Lim Gah-Hyun, Kachroo Aardra, Kachroo Pradeep
a Department of Plant Pathology , University of Kentucky , Lexington , KY , USA.
Plant Signal Behav. 2016 Sep;11(9):e1219829. doi: 10.1080/15592324.2016.1219829.
Systemic acquired resistance (SAR) is a highly desirable form of resistance that protects against a broad-spectrum of pathogens. SAR involves the generation of a mobile signal at the site of primary infection, which arms distal portions of a plant against subsequent secondary infections. A number of diverse chemical signals contributing to SAR have been isolated and characterized. Among these, salicylic acid (SA) functions in parallel to azelaic acid (AzA) and glycerol-3-phosphate (G3P), and both AzA and G3P function downstream of the free radicals nitric oxide and reactive oxygen species. We now show that phloem loading of AzA and G3P occurs via the symplast, whereas that of SA occurs via the apoplast. The symplastic transport of AzA and G3P is regulated by plasmodesmata localizing protein (PDLP) 5, which together with PDLP1 also plays a signaling role in SAR. Together, these results reveal the transport routes of SAR associated chemical signals, and the regulatory role of PDLPs in SAR.
系统获得性抗性（SAR）是一种非常理想的抗性形式，可抵御广谱病原体。SAR涉及在初次感染部位产生一种移动信号，该信号使植物的远端部分抵御随后的二次感染。已经分离并鉴定了许多促成SAR的不同化学信号。其中，水杨酸（SA）与壬二酸（AzA）和甘油-3-磷酸（G3P）协同发挥作用，并且AzA和G3P都在自由基一氧化氮和活性氧的下游发挥作用。我们现在表明，AzA和G3P的韧皮部装载通过共质体进行，而SA的韧皮部装载通过质外体进行。AzA和G3P的共质体运输由定位于胞间连丝的蛋白质（PDLP）5调节，PDLP5与PDLP1一起在SAR中也发挥信号传导作用。这些结果共同揭示了与SAR相关的化学信号的运输途径，以及PDLP在SAR中的调节作用。
