Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19716, USA.
Plant J. 2012 Nov;72(4):694-706. doi: 10.1111/j.1365-313X.2012.05116.x. Epub 2012 Sep 24.
Plants exist in a complex multitrophic environment, where they interact with and compete for resources with other plants, microbes and animals. Plants have a complex array of defense mechanisms, such as the cell wall being covered with a waxy cuticle serving as a potent physical barrier. Although some pathogenic fungi infect plants by penetrating through the cell wall, many bacterial pathogens invade plants primarily through stomata on the leaf surface. Entry of the foliar pathogen, Pseudomonas syringae pathovar tomato DC3000 (hereafter PstDC3000), into the plant corpus occurs through stomatal openings, and consequently a key plant innate immune response is the transient closure of stomata, which delays disease progression. Here, we present evidence that the root colonization of the rhizobacteria Bacillus subtilis FB17 (hereafter FB17) restricts the stomata-mediated pathogen entry of PstDC3000 in Arabidopsis thaliana. Root binding of FB17 invokes abscisic acid (ABA) and salicylic acid (SA) signaling pathways to close light-adapted stomata. These results emphasize the importance of rhizospheric processes and environmental conditions as an integral part of the plant innate immune system against foliar bacterial infections.
植物存在于复杂的多营养环境中，与其他植物、微生物和动物相互作用并竞争资源。植物具有复杂的防御机制，例如细胞壁覆盖着蜡质角质层，作为一种有效的物理屏障。虽然一些病原真菌通过穿透细胞壁来感染植物，但许多细菌病原体主要通过叶片表面的气孔侵入植物。叶部病原体丁香假单胞菌番茄亚种 DC3000（以下简称 PstDC3000）进入植物体内是通过气孔开口进行的，因此植物先天免疫的一个关键反应是气孔的暂时关闭，这会延迟疾病的进展。在这里，我们提供的证据表明，根际细菌枯草芽孢杆菌 FB17（以下简称 FB17）的定殖限制了 PstDC3000 通过气孔进入拟南芥。FB17 的根结合引发脱落酸（ABA）和水杨酸（SA）信号通路来关闭光适应的气孔。这些结果强调了根际过程和环境条件作为植物先天免疫系统抵御叶部细菌感染的一个组成部分的重要性。
