Xu Chenyi, Wang Bin, Luo Qingyun, Ma Yuandan, Zheng Tiefeng, Wang Yingying, Cai Yuyan, Zuo Zhaojiang
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China.
Zhejiang Provincial Key Laboratory of Forest Aromatic Plants-based Healthcare Functions, Zhejiang A&F University, Hangzhou, China.
Front Plant Sci. 2022 Dec 15;13:1072931. doi: 10.3389/fpls.2022.1072931. eCollection 2022.
Terpenes serve important functions in enhancing plant thermotolerance. mainly has eucalyptol (EuL), camphor (CmR), linalool (LnL) and borneol (BeL) chemotypes basing on the uppermost monoterpenes. To reveal the thermotolerance mechanisms of these uppermost monoterpenes (eucalyptol, camphor, linalool, and borneol) in , we surveyed the ROS metabolism and photosynthesis in the 4 chemotypes fumigated with the corresponding uppermost monoterpene after fosmidomycin (Fos) inhibiting monoterpene synthesis under high temperature at 38°C (Fos+38°C+monoterpene), and investigated the related gene expression in EuL and CmR. Meanwhile, the thermotolerance differences among the 4 uppermost monoterpenes were analyzed. In contrast to normal temperature (28°C), ROS levels and antioxidant enzyme activities in the 4 chemotypes increased under 38°C, and further increased in the treatment with Fos inhibiting monoterpene synthesis at 38°C (Fos+38°C), which may be caused by the alterations in expression of the genes related with non-enzymatic and enzymatic antioxidant formation according to the analyses in EuL and CmR. Compared with Fos+38°C treatment, Fos+38°C+monoterpene treatments lowered ROS levels and antioxidant enzyme activities for the increased non-enzymatic antioxidant gene expression and decreased enzymatic antioxidant gene expression, respectively. High temperature at 38°C reduced the chlorophyll and carotenoid content as well as photosynthetic abilities, which may result from the declined expression of the genes associated with photosynthetic pigment biosynthesis, light reaction, and carbon fixation. Fos+38°C treatment aggravated the reduction. In contrast to Fos+38°C treatment, Fos+38°C+monoterpene treatments increased photosynthetic pigment content and improved photosynthetic abilities by up-regulating related gene expression. Among the 4 uppermost monoterpenes, camphor showed strong abilities in lowering ROS and maintaining photosynthesis, while eucalyptol showed weak abilities. This was consistent with the recovery effects of the gene expression in the treatments with camphor and eucalyptol fumigation. Therefore, the uppermost monoterpenes can enhance thermotolerance as signaling molecules, and may have differences in the signaling functions.
萜类化合物在增强植物耐热性方面发挥着重要作用。基于最主要的单萜类化合物，主要有桉叶油醇（EuL）、樟脑（CmR）、芳樟醇（LnL）和冰片（BeL）化学型。为揭示这些最主要的单萜类化合物（桉叶油醇、樟脑、芳樟醇和冰片）在[植物名称未给出]中的耐热机制，我们在38°C高温下用磷霉素（Fos）抑制单萜类化合物合成后，对用相应最主要单萜类化合物熏蒸的4种化学型植物的活性氧代谢和光合作用进行了研究（Fos + 38°C + 单萜类化合物），并研究了EuL和CmR中的相关基因表达。同时，分析了4种最主要单萜类化合物之间的耐热性差异。与正常温度（28°C）相比，4种化学型植物在38°C下的活性氧水平和抗氧化酶活性增加，而在38°C下用Fos抑制单萜类化合物合成的处理（Fos + 38°C）中进一步增加，根据对EuL和CmR的分析，这可能是由与非酶促和酶促抗氧化剂形成相关的基因表达变化引起的。与Fos + 38°C处理相比，Fos + 38°C + 单萜类化合物处理分别降低了活性氧水平和抗氧化酶活性，这是由于非酶促抗氧化基因表达增加和酶促抗氧化基因表达减少所致。38°C的高温降低了叶绿素和类胡萝卜素含量以及光合能力，这可能是由于与光合色素生物合成、光反应和碳固定相关的基因表达下降所致。Fos + 38°C处理加剧了这种降低。与Fos + 38°C处理相比，Fos + 38°C + 单萜类化合物处理通过上调相关基因表达增加了光合色素含量并提高了光合能力。在4种最主要的单萜类化合物中，樟脑在降低活性氧和维持光合作用方面表现出较强的能力，而桉叶油醇表现较弱。这与樟脑和桉叶油醇熏蒸处理中基因表达的恢复效果一致。因此，最主要的单萜类化合物可以作为信号分子增强[植物名称未给出]的耐热性，并且在信号功能上可能存在差异。
