College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China.
PLoS One. 2012;7(12):e53136. doi: 10.1371/journal.pone.0053136. Epub 2012 Dec 28.
Extracellular ATP (eATP) has been implicated in mediating plant growth and antioxidant defense; however, it is largely unknown whether eATP might mediate salinity tolerance. We used confocal microscopy, a non-invasive vibrating ion-selective microelectrode, and quantitative real time PCR analysis to evaluate the physiological significance of eATP in the salt resistance of cell cultures derived from a salt-tolerant woody species, Populus euphratica. Application of NaCl (200 mM) shock induced a transient elevation in [eATP]. We investigated the effects of eATP by blocking P2 receptors with suramin and PPADS and applying an ATP trap system of hexokinase-glucose. We found that eATP regulated a wide range of cellular processes required for salt adaptation, including vacuolar Na⁺ compartmentation, Na⁺/H⁺ exchange across the plasma membrane (PM), K⁺ homeostasis, reactive oxygen species regulation, and salt-responsive expression of genes related to Na⁺/H⁺ homeostasis and PM repair. Furthermore, we found that the eATP signaling was mediated by H₂O₂ and cytosolic Ca²⁺ released in response to high salt in P. euphratica cells. We concluded that salt-induced eATP was sensed by purinoceptors in the PM, and this led to the induction of downstream signals, like H₂O₂ and cytosolic Ca²⁺, which are required for the up-regulation of genes linked to Na⁺/H⁺ homeostasis and PM repair. Consequently, the viability of P. euphratica cells was maintained during a prolonged period of salt stress.
细胞外三磷酸腺苷（eATP）已被牵涉到介导植物的生长和抗氧化防御；然而，eATP 是否可能介导耐盐性在很大程度上仍是未知的。我们使用共聚焦显微镜、非侵入性振动式离子选择性微电极和实时定量 PCR 分析来评估 eATP 在来自耐盐木本物种胡杨（Populus euphratica）的细胞培养物的耐盐性中的生理意义。应用 200 mM 的 NaCl 冲击会诱导 [eATP] 的瞬时升高。我们通过用苏拉明和 PPADS 阻断 P2 受体以及应用己糖激酶-葡萄糖的 ATP 捕获系统来研究 eATP 的效应。我们发现 eATP 调节了广泛的细胞过程，这些过程是耐盐适应所必需的，包括液泡中的 Na⁺区隔化、质膜（PM）上的 Na⁺/H⁺交换、K⁺稳态、活性氧物质的调节以及与 Na⁺/H⁺稳态和 PM 修复相关的基因的盐响应表达。此外，我们发现 eATP 信号是由 PM 中的嘌呤受体感知的，这导致下游信号如 H₂O₂和胞质 Ca²⁺的释放，这对于与 Na⁺/H⁺稳态和 PM 修复相关的基因的上调是必需的。因此，在长时间的盐胁迫下，胡杨细胞的活力得以维持。
