Morán-Diez María E, Tranque Eduardo, Bettiol Wagner, Monte Enrique, Hermosa Rosa
Spanish-Portuguese Institute for Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Campus de Villamayor, C/Duero, 12, 37185 Salamanca, Spain.
Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas "Margarita Salas" (CSIC), C/Ramiro de Maeztu, 9, 28040 Madrid, Spain.
Plants (Basel). 2020 May 14;9(5):626. doi: 10.3390/plants9050626.
species are well known biocontrol agents that are able to induce responses in the host plants against an array of abiotic and biotic stresses. Here, we investigate, when applied to tomato seeds, the potential of strains belonging to three different species, T6, T25, and T34, to control the fully pathogenic strain pv. () DC3000, able to produce the coronatine (COR) toxin, and the COR-deficient strain DC3118 in tomato plants, and the molecular mechanisms by which the plant can modulate its systemic defense. Four-week old tomato plants, seed-inoculated, or not, with a strain, were infected, or not, with a strain, and the changes in the expression of nine marker genes representative of salicylic acid (SA) ( and ) and jasmonic acid (JA) () biosynthesis, SA- (), JA- ( and ) and JA/Ethylene (ET)-dependent () defense pathways, as well as the abscisic acid (ABA)-responsive gene and the respiratory burst oxidase gene , were analyzed at 72 hours post-inoculation (hpi) with the bacteria. The significant increase obtained for bacterial population sizes in the leaves, disease index, and the upregulation of tomato genes related to SA, JA, ET and ABA in plants inoculated with DC3000 compared with those obtained with DC3118, confirmed the COR role as a virulence factor, and showed that both and COR synergistically activate the JA- and SA-signaling defense responses, at least at 72 hpi. The three strains tested reduced the DC3118 levels to different extents and were able to control disease symptoms at the same rate. However, a minor protection (9.4%) against DC3000 was only achieved with T25. The gene deregulation detected in -treated plus -inoculated tomato plants illustrates the complex system of a phytohormone-mediated signaling network that is affected by the pathogen and applications but also by their interaction. The expression changes for all nine genes analyzed, excepting , as well as the bacterial populations in the leaves were significantly affected by the interaction. Our results show that spp. are not adequate to control the disease caused by fully pathogenic strains in tomato plants.
某些物种是著名的生物防治剂，能够诱导宿主植物对一系列非生物和生物胁迫产生反应。在此，我们研究了将属于三个不同物种的菌株T6、T25和T34应用于番茄种子时，对番茄植株中能产生冠菌素（COR）毒素的完全致病菌株丁香假单胞菌番茄致病变种（Pseudomonas syringae pv. tomato (Pto)）DC3000以及COR缺陷型菌株DC3118的控制潜力，以及植物调节其系统防御的分子机制。对四周龄的番茄植株进行种子接种或不接种某菌株处理，然后接种或不接种致病菌株，在接种细菌后72小时（hpi）分析代表水杨酸（SA）（PR1和PR2）和茉莉酸（JA）（PDF1.2）生物合成、SA依赖性（PR1）、JA依赖性（PDF1.2和PI-II）和JA/乙烯（ET）依赖性（ERF1）防御途径的九个标记基因的表达变化，以及脱落酸（ABA）响应基因ABI5和呼吸爆发氧化酶基因RbohB的表达变化。与接种DC3118的植株相比，接种DC3000的植株叶片中细菌种群数量、疾病指数显著增加，且与SA、JA、ET和ABA相关的番茄基因上调，这证实了COR作为毒力因子的作用，并表明某菌株和COR至少在72 hpi时协同激活JA和SA信号防御反应。测试的三种某菌株在不同程度上降低了DC3118的水平，并能够以相同的速率控制疾病症状。然而，只有T25对DC3000有轻微的保护作用（9.4%）。在某菌株处理加致病菌株接种的番茄植株中检测到的基因失调说明了一个受病原体、某菌株应用及其相互作用影响的植物激素介导的信号网络的复杂系统。除RbohB外，分析的所有九个基因的表达变化以及叶片中的细菌种群均受到这种相互作用的显著影响。我们的结果表明，某菌株不足以控制番茄植株中由完全致病的致病菌株引起的疾病。
