College of Biological Science, Jining Medical University, Ri'zhao 276800, Shandong, China.
College of Life Science, Nanjing University, Nan'jing 210046, Jiangshu, China.
Int J Mol Sci. 2019 Jan 16;20(2):367. doi: 10.3390/ijms20020367.
DnaJ proteins, which are molecular chaperones that are widely present in plants, can respond to various environmental stresses. At present, the function of DnaJ proteins was studied in many plant species, but only a few studies were conducted in tomato. Here, we examined the functions of a novel tomato () DnaJ protein (SlDnaJ20) in heat tolerance using sense and antisense transgenic tomatoes. Transient conversion assays of protoplasts showed that SlDnaJ20 was targeted to chloroplasts. Expression analysis showed that expression was induced by chilling, NaCl, polyethylene glycol, and H₂O₂, especially via heat stress. Under heat stress, sense plants showed higher fresh weights, chlorophyll content, fluorescence (Fv/Fm), and D1 protein levels, and a lower accumulation of reactive oxygen species (ROS) than antisense plants. These results suggest that overexpression can reduce the photoinhibition of photosystem II (PSII) by relieving ROS accumulation. Moreover, higher expression levels of and were observed under heat stress in sense plants, indicating that overexpression contributes to expression. The yeast two-hybrid system proved that SlDnaJ20 can interact with the chloroplast heat-shock protein 70. Our results indicate that overexpression enhances the thermotolerance of transgenic tomatoes, whereas suppression of increases the heat sensitivity of transgenic tomatoes.
DnaJ 蛋白是一种广泛存在于植物中的分子伴侣，能够对各种环境胁迫做出响应。目前，已经在许多植物物种中研究了 DnaJ 蛋白的功能，但在番茄中仅有少数研究。在这里，我们使用反义及正义转基因番茄研究了一种新型番茄 SlDnaJ20 蛋白在耐热性方面的功能。质体的瞬时转化实验表明 SlDnaJ20 定位于叶绿体。表达分析表明， 表达受冷胁迫、NaCl、聚乙二醇和 H₂O₂诱导，尤其是受热胁迫诱导。在热胁迫下，正义植株的鲜重、叶绿素含量、荧光（Fv/Fm）和 D1 蛋白水平较高，活性氧（ROS）积累较低。这些结果表明，过表达 SlDnaJ20 可以通过缓解 ROS 积累来减轻对光系统 II（PSII）的光抑制。此外，在热胁迫下，正义植株中 和 的表达水平更高，表明 SlDnaJ20 过表达有助于 的表达。酵母双杂交系统证明 SlDnaJ20 可以与叶绿体热休克蛋白 70 相互作用。我们的研究结果表明，过表达 SlDnaJ20 增强了转基因番茄的耐热性，而抑制 则增加了转基因番茄的热敏感性。
