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

Abstract

Low, non-freezing temperatures and/or short daylength (SD) regulates cold acclimation and dormancy in fruit trees. Regarding cold acclimation, C-repeat binding factor (CBF/DREB) transcriptional activator genes have the well-documented ability to induce the expression of a suite of genes associated with increased cold tolerance. We isolated a full-length cDNA of a peach CBF gene, designated PpCBF1 (GenBank Accession HM992943), and constitutively expressed it using an enhanced 35S promoter in apple. Unexpectedly, constitutive overexpression of the PpCBF1 in apple resulted in strong sensitivity to short daylength. Growth cessation and leaf senescence were induced in transgenic lines exposed to SD and optimal growth temperatures of 25°C over a 4-week period. Following 1-4 weeks of SD and 25°C trees were returned to LD and 25°C in the greenhouse. Control (untransformed) plants continued to grow while transgenic lines receiving two or more weeks of SD remained dormant and began to drop leaves. Constitutive overexpression of the PpCBF1 in apple resulted in a 4-6°C increase in freezing tolerance in both the non-acclimated and acclimated states, respectively, compared with untransformed M.26 trees. This is the first instance that constitutive overexpression of a CBF gene has resulted in SD-induction of dormancy and to our knowledge the first time apple has been shown to strongly respond to short daylength as a result of the insertion of a transgene.

Study on the expression of dehydrin genes and activities of antioxidativeenzymes in floral buds of two sand pear (Pyrus pyrifolia Nakai) cultivarsrequiring different chilling hours for bud break

“…Therefore, clarifying dormancy mechanisms is important for controlling plant growth and development. Considerable improvement has been made in identifying dormancy-associated genes in woody and herbaceous perennial plants, including Japanese pear , peach (Jimenez et al, 2010), apple (Wisniewski et al, 2011), Japanese apricot (Yamane et al, 2008), and poplar (Ruttink et al, 2007), for the purpose of investigating dormancy. Most of these studies suggested that bud dormancy involves many biochemical pathways related to photoperiod, temperature, circadian clocks, water, energy, reactive oxygen species (ROS), and hormones.…”

Genomics and Functional Genomics of Winter Low Temperature Tolerance in Temperate Fruit Crops

“…In apple, overexpression of MbDREB1 upregulated the expression of COR15a and rd29B, further supporting the suggestion that DREB1 may be active in both ABA-dependent and ABA-independent pathways (Yang et al, 2011). Insertion of a peach CBF (PpCBF1) in an apple rootstock increased freezing tolerance in non-acclimated and cold acclimated plants over the wild type and resulted in high level of expression of an apple dehydrin (MdDhn1) in stems and leaves of the transgenic plant (Wisniewski et al, 2011). In apple, dormancy and cold acclimation are normally induced by low temperature not photoperiod (Heide and Prestrud, 2005).…”

“…Induction of PdCBF1 and PdCBF2 was higher during the early dark period of the photoperiod cycle suggesting both photoperiod and temperature regulation (Barros et al, 2012a, b). In apple, which acclimates and enters dormancy solely in response to low temperatures, apple CBFs (MdCBF1, MdCBF2) increased between 30 minutes and 2 hours in response to low temperature (Heide and Prestrud, 2005;Wisniewski et al, 2011). In addition, an apple DREB/CBF gene, with similarity to the Arabidopsis DREB2B, was up-regulated by cold, drought, heat and ABA within 2 hours and increased expression for 8 to 24 hours (Table 2) .…”

Molecular aspects of dormancy in peach (Prunus persica [L.] Batsch.)

“…Apple transformed with CBF transcription factor from peach showed higher sensitivity to short day-lenght and an increase to frost tolerance (Wisniewski et al, 2011).…”