Flores Oriana, Prince Camila, Nuñez Mauricio, Vallejos Alejandro, Mardones Claudia, Yañez Carolina, Besoain Ximena, Bastías Roberto
Laboratorio de Microbiología, Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
Departamento de Análisis Instrumental, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile.
Front Microbiol. 2018 Aug 22;9:1907. doi: 10.3389/fmicb.2018.01907. eCollection 2018.
In recent years, Chilean kiwifruit production has been affected by the phytopathogen pv. (Psa), which has caused losses to the industry. In this study, we report the genotypic and phenotypic characterization of 18 Psa isolates obtained from Chilean kiwifruits orchards between 2012 and 2016 from different geographic origins. Genetic analysis by multilocus sequence analysis (MLSA) using four housekeeping genes (, and ) and the identification of type III effector genes suggest that the Chilean Psa isolates belong to the Psa Biovar 3 cluster. All of the isolates were highly homogenous in regard to their phenotypic characteristics. None of the isolates were able to form biofilms over solid plastic surfaces. However, all of the isolates formed cellular aggregates in the air-liquid interface. All of the isolates, except for Psa 889, demonstrated swimming motility, while only isolate Psa 510 demonstrated swarming motility. The biochemical profiles of the isolates revealed differences in 22% of the tests in at least one Psa isolate when analyzed with the BIOLOG system. Interestingly, all of the isolates were able to produce indole using a tryptophan-dependent pathway. PCR analysis revealed the presence of the genes / and /, which are associated with the production of indole-3-acetic acid (IAA) and indole-3-acetyl-3-L-lysine (IAA-Lys), respectively, in . In addition, IAA was detected in the cell free supernatant of a representative Chilean Psa strain. This work represents the most extensive analysis in terms of the time and geographic origin of Chilean Psa isolates. To our knowledge, this is the first report of Psa being able to produce IAA. Further studies are needed to determine the potential role of IAA in the virulence of Psa during kiwifruit infections and whether this feature is observed in other Psa biovars.
近年来，智利猕猴桃生产受到植物病原体丁香假单胞菌猕猴桃致病变种（Psa）的影响，给该产业造成了损失。在本研究中，我们报告了2012年至2016年间从智利不同地理来源的猕猴桃果园分离得到的18株Psa菌株的基因型和表型特征。利用四个管家基因（、和）通过多位点序列分析（MLSA）进行的遗传分析以及III型效应子基因的鉴定表明，智利Psa分离株属于Psa生物变种3簇。所有分离株在表型特征方面高度同质。没有分离株能够在固体塑料表面形成生物膜。然而，所有分离株在气液界面形成细胞聚集体。除Psa 889外，所有分离株均表现出游泳运动性，而只有分离株Psa 510表现出群游运动性。当使用BIOLOG系统分析时，分离株的生化谱在至少一个Psa分离株的22%的测试中显示出差异。有趣的是，所有分离株都能够利用色氨酸依赖性途径产生吲哚。PCR分析揭示了基因/和/的存在，它们分别与吲哚-3-乙酸（IAA）和吲哚-3-乙酰-3-L-赖氨酸（IAA-Lys）的产生相关。此外，在一株代表性的智利Psa菌株的无细胞上清液中检测到了IAA。就智利Psa分离株的时间和地理来源而言，这项工作代表了最广泛的分析。据我们所知，这是Psa能够产生IAA的首次报道。需要进一步研究以确定IAA在猕猴桃感染期间Psa毒力中的潜在作用，以及其他Psa生物变种是否也有此特征。
