Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China.
Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China; University of the Chinese Academy of Sciences, Beijing 100049, China.
Cell. 2020 Sep 3;182(5):1109-1124.e25. doi: 10.1016/j.cell.2020.07.020. Epub 2020 Aug 24.
Chloroplasts are crucial players in the activation of defensive hormonal responses during plant-pathogen interactions. Here, we show that a plant virus-encoded protein re-localizes from the plasma membrane to chloroplasts upon activation of plant defense, interfering with the chloroplast-dependent anti-viral salicylic acid (SA) biosynthesis. Strikingly, we have found that plant pathogens from different kingdoms seem to have convergently evolved to target chloroplasts and impair SA-dependent defenses following an association with membranes, which relies on the co-existence of two subcellular targeting signals, an N-myristoylation site and a chloroplast transit peptide. This pattern is also present in plant proteins, at least one of which conversely activates SA defenses from the chloroplast. Taken together, our results suggest that a pathway linking plasma membrane to chloroplasts and activating defense exists in plants and that such pathway has been co-opted by plant pathogens during host-pathogen co-evolution to promote virulence through suppression of SA responses.
叶绿体在植物-病原体相互作用期间防御性激素反应的激活中起着至关重要的作用。在这里，我们表明，一种植物病毒编码的蛋白在植物防御被激活时从质膜重新定位到叶绿体，干扰了依赖叶绿体的抗病毒水杨酸 (SA) 生物合成。引人注目的是，我们发现来自不同王国的植物病原体似乎已经趋同进化，以靶向叶绿体，并在与膜结合后损害依赖 SA 的防御，这依赖于两个亚细胞靶向信号的共存，一个 N-豆蔻酰化位点和一个叶绿体转运肽。这种模式也存在于植物蛋白中，其中至少有一种蛋白反过来从叶绿体中激活 SA 防御。总之，我们的研究结果表明，在植物中存在一条将质膜与叶绿体连接并激活防御的途径，而这种途径在植物-病原体共同进化过程中被植物病原体所利用，通过抑制 SA 反应来促进毒力。
