Improved cold-resistant performance in transgenic grape (Vitis vinifera L.) overexpressing cold-inducible transcription factors AtDREB1b

Abstract

Dehydration response element binding (DREB)1b is a cold-inducible transcription factor in Arabidopsis thaliana. DREB1b driven by cauliflower mosaic virus 35S promoter was genetically introduced into grape Vitis vinifera L. cv. Centennial Seedless through Agrobacterium-mediated transformation for improving its cold resistance and exploring new genetic breeding approaches to obtain cold-resistant cultivars. In this study, Southern blot analysis showed the DREB1b gene was integrated into the transgenic grapevines with one to two copies. Northern blot analysis showed the presence of DREB1b transcripts in the independent transgenic lines 3, 5, 6, and 7. Further characterization of transgenic grapevines confirmed that both electrolyte leakage conductivity and the freezing point of the transgenic plants were lower than those of wild-type plants. After the cold treatment at -4°C for 12 h, 26% of transgenic plants wilted among which 95% plants recovered once being placed under the condition of temperature 22 to 25°C. However, subjected to the same treatment, 98% of non-transgenic plants wilted and only 2% recovered. Our results lead to the conclusion that activity of DREB1b in the transgenic grape could significantly improve its resistance to cold stress.