Takita Kazumi, Someya Nobutaka, Morohoshi Tomohiro
Department of Innovation Systems Engineering, Graduate School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585, Japan.
Institute for Plant Protection, National Agriculture and Food Research Organization (NARO), 2-1-18 Kannondai, Tsukuba, Ibaraki 305-8666, Japan.
FEMS Microbiol Lett. 2025 Jan 10;372. doi: 10.1093/femsle/fnae117.
Burkholderia gladioli produces a yellow-pigmented toxin called toxoflavin, and causes disease on a variety of plants. Previous studies have suggested that the pathogenicity of B. gladioli is regulated by an N-acyl-l-homoserine lactone (AHL)-mediated quorum sensing (QS) system. In this study, complete genome sequencing revealed that B. gladioli pv. gladioli MAFF 302385 possesses two types of AHL synthase and AHL receptor gene pairs: glaI1/glaR1 and glaI2/glaR2. Disruption of QS genes revealed that the glaI1/glaR1 QS system regulated swarming motility, biofilm formation, and colony formation via N-octanoyl-l-homoserine lactone. Although Escherichia coli harboring glaI2 produced N-(3-hydroxyoctanoyl)-l-homoserine lactone and N-(3-hydroxydecanoyl)-l-homoserine lactone, the expression of glaI2 was not confirmed in MAFF 302385 cells. We also found that toxoflavin production was regulated by the glaI1/glaR1 QS system in liquid medium, but not on agar medium. When pathogenicity tests were performed on gladiolus leaves, the wild-type and QS mutants showed a similar level of disease. Our results demonstrated that only the glaI1/glaR1-mediated QS system is active in MAFF 302385, but major virulence factors, especially toxoflavin, are not completely dependent on the QS system.
唐菖蒲伯克霍尔德氏菌产生一种名为毒黄素的黄色色素毒素，并能在多种植物上引发病害。先前的研究表明，唐菖蒲伯克霍尔德氏菌的致病性受N-酰基-L-高丝氨酸内酯（AHL）介导的群体感应（QS）系统调控。在本研究中，全基因组测序显示唐菖蒲伯克霍尔德氏菌pv. gladioli MAFF 302385拥有两种类型的AHL合酶和AHL受体基因对：glaI1/glaR1和glaI2/glaR2。对QS基因的破坏表明，glaI1/glaR1 QS系统通过N-辛酰-L-高丝氨酸内酯调控群体游动性、生物膜形成和菌落形成。虽然携带glaI2的大肠杆菌产生了N-（3-羟基辛酰基）-L-高丝氨酸内酯和N-（3-羟基癸酰基）-L-高丝氨酸内酯，但在MAFF 302385细胞中未证实glaI2的表达。我们还发现，在液体培养基中，毒黄素的产生受glaI1/glaR1 QS系统调控，但在琼脂培养基上不受此调控。当对唐菖蒲叶片进行致病性测试时，野生型菌株和QS突变体表现出相似的病害水平。我们的结果表明，在MAFF 302385中只有glaI1/glaR1介导的QS系统是活跃的，但主要毒力因子，尤其是毒黄素，并不完全依赖于QS系统。
