背景-植物胁迫感知与响应：Sensing of heat, high light (HL), or mechanical injury by a single leaf of a plant results in the activation of different systemic signals that reach systemic tissues within minutes and trigger systemic acquired acclimation (SAA) or systemic wound responses (SWRs), resulting in a heightened state of stress readiness of the entire plant. 

背景-植物胁迫感知后的系统性信号传递：Among the different signals associated with rapid systemic responses to stress in plants are electric, calcium and reactive oxygen species (ROS) waves. These signals propagate from the stressed or injured leaf to the rest of the plant through the plant vascular bundles, and trigger SWRs and SAA in systemic tissues. 

提出问题：However, whether they can propagate through other cell types, and whether or not they are interlinked, remain open questions. 

结果1：Here we report that in response to wounding or heat stress (HS), but not HL stress, the ROS wave can propagate through mesophyll cells of Arabidopsis (Arabidopsis thaliana). 

结果2：Moreover, we show that ROS production by mesophyll cells during these stresses is sufficient to restore SWR and SAA transcript accumulation in systemic leaves, as well as SAA to HS (but not HL). 

结果3：We further show that propagation of the ROS wave through mesophyll cells could contribute to systemic signal integration during HL&HS stress combination. 

结论：Our findings reveal that the ROS wave can propagate through tissues other than the vascular bundles of plants, and that different stresses can trigger different types of systemic signals that propagate through different cell layers and induce stress-specific systemic responses.

 摘 要 

植物单个叶片对高温、强光或机械损伤的感知导致了不同系统性信号的激活，这些信号在数分钟内传递到系统组织，并诱发系统获得性适应（SAA）或系统性创伤响应（SWR），从而提高了整个植株的胁迫准备状态。植物中，对于胁迫的快速系统性响应相关信号包括了电信号、钙波动和活性氧（ROS）波动。这些信号从受到胁迫或创伤的叶片中开始扩散，通过植物的维管束传递到同一植株的其它组织部位，诱导系统性的SAA和SWR。但是，这些信号是否可以通过其它类型的细胞进行传递，以及相互之间的关联情况，仍然还是一个有待解决的问题。本文中，作者报道了拟南芥中由创伤或热胁迫，而非强光胁迫所导致的ROS波动能够通过叶肉细胞进行扩散。此外，作者发现在这些胁迫期间，叶肉细胞产生的ROS足以恢复系统性叶片中SWR和SAA转录本的积累，以及SAA对热胁迫（但不是强光胁迫）的积累。作者进一步表明，ROS波动通过叶肉细胞的传播有助于强光+热胁迫组合过程中的系统性信号整合。本文的研究揭示了ROS波动能够通过除了维管束以外的细胞类型进行传递，而不同的胁迫会诱导不同类型的系统性信号，并且通过不同的细胞层进行传递，最终诱导胁迫特异的系统性响应。