DSF家族信号介导的群体感应，在十字花科黑腐病致病过程中发挥重要作用。DSF家族信号是一类主碳链含有12个碳原子的顺-2-脂肪酸，属于长链脂肪酸，然而野油菜黄单胞菌（Xcc）的外膜构成了这类物质通透的天然屏障。因此，如何吸收转运DSF家族信号是Xcc群体感应调控中有待解决的问题。根据生物信息学分析和前期研究的成果，本课题组选择Xcc XC1菌株为材料，采用遗传学、生物化学和分子生物学等技术，围绕Xcc DsfT开展以下四个方面的研究：（1）DsfT是否参与了Xcc对长链脂肪酸的吸收？（2）DsfT是否为Xcc吸收转运DSF家族信号的关键蛋白？（3）DsfT如何吸收转运长链脂肪酸，特别是DSF家族信号？（4）DsfT是否影响Xcc的植物致病性？其意义在于完善黄单胞菌群体感应机制，填补DSF家族信号吸收转运研究的空白；寻找阻断或干扰黄单胞菌群体感应新的靶点，为开发新的抗菌药物奠定理论依据。

Quorum-sensing (QS) system, mediated by molecules of the diffusible signal factor (DSF) family, plays important roles in regulation of the expression of factors that contribute to the black rot of crucifers. The DSF signal family is a novel structural class of fatty acids with cis-2 double bond and 12 carbon atoms in main chain. However, the outer membrane (OM) of Gram-negative bacteria forms an efficient barrier to transport long-chain fatty acids. Although it has been shown that import of long-chain fatty acids across the OM by Escherichia coli requires the β-barrel FadL protein, the uptake mechanism of DSF signal family remains enigmatic in Xanthomonas campestris pv. campestris (Xcc). In this proposal, we focus on Xcc DsfT and set out to investigate four important and interesting questions using genetics, biochemistry or molecular biology techniques: (1) Whether Xcc employs DsfT to transport long-chain fatty acids? (2) Whether DsfT is key transporter protein to uptake DSF signal family? (3) How does DsfT transport long-chain fatty acids, especially DSF signal family? (4) Whether DsfT affects the virulence of Xcc? The goal of this project is to understand quorum-sensing system of Xcc in more detail, especially DSF signal family transport mechanism. These researches will provide some references for discovering new targets to disturb quorum-sensing system in Xcc and facilitate the discovery of novel biopesticides to effectively control black rot of crucifers.