CBF1 Orthologs in Sour Cherry and Strawberry and the Heterologous Expression of CBF1 in Strawberry
By C. Owens, M. Thomashow, J. Hancock, A. Iezzoni. 2002
88 citations recorded by the source corpus.
Orthologs of CBF1, a cold-induced transcription factor important in the cold acclimation response in Arabidopsis thaliana were cloned from strawberry (Fragaria ×ananassa Duchesne) and sour cherry (Prunus cerasus L.) with degenerate PCR primers. The putative orthologs (Fragaria ×ananassa CBF1 (FaCBF1) and Prunus cerasus CBF1 (PcCBF1)) have 48% amino acid identity to CBF1 and mRNA levels were up-regulated in leaves of both crops following exposure to 4 °C from 15 minutes to 24 hours. However, mRNA of FaCBF1 and PcCBF1 was not detected in pistils of strawberry and sour cherry following 4 °C exposure. Agrobacterium-mediated transformation of a CaMV35S-CBF1 construct was conducted on Fragaria ×ananassa 'Honeoye' crown discs. Two transgenic lines were regenerated that expressed the transgene at low levels in both leaves and receptacles. Receptacles of the transgenic lines showed no significant change in freezing tolerance when compared to wild type plants, although the temperature at which 50 % electrolyte leakage occurred in detached leaf discs from the two transgenic lines was -8.2 °C and -10.3 °C, respectively. These freezing tolerance values were significantly greater than the value for the wild-type 'Honeoye' leaf discs of -6.4 °C. trait, manipulation of just one gene, CBF1, has been shown to improve the whole plant freezing tolerance of arabidopsis (Jaglo- Ottosen et al., 1998). Because CBF genes are key regulators of cold acclimation and overexpression of CBF1, 2, or 3 is capable of improving the freezing tolerance of arabidopsis, there is significant interest in determining if orthologs of the CBF gene family exist in cultivated species and function in a similar fashion to improve freeze tolerance. The distribution of many temperate fruit crops is restricted by low temperature stress. Floral damage is often the main form of freeze injury, particularly in several of the early blooming mem- bers of the Rosaceae (e.g., strawberry (Fragaria ×ananassa), cherry (Prunus avium and P. cerasus), peach, almond (Prunus dulcis), apricot (Prunus armeniaca) ) (Rodrigo, 2000). Many cultural techniques are used to mitigate the damage caused by freezes during bloom (Rieger, 1989). However, improved culti- vars with enhanced floral freezing tolerance would be of consid- erable interest to help prevent crop loss caused by freeze damage and to help stabilize yearly yield fluctuations. One approach to develop cultivars with enhanced freezing tolerance is to identify and use candidate genes playing important roles in this trait. It is plausible that cold-induced genes exist within the Rosaceae that are orthologous to those in arabidopsis capable of improving freezing tolerance. Whether these genes can be used, through either biotechnological manipulation or exploitation of natural variation, to improve floral freezing toler- ance in rosaceous crops is unknown. It is also unknown if the same relationship exists between cold-induced gene expression and onset of cold-acclimation in rosaceous flowers. The interaction between low temperature and photoperiod on cold acclimation of woody fruit crops has been extensively studied (Howell and Weiser, 1970; Weiser, 1970), and it is known that the over-wintering structures of perennial, temperate fruit crops possess the ability to cold acclimate. When tested under controlled conditions, detached pistils from sour cherry (Prunus cerasus) do not appear to have the ability to cold acclimate (C. Owens, unpublished results). In contrast, receptacles with at- tached pistils of strawberry show an improvement in freezing
Subfields: Molecular Biology, Plant Science
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Citations in the corpus
- Strawberry Genes and Genomics (2006, background): “and the latter was installed back into the Honeoye cultivar under constitutive 35S direction (Owens et al., 2002).”