Kang Minhee, Lee Duyoung, Mannaa Mohamed, Han Gil, Choi Haeun, Lee Seungchul, Lim Gah-Hyun, Kim Sang-Woo, Kim Tae-Jin, Seo Young-Su
Department of Integrated Biological Science, Pusan National University, Pusan 46241, Republic of Korea.
Institute of System Biology, Pusan National University, Pusan 46241, Republic of Korea.
Plants (Basel). 2024 Sep 23;13(18):2657. doi: 10.3390/plants13182657.
Quorum sensing (QS) is a mechanism by which bacteria detect and respond to cell density, regulating collective behaviors. , the causal agent of rice seedling blight, employs the LuxIR-type QS system, common among Gram-negative bacteria, where LuxI-type synthase produces QS signals recognized by LuxR-type regulators to control gene expression. This study aimed to elucidate the QS mechanism in KACC18965. Through whole-genome analysis and autoinducer assays, the gene, responsible for QS signal production, was identified. Motility assays confirmed that C8-homoserine lactone (C8-HSL) serves as the QS signal. Physiological experiments revealed that the QS-defective mutant exhibited reduced virulence, impaired swarming motility, and delayed biofilm formation compared to the wild type. Additionally, the QS mutant demonstrated weakened antibacterial activity against and decreased phosphate solubilization. These findings indicate that QS in significantly influences various pathogenicity and survival traits, including motility, biofilm formation, antibacterial activity, and nutrient acquisition, highlighting the critical role of QS in pathogen virulence and adaptability.
群体感应（QS）是细菌检测并响应细胞密度以调节群体行为的一种机制。水稻白叶枯病菌，水稻白叶枯病的病原体，采用革兰氏阴性菌中常见的LuxIR型群体感应系统，其中LuxI型合酶产生被LuxR型调节因子识别的群体感应信号以控制基因表达。本研究旨在阐明水稻白叶枯病菌KACC18965中的群体感应机制。通过全基因组分析和自诱导物测定，鉴定出负责群体感应信号产生的基因。运动性测定证实C8-高丝氨酸内酯（C8-HSL）作为群体感应信号。生理学实验表明，与野生型相比，群体感应缺陷型突变体的毒力降低、群体游动性受损且生物膜形成延迟。此外，群体感应突变体对[此处原文缺失相关菌名]的抗菌活性减弱且磷酸盐溶解能力下降。这些发现表明水稻白叶枯病菌中的群体感应显著影响各种致病性和生存特性，包括运动性、生物膜形成、抗菌活性和养分获取，突出了群体感应在病原体毒力和适应性中的关键作用。
