navarro et al 2009;El Kayal et al 2006), grape (Xiao et al 2006), sweet cherry (Prunus avium) (Kitashiba et al 2004), citrus (Champ et al 2007), blueberry (Vaccinium corymbosum) (Polashock et al 2010), and dwarf apple (Malus baccata) (Yang et al 2010) .…”

Isolation and characterization of a C-repeat binding factor (CBF)-like gene in cassava (Manihot esculenta Crantz)

“…The amino acid change is also found in CBF4 from A. thaliana, HbCBF1 from H. brasiliensis, CBFs from Vaccinium myrtillus. It has been previously demonstrated that the change in V. myrtillus CBFs do not inhibit the binding of CBF to the DRE/CRT DNA motif (Polashock et al 2010;Walworth et al 2012;Oakenfull et al 2013). Therefore, the change in cassava MeCBF1 may not inhibit its function.…”

Transcriptomic changes reveal gene networks responding to the overexpression of a blueberry DWARF AND DELAYED FLOWERING 1 gene in transgenic blueberry plants

“…In this study, we showed a blueberry-derived CBF ( BB-CBF ), which was initially considered to be an orthologue of CBF2 that promoted freezing tolerance in A. thaliana [50], was more similar to A. thaliana DDF1 . Overexpression of the BB-CBF (herein renamed as VcDDF1 ) enhanced cold tolerance in leaves and dormant buds but not in flower tissues of a southern highbush blueberry cultivar [51].…”