State Key Laboratory for Agrobiotechnology and Key Laboratory of Crop Heterosis and Utilization (MOE), Key Laboratory of Crop Genomics and Genetic Improvement (MOA), Beijing Key Laboratory of Crop Genetic Improvement, National Plant Gene Research Centre (Beijing), China Agricultural University, Yuanmingyuan Xi Road NO. 2, Haidian District, Beijing, 100193, China.
Plant Mol Biol. 2015 Jan;87(1-2):31-45. doi: 10.1007/s11103-014-0259-9. Epub 2014 Oct 18.
Previously, we found an ethylene-responsive transcriptional co-activator, which was significantly induced by heat stress (HS) in both thermo-sensitive and thermo-tolerant wheat. The corresponding ORF was isolated from wheat, and named TaMBF1c (Multiprotein Bridging Factor1c). The deduced amino acid sequence revealed the presence of conserved MBF1 and helix-turn-helix domains at the N- and C-terminus, respectively, which were highly similar to rice ERTCA (Ethylene Response Transcriptional Co-Activator) and Arabidopsis MBF1c. The promoter region of TaMBF1c contained three heat shock elements (HSEs) and other stress-responsive elements. There was no detectable mRNA of TaMBF1c under control conditions, but the transcript was rapidly and significantly induced by heat stress not only at the seedling stage, but also at the flowering stage. It was also slightly induced by drought and H2O2 stresses, as well as by application of the ethylene synthesis precursor ACC, but not, however, by circadian rhythm, salt, ABA or MeJA treatments. Under normal temperatures, TaMBF1c-eGFP protein showed predominant nuclear localization with some levels of cytosol localization in the bombarded onion epidermal cells, but it was mainly detected in the nucleus with almost no eGFP signals in cytosol when the bombarded onion cells were cultured under high temperature conditions. Overexpression of TaMBF1c in yeast imparted tolerance to heat stress compared to cells expressing the vector alone. Most importantly, transgenic rice plants engineered to overexpress TaMBF1c showed higher thermotolerance than control plants at both seedling and reproductive stages. In addition, transcript levels of six Heat Shock Protein and two Trehalose Phosphate Synthase genes were higher in TaMBF1c transgenic lines than in wild-type rice upon heat treatment. Collectively, the present data suggest that TaMBF1c plays a pivotal role in plant thermotolerance and holds promising possibilities for improving heat tolerance in crops.
先前，我们发现一个乙烯响应转录共激活因子，它在热敏和耐热小麦中都受到热胁迫（HS）的显著诱导。我们从小麦中分离出相应的 ORF，并将其命名为 TaMBF1c（多蛋白桥连因子 1c）。推导的氨基酸序列揭示了 N 端和 C 端分别存在保守的 MBF1 和螺旋-转角-螺旋结构域，与水稻 ERTCA（乙烯响应转录共激活因子）和拟南芥 MBF1c 高度相似。TaMBF1c 的启动子区域含有三个热激元件（HSEs）和其他应激响应元件。在对照条件下，未检测到 TaMBF1c 的 mRNA，但该转录物不仅在幼苗期，而且在花期受到热胁迫的快速显著诱导。它也被干旱和 H2O2 胁迫以及乙烯合成前体 ACC 的应用轻微诱导，但不受昼夜节律、盐、ABA 或 MeJA 处理的影响。在正常温度下，TaMBF1c-eGFP 蛋白主要定位于细胞核，在轰击的洋葱表皮细胞中有一些细胞质定位，但在高温条件下培养时，它主要定位于细胞核，细胞质中几乎没有 eGFP 信号。在酵母中过表达 TaMBF1c 与单独表达载体的细胞相比，赋予了对热胁迫的耐受性。最重要的是，过表达 TaMBF1c 的转基因水稻植株在幼苗期和生殖期均表现出比对照植株更高的耐热性。此外，在热处理后，TaMBF1c 转基因系中六个热休克蛋白和两个海藻糖磷酸合酶基因的转录水平高于野生型水稻。总的来说，这些数据表明 TaMBF1c 在植物耐热性中发挥着关键作用，并为提高作物的耐热性提供了有希望的可能性。
