To understand high temperature tolerance, Heliotropium thermophilum, a flowering plant thriving in a geothermal field with a soil temperature ranging between 55 and 65 °C, was grown in controlled laboratory conditions and two different soil temperatures were applied to the plants. One of them was the control group (CT 25 ± 3 °C) and the other was the high temperature group (HT 60 ± 4 °C). Water potential, dry weight, cell membrane injury (CMI), lipid peroxidation, hydrogen peroxide, chlorophylls, carotenoids, flavonoids, anthocyanins, proline and total soluble sugar contents were measured. Contents of total soluble sugars, phenolics, flavonoids, anthocyanins, proline were found to be higher in HT group than CT while CMI was opposite. Moreover, no difference was determined in water potential, dry weight, lipid peroxidation, total chlorophyll and carotenoids between CT and HT. H. thermophilum plants adapted to high temperature under laboratory conditions through changing membrane lipid saturation, accumulating osmotically active compounds to save water or increase its uptake and inducing antioxidants such as phenolic compounds to keep reactive oxygen species under control. In conclusion, this study showed that H. thermophilum plant was highly resistant to high soil temperature under optimized laboratory conditions. Moreover, a plant that can withstand 60 °C for a long period of time up to 60 days under laboratory conditions was reported for the first time.

中文翻译：

---

嗜热性日光菌（Heliotropium thermophilum）是一种极耐高温的物种，有望使植物适应高土壤温度条件。

要了解高温耐受性，嗜热嗜盐菌这是一种在地热场中繁衍生息的开花植物，其土壤温度介于55到65°C之间，是在受控的实验室条件下生长的，并且将两种不同的土壤温度应用于该植物。其中一个是对照组（CT 25±3°C），另一个是高温组（HT 60±4°C）。测量了水势，干重，细胞膜损伤（CMI），脂质过氧化，过氧化氢，叶绿素，类胡萝卜素，类黄酮，花色苷，脯氨酸和总可溶性糖含量。HT组的总可溶性糖，酚类，类黄酮，花色苷，脯氨酸的含量高于CT，而CMI相反。此外，CT和HT之间的水势，干重，脂质过氧化，总叶绿素和类胡萝卜素没有差异。嗜热链球菌通过改变膜脂质饱和度，积累渗透活性化合物以节省水或增加其吸收并诱导抗氧化剂（如酚类化合物）以控制活性氧，在实验室条件下适应高温。总之，这项研究表明，在优化的实验室条件下，嗜热链球菌对高土壤温度具有很高的抵抗力。此外，首次报道了在实验室条件下可以承受60°C长达60天的长时间的植物。