Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA.
Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA.
Cell Host Microbe. 2016 Apr 13;19(4):541-9. doi: 10.1016/j.chom.2016.03.006.
Systemic acquired resistance (SAR) in plants is mediated by the signaling molecules azelaic acid (AzA), glycerol-3-phosphate (G3P), and salicylic acid (SA). Here, we show that AzA and G3P transport occurs via the symplastic route, which is regulated by channels known as plasmodesmata (PD). In contrast, SA moves via the extracytosolic apoplast compartment. We found that PD localizing proteins (PDLP) 1 and 5 were required for SAR even though PD permeability in pdlp1 and 5 mutants was comparable to or higher than wild-type plants, respectively. Furthermore, PDLP function was required in the recipient cell, suggesting regulatory function in SAR. Interestingly, overexpression of PDLP5 drastically reduced PD permeability, yet also impaired SAR. PDLP1 interacted with AZI1 (lipid transfer-like protein required for AzA- and G3P-induced SAR) and contributed to its intracellular partitioning. Together, these results reveal the transport routes of SAR chemical signals and highlight the regulatory role of PD-localizing proteins in SAR.
植物中的系统性获得抗性 (SAR) 是由信号分子壬二酸 (AzA)、甘油-3-磷酸 (G3P) 和水杨酸 (SA) 介导的。在这里，我们表明 AzA 和 G3P 通过质体途径运输，该途径受称为胞间连丝 (PD) 的通道调节。相比之下，SA 通过细胞外质外体腔移动。我们发现 PD 定位蛋白 (PDLP) 1 和 5 即使在 pdlp1 和 5 突变体中的 PD 通透性分别与野生型植物相当或更高，也需要 PD 定位蛋白 1 和 5 来介导 SAR。此外，PDLP 的功能需要在受体细胞中，这表明在 SAR 中具有调节功能。有趣的是，PDLP5 的过表达大大降低了 PD 的通透性，但也损害了 SAR。PDLP1 与 AZI1（脂质转移样蛋白，需要 AzA 和 G3P 诱导 SAR）相互作用，并有助于其细胞内分区。总之，这些结果揭示了 SAR 化学信号的运输途径，并强调了 PD 定位蛋白在 SAR 中的调节作用。
