Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Seoul, 136-713, Korea.
Plant Mol Biol. 2014 Feb;84(3):329-44. doi: 10.1007/s11103-013-0137-x. Epub 2013 Oct 2.
Phospholipases hydrolyze phospholipids into fatty acids and other lipophilic substances. Phospholipid signaling is crucial for diverse cellular processes in plants. However, the precise role of phospholipases in plant cell death and defense signaling is not fully understood. Here, we identified a pepper (Capsicum annuum) patatin-like phospholipase (CaPLP1) gene that is transcriptionally induced in pepper leaves by avirulent Xanthomonas campestris pv. vesicatoria (Xcv) infection. CaPLP1 containing an N-terminal signal peptide localized to the cytoplasm and plasma membrane, leading to the secretion into the apoplastic regions. Silencing of CaPLP1 in pepper conferred enhanced susceptibility to Xcv infection. Defense responses to Xcv, including the generation of reactive oxygen species (ROS), hypersensitive cell death and the expression of the salicylic acid (SA)-dependent marker gene CaPR1, were compromised in the CaPLP1-silenced pepper plants. Transient expression of CaPLP1 in pepper leaves induced the accumulation of fluorescent phenolics, expression of the defense marker genes CaPR1 and CaSAR82A, and generation of ROS, ultimately leading to the hypersensitive cell death response. Overexpression (OX) of CaPLP1 in Arabidopsis also conferred enhanced resistance to Pseudomonas syringae pv. tomato (Pst) and Hyaloperonospora arabidopsidis infection. CaPLP1-OX leaves showed reduced Pst growth, enhanced ROS burst and electrolyte leakage, induction of the defense response genes AtPR1, AtRbohD and AtGST, as well as constitutive activation of both the SA-dependent gene AtPR1 and the JA-dependent gene AtPDF1.2. Together, these results suggest that CaPLP1 is involved in plant defense and cell death signaling in response to microbial pathogens.
磷脂酶将磷脂水解成脂肪酸和其他亲脂性物质。磷脂信号对于植物的各种细胞过程至关重要。然而，磷脂酶在植物细胞死亡和防御信号中的精确作用尚不完全清楚。在这里，我们鉴定了一个辣椒（Capsicum annuum）类脂酶（CaPLP1）基因，该基因在辣椒叶片中由无毒黄单胞菌（Xanthomonas campestris pv. vesicatoria）（Xcv）感染转录诱导。含有 N 端信号肽的 CaPLP1定位于细胞质和质膜中，导致其分泌到质外体区域。在辣椒中沉默 CaPLP1 会导致对 Xcv 感染的敏感性增加。对 Xcv 的防御反应，包括活性氧（ROS）的产生、过敏性细胞死亡和水杨酸（SA）依赖性标记基因 CaPR1 的表达，在 CaPLP1 沉默的辣椒植物中受到损害。CaPLP1 在辣椒叶片中的瞬时表达诱导荧光酚类物质的积累、防御标记基因 CaPR1 和 CaSAR82A 的表达以及 ROS 的产生，最终导致过敏性细胞死亡反应。CaPLP1 在拟南芥中的过表达（OX）也赋予了对丁香假单胞菌 pv.番茄（Pst）和黄瓜黑星病菌（Hyaloperonospora arabidopsidis）感染的增强抗性。CaPLP1-OX 叶片表现出减少的 Pst 生长、增强的 ROS 爆发和电解质泄漏、防御反应基因 AtPR1、AtRbohD 和 AtGST 的诱导以及 SA 依赖性基因 AtPR1 和 JA 依赖性基因 AtPDF1.2 的组成性激活。总之，这些结果表明 CaPLP1 参与了植物对微生物病原体的防御和细胞死亡信号转导。
