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Summary: Quorum sensing (QS) is widely utilized by bacterial pathogens to regulate biological functions and pathogenicity. Recent evidence has shown that QS is subject to regulatory cascades, especially two‐component systems that often respond to environmental stimulation. At least two different types of QS systems regulate pathogenesis in Burkholderia cenocepacia. However, it remains unclear how this bacterial pathogen controls these QS systems. Here, we demonstrate a novel two‐component system RqpSR ( Regulating Quorum sensing and Pathogenicity), which plays an important role in modulating QS and pathogenesis in B. cenocepacia. We demonstrate strong protein‐protein binding affinity between RqpS and RqpR. Mutations in rqpS and rqpR exerted overlapping effects on B. cenocepacia transcriptomes and phenotypes, including motility, biofilm formation and virulence. In trans expression of rqpR rescued the defective phenotypes in the rqpS mutant. RqpR controls target gene expression by direct binding to DNA promoters, including the cis‐2‐dodecenoic acid (BDSF) and N‐acylhomoserine lactone (AHL) signal synthase gene promoters. These findings suggest that the RqpSR system strongly modulates physiology by forming a complicated hierarchy with QS systems. This type of two‐component system appears to be widely distributed and coexists with the BDSF QS system in various bacterial species. [ABSTRACT FROM AUTHOR]

In 2013, bitter rot of grape was observed in Changbei Vineyard located in Nanchang City, Jiangxi Province, China. Greeneria species was consistently isolated from the diseased grape berries ( Vitis labruscana cv. Kyoho) at approximately 91% of isolation rate in three independent experiments. The species was identified as Greeneria uvicola based on the morphological characteristics, cultural appearance and sequence analysis. Koch's postulates were fulfilled through pathogenicity tests on detached healthy Kyoho grape berries. To our knowledge, this is the first report of G. uvicola causing bitter rot of grape in China. [ABSTRACT FROM AUTHOR]