A DREB1 gene from zoysiagrass enhances Arabidopsis tolerance to temperature stresses without growth inhibition.

The DREB (dehydration-responsive element binding) protein family comprises transcription factors that can increase the survivability of a plant under abiotic stresses by regulating expression of multiple genes and altering downstream metabolism at the cost of growth retardation and developmental delay. In this study, a gene for the DREB1-type transcription factor, designated ZjDREB1.4, was isolated from zoysiagrass (Zoysia japonica Steud.), a popular warm-season turfgrass. This gene contains a conserved AP2/ERF DNA-binding domain flanking the signature sequence of DREB1 and belongs to a DREB1 branch in the grass family that expands in the warm-season species. The expression of ZjDREB1.4 was significantly induced by chilling stress (4-15 °C), moderately induced by salt stress, and only slightly induced by drought stress. The product of ZjDREB1.4 was targeted to the nucleus and showed strong transactivation activity but weak binding to the DRE with ACCGAC as the core sequence. The ZjDREB1.4 protein bound to GCCGAC more preferentially than to ACCGAC. Overexpression of ZjDREB1.4 in Arabidopsis induced the expression of multiple genes including a part of the CBF-regulon, and moderately increased the levels of proline and soluble sugars under normal growth conditions. The transgenic Arabidopsis plants showed an increase in tolerance to high and freezing temperature stresses without obvious growth inhibition and with only a few days delay in bolting. ZjDREB1.4 is potentially useful for producing transgenic plants that are tolerant to high temperature and/or cold stresses with few negative effects.