Cold stress is one of the major environmental factors that limit growth and utilization of bermudagrass [Cynodon dactylon (L.) Pers], a prominent warm-season turfgrass. However, the molecular mechanism of cold response in bermudagrass remains largely unknown. In this study, we characterized a cold-responsive ERF (ethylene responsive factor) transcription factor, CdERF1, from bermudagrass. CdERF1 expression was induced by cold, drought and salinity stresses. The CdERF1 protein was nucleus-localized and encompassed transcriptional activation activity. Transgenic Arabidopsis plants overexpressing CdERF1 showed enhanced cold tolerance, whereas CdERF1-underexpressing bermudagrass plants via virus induced gene silencing (VIGS) method exhibited reduced cold resistance compared with control, respectively. Under cold stress, electrolyte leakage (EL), malondialdehyde (MDA), H2O2 and O2- contents were reduced, while the activities of SOD and POD were elevated in transgenic Arabidopsis. By contrast, these above physiological indicators in CdERF1-underexpressing bermudagrass exhibited the opposite trend. To further explore the possible molecular mechanism of bermudagrass cold stress response, the RNA-Seq analyses were performed. The result indicated that overexpression of CdERF1 activated a subset of stress-related genes in transgenic Arabidopsis, such as CBF2, pEARLI1 (lipid transfer protein), PER71 (peroxidase) and LTP (lipid transfer protein). Interestingly, under-expression of CdERF1 suppressed the transcription of many genes in CdERF1-underexpressing bermudagrass, also including pEARLI1 (lipid transfer protein) and PER70 (peroxidase). All these results revealed that CdERF1 positively regulates plant cold response probably by activating stress-related genes, PODs, CBF2 and LTPs. This study also suggests that CdERF1 may be an ideal candidate in the effort to improve cold tolerance of bermudagrass in the further molecular breeding.

中文翻译：

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狗牙根（Cynodon dactylon）的乙烯反应因子CdERF1正向调节耐寒性

冷胁迫是限制狗牙根 [Cynodon dactylon (L.) Pers]（一种著名的暖季草坪草）生长和利用的主要环境因素之一。然而，狗牙根冷反应的分子机制在很大程度上仍是未知的。在这项研究中，我们表征了来自百慕大草的冷响应 ERF（乙烯响应因子）转录因子 CdERF1。CdERF1 表达是由寒冷、干旱和盐分胁迫诱导的。CdERF1 蛋白是细胞核定位的，包含转录激活活性。与对照相比，过表达 CdERF1 的转基因拟南芥植物表现出增强的耐寒性，而通过病毒诱导的基因沉默 (VIGS) 方法表达的 CdERF1 低表达的狗牙根植物分别表现出降低的耐寒性。在冷应力下，电解液泄漏（EL），转基因拟南芥中丙二醛 (MDA)、H2O2 和 O2- 含量降低，而 SOD 和 POD 活性升高。相比之下，CdERF1 低表达的狗牙根中的上述生理指标表现出相反的趋势。为了进一步探索狗牙根冷应激反应的可能分子机制，进行了 RNA-Seq 分析。结果表明，CdERF1 的过表达激活了转基因拟南芥中的一部分应激相关基因，如 CBF2、pEARLI1（脂质转移蛋白）、PER71（过氧化物酶）和 LTP（脂质转移蛋白）。有趣的是，CdERF1 的低表达抑制了 CdERF1 低表达的狗牙根中许多基因的转录，还包括 pEARLI1（脂质转移蛋白）和 PER70（过氧化物酶）。所有这些结果表明，CdERF1 可能通过激活胁迫相关基因、PODs、CBF2 和 LTPs 来正向调节植物冷反应。该研究还表明，CdERF1 可能是在进一步分子育种中提高狗牙根耐寒性的理想候选者。