Instituto de Ciencia y Tecnologia Dr. Cesar Milstein, Fundación Pablo Cassará, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
Plant Signal Behav. 2009 Dec;4(12):1114-6. doi: 10.4161/psb.4.12.10062.
Bacteria and fungi are capable of triggering stomatal closure through pathogen-associated molecular patterns (PAMPs), which prevents penetration through these pores. Therefore, the stomata can be considered part of the plant innate immune response. Some pathogens have evolved mechanisms to evade stomatal defense. The bacterial pathogen Xanthomonas campestris pv. campestris (Xcc), which infects plants of the Brassicaceae family mainly through hydathodes, has also been reported to infect plants through stomata. A recent report shows that penetration of Xcc in Arabidopsis leaves through stomata depends on a secreted small molecule whose synthesis is under control of the rpf/diffusible signal factor (DSF) cell-to-cell signaling system, which also controls genes involved in biofilm formation and pathogenesis. The same reports shows that Arabidopsis ROS- and PAMP-activated MAP kinase 3 (MPK3) is essential for stomatal innate response. Other recent and past findings about modulation of stomatal behaviour by pathogens are also discussed. In all, these findings support the idea that PAMP-triggered stomatal closure might be a more effective and widespread barrier against phytopathogens than previously thought, which has in turn led to the evolution in pathogens of several mechanisms to evade stomatal defense.
细菌和真菌能够通过病原体相关分子模式（PAMPs）触发气孔关闭，从而防止其穿透这些孔隙。因此，气孔可以被视为植物先天免疫反应的一部分。一些病原体已经进化出了逃避气孔防御的机制。细菌病原体野油菜黄单胞菌 pv. 芸薹（Xcc）主要通过水孔感染十字花科植物，也有报道称其通过气孔感染植物。最近的一份报告表明，Xcc 在拟南芥叶片中通过气孔的渗透依赖于一种分泌的小分子，其合成受 rpf/扩散信号因子（DSF）细胞间信号系统的控制，该系统还控制参与生物膜形成和发病机制的基因。同一份报告表明，拟南芥活性氧和 PAMP 激活的 MAP 激酶 3（MPK3）对于气孔先天反应是必不可少的。还讨论了其他关于病原体对气孔行为的调节的最新和过去的发现。总之，这些发现支持了这样一种观点，即 PAMP 触发的气孔关闭可能是一种比以前认为的更有效和更广泛的针对植物病原体的屏障，这反过来又导致了病原体进化出几种逃避气孔防御的机制。
