Use of a stress inducible promoter to drive ectopic AtCBF expression improves potato freezing tolerance while minimizing negative effects on tuber yield

Abstract

591 SummarySolanum tuberosum is a frost-sensitive species incapable of cold acclimation. A brief exposure to frost can significantly reduce its yields, while hard frosts can completely destroy entire crops. Thus, gains in freezing tolerance of even a few degrees would be of considerable benefit relative to frost damage. The S . tuberosum cv. Umatilla was transformed with three Arabidopsis CBF genes ( AtCBF1-3 ) driven by either a constitutive CaMV35S or a stress-inducible Arabidopsis rd29A promoter. AtCBF1 and AtCBF3 overexpression via the 35S promoter increased freezing tolerance about 2 ° C, whereas AtCBF2 over-expression failed to increase freezing tolerance. Transgenic plants of AtCBF1 and AtCBF3 driven by the rd29A promoter reached the same level of freezing tolerance as the 35S versions within a few hours of exposure to low but non-freezing temperatures.Constitutive expression of AtCBF genes was associated with negative phenotypes, including smaller leaves, stunted plants, delayed flowering, and reduction or lack of tuber production.While imparting the same degree of freezing tolerance, control of AtCBF expression via the stress-inducible promoter ameliorated these negative phenotypic effects and restored tuber production to levels similar to wild-type plants. These results suggest that use of a stressinducible promoter to direct CBF transgene expression can yield significant gains in freezing tolerance without negatively impacting agronomically important traits in potato.

Arabidopsis DPB3-1, a DREB2A Interactor, Specifically Enhances Heat Stress-Induced Gene Expression by Forming a Heat Stress-Specific Transcriptional Complex with NF-Y Subunits

“…The overexpression of transcription factors that have constitutive activity, such as DREB1A, DREB2A CA, and HsfA2, often causes severe growth retardation under normal conditions (Liu et al, 1998;Sakuma et al, 2006a;Ogawa et al, 2007). Therefore, the application of these strong transcription factors to the molecular breeding of crops requires an optimized stress-inducible promoter for the control of gene expression to minimize negative effects on plant growth (Kim et al, 2003;Sakuma et al, 2006a;Nakashima et al, 2007;Pino et al, 2007). However, the optimization of stress-inducible promoters for each gene and plant species is time-consuming.…”

Hv-CBF2A overexpression in barley accelerates COR gene transcript accumulation and acquisition of freezing tolerance during cold acclimation

“…d CBF4, CBF9, CBF14, CBF12, CBF15, and CBF16 transcript signals normalized to actin (y-axis). e CBF12, CBF15, and CBF16 in 'Golden Promise' relative to the mean of Hv-CBF2A overexpressor lines 2, 6, 10, 13, and 15 (y-axis) b Plant Mol Biol circumvent the growth related defects resulting from constitutive high level CBF overexpression, the use of a stressinducible promoter such as the rd29A promoter, which has been used in other systems (Kasuga et al 1999;Pino et al 2007), may be one means. Alternatively, the use of a weak promoter such as the NOS promoter (Sanders et al 1987;Horstmann et al 2004) may also provide a sufficient increase in transcript levels to effect an increase in regrowth following freezing without causing penalty.…”

Components Acting Downstream of Short Day Perception Regulate Differential Cessation of Cambial Activity and Associated Responses in Early and Late Clones of Hybrid Poplar

“…What is the molecular basis for the differential regulation of cold tolerancerelated transcripts in the early and late clones? Our data strongly suggest that it results from differences in the regulation of CBF/DREB-related transcription factors (DREB and DRTY) that regulate the expression of cold tolerance-related genes (Jaglo-Ottosen et al, 1998; Benedict et al, 2005;Pino et al, 2007;Welling and Palva, 2008). The accumulation of DREB and DRTY transcripts was slower in the late clone, and peak transcript accumulation was lower.…”