Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Daejeon 34141, South Korea; Department of Environmental Biotechnology, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Daejeon 34113, South Korea; Sweetpotato Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Xuzhou 221121, Jiangsu, China.
Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Daejeon 34141, South Korea.
Plant Physiol Biochem. 2017 Sep;118:45-54. doi: 10.1016/j.plaphy.2017.06.002. Epub 2017 Jun 3.
Dehydration-responsive element-binding/C-repeat-binding factor (DREB/CBF) proteins regulate the transcription of genes involved in cold acclimation in several species. However, little is known about the physiological functions of CBF proteins in the low temperature-sensitive crop sweetpotato. We previously reported that the DREB1/CBF-like sweetpotato gene SwDREB1/IbCBF3 is involved in responses to diverse abiotic stresses. In this study, we confirmed that IbCBF3 is localized to the nucleus and binds to the C-repeat/dehydration-responsive elements (CRT/DRE) in the promoters of cold-regulated (COR) genes. We generated transgenic sweetpotato plants overexpressing IbCBF3 under the control of the CaMV 35S promoter (referred to as SC plants) and evaluated their responses to various abiotic stresses. IbCBF3 expression was dramatically induced by cold and drought but much less strongly induced by high salinity and ABA. We further characterized two SC lines (SC3 and SC6) with high levels of IbCBF3 transcript. The SC plants displayed enhanced tolerance to cold, drought, and oxidative stress on the whole-plant level. Under cold stress treatment (4 °C for 48 h), severe wilting and chilling injury were observed in the leaves of wild-type (WT) plants, whereas SC plants were not affected by cold stress. In addition, the COR genes were significantly upregulated in SC plants compared with the WT. The SC plants also showed significantly higher tolerance to drought stress than the WT, which was associated with higher photosynthesis efficiency and lower hydrogen peroxide levels. These results indicate that IbCBF3 is a functional transcription factor involved in the responses to various abiotic stresses in sweetpotato.
脱水应答元件结合/C-重复结合因子（DREB/CBF）蛋白调节几种物种中冷驯化相关基因的转录。然而，关于低温敏感作物甘薯中 CBF 蛋白的生理功能知之甚少。我们之前报道过 DREB1/CBF 样甘薯基因 SwDREB1/IbCBF3 参与了对多种非生物胁迫的响应。在本研究中，我们证实 IbCBF3 定位于细胞核，并与冷调节（COR）基因启动子中的 C 重复/脱水应答元件（CRT/DRE）结合。我们利用 CaMV 35S 启动子（称为 SC 植物）控制过表达 IbCBF3 的转基因甘薯植株，并评估了它们对各种非生物胁迫的响应。IbCBF3 的表达受冷和干旱诱导显著，但受高盐度和 ABA 诱导较弱。我们进一步表征了两个 IbCBF3 转录本水平较高的 SC 系（SC3 和 SC6）。SC 植物在全株水平上表现出对冷、干旱和氧化胁迫的增强耐受性。在冷胁迫处理（4°C 48 小时）下，野生型（WT）植物的叶片出现严重萎蔫和冷害，而 SC 植物不受冷胁迫影响。此外，与 WT 相比，COR 基因在 SC 植物中显著上调。SC 植物对干旱胁迫的耐受性也明显高于 WT，这与光合作用效率较高和过氧化氢水平较低有关。这些结果表明 IbCBF3 是一种功能性转录因子，参与了甘薯对各种非生物胁迫的响应。
